ndt handbook

Non-Destructive Testing Inspector's

'v Handbook

Visual Inspection (VT)

Liquid Penetrant Inspection (PT)

Magnetic Particle Testing (MT)

Ultrasonic Testing (UT)

Eddy Current Testing (ET)

Radiographic Inspection (RT)

Preface

This reference book was designed for use in the field and to support onthe-job training. It should not be L ised as a standard or referred to as a stand-alone document. This book covers basic formulas, charts, and other

NDT related information.

Dedication To all the people who have influenced my naval career and where I am today in the NonDestructive field.

Thank you. I originally started this project as a self-knowledge application and began receiving comments from my fellow colleagues requesting a copy. I soon realized that this would prove to be an invaluable tool for general infomation in our field. I have received support from both military and civilian personnel and have taken a sample of their suggestions and compiled them for you, the end user. I wanted to take personal credit for this project and realized it would not benefit the NDT field as a whole. Instead, I encourage you, the end user, to change, manipulate, or configure this book for yourself. In closing, "Share the Wealth with Others."

Last Revision Date 20 April 2002

Contact Information [email protected] ndthandbook.zapto.org

Disclaimer This book is not intended for sale or any monetary benefit to the editor.

Inspector's Handbook

Table of Contents Scope of Standards .............................................................................................................................................. iv . .

................................................................. Chapter 1 - General Information I d .............................................................................................................. Schedule Designations of Pipe Sizes

. Copper Tubing Wall Thickness ..................................................................................................................... 1 1 .......................................................................................................................................... . Decimal to Inches 1 1

. ............................................................................................................................ Temperature Conversions -1 1 Fraction to Decimal Equivalent .................................................................................................................. 1-2 Decimal to Second Conversion ..................................................................................................................... 1-2

...................................................................................................................... Numerical Place Value Chart 1 - 2 Elements of a Nondestructive Examination Symbol .................................................................................... 1-3 Elements of a Welding SyrnboL .................................................................................................................... 1-3

.................................................................................................................................... Examples of Grooves 1-4 .................................................................................................................................. Basic Joints (Welding) 1-4

................................................................................................. Order of Performing Arithmetic Operations 1-5 .................................................................................................................................... Ratio And Proportion 1-6

.................................................................................................................................... Calculation of Area 1 - 7 Weld Area Calculation .................................................................................................................................. 1-7

....................................................................................................................... Common Symbols and Terms 1-7 ............................................................................................................... Solution of Right-angled Triangles 1-9

................................................................................................................... . Basic Illustration of a Weld 1 10 ....................................................................................................................................... Welding Processes - 1 1

.................................................................................................. . Backing Ring Common Defect Locations 1 12 .......................................................................................... . Consumable Insert Common Defect Locations 1 12

............................................................................................................ Primary Processing Discontinuities 4

Finish Processing Discontinuities ................................................................................................................ .............................................................................................................................. Dial Indicating Calipers 1 - 15

............................................................................................................................................... Micrometer 1 - 15 ................................................................................................................. Thread Terminology (fasteners) 1 - 16

............................................................................................................................. Tap and Drill Size Chart: 1- 16 ................................................................................................................. Julian Date Calendar (Perpetual) 1 - 17 .............................................................................................................. Julian Date Calendar p a p Year) -1 -18

Chapter 2 . Visual Inspection ...................................................................... 2-1 ........................................................................................................... Common Definitions and Examples 2 - 1

Chapter 3 . Liquid Penetrant Testing .......................................................... 3-1 Common Terms and Definitions .................................................................................................................. -3-1 Prorated Maximum Number of Indications .................................................................................................. 3-6 Areas of Circles ............................................................................................................................................. 3-6 Penetrant Wetting Characteristics ................................................................................................................. 3-7

Chapter 4 . Magnetic Particle Testing ......................................................... 4-1 ............................................................................................................. Common Definitions and Examples 4. 1

.................................................................................................. Longitudinal Magnetization Math Formula 4F7

.................................................................................................. Prorated Maximum Number of Indications - ............................................................................................................................................. Areas of Circles 4

Common Types of Magnetization ................................................................................................................ 4-9

Inspector's H m m k

.......................................................................................................................... Theory: "RigheHand Rule -4-9 ........................................................................................................................................ Hysteresis=Curve -4- 10

.............................................................................................. Magnetic Particle Field Indicator (Pie Gage) 4- 11

. .................................................................... * & Chapter 5 Ultrasonic Testing 5- 1

................................................................................................................... Common Terms and Definitions 5-1 ............................................................................................................................ Common Math Formulas 5- 12

............................................................................................................. Calibration Chart . UT Shearwave 5- 13 FPADSCRhD .............................................................................................................................................. 5- 14

............................................................................................................................................. Velocity Chart 5- 15

Chapter 6 . Eddy Current Testing ............................................................... 6-1 ................................................................................................................... Common Terms and Definitions - 1

Two Types of Electrical Current ................................................................................................................... 6-6 Conductivity and the IACS ........................................................................................................................... 6-7 Right Hand Rule ............................................................................................................................................ 6-7 Magnetic Domains ........................................................................................................................................ 6-9 Depth of Penetration ................................................................................................................................... 6-12 Limitations of Eddy Current Testing ......................................................................................................... 6-18 Advantages of Eddy Current Testing ...................................................................................................... 6 18 Summary of Properties of Eddy Currents ................................................................................................... 6-18 Eddy Current Relationship of Properties ............................................................................................ 6 - 18

........................................................... Chapter 7 . Radiographic Inspection 7-1 Common Definitions and Examples ............................................................................................................ -7-1

.......................................................................................................... Structure of the Atom and an Element 7-8 ............................................................................................................................. Components of an Isotope 7-8

Characteristics of A Radioactive Element .................................................................................................... 7-8 Two Types of Radiation ................................................................................................................................ 7-8 History of Radiography ................................................................................................................................. 7-9 60' Coverage for Pipes and Location Marker Measurements .................................................................... 7-11 Common Math Formulas ....................................................................................................................... 7 12 Magic Circles ....................................................................................................................................... 7 1 5 Single Wall Exposure I Single Wall Viewing for Plate ........................................................................... 7-15 Single Wall Exposure 1 Single Wall Viewing for Pipe ............................................................................. 7-16 Double Wall Exposure 1 Double Wall View (superimposed) ................................................................... 7-16 Double Wall Exposure I Double Wall View (offset) ............................................................................. 7-17 Double Wall Exposure 1 Single Wall View ............................................................................................... 7-17 KILLER CARL ........................................................................................................................................... 7-18 Penetrameter Material and Group Numbers .............................................................................................. 7-18 Penny T-Hole Maximum Density ..................................................................................................... 7 19 2% Penetrameter Quality Conversion Chart (X-RAY ONLY) ................................................................... 7-20 Basic Components of an X-ray Tube .......................................................................................................... 7-25 Types of Scatter Radiation .......................................................................................................................... 7-25 . . Radiographc Fllm Interpretation ................................................................................................................ 7-25 . . ................................................................................................................ Radiographic Film Interpretation 7-26

................................................... Probable Causes and Corrective Action for Automatic Film Processing 7-50 ................................................ Probable Causes and Corrective Action for Processed Radiographic Film 7-51

Inspector's Handbook iii

Scope of Standards ..

NSTP 271 REQUIREMENTS FOR NONDESTRUCTIVE TESTING METHODS - -

This document covers the requirements for conducting nondestructive tests (NDT) used in detenninin( presence of surface and internal discontinuities in metals. It also contains the -mum requirements necessary . qualifL nondestructive test and inspection personnel, procedures, and nondestructive equipment. This document does not contain acceptance criteria for nondestructive test. This document does not cover all of the requirements for performing nondestructive tests in an underwater environment. Nondestructive tests in an underwater environment shall be performed as specified in NAVSEA S0600-AA-PRO-070.

NSTP 248 REQUIREMENTS FOR WELDING AND BRAZING PROCEDURE AND PERFORMANCE QUALIFICATION

This document contains the requirements for the qualification of welding and brazing procedures, welders, welding operators, brazers and brazing operators that must be met prior to any production fabrication. It includes manual, semiautomatic, automatic and machine welding and brazing of ferrous, nonferrous, and dissimilar metals. The qualification tests required by this document are devised to demonstrate the adequacy of the welding or brazing procedures and to demonstrate the ability of welders, brazers, welding operators and brazing operators to produce sound welds or brazes.

NSTP 278 REQUIREMENTS FOR FABRICATION WELDING AND INSPECTION, AND CASTING INSPECTION AND REPAIR FOR MACHINERY, PIPING, AND PRESSURE VESSELS

This document contains the welding and allied processes (except brazing) and casting requirements including inspection for the fabrication, alteration, or repair of any item or component of machinery, piping, and pressure vessels in ships of the United States Navy.

MILSTD 2035 NONDESTRUCTIVE TESTING ACCEPTANCE CRITERIA The acceptance criteria contained herein are for use in determining the acceptability of nondestructive t. -

(NDT) discontinuities in castings, welds, forgings, extrusions, cladding, and other products when specified by the applicable Naval Sea Systems Command (NAVSEA) drawing, specification, contract, order, or directive.

NSTP 1688 FABRICATION, WELDING AND INSPECTION SUBMARINE APPLICATIONS This document contains minimum requirements for fabrication and inspection of submarine and non

combatant submersible structures, including shipbuilding practices, specifications for materials, weld joint design, workmanship, welding, inspection, and record requirements.

MILSTD 1689 FABRICATION, WELDING, AND INSPECTION OF SHIPS STRUCTURE This standard contains the minimum requiremeas for the fabrication and inspection of the hull and

associated structures of combatant surface ships. The requirements for shipbuilding, materials, welding, welding design, mechanical fasteners, workmanship, inspection, forming, castings and records are included. It also applies to those submarine structures which are not high-yield strength steels.

MILSTD 22D WELDED JOINT DESIGN This standard covers welded joint designs for manual, semiautomatic, and automatic arc and gas welding

processes for use onmetals and weldments, as applicable, when invoked by a fabrication document. The welded joint designs shown herein represent standard joint designs used in welded fabrication and are not intended to be all inclusive.


NSTP CHAPTER 074 - VOLUME 1 WELDING AND ALLIED PROCESSES This chapter furnishes both the minimum mandatory requirements (indicated by the word shall) and

guidance information (indicated by the words should or may) necessary for welding, brazing, inspection, and safety when used for ship maintenance, repair, and alteration.

-NSTP CHAPTER 074 - VOLUME 2 NONDESTRUCTIVE TESTING OF METALS QUALIFICATION AND CERTIFICATION REQUIREMENTS FOR NAVAL PERSONNEL (NON-NUCLEAR)

This chapter is M s h e d to ensure achievement of uniform and reliable nondestructive tests on naval materials and components, implementation of the training, qualification, and certification programs described in this chapter should be followed precisely.


Decimal to Inches

inches 1 12 = decimal

decimal 12 = inches

Temperature Conversions -

Fahrenheit = (915 * C) + 32

Celsius = (F - 32) * 519

Copper Tubing Wall Thickness


Fraction to Decimal Eauivalent 1 I Decimal to Second Conversion I

I PLACE) I

Numerical Place Value Chart I

F o r E x a m p l e 2 , 2 6 2 . 3 5 7 . 6 1 9 8 4 4

2

THOUSANDS

bI UNITS I 1 I L I

2

3

5

MILLIONS

100,MK)

TEN THOUSANDS

THOUSANDS

HUNDREDS

TENS

1,000,000

E

10,000

1,000

loo

10

D

1

C

1

A

6

HUNDREDTHS

9

8

4

TENTHS I

1/10 I 0.1

1/100

THOUSANDTHS

TEN THOUSANDTHS HUNDRED TEN

THOUSANDTHS

MILLIONTHS

0.01

111,000

1110,000

1H00.000

111,000,000

0.001

0.0001

0.00001

0.000001

Elements of a Nondestructive Examination Symbol

Elements of a Welding Symbol

NUMBER OF EXAMINATIONS LENGTH OF SECTION TO BE EXAMINED

REFERENCE LINE -EXAMINE IN FIELD

SPECIFICATION OR OTHER REFERENCE EXAMINE-ALL-AROUND

TAIL ARROW

GROOVE ANGLE: INCLUDED ANGLE OF FINISH SYMBOL COUNTERSINK FOR PLUG WELDS

ROOT 0PENING:DEPTH OF FILLING FOR PLUG GROOVE WELD SIZE AND SLOT WELDS

DEPTH OF BEVEL; SIZE OR STRENGTH FOR LENGTH OF WELD CERTAIN WELDS PITCH OF WELDS

-FIELD WELD

SPECIFICATION OR OTHER

NOT USED) REFERENCE (OMITTED WHEN T WELD-ALL-AROUND

TAIL ARROW

NUMBER OF SPOT, SEAM, STUD, PLUG. OR PROJECTION WELDS

A

RADIATION DIRECTION EXAMINE ALL AROUND

Plug or Spot or Back or Flange Fillet Slot Stud Projetiin Seam Backing Surfacrng Edge 1 Corner

FIELD EXAMINATION

/ L

GROOVE

Basic Weld Symbols

Square

- - LL- - - - i


Scad

-- . - 7r -

Weld all around

V

-v- - -A -

Field Weld

/-- i

Mvel

- - -1'T--

Melt ~hrough

-Tee

U

--Y-- - -A- -

Consumable Insen

(Square)

J

--Y-- --K-

Backing or Spacer

(Recrangle)

Flare-V

-I/_- -2 x- -

,Contour

Flare- bevel

--LC- --rc-

Flush or Flat Convex Concave

Examples of Grooves

square Single J Single Bevel

Single Vee Double Bevel Single U

Basic Joints (Welding) I

I Lav

' / I corner / /

w e Tee


Order of Performing Arithmetic Operations

When several numbers or quantities in a formula are connected by signs indicating that additions, subtractions, multiplications, or divisions are to be made, the multiplications and divisions should be carried out

1, %st, in the order in which they appear, before the additions or subtractions are performed.

Examples: 10+26X7-2=10+182-2=190 18+6+15X3=3+45=48 1 2 + 1 4 + 2 - 4 = 1 2 + 7 - 4 = 1 5

When it is required that certain additions and subtractions should precede multiplication's and divisions, use is made of parentheses 0 and brackets n. These indicate that the calculation inside the parentheses or brackets should be carried out complete by itself before the remaining calculations are commenced. If one bracket is placed inside of another, the one inside is first calculated.

Examples: ( 6 - 2 ) X 5 + 8 = 4 X 5 + 8 = 2 0 + 8 = 2 8 6X(4+7)+22=6X 11 -22=66+22=3 2+[1OX6(8+2) -4 ]X2=2+[1OX6Xl0-4 ]X2

=2+[600-4]X2=2+596X2=2+1192=1194

The parentheses are considered as a sign of multiplication; for example, 6(8 + 2) = 6 x (8 + 2).

The line or bar between the numerator and denominator in a fractional expression is to be considered as a division sign. For Example,

In formulas the multiplicationsign (X) is often left out between symbols or letters, the values of which are to be multiplied. Thus

ABC AB=AXB,and-= (AXBXC)+D

D


Ratio And Proportion

The ratio between two quantities is the quotient obtained by dividing the first quantity by the second. For example, the ration between 3 and 12 is '14, and the ratio between 12 and 3 is 4. Ratio is generally indicated P - *

sign (:); thus 12 : 3 indicates the ratio of 12 to 3. d

A reciprocal or inverse ratio is the reciprocal or the original ratio. Thus, the inverse ratio 5 : 7 is 7 : 5.

In a compound ratio each term is the product of the corresponding terms in two or more simple ratios. Thus when

then the compound ratio is:

Prop is the equality of ratios. Thus,

The first and last tenns in a proportion are called the extremes; the second and thirds, the means. The product of the extremes is equal to the product of the means. Thus,

If third terms in the proportion are known, the remaining term may be found by the following rules:

1) The first term is equal to the product of the second and third terms, divided by the fourth term.

2) The second term is equal to the product of the first and fourth terms, divided by the third.

3) The third term is equal to the product of the first and fourth terms, divided by the second.

4) The fourth term is equal to the product of the second and third tenns, divided by the first.


Calculation of Area

Square/Rectangle = Length * Width

Circles - - w2

Triangle = Height * Base * 1/2

Sphere - - 4m2

Weld Area Calculation

Structural Welds = Length * Width (measured)

Piping Welds = Circumference (OD*7t) * Width

Socket Welds = L x W L = ((OD at A + OD at B) / 2) *7t W = Width of the weld is measured.

Common Symbols and Terms

3.1415

Diameter / 2

Inside Diameter

Outside Diameter

Less Than (ie 6 ~ 9 )

Greater Than (ie 9>6)

Equal To or Less Than

Equal To or Greater Than

Plus or Minus

InspectaPs Handbook

Change percent ( % ) to decimal (0.0) . Move decimal point 2 spaces to the left and drop the percent sign., Example: 2% = 2.0% = -02 d

Change decimal (0.0) to percent ( % ) . . . Move decimal point 2 units to the right and add the percent sign. Example: .43 = 43%

Change a fraction to a decimal. Divide the numerator by the denominator. Example: 1/2 = 1 divided by 2 = .5

Tm = Material Thickness, thickness of the thinner member excluding reinforcements.

Ts = Specimen Thickness, thickness of the thinner member including reinforcements.

Minimum Weld Throat Thickness = .7 x Tm Based upon 1T X 1T


Solution of Right-angled Triangles

Basic Illustration of a Weld

FILLET LEG SIZE OF WEW

1qxctoP"s Handbook

Welding Processes ha

ELECTRODE COVERING

Shielded Metal Arc Welding (SMAW) An arc welding process, which melts and

b ,ins metals by heating them with an arc oetween a covered metal electrode and the work. Shielding gas is obtained from the electrode outer coating, often called flux. METAL AND SLAG Commonly referred to as "stick" welding. SOLIDIFIEL) SLAG

SHELDINGGASIN ON

WELD CURRENT CONDUCTOR

WIRE GUIDE DIRECTION AND CONTACT

Gas Metal Arc Welding (GMAW) OF WELDING An arc welding process, which joins metals by heating them

GAS NOZZLE with an arc. The arc is between a continuously-fed filler metal (consumable) electrode and the mrk piece. Shielding gas is supplied from an external source of inert gas, normally argon, helium, or a mixture of the two. Commonly referred to as "MIG" welding.

joins metals by heating them with an arc WIRE GUIDE 6. between a continuous, consumable electrode CONTACT TUBE wire and the work Shielding is obtained from a

flux contained within the electrode core. Depending upon the type of flux-cored wire, added shielding may or may not be provided from externally supplied gas or gas mixture.

tungsten electrode, which should not become part of the

L *ompleted weld. Filler metal is normally used when welding. Jsually helium or argon, or mixture, is used for shielding gas.

Inspector's Handbook 1-1 1

Backing Ring Common Defect Locations

CRACKING OVERLAP SLAG/OXIDE INCLUSIONS i

\ u

UNDERCUT TUNGSTEN INCLUSIONS POROSITY INCOMPLETE (LACK OF) FUSION

I CRACKING

BURN-THROUGH

Consumable Insert Common Defect Locations

/ INCOMPLETE (LACK OF) PENETRATION

SLAG OR UNDERCUT AT THE ROOT TOES

CRACKING OVERLAP SLAG/OXIDE INCLUSIONS

UNDERCU INcLuSroNS INCOMPLETE (LACK OF) FUSION

POROSITY I CRACKING

BAD FITUP SLAG BETWEEN BACKING RING AND PIPE ID

u

CONCAVITY MELT-THROUGH BURN-THROUGH INCOMPLETE (LACK OF) FUSION 4

UNDERBEAD CRATERS CENTERLINE CREASE OVERLAP CRACKING UNDERCUT AT THE#OO&OTTO# BACKING GAS LOS A% MPLETE (LACK OF) PENETMTION

CRACKING MELT-THROUGH

Hot Tear

Primary Processing Discontinuities

I Difference in cooling rates between thin sections and thick sections

1 surface I

Location

Surface

Caused By Lack of h i o n between two intercepting surfaces of metal as it flows into the cast

Process

:L

Casting

I Porosity I Entrapped internal gasses

Discontinuity

Cold Shut

Blow Holes

Cavity

Microshrinkage

Inability of external gasses to escape h m the mold

Forging

I I Flattening and lengthening of discontinuities L sdgem (bar found in parent material

( Subsurface I

Lack of enough molten metal to fill the space created by shrinkage

Improperly designed mold causing premature blockage at the mold gate

Surface

I Laminations (flat plate)

Lengthening of surface cracks found in parent I Surface I

Subsurface

Subsurface

Lap

Burst

Flattening and lengthening of discontinuities in parent material I Subsurface (

F r I L a C k o f Fusion I Incomplete weld I Surface (inner and outer)

Folding of metal in a thin plate on the surface of the forging

Forging at improper temperature

Surface

Surface or Subsurface

Seams

pipe

I Present in the parent material (round bar stock)

Laminations

Gouges

Seamless Pipes and Tubes

I Sizing mandrel dragging

Present in the parent material (sheet or parent material)

1- Seams

Subsurface

Slugs

Present in parent material ( Surface 1 Porosity ( Present in parent material

, Metal buildup on piercing material

Inner Surface

Inspector's Handbook 1- 13

I

I

w 1

Galling (cracks) Improper metal flow through the die Surface

I Heat Treating

Finish Processing Discontinuities

Explosive Forming

Process

Grinding

Welding

Stress Cracks

Discontinuity

Cracks

Cracks and Tears

Crater Cracks (star, transverse, and longitudinal)

Caused By Excess localized heat created between the grinding wheel and the material

Stress Cracks

Location

Surface .-/

- -

Porosity

Slag Inclusions

Tungsten Inclusions I Lack of Penetration

Lack of Fusion

Undercut

Overlapping I

Extreme deformation overstresses the material I surface I

~ -

Stress built up by improper processing - unequal heating and cooling

Improper use of heat source

Surface

Surface or I Subsurface I

Entrapped gasses

Stresses built up by the weld contraction (if material is restrained)

Surface or I Subsurface

Surface

Excessive current used during GTAW

Incomplete cleaning of slag fiom the weld between passes

I Subsurface I

Surface or Subsurface

Improper welding technique Surface or I Subsurface I Improper welding technique Subsurface 1 Improper welding technique I surface (

Weld overlaps parent material - not b e d I surface I I Bending Cracks I

- -

Overstress of material

I Machining 1 Tears I Working with dull tools or cutting too deep 1 Surface I I Pz?," I Cracks

1 Electroplating I Cracks

Inspector's Harrdbook

Relief of internal stress

Relief of internal stress

Surface

Surface

Dial Indicating Calipers

1. VerifL the caliper's calibration date is current, and clean all dirt fiom measuring faces. Perform user calibration on dial indicator, ensure reading is zero, and tighten the bezel clamp as needed.

2. Adjust measuring faces, contact points, to fit item being measured.

3. Apply f m pressure to fine adjusting roll and ensure measuring contacts are in contact with the material being measured.

4. Apply lock screw and read measurement in place if practical. If not, remove calipers carefully to prevent false measurements.

Micrometer

PART TO BE MEASURED

GRADUATIONS

TO BE READ

FRAME READING L I N E

1. Verifj. that the micrometer's calibration date is current, and clean all dirt from measuring contacts. VEPN~ER

C

.000/ G I R H R T / O N S

IS

2. Attach ball if measuring curved surfaces.

3. Adjust micrometer to fit the item s-L f CYrC

being measured, do not spin frame to - too 4%vo. Olb GRRDVRT/O/YS

adjust the micrometer.

4. Slip the micrometer over the area to be measured by placing the anvil f d y against the material and slowly turn the thimble clockwise until spindle is firmly against the material. Then turn the ratchet three clicks to be sure equal pressure is applied.

5. Take reading in place, or set the locking nut and remove fiom the item. Determine reading on scale and note w accordingly. Do not forget to minus the ball measurement if used.


AXIS

PITCH DIAMETER

Tap and Drill Size Chart

7 THREAD 1 SIZE

CREST

R m


Inspector's Handbook 1-17

"w

L'

L

Day I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Dec 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365

Nov 305 306 307 308 309 310 311 - 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334

Oct 274 275 276 277 278 279 280 281 - 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304

Sep 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273

(Perpetual)

Aug 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243

July 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212

Date Calendar

June 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181

Julian

May 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151

Apr 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 I13 114 115 116 117 118 119 120

Mar 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090

Feb 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059

Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

. 31

Jan 0 0 1 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031

1-18 Inspector's Handbook

Day 1 2 3 4 5 6 7 8 9 I 0 I 1 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Jan 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031

Feb 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060

Mar 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091

Apr 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121

Julian

May 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152

Date Calendar

June 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182

(Leap July 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213

Year)

Aug 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244

Sep 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274

Dec 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366

Oct 275 276 277 278 279 280 281 282 283 284 285

2 8 6 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305

Nov 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335

i C

1 *

2 3 4 5 6 7 8 9 I 0 I 1 12 13 14 15 ' l b ,

v

17 18 19 20 21 22 23 24 25 26 27 28 29 30 3 . 4

Chapter 2 - Visual Inspection

Common Definitions and Examples r Aligned rounded indications i/ Four or more indications in a line, where each is separated

from the adjacent indication by less then 1/16 inch or D, whichever is greater, where D is the major diameter of the larger of the adjacent indication.

Arc strike Any localized heat-effected zone or change in the contour of

the surface of the finished weld or adjacent base metal resulting from m atc or heat generated by the passage of electrical energy between the surface of the finished weld or base metal and a current source, such as welding electrodes or magnetic particle inspection prods.

Burn throu~h A void or open hole that extends through a backing ring, strip, fused root, or adjacent base metal.

Burst A rupture caused by forging at improper temperatures. Bursts may be either internal or external to the

surface.

Cold shut The result of pouring metal over solidified metal.

/

Track or tear + A linear rupture of metal under stress.

Crater pit An approximately circular surface condition exceeding into

the weld in an irregular manner caused by insufficient filler metal at the weld stop.

Defect One or more flaws whose aggregate; size, shape, orientation,

location, or properties do not meet the specified acceptance criteria and are rejectable.

Discontinuity Any interruption in the normal physical structure or

configuration of a part, which will cause a detectable indication or signal when nondestmctively examined.

Evaluation A review, following interpretation of the indications noted, to determine whether they meet specified

cceptance criteria. L


False indication An indication that is interpreted to be caused by a condition other than a discontinuity or imperfection.

Heat checks Fissures or tears in the weld heat affected zone of material containing low melting point.

Indicatic I

ure of quality characteristic from its intended condition.

Ln Zvidence of a discontinuity that requires interpretation to determine its significance.

ete fusion I ,ack of complete fusion of some portion of the metal in a

Weld jolnt with adjacent metal. The adjacent metal may be either base metal or previously deposited weld metal, or consumable insert.

Incomplete penetration Lack of penetration of the weld through the thickness of the

joint, or penetration which is less than specified.

Interpretation The determination of whether indications are relevant,

nonrelevant, or false.

Lap (forginas) Folding of metal on the surface of the forging, usually occ ' u

when some of the forging metal is squeezed out between the two dies.

Linear indication An indication in whichthe length is equal to or

greater than three times the width.

Melt through A convex or concave irregularity on the surface of a backing ring or strip, fused root, or adjacent base metal

resulting from fusion completely through a localized region but without development of a void or open hole.

Non-linear rounded indications Indication whose length is less than three times its width.

Nonrelevant indications An indication that is caused by a condition or type of discontinuity that is not relevant.


Oxidation A condition resulting from partial or complete lack of inert gas shielding of a surface which is heated

ring welding resulting in formation of oxide on the surface. This condition may range fiom slight oxidation idenced by a multicolored or tightly adhering black film to the extreme of a very rough surface having a

crystalline appearance.

Porosity Gas pockets or voids in weld metal or castings.

Quench crack A crack formed as a result of the& stresses produced by

rapid cooling fiom a high temperature.

Root surface concavity A depression on the root surface of a weld which may be due

to gravity, internal purge, or shrinkage.

Root surface centerline crease or shrinkage An intermittent or continuous peripheral centerline concavity formed on the root surface.

Root undercut A groove in the internal surface of a base metal or backing ring or strip along the edge of the root of the

weld.

Shrinkage Void, or voids, that may occur in molten metal due to

contraction during solidification.

s& Non-metallic solid material entrapped in the weld metal,

between weld metal and base metal, or in a casting.

Tungsten inclusion Tungsten entrapped in the weld deposit.

Undercut A groove melted into the base metal at the toe of the weld and left unfilled by weld metal.

Unfused chaplet A metal support used in the casting process, which has not

fused with casting material.

Weld spatter Metal particles which deposit on the surface of the weld or

adjacent base metal during welding and which do not form a part of the weld.


Chapter 3 - Liquid Penetrant Testing

Common Terms and Definitions Alkaline

L Any soluble mineral salt or mixtures of salt capable of neutralizing acids.

Angstrom Unit (A) A unit of length equal to lo8 cm and used to express wavelengths of light; i.e., electromagnetic radiation.

Background The surface upon which an indication is viewed. It may be the natural surface of the test article or it may be

the developer coating on the surface. This background may contain traces of unremoved penetrant (fluorescent or visible), which, if present, can interfere with the visibility of indications.

Background Fluorescence Fluorescent residues observed over the general surface of the test article during fluorescent penetrant

E h Term used colloquially to designate the liquid penetrant inspection materials into which test articles are

immersed during inspection process.

Black Li~ht Light radiation in the near ultraviolet range of wavelengths (3200 to 4000 A), just shorter than visible light.

Black Light Filter L A filter that transmits black light while suppressing visible light and hard ultraviolet radiation with

wavelengths less than 3200 angstroms.

Bleedout The action of the entrapped Penetrant in spreading out from surface discontinuities to form an indication.

Blotting The action of the developer in soaking up the entrapped penetrant from d a c e discontinuities to form an

indication.

Capillary Action or Capillarity The tendency of liquids to penetrate or migrate into small openings such as cracks, pits, or fissures.

Carrier Fluid (Vehicle or Medium) A fluid in which liquid penetrant inspection materials are dissolved or suspended.

Clean Free from interfering solid or liquid contamination on the d a c e .

Comparative Test Block An intentionally cracked metal block having two separate but adjacent areas for the application of different

penetrants so that a d<ect comparison of their relative effeativeness can be obtained. Can also be used to evaluate ?enetrant test techniques and test conditions.


Contact Emulsifier An emulsifier that begins emulsifying penetrant upon simple contact with the penetrant; usually oil-base

(Lipophilic).

Contrast w

The difference in visibility (brightness or coloration) between an indication and the surrounding surface.

Dark Adaptation The adjustment of the eyes when one passes from a bright to a darkened area.

Detergent Remover A penetrant remover that is a solution of a detergent in water. Also Hydrophilic Emulsifjer.

Developer A material that is applied to the test article surface after excess penetrant has been removed and that is

designed to enhance the penetrant bleedout to form indications. The developer may be a fine powder, a solution that dries to a fine powder, or a suspension (in solvent, water, alcohol, etc.) that dries leaving an absorptive film on the test surface.

Developing Time The elapsed time necessary for the applied developer to bring out indications from penetrant entrapments.

Also called Development Time.

Dragout The canput or loss of penetrant materials as a result of their adherence to the articles being processed.

Drain Time w

That portion of the penetrant inspection process during which the excess penetrant, emulsifier, detergent remover, or developer is allowed to drain fiom the test article.

Dry Developer A fine, dry powder developer that does not employ a carrier fluid.

Drying Oven An oven used for drying test articles.

Drvinn Time A time allotted for a test article to dry.

DuaLresponse Penetrant A penetr- that contains a combination of visible and fluorescent dyes.

Dwell Time The total time that the penetrant or emulsifier is in contact with the test surface, including the time required

for application and the drain time. Also see Emulsification Time.

Electrostatic Spraying A technique of spraying wherein the material being sprayed is given a high electrical charge while the test

axticle is grounded. u


Emulsification Time The period of time that an emulsifier is permitted to combine with the penetrant prior to removal. Also

called Emulsifier Dwell Time.

Tmulsifier 'v

A liquid that combines with an oily penetrant to make the penetrant water-washable. Also see Hydmphilic Emulsifier &d Lipophilic Emulsifier.

Flash Point The lowest temperature at whicha volatile, flammable liquid will give off enough vapor to make a

combustible explosive mixture in the air space surrounding the liquid surface.

Fluorescence The emission of visible radiation by a substance as a result of, and only during, the absorption of black light

radiation.

Fluorescent Dye Penetrant An inspection penetrant that is characterized by its ability to fluoresce when excited by black light.

Halogen (Halonenous) Any of four very active nonmetallic elements; chlorine, iodine, fluorine and bromine.

Hydrophilic Emulsifier A water-base agent that, when applied to an oily penetrant, renders the penetrant water-washable. Can be

used as a Contact Emulsifier, but more often the emulsifier is added to the water rinse and accompanied by some form of mechanical agitation or scrubbing to remove excess penetrant. Sometimes called a Hydrophilic Scrubber. - ~ e a k Testing

A technique of liquid penetrant testing in which the penetrant is applied to one side of the surface while the other side is inspected for indications that would indicate a through- leak or void.

Lipophilic Emulsifier An oil-base agent that, when applied to an oily penetrant, renders the penetrant water-washable. Usually

applied as a Contact Emulsifier.

Near Surface Discontinuity A discontinuity not open to, but located near, the surface of a test article.

,Nonaqueous Wet Develowr A developer in which the developing powder is applied as a suspension in a quick-drying solvent. Also

called Solvent Developer.

Penetrability The property of a penetrant that causes it to find its way into very fine openings, such as cracks.

Penetrant A liquid (sometimes gas) capable of entering discontinuities open to the surface, and which is adapted to

the inspection process by being made highly visible in small traces. Fluorescent penetrants fluoresce brightly under black light while the visible penetrants are intensely colored to be noticeable under visible light.

L


Post-emulsification Penetrant A penetrant that requires the application of a separate emulsifier to render the surface penetrant water-

washable. Also can be removed by applying a solvent remover.

Precleaning 4 The removal of surface contaminants or smeared metal from the test article so that they cannot interfere

with the penetrant inspection process.

Ouenchin~ of Fluorescence The extinction of fluorescence by causes other than removal of black light (the exciting radiation).

Resolution The property of a test system that enables the separation of indications of close proximity in a test article..

Rinse - The process of removing liquid penetrant inspection materials from the surface of an article by washing or

flooding with another liquid-usually water. Also called Wash.

See- ability The characteristic of an indication that enables th: observer to see it against the conditions of background,

outside light, etc.

Self-developinn Penetrant A penetrant not requiring the use of a developer. Useful for production work in the detection of gross

discontinuities.

Sensitivity .'v

The ability ofthe penetrant process to detect minute surface discontinuities.

Solvent Removed A penetrant-removal technique wherein the excess penetrant is washed or wiped from the test surface with

a solvent remover.

Solvent Remover A volatile liquid used to remow excess surface penetrant from the test article. Sometimes called Penetrant

Remover.

Surface Tension That property of liquids which, due to molecular forces, tends to bring the contained volume into a form

having the least superficial area.

Viscosity The state or degree of being viscous. The resistance of a fluid to the motion of its particles.

Visible Dye Penetrant An inspection penetrant that is characterized by its intense visible color-usually red. Also called Color

Contrast or Nonfluorescent Penetrant.

Water-soluble Developer A developer in which the developer powder is dissolved in a water carrier to form a solution. Not a

d

suspension.


Water-suspended Particle Developer A developer in which the developer particles are mixed with water to firm a suspension.

Water-wash L A penetrant-removal technique wherein excess penetrant is washed or flushed from the test surface with

water.

Water-washable Penetrant A type of penetrant that contains its own emulsifier, making it water-washable.

Water Tolerance The amount of water that a penetrant, emulsifier, or wet developer can absorb before its effectiveness is

impaired.

Wet Developer A developer in which the developer powder is applied as a suspension or solution in a liquid-usually water

or alcohol.

Wetting Ability The ability of a liquid to spread out spontaneously and adhere to the test article's surfaces.


w (MAX # OF INDICATIONSl36) X ACTUAL AREA = NEW MAX # OF INDICATIONS I

- I .I00 .0079 Area = m2


Penetrant Wetting Characteristics

Inspector's HandGook

Inspector's Randbook

Chapter 4 - Magnetic Particle Testing

Common Definitions and Examples

-.& gap When a magnetic circuit contains a small gap, which the magnetic flux must cross, the space is referred to

as an air gap. Cracks produce small air gaps on the surface of an article.

Alternating current Electric current periodically reversing in polarity or direction of flow.

AmDere The unit of electrical current. One ampere is the current that flows through a conductor having a resistance

of one ohm at a potential of one volt.

Ampere turns The product of the number of turns in a coil and the number of amperes flowing through it. A measure of

the magnetizing or demagnetizing strength of the coil.

W h The suspension of iron oxide particles in a liquid vehicle (light oil or water).

J

Black light Radiant energy in the near ultraviolet range. This light has a wavelength of 3200 to 4000 angstrom units

(A), peaking at 3650 A, on the spectrum. This between visible light and ultraviolet light.

$lack light filter A filter that transmits black light while surprising the transmission of visible light and harrml ultraviolet

radiation.

Carbon steel Steel that does not contain significant amounts of alloying elements other than carbon and maganese.

Carrier fluid The fluid in which fluorescent and no* fluorescent magnetic particles are suspended to facilitate their

application in the wet method.

Central conductor An electrical conductor that is passed through the opening in a ring or tube, or any hole in an article, for the

purpose of creating a circular field in the ring or tube, or around the hole.

Circular field See Field, Circular Magnetic.

Circular magnetization A method of inducing a magnetic field in an article so that the magnetic lines of force take the form of

concentric rings about the axis of the current. This is accomplished by passing the current directly through the article or through a conductor which passes into or through a hole in the article. The circular method is applicable for t h detection of discontinuities with axes approximately parallel to the axis of current through the article.


Coercive force The reverse magnetizing force necessary to remove residual magnetism in demagnetizing an article.

Coil shot A pulse of magnetizing current passed through a coil surrounding an article for the purpose of longid -

magnetization.

Contact headshot The electrode, faed to the magnetic particle testing unit, through which the magnetizing current is drawn.

Contact pads Replaceable metal pads, usually of copper braid, placed on contact heads to give good electrical contact

thereby preventing damage to the article under test. 1

Continuous method An inspection method in which ample amounts of magnetic particles are applied, or are p resa on the

piece, during the time the magnetizing current is applied.

Core - That part of the magnetic circuit that is within the electrical winding.

Curie point The temperature at which ferromagnetic materials can no longer be magnetized by outside forces, and at

which they lose their residual magnetism: approximately 1200 to 1600' F (646 to 871° C) for many metals.

Current Flow Technique A technique of circular magnetization in which current is passed through an article via prods or contact 4

heads. The current may be alternating, half- wave rectified, rectified alternating, or direct.

C m t Induction Technique A technique of magnetization in which a circulating current is induced in a ring-shaped component by a

fluctuating magnetic field.

Demamethtio n The reduction in the degree of residual magnetism to an acceptable level.

Diamagnetic Materials whose atomic structure won't permit any real magnetization. Materials such as bismuth and

copper are diamagnetic.

Diffused Indications Indications that are not clearly defined, such as indications of subsurface defects.

Direct Contact Magnetization A magnetic particle testing technique in which current is passed throdgh the test article. These include

headshots and prod shots.

Direct Current An electrical current, which flows steadily in one direction

4-2 Inspector's Handboak

Distorted Field A field that does not follow a straight path or have a uniform distribution. This occurs in irregularly shaped

objects.

b Dry Medium Magnetic particle inspection in which the particles employed are in the dry powder f o m

Dry Powder Finely divided ferromagnetic particles suitably selected and prepared for magnetic particle inspection.

Electromagnet A magnet created by inserting a suitable metal core within or near a magnetizing field formed by passing

electric current through a coil of insulated wire.

Etching The process of exposing subsurface conditions of metal articles by removal of the outside surface through

the use of chemical agents. Due to the action of the chemicals in eating away the surface, various surface or subsurface conditions are exposed or exaggerated and made visible to the eye.

Ferromagnetic A term applied to materials that can be magnetized and strongly attracted by a magnetic field.

Field, Circular Mametic Generally the magnetic field in and surrounding any electrical conductor or article resulting from a current

being passed through the conductor or article or fiom prods.

.field, Longitudinal Magnetic A magnetic field wherein the flux lines traverse the component in a direction essentially parallel with the

axis of the magnetizing coil or to a line connecting the two poles at the magnetizing yoke.

Field, Magnetic The space within and surrounding a magnetized article, or a conductor carrying current in which the

magnetic force is present.

Field, Magnetic Leakwe The magnetic field that leaves or enters the surface of an article at a magnetic pole.

Field. Multidirectional A magnetic field that is the result of two magnetic forces impressed upon the same area of a magnetizable

object at the sametime-sometimes called a "vector field."

Field, Residual Mametic The field that remains in magnetizable material after the magnetizing force has been removed

Flash Magnetization Magnetization by a current flow of very brief duration.

Fluorescence W ,J The emission of visible radiation by a substance as the result of and only during the absorption of black

light radiation.


Fluorescent Magnetic Particle Inspection The magnetic particle inspection process employing a finely divided fluorescent ferromagnetic inspection

medium that fluoresces when activated by black light. V

Flux Density The normal magnetic flux per unit area It is designated by the letter "B" and is expressed in telsa (SI units)

or gauss (cgs units).

Flux Leakage Magnetic lines of force which leave and enter an article at poles on the surface.

Flux Lines Imaginary magnetic lines used as a means of explaining the behavior of magnetic fields. Their conception

is based on the pattern of lines produced when iron filings are sprinkled over a piece of paper laid over a permanent magnet. Also called Lines of Force.

Flux Penetration, Magnetic The depth to which a magnetic flux is present in an article.

Furring Buildup or bristling of magnetic particles due to excessive magnetization of the article.

Gauss The unit of flux density. Numerically, one gauss is one line of flux per square centimeter of area and is

designated by the letter "B." -

w Head Shot

A short pulse of magnetizing current passed through an article or a central conductor while clamped between the head contacts of a stationary magnetizing unit for the purpose of circularly magnetizing the article.

Heads The clamping contacts on a stationary magnetizing unit.

Horseshoe Magnet A bar magnet bent into the shape of a horseshoe so that the two poles are adjacent. Usually the term applies

to a permanent magnet.

Hysteresis The lagging of the magnetic effect when the magnetic force acting upon a ferromagnetic body is changed;

the phenomenon exhibited by a magnetic system wherein its state is influenced by its previous magnetic history.

Hysteresis Loop A curve showing the flux density, "B," plotted as a hc t ion of magnetizing force, "H." As the magnetizing

force is increased to the saturation point in the positive, negative, and positive direction sequentially, the curve forms a characteristic S-shaped loop. Intercepts of the loop with the "B" and "H" axes and the points of maximum and minimum magnetizing force define important magnetic characteristics of the material.

Inductance w

The magnetism produced in a ferromagnetic body by some outside magnetizing force. The magnetism is not the result of passing current through the article.

4-4 Inspector's Randbook

Leakage Field The magnetic field forced out into the air by the distortion of the field within an article.

',ifit Intensitv L

. , The light energy reaching a unit of surface area per of time.

Lonnitudinal Magnetization The process of inducing a magnetic field into the article such that the magnetic lines of force extending

through the article are approximately parallel to the axis of the magnetizing coil or to a line connecting the two poles when yokes (electromagnets) are used.

Magnet, Permanent A highly-retentive metal that has been strongly magnetized; i.e., the alloy Alnico.

Mmetic Field Indicator An instrument designed to detect andlor measure the flux density and polarity of magnetic fields.

Magnetic Field Strength The measured intensity. of a magnetic field at a point always external to the magnet or conductor; usually

expressed in amperes per meter or oersted (Oe).

Magnetic Material Those materials that are attracted by magnetism.

Magnetic Particles Finely divided ferromagnetic material.

i/

Magnetic Particle Inspection A nondestructive inspection method for locating discontinuities in ferromagnetic materials.

Magnetic Poles Concentration of flux leakage in areas of discontinuities, shape changes, permeability variations, etc.

Magnetic Writing A form of nonrelevant indications caused when the suface of a magnetized part comes in contact with

another piece of ferromagnetic material that is magnetized to a different value.

Magnetizing Current The flow of either alternating, rectified alternating, or direct current used to induce magnetism into the

article being inspected.

Magnetizin~ Force ,The magnetizing field applied to a ferromagnetic material to induce magnetization.

Medium The fluid in which fluorescent and nonfluorescent magnetic particles are suspended to facilitate their

application in the wet method.

b Jear Surface Discontinuitv A discontinuity not open to, but located near, the surface of a test article.


Oersted A unit of field strength, which produces magnetic induction and is designated by the letter "H."

/

Paramagnetic 4 Materials which are slightly affected by a magnetic field. Examples are chromium, manganese, aluminun,

and platinum. A small group of these materials are classified as ferromagnetic.

Permeability The ease with which the lines of force are able to pass through an article.

Pole - The area on a magnetized article fiom which the magnetic field is leaving or returning to the article.

Prods Hand-held electrodes attached to cables used to transmit the magnetizing current from the source to the

article under inspection.

Rectified Alternating Current Alternating current, which has been converted into direct current.

Reluctance The resistance of a magnetic material to changes in magnetic field strength.

Residual Magnetism The amount of magnetism that a magnetic material retains after the magnetizing force is removed. Also

called "residual field" or "remanence." w

Residual Technique A procedure in which the indicating material is applied after the magnetizing force has been discontinued.

Retentivity The ability of a ~mterial to retain a certain portion of residual magnetization. Also known as rernanence.

Saturation The point at which increasing the magnetizing force produces no Mher magnetism in a material.

Sensitivity The capacity or degree of responsiveness to magnetic particle inspection.

Settling Test A procedure used to determine the concentration of magnetic particles in a medium or vehicle.

Skin Effect The description given to alternating current magnetization due to its containment to the surface of a test

article.

Solenoid (Coil) An electric conductor formed into a coil often wrapped around a central core of highly permeable mate ,,


Suspension The correct term applied to the liquid bath in which the ferromagnetic particles used in the wet magnetic

particle inspection method &e suspended. >

Lrest Article An article containing known artificial or natural defects used for checking the efficiency of magnetic

particle flaw detection processes.

Wet Medium An inspection employing ferromagnetic particles suspended in a liquid (oil or water) as a vehicle.

Yoke A U-shaped or C-shaped piece of highly permeable magnetic material, either solid or laminated, sometimes

with adjustable pole pieces (legs) amund which is wound a coil carrying the magnetizing current.

Yoke Magnetization A longitudinal magnetic field induced in an article or in an area of an article by means of an external

electromagnei shaped like a yoke.

Longitudinal Magnetization Math Formula

45,000 (+/- lo?!) AT =

W)

A = ampere T = turns of the coil L = length of the item D = diameter or cross section of the item

The minimum UD ratio is 2 The maximum L used in calculations is 20 inches


Common Types of Magnetization

Central Conductor (circular) Horse shoe (longitudinal)

Coil Shot (longitudinal)

Yoke (longitudinal)

Discontinuities

Theory: "Right-Hand Rulen

CURRENT FLOW


Hysteresis Curve

B+ (FLUX DENSITY)

0 - A = Referred to as the virgin curve L/ A = Saturation point -

B = Residual field 0 - C = Coercive force

D = Reverse saturation point E = Reverse residual field

0 - F = Reverse coercive force

H- (MAGNETIZING FORCE OF OPPOSITE POLARITY TO H+) H= (MAGNETIZING FORCE)

R (FLUX DENSITY OF OPPOSITE POLARITY TO B+)

SLENDER LOOP WIDE LOOP

HIGH PERMEABILITY LOW PERMEABILITY LOW RENTENTIVITY HIGH RENTENTMTY LOW COERCIVE FORCE HIGH COERCIVE FORCE d

LOW RELUCTANCE HIGH RELUCTANCE LOW RESIDUAL MAGNETISM HIGH RESIDUAL WU3FETISM

Inspector's Hadbook

Magnetic Particle Field Indicator (Pie Gage) Eight low carbon steel pie sections, furnace brazed

Artificial flaw (all segment 1 in. interfaces)

,' I ' I ' I Nonferrous handle of any

/J Convenient length

Copper plate 0.010 in t 0.001 in thick 7

\ Braze weld or mechanically I \ attach nonferrous trunnions


Inspector's Hanetbook

Chapter 5 - Ultrasonic Testing

Common Terms and Definitions

-\-scan Display A dimlav in which the received signal is displayed as a vertical displacement fiom the horizontal sweep

time trace, wkl; the horizontal distance between a& G o signals represents the sound path distance (or time of travel) between the two.

Absorption Coefficient, Linear The fractional decrease in transmitted intensity per unit of absorber thickness. It is usually designated by

the symbol and expressed in units of cml.

Acceptance Standard A control specimen containing natural or artificial discontinuities that are well defined and, in size or

extent, similar to the maximum acceptable in the product. Also may refer to the document defining acceptable discontinuity size limits.

Acoustic Impedance The factor which controls the propagation of an ultrasonic wave at a boundary interface. It is the product of

the material density and the acoustic wave velocity within that material.

Amplifier A device to increase or amplify electrical impulses.

Amplitude. Indication b. The vertkal height of a received indication, measured fiom base-to-peak or peak-to-peak.

Angle Beam Testing A testing method in which trammission is at an angle to the sound entry surface.

Amle of Incidence The angle between the incident (transmitted) beam and a normal to the boundary interface.

Angle of Reflection .

The angle between the reflected beam and a normal to the boundary interface. The angle of reflection is equal to the angle of incidence.

Angle of Refraction The angle between the refracted rays of an ultrasonic beam and the normal (or perpendicular line) to the

rehcting surface.

Angle Transducer A transducer that transmits or receives the acoustic energy at an acute angle to the surface to achieve a

specific effect such up the setting up of shear or surface waves in the part being inspected.

Anisotropic A condition in which properties of a medium (velocity, for example) vary according to the direction in ,, vhich they are measured.


Array Transducer A transducer made up of several piezoelectric elements individually connected so that the signals they

transmit or receive nay be treated separately or combined as desired. \ s-,

Attenuation Coefficient A factor which is determined by the degree of scatter or absorption of ultrasound energy per unit distance

traveled.

Attenuator A device for measuring attenuation, usually calibrated in decibels (dB).

B-scan Display A cathode-ray tube display in which the received signal is displayed as an illuminated spot. The face of the

CRT represents the area of a vertical plane through the material. The display shows the location of a discontinuity, as it would appear in a vertical section view through the thickness direction of the material.

Back Reflection . The signal received from the back surface of a test object.

Back Scatter Scattered signals that are directed back to the transmitterlreceiver.

Background Noise Extraneous signals caused by signal sources within the ultrasonic testing system, including the material in

test. w

Barium Titanate (Polycrystalliie Barium Titanate - Barn3) A ceramic transducer material composed of many individual crystals fired together and polarized by the

application of a dc field.

Baseline The horizontal line across the bottom of the CRT created by the sweep circuit.

Basic.Calibration The procedure of standardizing an instrument using calibration reflectors described in an application

. document.

B i- modal The propagation of sound in a test article where at least a shear wave and a longitudinal wave exists. The

operation of angle beam testing at less than first critical angle.

Boundary Indication A reflection of an ultrasonic beam from an interface.

Broad Banded Having a relatively wide frequency bandwidth. Used to describe pulses which display a wide frequency

spectnun and receivers capable of amplifying them. 4


C-scan A data presentation method yielding a plan (top) view through the scanned surface of the part. Through

gating, only indications arising from the interior of the test object are indicated.

X/ ",libration To determine or mark the graduations of the ultrasonic system's display relative to a known standard or

reference.

Calibration Reflector A reflector with a known dimensioned surface established to provide an accurately reproducible reference.

Collimator An attachment designed to reduce the ultrasonic beam spread.

Compensator An electrical matching network to compensate for circuit impedance differences.

Compressional Wave A wave in which the particle motion or vibration is in the same direction as the propagated wave

(longitudinal wave).

Contact Testing A technique of testing in which the transducer contacts the test surface, either directly or through a thin

layer of couplant.

Contact Transducer A transducer which is coupled to a test surface either directly or through a thin film of couplant.

L.

Continuous Wave A wave that continues without interruption.

Contracted Sweep A contraction of the horizontal sweep on the viewing screen of the ultrasonic instrument. Contraction of

this sweep pennits viewing reflections occurring over a greater sound-path distance or duration of time.

Comer Effect The strong reflection obtained when an ultrasonic beam is directed toward the inner section of two or three

mutually perpendicular surfaces.

Couplant A substance used between the face of the transducer and test surface to permit or improve transmission of

ultrasonic energy across this b o u n w or interface. Primarily used to remove the air in the interface.

Critical An~le The incident angle of the sound beam beyond which a specific refracted mode of vibration no longer exists.

Cross Talk An unwanted condition in which acoustic energy is coupled from the transmitting crystal to the receiving

.,pystal without propagating along the intended path through the material. Ld


Damping (transducer) Limiting the duration of vibration in the search unit by either electrical or mechanical means.

Dead Zone The distance in a material from the sound entry surface to the nearest inspectable sound path. \ 4

Decibel (dB) The logarithmic expression of a ratio of two amplitudes or intensities of acoustic energy

Delamination A laminar discontinuity, generally an area of unbonded materials.

Delay Line A material (liquid or solid) placed in front of a transducer to use a time delay between the initial pulse and

the fiont surface reflection.

Delayed Sweee A means of delaying the start of horizontal sweep, hereby eliminating the presentation of early response

data.

Delta Effect Acoustic energy re-radiated by a discontinuity.

Detectability The ability of the ultrasonic system to locate a discontinuity.

Difiction The deflection, or "bending," of a wave front when passing the edge or edges of a discontinuity.

Diffise Reflection Scattered, incoherent reflections caused by rough surfaces or associate interface reflection of ultrasonic

waves from irregularities of the same order of magnitude or greater than the wavelength.

Discontinuity An interruption or change in the physical structure or characteristics of a material.

Dispersion, Sound Scattering of an ultrasonicbeam as a result of diffuse reflection from a highly- irregular surface.

Distance Amplitude Correction PAC) Compensation of gain as a function of time for difference in amplitude of reflections fiom equal reflectors

at different sound travel distances. Also referred to as time corrected gain (TCG), time variable gain (TVG) and sensitivity time control (STC).

Divergence Spreading of ultrasonic waves after leaving search unit, and is a function of diameter and frequency.

Dual-Element Technique The technique of ultrasonic testing using two transducers with one acting as the transmitter and one as f .&

receiver.


Dual-Element Transducer A single transducer housing containing two piezoelectric elements, one for transmitting and one for

receiving.

zffective Penetration The maximum depth in a material at which the ultrasonic transmission is sufficient for proper detection of

discontinuities.

Electrical Noise Extraneous signals caused by externally radiated electrical signals or from electrical interferences within

the ultrasonic instrumentation.

Electromametic Acoustic Transducer (EMAT) A device using the magneto effect to generate and receive acoustic signals for ultrasonic nondestructive

tests.

Far Field The region beyond the near field in which areas of high and low acoustic intensity cease to occur.

First Leg The sound path beginning at the exit point of the probe and extending to the point of contact opposite the

examination surface when performing angle beam testing.

Focused Transducer A transducer with a concave face which converges the acoustic beam to a focal point or line at a d e f d

distance from the race.

LZ Focusing

Concentration or convergence of energy into a smaller beam.

Frequency Number of complete cycles of a wave motion passing a given point in a unit time (1 second); number of - - -

times a vibration is repeated at the same point in the same direction per unit time (usually per second).

Gate - An electronic means to monitor an associated segment of time, distance, or impulse.

Ghost An indication which has no direct relation to reflected pulses from discontinuities in the materials being

tested.

Emz (Hz) One cycle per second.

Horizontal Linearity A measure of the proportionality between the positions of the indications appearing on the baseline and the

positions of their sources.

'Immersion Testing b A technique of testing, using a liquid as an ultrasonic couplant, in which the test part and at least the

transducer face is immersed in the couplant and the transducer is not in contact with the test part.


Impedance (acoustic) A material characteristic defined as a product of particle velocity and material density.

Indication (ultrasonics) The signal displayed or read on the ultrasonic systems display.

Initial Pulse The first indication which may appear on the screen. This indication represents the emission of ultrasonic

energy from the crystal face (main bang).

Interface The physical boundary between two adjacent acoustic mediums.

Insonification Irradiation with sound.

Isotropy A condition in which significant medium properties (velocity, for example) are the same in all directions.

Lamb Wave A type of ultrasonic vibration guided by parallel surfaces of thin mediums capable of propagation in

different modes.

Linearity (area) A system response in which a linear relationship exists between amplitude of response and the

discontinuity sizes being evaluated necessarily limited by the size of the ultrasonic beam. v

Linearity (depth) A system response where a linear relationship exists with varying depth for a constant size discontinuity.

Longitudinal Wave Velocity The unit speed of propagation of a longitudinal (compressional) wave through a material.

Loss of Back Reflection Absence of or a significant reduction of an indication from the back surface of the article being inspected.

Maior Screen Divisions The vertical graticule used to divide the CRT into 10 equal horizontal segments.

Manipulator A device used to orient the transducer assembly. As applied to immersion techniques, it provides either

angular or normal incidence and fmes the transducer-to-part distance.

Material Noise Extraneous signals caused by the structure of the material being tested.

Miniature Angle Beam Block A specific type of reference standard used primarily for the angle beam method, but also used for straig w

beam and surface wave tests.

Inspeetor's Handbook

Minor Screen Divisions The vertical graticule used to divide the CRT into fifty equal segments. Each major screen division is

divided into five equal segments or minor divisions.

; M o d e Conversion The change of ultrasonic wave propagation upon reflection or refraction at acute angles at an interface.

Mode The manner in which acoustic energy is propagated through a material as characterized by the particle

motion of the wave.

Multiple Back Reflections Repetitive indications from the back d a c e of the material being examined.

Nanosecond One billionth of a second.

Narrow Banded A relative term denoting a restricted range of frequency response.

Near Field. A distance immediately in front of a transducer composed of complex and changing wave front

characteristics. Also known as the Fresnel field.

Node The point on the examination surface where the V-path begins or ends.

L. L40ise

Any undesired indications that tend to interfere with tk interpretation or processinn of the ultrasonic - information; also referred to as "grass."

Normal Incidence A condition where the angle of incidence is zero.

Orientation The angular relationship of a surface, plane, defect axis, etc., to a reference p l w or sound entry surface.

Penetration (ultrasonic) Propagation of ultrasonic energy through an article.

Phased Array A mosaic of probe elements in which the timing of the element's excitation can be individuallv controlled

to produce certain desired effects, such as steering the beam axis or focusing the beam.

Piezoelectric Effect The characteristic of certain materials to generate electrical charges when subjected to mechanical

vibrations and, conversely to generate mechanical vibrations when subjected to electrical pulses.


Polarized Ceramics Ceramic materials that are sintered (pressed), created (approximately 100oOc), and polarized by applying a

direct voltage of a few thousand volts per centimeter of thickness. The polarization is the process that makes these ceramics piezoelectric. Includes sodium bismuth titanate, lead metaniobate, and several materials based on lea+ zirconate titanate (PZT). u

Presentation The method used to show ultrasonic information. This may include (among others) A-, R, or C-scans

displayed on various types of recorders, CRTs, LCD's or computerized displays.

Probe Transducer or search unit.

Propagation Advancement of a wave through a medium.

Pulse Echo Technique An ultrasonic test technique using equipment which transmits a series of pulses separated by a constant

period of time; e., energy is not sent out continuously.

Pulse Len* Time duration of the pulse from the search unit.

Pulse Rate For the pulse echo technique, the number of pulses transmitted in a unit of time (also called pulse repetition

rate). ..r

Radio Frequency Display (RF) The presentation of unrectified signals in a display.

i.bxs The maximum ultrasonic path length that is displayed.

Rarefaction The thinning out or moving apart of the consistent particles in the propagating medium due to the

relaxation phase of an ultrasonic cycle. Opposite in its effect to compression. The sound wave is composed of alternate compressions and rehctions of the particles in a material.

Raylei& WaveISurface Wave A wave that travels on or close to the surface and readily follows the curvature of the part being examined.

Reflections occur only at sharp changes of direction of the surface.

Receiver The section of the ultrasonic instrument that amplifies the electronic signals returning from the test

specimen. Also, the probe that receives the reflected signals.

Reference Blocks A block or series of blocks of material containing artificial or actual discontinuities of one or more

reflecting areas at one or more distances *om the sound entry surface. These are used for calibrating instrume and in defining the size and distance of discontinuous areas in materials.

5-8 Inspector's EI.andbook

Reflection The characteristic of a surface to change the direction of propagating acoustic energy; the retun of sound

3- -res from surfaces. L Pehction

A change in the direction and velocity of acoustic energy after it has passed at an acute angle through an interface between two different mediums.

Refractive Index The ratio of the velocity of a incident wave to the velocity of the refhcted wave. It is a measure of the

amount a wave will be refracted when it enters the second medium after leaving the first.

Reiect/Suppression An instrument function or control used for reducing low amplitude signals. Use of this control may affect

vertical linearity.

Repetition Rate The rate at which the individual pulses of acoustic energy are generated; also Pulse Rate.

Resolving Power The capability measurement of an ultrasonic system to separate in time two closely spaced discontinuities

or to separate closely spaced, multiple reflections.

Resonance Technique A technique using the resonance principle for determining velocity, thickness or presence of laminar

L Siscontinuities.

,iesonance The condition in which the hquency of a forcing vibration (ultrasonic wave) is the same as the natural

vibration frequency of the propagation body (test object), resulting in large amplitude vibrations.

Saturation (scope) A term used to describe an indication of such a size as to exceed full screen height (100%).

Scanning (manual and automatic) The moving of the search unit or units along a test surface to obtain complete testing of a material.

Scattering Dispersion of ultrasonic waves in a medium due to causes other than absorption

Second Leg The sound path beginning at the point of contact on the opposite surface and extending to the point of

contact on the examination surface when performing angle beam testing.

Sensitivity The ability to detect small discontinuities at given distances. The level of amplification at which the

receiving circuit in an ultrasonic instrument is set.

Shear Wave The wave in which the particles of the medium vibrate in a direction perpendicular to the direction of

propagation.

Inspector's Handbook 5-

Signal- to-Noise Ratio (SNR) The ratio of amplitudes of indications from he smallest discontinuity considered significant and those

caused by random factors, such as heterogeneity in grain size, etc. , - u

Skip Distance In angle beam tests of plate, pipe, or welds, the linear or surface distance from the sound entry point to the

first reflection point on the same surface.

Snell's Law The law that defines the relationship between the angle of incidence and the angle of refkction across an

interface, based on a range in ultrasonic velocity.

Specific Acoustic Impedance A characteristic which acts to determine the amount of reflection which occurs at an interface and

represents the wave velocity and the product of the density of the medium in which the wave is propagating.

Straight Beam An ultrasonic wave traveling normal to the test surface.

Sweep The uniform and repeated movement of a spot across the screen of a CRT to form the baseline.

Through-Transmission A test technique using two transducers in which the ultrasonic vibrations are ernitted by one and received

by the other, usually on the opposite side of the part. The ratio of the magnitudes of vibrations transmitted and received is used as the criterion of soundness. ' 4

Tip Diffiction The process by which a signal is generated from the tip (i.e., top of a fatigue crack) of a discontinuity

through the interruption of an incident sound beam propagating through a material.

Transducer (search unit) An assembly consisting basically of a housing, piezoelectric element, backing material, wear plate

(optional) and electrical leads for converting electrical impulses into mechanical energy and vice versa.

Transmission Angle The incident angle of the transmitted ultrasonic beam. It is zero degrees when the ultrasonic beam is

perpendicular to the test swface.

Transmitter The electrical circuit of an ultrasonic instrument that generates the pulses emitted to the search unit. Also

the probe that emits ultrasonic signals.

Two Probe Method Use of two transducers for sending and receiving. May be either send-receive or through transmission.

Ultrasonic Absorption A damping of ultrasonic vibrations that occurs when the wave transverses a medium.


Ultrasonic Spectrum The frequency span of elastic waves greater than the highest audible kquency, generally regarded as being

higher than 20,000 hertz, to approximately 1O00 megahertz.

'Jltrasonic Svstem The totality of components utilized to perform an ultrasonic test on a test article.

V-path The vath of the ultrasonic beam in the test object from the point of entry on the examination surface to the

back surface' and reflecting to the front surface again.

Velocity The speed at which sound travels through a medium.

Video Presentation A CRT presentation in which radio frequency signals nave been rectified and usually filtered.

Water Path The distance fnrm the face of the search unit to the entry surface of the material under test in immersion

testing.

Wavelength The distance in the direction of propagation for a wave to go through one complete cycle.

Wedgelshoe A device used to adapt a straight beam probe for use in a specific type of testing, including angle beam or

L d a c e wave tests and tests on curved surfaces.

Wraparound Nonrelevant indications that appear on the CRT as a result of a short pulse repetition rate in the pulser

circuit of the test instrument.


Common Math Formulas

Wavelength

L I

T

5-12 Inspectar's Handbook

r ? = Wavelength V = Veloocity F = Frequency

Reflected Acoustic Energy

21-22 ) 2 ER= 100 (-

21 +22

ER = Energy reflected Z1 = Acoustic impedance material #1 22 = Acoustic impedance material #2

Nearfield (nearzone) u

N = D * (F) 4 (V)

N = Length of the near field D = Diameter of the transducer F = Transducer frequency V = Materials velocity

Crystal Thickness h CT = 2

CT = Crystal thickne$s h = Wavelength

Use .23 if material is unknown

Energy Transmitted

ET = El - ER

ET = Energy transmitted El = Energy intiated

ER = Energy reflected

Acoustic Impedance

z = POI)

Z = Acoustic impedance P = Materials density V = Acoustic velocity

Half Angle Beam Spread

v SIN 0 = K ( )

D*F

K= 1.22 V = Velocity of the material D = Diameter of the transducer F = Frequency of the transducer

Times 2 for full angle beam spread

Decibel Difference

A1 Db=20 [LOG (-)I A2

Db = Decibel difference LOG = Natural logrithm

A1 = Amplitude number one A2 = Amplitude number two

Rule of thumb: every 6 Db doubles the size of the indication height (pip)

Snell's Law & Angle of Reflection

SIN 01 = SIN 02 * V1

V2

Angle of incidence * 1st critical angle V2 is long = 90°

Critical angle* 2nd critical angle V2 is shear = 90° Wedge angle

SIN 02 = 'IN * V2 v1

Half / Full Sound Path & Skip / Setback Distance

T HALF SKIP = T TAN 8 HSP= -

COS 0

2T FULL SKIP = 2T * TAN 0 FSP= - cos e

T =Member thickness

Surface Distance to Defect / Depth of Defect

SDD = Sound Path * SIN 8 #DD = Sound Path * COS 8

##DD = (Sound Path * COS 0) - 21

SDD Surface distance to defect #DD =Depth of defed during half sound path

##OD =Depth of defect during full sound path T =Member thickness

Calibration Chart - UT Shearwave b

PLATE THICKNESS *HALF SKIP

1" 112" 314" 1"

PLATE THICKNESS FULL SKIP

I 1 - 112" 1 - 314" 2"

* Applicable holes in the M.I. block for calibration


Velocity Chart

I I I LONGITUDINAL 1 SHEAR I ACOUSTIC 1

Aluminum Aluminum Oxide Bertilium

Copper I 8.9 I -18 I .089 I 41.6 Crown Glass 2.5 .21 . I2 18.9

Ice 1 .OO . I6 .08 3.5 ,Inconel - - - - .22 . I2 47.2 Iron - - - - .23 . I3 45.4

2.7 - - - - 1.82

.43 I - - - - I ,#~&~~~;@~$~g+;~~~~$[@:@~,t

KrTnCarb ie I - - - -

Mercurv - - - - .057 I - - - - I 19.6 Molvbdenum 1 10.09 1 .25 . I3 64.2

Cadium 8.6 .ll 1 .059 ! 24

, , , - ,*,.,. $> , . s , , ~ v . x< ,,,, ..", ~~~&~'i~$&iia$gfigp& +

.25

.39 -51

$~f&<gg$-@@#

lOil (SAE 30) I 0.95 1 .067 I - - - - 1.5 I

Monel - - - - ' ,"":G,~w$~.~$s~&-&~. ,, ";?$;>$..p$",2$$2 ~~~wp&n8:F~w~;&~k~&iyr.~I-j~.t~~ . . . Nickel I 8.3

.I 2

.23

.35

Steel, Mild I 7.7 I .23 I . I3 I 46 ,Steel, Stainless I 8.03 1 .23 -12 I 45.4

17 32 23

.21 I -1 1 ~%;62%,:*, " ' y , ' ' % ~ ; ~ ~ ~ ~ !$%:?>&@&$?& & ,..<:: ; & 4 ~ ; . ~ ~ % < ~ $ ~ & ~ ~ i - ~ f ,6"t*~5-i.&i&+&r.

-22 I .12

Polyethylene Polvstyrene Polyurethane

47.6 2@&d@@& ' w'*'",*

;>:'. 5~;,%k.a3g&&g$$ 49.5


- - - - 1.06 - - - -

Titanium Tungsten Uranium

.07 .093 .07

4.54 19.25 - - - -

.02

.04 - - - -

.24

.20

. I3

1.7 2.5 1.9

-12 .I 1 .OW

27.3 101 63

Pnspector's Handbook

Chapter 6 - Eddy Current Testing

Common Terms and Definitions Absolute Coil

b A test arrangement which tests the specimen without any comparison to either another portion of the test specimen or to a known reference.

Alternating A voltage, current or magnetic field that reverses direction at regularly recurring intervals.

Bobbin Coil A coil or coil assembly used for eddy current testing by insertion into the test piece; e.g., an inside probe

for tubing. Also referred to as Inside Coil or IP Coil.

Coil - Conductor wound in one or more loops to produce an axial magnetic field when current is passed through

it.

Coil Spacing The axial distance between two encircling coils of a differential system.

Conductivity / The willingness of a test circuit or test specimen to conduct current.

Coupling A measure of the degree to which the magnetic field of the coil passes through the test specimen and is

w ffkted by the magnetic field created by the flow of eddy currents.

Defed Resolution A property of a test system which enables the separation of signals due to defects in.the test specimen that

are located in close proximity to each other.

Diamagnetic A material having a permeability less than that of a vacuum.

Differential Coil A test arrangement which tests the specimen by comparing the portion being tested with either another

portion of the same specimen or to a known reference specimen.

Discontinuitv, Artificial Reference discontinuities, such as holes, grooves, or notches, which are introduced into a reference

standard to provide accurately reproducible sensitivity levels for electromagnetic test equipment.

Double Coil A test arrangement where the alternating current is supplied through one coil while the change in material

condition is measured from a second coil.

Eddy Current L A circulating electrical current induced in a conductive material by an alternating magnetic field.


Edge or End Effect The disturbance of the magnetic field and eddy currents due to the proximity of an abrupt change in

geometry (edge, end). The effect generally results in the masking of discontinuities within the affected region. f

Effective Depth of Penetration d

The depth in a material beyond which a test system can no longer detect a change in material properties.

Effective Permeability A hypothetical quantity

conductor in an encircling coil. which is used to describe the magnetic field distribution within a cylindrical The field strength of the applied magnetic field is assumed to be uniform over the

entire cross section of the test specimen with the effective permeability, which is characterized by the conductivity and diameter of the test specimen and test frequency, assuming values between zero and one, such that its associated amplitude is always less than one within the specimen.

Electromagnetic Induction The process by which a varying or alternating current (eddy current) is induced into an electrically

conductive test object by a varying electromagnetic field.

Electromagnetic Testing That nondestructive test method for engineering materials, including magnetic materials, which uses

electromagnetic energy having frequencies less than those of visible light to yield information regarding the quality of the tested material.

Encircling Coil A coil, coils, or coil assembly that surrounds the part to be tested. Coils of this type are also referred to as

circumferential, OD or feed-through coils. w

External Reference Differential A differential test arrangement that compares a portion of the test specimen to a known reference standard.

Ferromagnetic A material which, in general, exhibits hysteresis phenomena, and whose permeability is dependent on the

magnetizing force.

Fill Factor For an inside coil, it is the ratio of the outside diameter of the coil squared to the inside diameter of the

specimen squared. For an encircling coil, it is the ratio of the outside diameter of the specimen squared to the inside diameter of the coil squared.

Flux Density A measure of the strength of a magnetic field expressed as a number of flux lines passing through a given

area.

Henry The unit of inductance. More precisely, a circuit in which an electromotive force of one volt is induced

when the current is changing at a rate of one ampere per second will have an inductance of one henry. (Symbol: H)

Hertz The unit of frequency (one cycle per second). (Symbol: Hz)

High Pass Filter An electronic circuit designed to block signals of low frequency while passing high frequency signals.

IACS k The International Annealed Copper Standard. A value of conductivity established as a standard against w

which other conductivity values are referred to in percent IACS.

Impedance The ovtmsition to current flow in a test circuit or a coil due to the resistance of that circuit or coil, plus the

electrical of the coil as affected by the coil's magnetic field.

Impedance Analysis An analytical method which consists of correlating changes in the amplitude, phase, or quadrature

components (or all of these) of a complex test signal voltage to the electromagnetic conditions within the specimen.

Impedance-plane Diagram A graphical representation of the locus of points indicating the variations in the impedance of a test coil as

a function of basic test parameters.

Inductance The inertial element of the electric circuit. An inductor resists any sudden change in the current flowing

through it.

Inductive Reactance The opposition to current flow in a test circuit or coil when an alternating voltage source is applied and due

solely to the electrical properties of the mil as affected by the magnetic field. b

Inertia The property of matter which manifests itself as a resistance to any change in the momentum of a body.

Lift-off The distance between a swface probe coil and the specimen.

Lift-off Effect The effed observed due to a change in magnetic coupling between a test specimen and a probe coil

whenever the distance between them is varied.

Low Pass Filter An electronic circuit designed to block signals of high frequency while passing low frequency signals.

Magnetic Field A condition of space near a magnet or current-carrying wire in which forces can be detected.

Magnetic Flux Lines A closed curve in a magnetic field through points having equal magnetic force and direction.

Noise Any undesired signal that tends to interfere with the normal reception or processing of a desired signal.. In

haw detection, undesired response to dimensional and physical variables (other than flaws) in the test part is called "part noise.

Inspector's Handbook 6- 3

Nonferroma.gnetic A material that is not magnetizable and hence, essentially not affected by magnetic fields. This would

include paramagnetic materials having a magnetic permeability slightly greater than that of a vacuum and approximately independent bf the magnetizing force and diamagnetic materials having a permeability less tha- '' of a vacuum. V

Paramagnetic A material having a permeability which is slightly greater than that of a vacuum, and which is

approximately independent of the magnetizing force.

Permeability A measure of the ease with which the magnetic domains of a material align themselves with an externally

applied magnetic field.

Permeability Variations Magnetic inhomogeneities of a material.

Phase Analysis An instrumentation technique which discriminates between variables in the test part by the different phase

angle changes which these conditions produce in the test signal.

Phase Angle The angle measured degrees that the current in the test circuit leads or lags the voltage. One complete

cycle is equal to 360".

Phase Shift A change in the phase relationship between two alternating quantities of the same frequency. w

Probe Coil Asmall coil or coil assembly normally used for surface inspections.

- Reference Standard A test specimen used as a basis for calibrating test equipment or as a comparison when evaluating test

results.

Reiection Level The setting of the signal level above or below which all parts are rejectable or in an automatic system at

which objectional parts will actuate the reject mechanism of the system.

Resistance The opposition to current flow in a test circuit or coil based on specific material properties and cross-

sectional area and length of a conductor.

Response Amplitude The property of the test system whereby the amplitude of the detected signal is measured without regard to

phase.

Saturation The degree of magnetization produced in a ferromagnetic material for which the incremental permeabili

has decreased substantially to unity.


Self-comparison Differential A differential test arrangement that compares two portions of the same test specimen.

Signal- to-noise Ratio L The ratio of response or amplitude of signals of interest to the response or amplitude of signals containing

no usell information.

Single Coil A test arrangement where the alternating current is supplied through the same coil from which the -

indication is taken.

Skin Effect A phenomenon where, at high frequencies, the eddy current flow is restricted to a thin layer of the test

specimen close to the coil.

Standard A reference used as a basis for comparison or calibration; a concept that has been established by authority,

custom, or agreement to serve as a model or d e in the measurement of &tity or the establishment of a practice or a procedure.

Standard Depth of Penetration The depth in a test specimen where the magnitude of eddy current flow is equal to 37 percent of the eddy

current flow at the surface.


Two Types of Electrical Current

Direct Current (DC) 4

- Current flow is constant over time - Current is distributed uniformly over the cross-section of the conductor - Example: battery

Current strength and direction remain constant over time

Time

Alternating Current (AC)

- Current flow varies over time w - Current flows at or near the surface of the conductor - this phenomenon is called the SL,

effect - Example: 60 cycle ac in wall sockets

Current strength varies over time; current direction reverses every 112 cycle

Time

Inspector's Handbook'

Conductivity and the IACS

Conductivity of a metal is usually expressed as a percentage (%) and is based on the international annealed copper standard (IACS).

k. A specific grade of high purity copper was designated as 100 % conductivity. All other metals (except silver) are designated some % less then 100 %. These percentages indicate the relative efficiencies of the various metals for carrying electric current.

Right Hand Rule

L An easy method for fmding the direction of an electrically induced magnetic field is to imagine grasping the conductor in the right hand with the thumb pointing in the direction of the current flow. The fingers will then point in the direction of the lines of force. This is the right hand rule and is shown below. From this figure it can be seen that the current flow in the conductor creates circular lines of force.

CURRENT FLOW

The coil's magnetic field intensity (strength) decreases with'in~reasin~ distance away from the outside of the coil. C*

The field intensity at point C is less than at point B, and point B's intensity

C is less than point A's B

A


C1

The coil's field intensity (strength) is assumed to be constant across the inside diameter of the coil. This assumption is based on the use of AC and small diameter coils, and for all practical purposes the assumption is valid. W'

' \./- Y

Lines of Force

The coil's magnetic field can be viewed as a distribution of lines of force around the coil. These lines of force are call magnetic flux, and represent the coil's magnetic force (symbol 'H').

Current Current in

- 0 -

out C . - - -

0 I

When a metal rod is placed inside the coil, the coil flux passes through the rod. The number of lines of force in the rod divided by the cross-sectional 'N

area of the rod equals the flux density (symbol 'B') in the rod. The flux density in the rod depends on the metal's willingness to cany the magnetic , ' flux. The metal's willingness to carry these magnetic flux lines is called /

permeability. The symbol for permeability is 'p' (mu). \ ' N - * ---I- w

Mathematically, permeability is expressed as the flux density in the material (B) divided by the magnetizing force (H) that caused it.

Permeability B

= o r p H

Flux densih Magnetizing force

Like conductivity, permeability is a material property that is the same for all samples of a particular material (assume same chemistry, etc.).

example: p, for air = 1 p for copper alloys = 1 p, for steels = several thousand

The permeability value of 1 for air and copper alloys (and all other nonmagnetic materials) means that the magnetic flux in the material is exactly equal to the flux coming from the coil.

b

stated another way: b/h = 1 only when b = h

The high permeability value of steels (and all other ferromagnetic metals) means that the magnetic flux in the metal is thousands of times greater than the applied flux fiom the coil.

stated another way: b/h = 2000 means h,, = 2000 x h,,

Magnetic Domains

Obviously, something is happening in the ferromagnetic metals to create all this additional flux that is not happening in the nonmagnetic materials. Magnetic domains are groups of atoms within a ferromagnetic metal which behave like tiny permanent magnets.

In unmagnetized magnetic materials, the domains are randomly oriented and neutralize each other, producing no observable magnetic flux in the

. metal. w

When the magnetizing force fiom the coil, is applied, the domains begin to align in the direction of the applied flux. Their combined individual magnetism starts to produce an observable increase in the flux in the metal, over and above the applied flux (H).

When the domains are completely aligned, the metal is said to be saturated, and the flux 'B' is many thousands of times greater than the applied flux 'HI. This domain behavior is responsible for the mrrlinear relationship between (E3) and (H) in ferromagnetic metals and for the hysteresis effect.

Partially Oriented Domains


Completely Oriented Domains (saturation)

When a coil of wire carrying alternating current is brought into proximity to a conducting article. The alternating magnetic field that surrounds the coil will penetrate the article, generating small circulating electrical currents, called eddy currents, in an article.

Note: When a generator's electrical current reverses it direction, the direction of the eddy currents will ako reverse. I I I I Electrical current

$4 Test coil

Article being tested

Eddy currents are circulating electrical currents induced in an isolated conductor by an alternating magnetic field. Note that there is no direct electrical contact between the coil and the test article - eddy currents are generated by electromagnetic induction.

Direction of coil's field The "primary" magnetic field surrounding the ac coil will penetrate the test articles and induce eddy c m t s in the article. The circulating Ac eddy currents possess their own "secondary" magnetic field. This secondary field will oppose the coils . 1 . I

and reduce the size and strength of the \ I , # - -*

coil's field. A Eddy current field opposes coil's field

Inspector's I F a n h k

Changes in the strength or shape of the secondary field will affect the primary field, which will affect the AC flowing in the coil, where it will be sensed.

LTn this way, variations of the test article that disturb or alter the flow of the eddy currents will disturb the electromagnetic coupling between the two fields and cause indications on the test instnunent

Characteristics of Eddy Current

1) Can only be induced in conductors

Test circuit

Changes in conductivity

Coated (i.e. painted) articles may be tested, since the coils field will pass through the nonconducting coating and

&@) onc conductive material

\

generate eddy currents in the metal \e

- Change in coil's impedance -------------.----I--------------------.

Change in coil's magnetic field

beneath.

Change in meter reading

Plated articles should not be tested, since the coil's field will generate eddy currents in both the metallic plating and the base material. Consequently, ET indications could originate from either the base metal or the plating, confusing the inspection.

Material

1--conductive material

*Conductive material

-Conductive mate

2) Can be generated only by an alternating magnetic field - there must be relative motion between the field and the test article. A DC field will not generate eddy currents. The moving AC field which builds up, then breaks down and reverses direction every 112 cycle, is essential to the production of eddy currents.

3) Eddy currents flow in circular paths, parallel to the coil windings.

/ENCIRCLING COIL

CRACK

EDDY CURRENTS

Depth of Penetration

Eddy currents are strongest at the surface nearest the coil (due to skin effect) and weaken with depth. The depth of eddy current penetration below the surface is directly affkcted by the nearness of the coil to the test article, the operating frequency, and the test article conductivity and permeability.

I 4

(A) Coil position - since the coil's field is limited in size and decreases in strength with increasing distance away from the coil, maximum field penetration into the article and, therefore, maximum depth of eddy current penetration is achieved by mving the coil as close as practical to the test article surface.

02, /='

I I \ \ 1 + ' 8

coil far away 71 from article 1 I - being tested

possible to the article being tested

(B) Operating frequency - a relationship also exists between the frequency of the ac applies to the test coil and the eddy current depth of penetration. As the frequency is increased, eddy current distribution concentrates near the surface and decreases deep with the test article. The reverse is also true. As the frequency is lowered, the eddy current distribution extends deeper into the article.

Depth of

Penetration

I I

View A

Frequency \ -

Depth of Eddy Current Penetration

View B

In both view A and B above, the material and the test coil are the same. Since view a shows deeper eddy current penetration into the material, this means that a lower frequency was used. View B shows shallower penetration, so a high frequency was used. Keep in mind that a high frequency causes the eddy currents to accumulate near the surface closest to the test coil.

c) Conductivity - the figure below illustrates that the depth of eddy current penetration also varies with metal's electrical conductivity. As conductivity increases, the depth of eddy currents decreases.

In the figure, the coil and test frequency are the same in each view. Only the material type is different. You can verifl that tin is more conductive the lead, and that copper is much more conductive than either, by referring to the % IACS conductivity chart shown earlier. As the figure shows, the less conductive metals achieve deeper eddy current penetration than the more conductive metals.

'c/ Indicator Indicator Indicator

oil Coil oil

d) Magnetic permeability - f d y , a metal's magnetic permeability (p) affects the depth of eddy current penetration. The depth of penetration decrease as the permeability increases. There are 3 basic types of eddy current test: surface , encircling , and inside. A surface coil is designed to be used on localized areas on a surface, and is usually contained in a hand-held probe.

'L

Depth of Eddy Current Penetration

An encircling coil, on the other hand, is large enough to surround an object about one of its axes and is designed to test an entire segment of the object at one time.

2 .'.::..::.'.:::.:;:.: :..::-.:::.::.::. . . ..... .. .. :. :::.,::::: :.: Depth of - Eddy Current Penetration


Lead Tin copper

Encircling Coil

An inside coil is designed to be placed inside a hole or cavity in the object, and is especially suited for testing thin wall tubing.

ARTICLE

b b $ L c --,co,L

INSIDE COIL

Note that with each of the coil types: - The eddy currents circulate parallel to the coil windings - The eddy currents hug the surface that is nearest the coil

Each of these 3 coil types may be used in either the differential or absolute test mode.

In the differential coil arrangement, two side-by-side coils are wound and connected so that the output of on cancels the output of the other as long as the test object properties are the same under both coils. This mode is most ensitive to small defects and is relatively insensitive to material variations such as hardness, gross surface megularities, etc.

P1 D I F F E R E N TlAL

In the absolute mode, a single coil tests the area of the test object beneath it without comparison to a reference area This mode is most sensitive to large defects longer than the coil, and to material variations such as hardness, gross surface irregularities, etc.

ABSOLUTE COIL

The 3 general material variables (properties) that affect the flow of eddy currents in the material are:

1) Changes in conductivity - conductivity changes may be caused by variations in alloy chemistry or heat treatment, or may be due to the presence of defects. Since cracks or other discontinuities force the eddy currents to take a longer path by flowing around them, the overall effect of the discontinuity is to reduce the conductivity of the metal.

TEST COI L EDDY CURRENT MAGNETIC FIELD MAGNETIC FIELD ,TEST COIL

EDDY CURRENT MAGNETIC FIELD

CRACK EDDY CURRENT

As the figure illustrates, the eddy currents must flow around the crack, effectively reducing the conductivity of the metal.

2) The second material variable affecting eddy current flow is magnetic permeability. Eddy currents are induf ' by flux changes in the metal and are directly related to the density or amount of flux. Since changes in ' 4

permeability cause changes in the amount of flux in the metal, they also cause a pronounced (and detectable) change in the eddy current flow.

3) Changes in the physical dimensions, or size and shape of the test object also affect the eddy current flow. Although the figure below is a gross example, it clearly illustrates how a change in physical dimension can alter the electromagnetic coupling between the coil and the object.

Two more dimensional of eddy current testing is edge effect and lift-off.

Edge effed is the false indication caused by disruption of by disruption of the eddy current path when the coil approaches an end or edge of the material.

w

The effect is strong enough to "mask' any changes due to other factors. In effect, the edge of the material looks h e a very large crack to the eddy current instrument.

On the other hand, the false indication caused by changing the spacing between the test coil and the material d a c e is called lift-off.

-------------' \ MAGNETIC


Lift-off has a very large effect on the ET output display due to the decrease in primary field flux in the material as the coil distance from the materials surface is increased.

The lift-off effect can be used to measure the thickness of nonconducting coatings, such as paint, on a conducting object.

WONCONDUC SURFACE

I

1 CvnOUCTlVE MATERIAL I I ARTICLE

b

A c e eddy currents cannot be generated in the nonconductor, a coil placed in contact with the painted surface "sees" the paint thickness simply as lift-off distance.

Another important relationship between eddy current flow and the presence of discontinuities is that the discontinuity must lie perpendicular to the direction of eddy current flow to be detected.

\

INSPECTION COIL

EDDY CURRENTS

' SURFACE CRACK

SUBSURFACE LAMINAR SEPARATION

In the situation above, a surface coil passes over a surface crack and a subsurface lamination in the metal. It is easy to see that the crack will force the eddy currents to take a longer path around it, causing a detectable disruption in - their flow. The lamination on the other hand, will not cause much disruption of the eddy current path since the

. netal separation lies parallel to the direction of current flow.


Limitations of Eddy Current Testing

1. Inspect only conducting articles (i.e. metals).

2. Can locate only d a c e and shallow subsurface discontinuities; inspection depth is limited to less then 1 ii.

3. Separation of the effects of conductivity, permeability, and dimension variables is difficult and often not possible.

4. ET is an indirect inspection requiring the use of calibration standards; you must know what you are looking for in order to find it.

Advantages of Eddy Current Testing

1. Able to inspect through nonconductive coatings (i.e. paint).

2. Fast, real-time inspection.

3. Totally nondestructive; no interference with the test item.

Summary of Properties of Eddy Currents

1. Generated by an alternating magnetic field.

2. Flow only in conductors. 4

3. Circulates parallel to coil windings.

4. Eddy current flow is affected by changes in the material's conductivity, dimension, magnetic permeability.

5. Limited to surface/shallow s u b d a c e testing.

6. Depth of penetration is affected by conductivity and permeability of test object, by test frequency, and by nearness of the coil to the test object.

7. Able to test through surface coatings (nonconducting) but not through plating (metal).

Eddy Current Relationship of Properties


Penetration Decrease Increase

Frequency Increase Decrease

Conductivity Increase Decrease

Permeability Increase Decrease

Chapter 7 - Radiographic Inspection

Common Definitions and Examples

w Absorbed dose The amount of energy imparted to matter by an ionizing particle per unit mass of irradiated material at the

place of interest. It is expressed in "'rads."

Accelerator A device that accelerates charged atomic particles to high energies. An x-ray machine is an accelerator.

Activity A measure of how radioactive a particular radioisotope is. The number of atoms decaying per unit of time

calculates activation. Its unit of measurement is the "curie."

Alpha particle A positively charged particle emitted by certain radioactive materials. It is made up of two neutrons and

two protons; hence it is identical with the nucleus of a helium atom.

Alpha ray A stream of fast-moving helium nuclei (alpha particles). This radiation is strongly ionizing with very weak

penetration.

An~strom A unit of length used to express wavelength. One angstrom equals lo-* centimeters.

-Q. W e (target side) The positive terminal of an x-ray tube. It is a high melting point element that receives the electron

bombardment from the cathode (filament).

Atom The smallest part of an element. The atom consists of a nucleus composed, with the exception of hydrogen,

of a number of protons and neutrons. Included in the atom is an extranuclear portion composed of electrons equal in number to the protons in the nucleus. The hydrogen atom includes a nucleus of one proton and extranuclear portion of one electron.

Autotransformer A special type of transformer in which the output voltage can be easily varied. The autotransformer is

employed to adjust the primary voltage applied to the step-up transformer that produces the high voltage applied to the x-ray tube.

Background radiation The radiation of man's radiation natural environment, consisting of radiation that comes from cosmic rays

and from the naturally radioactive elements of the earth, including radiation from within man's body. The term may also mean radiation extraneous to an experiment.

Backscatter Radiation scattered h m the floor, walls, equipment, and other items in the area of a radiation source.

Sackscatter includes secondary radiation resulting from the interaction between the primary radiation from the , ' source and the material being radiated.


Beta particle An electron or position emitted from a nucleus during radioactive decay.

Bremsstrahlung ~lectroka~netic radiation (photon) emitted by charged particles when they are slowed down by e l e d L-

fields in their passage through matter. Literally means, "braking radiation" in German.

200 Kev Electron Leaving

400 Kev Electron 8

200 Kev X-Ray

A lightproof container, which may or may not contain intensifying andlor filter screens, that is used for holding the radiographic films in position during the radiographic exposure.

Cathode (filament side) The negatively-biased electrode of the x-ray tube. 's/

A device used to surround a radiation source and so constructed as to both minimize the scattered radiation and to direct the primary or useful radiation into a more or less parallel beam onto a localized area.

Compton Effect The glancing collision of an x-ray or gamma ray with an electron to an orbital electron in matter with a

lower enxgy in matter with a lower energy photon scattered at an angle to the original photon path. The electron does not absorb all of the energy.

High energy Photon de-.

0e \

Ejected electron / / Photon /@-o-.

1 \ continues with 4 - \

e'L-- \ ' less energy

' I \

I . \ \


Contrast (film) The change in density recorded on the film that results from a given change in radiation input. Contrast is

determined h t h e slope of the characteristic curve.

Tontrast (radiographic) L The measure of difference in the film blackening resulting from various x-ray intensities transmitted

through the object and recorded as density differences in the image. Thus, difference in film blackening from one area to another is contrast.

Contrast (subiect] The ratio of radiation intensities passing through selected portions of a specimen.

Definition The measure of sharpness in the outline of the image of an object recorded on film, the sharpness is the

function of the types of screens, exposure geometry, radiation energy and film characteristic.

Densitometer An instrument utilizing the photoelectric principle to determine the degree of darkening of developed

photographic film.

Developer A chemical solution that reduces exposed silver halide crystals to metallic silver.

Dose - The amount of ionizing radiation energy absorbed per unit mass of irradiated material at a specific location,

such as a part of the human body.

'Y Dose rate The radiation dose delivered per unit time and measured, for instance, in rems per hour.

Dosimeter A device that measures radiation dose, such as a film badge or ionization chamber.

Duty cvcle Usually expressed in a percentage to represent the time used versus the time not used.

Electromametic Spectrum Represents the electromagnetic waves of different wave lengths. The lines are not definie boundaries but

rather phase into one another.

DECREASING - WAVELENGTH - INCREASING

INCREASING - FREQUENCY - DECREASING

X-RAYS AND

GAMMA RAYS

L INCREASING - ENERGY - DECREASING


ULTRAVIOLET RAYS

LIGHT RAYS

INFRARED RAYS

RADAR SHORT WAVE RADIO

LONG WAVE RADIO

Electron volt Is an amount of energy equal to the energy gained by one electron when it is accelerated by one volt.

Emulsion A gelatin and silver bromide crystal mixture coated onto a transparent film base.

Encapsulation The process of sealing radioactive materials to prevent contamination.

Filament A piece of wire in the cathode side, negative side, of the x-ray tube used to produce electrons when heated.

Specialized film used for radiographic purposes. The components of the film are two protective layers, two emulsion layers, and one acetate base layer.

acetate protective , . . . . . . . . . . . . . . . . . . . . . . . base t layers

Film bad~e A package of photographic film worn as a badge by workers in the nuclear industry to measure exposure to

ionization radiation. The absorbed dose can be calculated by the degree of film darkening caused by the irradiation.

Filter A layer of absorptive material that is placed in the beam of radiation for the purpose of absorbing rays, .d

certain wavelengths and thus controlling the quality of the radiograph.

Fixer - A chemical solution that dissolves unexposed silver halide crystals from developed film emulsions.

Fon A darkening of the film resulting from chemical action of the developer, aging, scattered or secondary

radiation, pre-exposure to radiation, or exposure to visible light.

Geiger counter A radiation detection and measuring instrument. It contains a gas- filled tube that discharges electrically

when ionizing radiation passes through it. Discharges are counted to measure the radiation's intensity.

Graininess A film characteristic that consists of the grouping or clumping together of the countless small silver grains

into relatively large masses visible to the naked eye or with slight magnification.

Half- life The time in which half the atoms in a radioactive substance decay. Time is dependant upon the element.

Half- life (biological) The time required for a biological system, such as a man or an animal, to eliminate, by natural processr _c

half the amount of a substance that has entered it.


Hal6 value layer The thickness of a material required to absorb one half of the impinging radiation.

F

Intensifying screen A layer of material placed in contact with the film to increase the effect of the radiation, thereby shortening

'v h e exposure.

Interlock A device for precluding access to an area of radiation hazard either by preventing entry or by automatically

removing the hazard.

Ion - A charged atom or molecularly-bound group of atoms; sometimes also a free electron or other charged

subatomic particles.

Ion pairs A positive ion and a negative ion, or electron, having charges of the same magnitude and formed from a

neutral atom or molecule by the action of radiation or by any other agency that supplies energy.

Ionization The process of adding electrons to, or knocking electrons from, atoms or molecules thereby creating ions.

High tempe~tures, ele~tricaldischar~es, and nuclear radiation can cause ionization.

Ionization chamber An instrument that detects and measures ionizing radiation by observing the electrical current created when

radiation ionizes gas in the chamber making the gas a conductor of electricity.

,onizing radiation Any radiation that directly or indirectly displaces electrons from the orbital shells of atoms.

&v The energy of X-rays or gamma rays measured in thousand electron volts.

Latent image The potential image that is stored in the form of chemical changes in the film emulsion and is brought out

by development of the film.

Latitude Latitude most closely aligned with contrast is commonly called the scale of the film. Latitude is the range

of thickness of material that canbe transferred or recorded on the radiograph within the usell reading range of film density. A high contrast film has little latitude and conversely a low contrast film has great latitude.

Leak test A test on sealed sources to assure that radioactive material is not being released.

Licensed material Source material, special nuclear material, or by-product material received, possessed, used, or transferred

under a general or speciailicense issued by the Nuclear Regulatory Commission.


Mev - The energy of X-rays or gamma rays measured in million electron volts.

Microshrinkage Cracks that appear as dark feathery streaks, or irregular patches, that indicate cavities in the grain \ w

boundaries.

Monochromatic radiation A rare condition, hypothetical, in which all gamma rays oi x-rays produced are of the same wavelength.

Pair production The transformation of a high-energy ray into pair of particles (an electron and a positron) during its passage

through matter.

Particle A minute constituent of matter with a measurable mass, such as a neutron, proton, or meson.

Penetrameter A small strip of material of the same

composition as the specimen being tested. Its thickness

T = thickness 4TDIA T DIA 2T DIA I k I

represents a percentage of the specimen thickness. I When placed in the path of the rays, its image on the radiograph provides a check on the radiographic technique employed.

Penumbra The shadow cast when the incident radiation is partly, but not wholly, cut off by an intervening body; t -

space of partial illumination between the umbra, or perfect shadow, on all sides and the fidl light.

Photoelectric effect This process involves the complete absorption of the photon during the process of knocking an electron out

of orbit. It occurs primarily with lower energy X-rays photons of 10 Kev to 500 Kev.

Approaching Photon

....a /e Ejected electron (negative ion)

Photon absorbed 0 @

/ 4-. \

/ \ / g4-' .\ '

/ \ '

I \ \ \

' \ \ \ \ '.-- 0

\

,' \ /

' Charged atom

--e4 ' (positive atom)

Photon 4

A discrete quantity of electromagnetic energy. Photons have no momentum but no mass or electrical charge.


Positron A hdamental atomic particle having a mass equal to that of the electron and possessing a positive charge

equal to the negative charge of the electron. <

'VRoentaen A unit of exposure dose of ionizing radiation. It is that amount of gamma or x-rays required to produce ions

carrying 1 electmst&ic unit of electrical charge in one cubic centimeter of dry air under standard conditions.

Safelight A special lamp used in the darkroom to provide working visibility without affecting the photosensitive

emulsion of the radiographic film.

Scatter Secondary radiation that is emitted in all directions.

Screens Metallic or fluorescent sheets used to intensify the radiation effects on films.

Sensitivity A term usually referring to the ability of the radiographic procedure to detect discontinuities.

Specific activity Total radioactivity of a given isotope per gram of element.

Source- film-distance The distance between the focal spot of an x-ray tube or radiation source and the film, generally expressed

.n inches.

Tar~et The piece of material, usually tungsten, embedded in the anode side, positive side, of the x-ray tube. A

effective and efficient target has the following four properties high atomic number, high melting point, high thermal conductivity, and low vapor pressure.

Two- film technique A procedure wherein two films of different relative speeds are used simultaneously to radiograph both the

thick and the thin sections of an item.


Structure of the Atom and an Element

$ Proton - A heavy atomic particle with a positive charge. 0 Neutron - Close to the same weight and size of the proton with a neutral charge.

Electron - A negative charged particle weighing about 111840'~ of a proton or a neutron.

Nucleus - The proton(s) and ~utron(s) are group here in the center of the atom. Atomic number "Z" - This number represents the number of protons in the atom. Mass number "A" - This number represent the number of protons and neutrons in the atom.

fi Helium Atom

E = element symbol Z = atomic number A = mass number

Components of an Isotope

Isotope - One or more of the same element having the same number of protons but not the same number of neutrons. Natural isotopes - Those that occur naturally. v/ Artificial isotope - Those elements that are created by bombarding with swarms of neutrons. Activation - This is the process of creating artificial isotopes. Stable isotopes - Atoms that are not radioactive. Unstable isotopes - Atoms that are radioactive.

Characteristics of A Radioactive Element

During the decay or disintegration process tiny particles of energy are emitted in the form of particles and waves h m the nucleus.

Alpha particles (a) - The biggest and heaviest of the radiation particles and is composed of two protons and two neutrons. Beta particles (13) - A very light particle, actually a high-speed electron. Gamma rays (?) - A form of energy that is a wave not a particle.

Two Types of Radiation

Gamma radiation - A product of nuclear disintegration or decay of radioactive elements.

X-rays - An artificial produced wave from a high voltage electron tube. 1) Soft x-rays - low energy. 2) Hard x-rays - high energy.


History of Radiography

X-rays were discovered in 1895 by Wilhelm Conrad Roentgen (1 845- 1923) who was a Professor at Wuerzbug University in Germany. Working with a cathode- - -ay tube in his laboratory, Roentgen observed a fluorescent glow of crystals on a table near his tube. The tube that Roentgen was working with consisted of a glass envelope (bulb) with electrically positive and negative electrodes encapsulated in it. The tube was evacuated of air, and when a high voltage was applied to it, the tube would produce a fluorescent glow. Roentgen shielded the tube with heavy black paper, and found that a green colored fluorescent light could be seen from a screen setting a few feet away from the tube. He concluded that a new type of ray emitted from the tube. This ray was capable of passing through the heavy paper covering. He also found that the new ray would pass through most substances casting shadows of solid objects. In his discovery, Roentgen found that the ray would pass through the tissue of humans leaving the bones and metals visible. One of Roentgen's first experiments late in 1895 was a film of his wife, Bertha's hand with a ring on. However, it can be argued that the fkst use of X-rays was for an industrial (not medical) application as Roentgen produced a radiograph of a set of weights in a box to show his colleagues.

Roentgen's discovery was a scientific bombshell, and was received with extraordinary interest by both scientist and laymen. Scientists everywhere could ,duplicate his experiment because the cathode tube was very well known during this period. Many scientist dropped other lines of research to pursue the mysterious rays, and the newspapers and magazines of the day provided the public with numerous stories, some true, others fanciful, about the properties of the newly discovered rays. The public fancy was caught by the invisible ray with the ability to pass through solid matter, and, in conjunction with a photographic plate, provide a picture, albeit a shadowy diffuse one, of the bones and interior of the body. Scientific fancy was captured by an extraordinary new radiation, of shorter wavelength than light, that presaged new and great vistas in physics, and the structure of matter. Both the scientist and the public were enthusiastic about potential applications of the newly discovered rays as an aid in medicine and surgery. Thus, within a month after the

announcement of the discovery, several medical radiographs had been made & Europe and the United States that were used by surgeons to guide them in their work. In June 1896, only 6 months after Roentgen announced his discovery, X-rays were being used by battlefield physicians to - - locate bullets in wounded soldiers.

Prior to 1912, X-rays were used little outside the realms of medicine, and dentistry, though some X-ray pictures of metals were produced. The main reason that were not used in industrial application before this date was because the X-ray tubes (the source of the X-rays) of that period broke down under the voltages required to produce rays of satisfactory penetrating power for industrial purpose. However, that changed in 19 13 when the high vacuum X-ray tubes designed by Coolidge became available. The high vacuum tubes were an intense and reliable X-ray sources, operating at energies up to 100,000 volts. In 1922, industrial radiography took another step forward with the advent of the 200,000-volt X-ray tube that allowd radiographs of three inches thick steel parts to be produced in a reasonable amount of time. In 1931, General Electric Company developed 1000,000 volt X-ray

L/ qenerators. That same year, the American Society of Mechanical Engineers (ASME) permitted X-ray approval of fusion welded pressure vessels.


gatherin types of :--.--+: - certain I fluoresc

Shortly after the discovery of X-rays, another form of penetrating rays was discovered. In 1896, French scientist Henri Becquerel discovered radioactivity somewhat by accident, like many other great scientific discoveries. Many of the scientists of the period were working with cathode rays, and other scientists were

~g evidence on the theory that the atom could be subdivided. Some of this new evidence showed that cer'qi- /

' atoms disintegrate by the rnselves. It was Henri Becquerel who discovered this phenomenon while d

ulvcar~~ating the properties of fluorescent minerals. Becquerel was working on the principles of fluorescence, minerals glow (fluoresce) when exposed to sunlight. He utilized photographic plates to record this :ence.

I

expose - A

questior the fog - - - . - -. . .

led whal * g was . - - . .. .

One of the minerals Becquerel worked with was a uranium compound. On a day when it was too cloudy to his samples to direct sunlight, Becquerel stored some of the compound in a drawer with photographic

dates. When he developed these plates a couple of days later, he discovered that they were fogged. Becquerel t would have caused this fogging. He knew he had wrapped the plates tightly before using them, so - not due to stray light. In addition, he noticed that only the plates that were in the drawer with the

umuum compound were fogged. Becquerel concluded that the uranium compound gave off a type of radiation that could penetrate heavy paper and affect photographic film. Becquerel continued to test many samples of uranium compounds and determined that the source of radiation was the element uranium. At this time, enough information was gathered to determine that an element, which gives off radiation, is said to be radioactive, and possesses the property of radioactivity. Becquerel's discovery was, unlike that of the X-rays, virtually unnoted by the layman and scientist alike. Only a relatively few scientist were interested in Becquerel's findings, and it was not until the discovery of radium by the Curies two years later that interest in radioactivity became wide spread.

While working in France at the time of Becquerel's discovery, Polish scientist Marie Curie became very interested in his work. She too, suspected that a uranium ore known as pitchblende contained other radioactive elements. Marie and her husband, a French scientist, Pierre Curie started looking for these other elements. In 1898, the Curies discovered another radioactive element in pitchblende; they named it 'polonium' in honor of Marie Curie's native homeland. Later that same year, the Curie's discovered another radioactive element for which the*- named 'radium', or shining element. Both polonium and radium are more radioactive than uranium. Since thes~ - discoveries, many other radioactive elements have been discovered or produced.

The initial gamma ray source was radium, which allows radiography of castings up to 10 to 12 inches thick During World War 11, industrial radiography grew tremendously as part of the Navy's shipbuilding program. Shortly after the war, manmade gamma ray sources such as cobalt and iridium became available in 1946. These new sources were far stronger than radium sources and were less expensive. Thus the manmade sources rapidly replaced radium, and the use of gamma rays grew quickly in industrial radiography.


60" Coverage for Pipes and Location Marker Measurements

I General Information I Distance Between Location Markers (centerline) 1

Outside Circumference

k.4.

I

Outside Circumference 60" L~ NPS Diameter (OD times pi) Coverage


12 5 I 1 7 9 6 8 10

Common Math Formulas

Ii(D1) = 12(D2) 2

Ma, (SFD , ) 2 - Ma, - (SFD 1

2

2

Ma, (SFD 2 ) 2 - Ma - (SFD )

1

Ma=Milliamperage SFD=Source to film distance

J",:'" ," SFD , ,=

a, (SFD 1 ) 2 a, =

2 (SFD )

SFD , a , (SFD )

a 2

(SFD ) 1

Ci=Curie SFD=Source to film distance


2 Ef, (SFD ,

Ef , = 2

(SFD )

Ef (SFD 2 ) ' Ef, =

(SFD )

Ef=Exposure factor SFD=Source to film distance

SFD ;i' T 2 (SFD 1 ) 2

1

- T 1 (SFD 2 ) 2

SFD T 2 -

(SFD ) 1

T=Time SFD=Source to film distance

OF, (SFD ) OF, =

(SFD ) 2

2

SFD ;i' OF (SFD 2 )

OF 2

OF (SFD ) ' OF, =

(SFD ) 1

OF=Offset SFD=Source to film distance


(TS + GAP) x OM SFD = new SFD TS

TS=Depends on technique used 7 SFD=Source to film distance

GAP=Film to specimen distance

Dm( Efi) = Dm ( Efl) Dn=Densitv Ef=Ex~osure factor

(TM or TS) X DS MS

TM)=Thickness (TM if location marker is on TM) - DS=Defect shift MS=Marker shift

FSS = IS - (2 X PHs) FSS=Focal spot size IS=lmage size

PHS=Pin hole size

Adding / Removing Shielding

I = Intensity after adding shielding 10 = Original intensity

HVL = # of Half-value layers added

Determining Shielding Required

h (A) HVL = I

.693

HVL = # of HVCs required to reduce intensity In = Natural logrithm lo = Original intensity I = Desired intensity

Decay Fomula

A = New activity Ao = Original known activity

n = TlHL T = Time passed since known activity passed

HL = Half-life of the isotope

I = Intensity after removing shielding 10 = Original intensity

HVL = # of Half-value layers added -

Common Half-Value Layers for IRl 92 d

Concrete 1.75" Steel .500" Lead .190" Tungsten .130"

Kodak Radiographic Films

Type Speed Grain R 8 Ultra fine M 4 Extra fine T 2 Extra fine AA 1 Fine

Gamma Radiation Exposure Calculator Experienced Based Roentgen Factors (Steel)


D E N S I T Y F 1.0

.652 1.3

2.6

I L M

AA T

M

1.5 .730 1.46

2.92

2.5 1.25 2.5

5.5

2.0 1.0 2.0

4.0

3.0 1.55 3.1

6.2

4.0 2.4 4.8

9.6

Magic Circles

D=Dose DR=Dose rate T=Time

Ef-Exposure factor Ma=Milliamperage T=Time

EeExposure factor Ci=Curie

L T=Time

Single Wall Exposure 1 Single Wall Viewing for Plate

I SWE 1 SWV (PLATE) 1

Film Pb "B"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON Tm

SHIM = BASED ON (1) WELD AND (1) ROOT REINFORCEMENT

SFD = BASED ON Ts ENERGY = BASED ON Ts

Inspector's Handbook 7- 15.

Single Wall Exposure 1 Single Wall Viewing for Pipe

I SWE I SWV (PIPE) 1

Source * Film

Pb "6"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON Tm

SHlM = BASED ON (1) WELD AND (1) ROOT REINFORCEMENT

SFD = BASED ON Ts ENERGY = BASED ON Ts

Double Wall Exposure 1 Double Wall View (superimposed)

I DWE 1 DWV I Source *

Film I Pb "B"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON (2) Tm


SFD = BASED ON OUTSIDE OD ENERGY = BASED ON (2) Tm, (2) WELD AND

I *

(2) ROOT REINFORCEMENTS I

Double Wall Exposure / Double Wall View (offset) I DWE I DWV I

Source +% - T m F

Consumable lnsert

I markers I

I Film

I Pb "B"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON (2) Tm


SFD = BASED ON OUTSIDE OD ENERGY = BASED ON (2) Tm, (1) WELD AND

(1) ROOT REINFORCEMENT

- Double Wall Exposure / Single Wall View

DWE I SWV

I Consumable Insert I

Film

Pb "B"

TM = DESIGN MATERIAL THICKNESS PENNY = BASED ON (1) Tm FILM SIDE PENNY CHART

SHlM = BASED ON ( I ) WELD AND (1) ROOT REINFORCEMENT

SFD = BASED ON (1) Ts u ENERGY = BASED ON (2) Tm, (1) WELD AND

(1) ROOT REINFORCEMENT

Inspectds Handbook

KILLER CARL

Magnesium

Aluminum

Penetrameter Material and Group Numbers

Titianium . ? 1 G R O U P 0 1 S-51.S-52,s-53

Carbon steel Alloy steel Stainless steel Manganesse-nickel-aluminum bronze S-I 1 C. S-11 D. S-36B, S-37A.

Aluminum bronze 1 1 . jGROUP 2 S-35, S-36

Nickel-chromium- iron alloy V~GROUP 3 S-42, S-43. S-44

Nickel-copper alloys Copper-nickel alloys

Tin bronze Gun metals Valve bronze

Inspector's Eandbook

- -


2% Penetrameter Quality Conversion Chart (X-RAY ONLY)

Basic Components of an Xray Tube

Highvoltage Cathode Struc Power supply

Low- I ' / Filament 87 I/ , Electron

supply

Focusing cup

voltage power 7

\ Tube

1 envelope X-ray beam

Types of Scatter Radiation

Test piece

L (a) Internal - (b) Side - (c) Back scatter scatter scatter


Radiographic Film Interpretation

Arc strikes

DEFINITION: 4

Any localized heat-affected zone or change in the contour of the surface of the furished weld or adjacent base metal resulting from .an arc or heat generated by the passage of electrical energy between the surface of the finished weld, base material and a current source, such as welding electrodes or magnetic particle inspection electrodes.

RADIOGRAPHIC APPEARANCE: A localized area, rounded or irregular, and generally found adjacent to the edge of the weld image on the

base metal. The density of the indication appears lighter when the discontinuity is convex from the addition of filler metal with arc strikes resulting from SMAW process. The density of the indication appears darker when the discontinuity is concave resulting from a gouging of the material with arc strikes resulting from the GTAW or SMAW processes.

CAUSES: Not initiating the arc as required by the welding procedure. Accidentally striking an arc on the completed weld or base material. Engaging the magnetizing current prior to establishing fm contact with the test surface when using prods. Moving or removing the prods from the test surface without disengaging the magnetizing current.

REMARKS/SPECIAL CONSIDERATIONS: Arc strikes from welding and MT are generally revealed and dispositioned upon acceptance Visual inspection.

However, welding arc strikes may occur from another welding operation in the area after the VTPT inspectior and prior to the RT. Arc strikes occurring in this sequence have a random location and can be found on the we. Y

well as on the base metal. Arc strikes fiomMT will be difficult to detect by RT.

Visual inspection should always be performed to confirm arc strikes.


Burn through

DEFINITION: A. void or open hole extending into a backing ring or strip, fused A

oot or ac liacent b&e metal. - -

IXAULWKAYHIC APPEARANCE: m irregular localized area of darker density, often rounded,

gmerdlly found at the center of the weld image. If excessive globules of the weld puddle resulting from the burn through, are present on the inside of the weld joint, their appearance will have a lighter density due to the additional weld metal. The nature of burn through is such that the

Using ' Improy

- - .

s edges

u.

a weld c jerly pre too slou Idle. - -- C L ---

of the in i may or may not be sharply defined.

:urrent h paring t

.

CAUSE; igher than allowed by the welding procedure.

t he tungsten electrode tip. Using r a weldp d of travel will cause overheating of the

weld put Improper n r up of the wela jomt (unacceptable root gap).

ECIAL ( IERATIONS : - I 11G u ~ s ~ ~ l ~ ~ s h i n g fea~urt; U G L ~ X I I a burn through and a melt through is that a burn through results in an open hole on the ID of the pipe.

Burn through most often occur during the welding of the root pass, although it is possible for this discontinuity to be introduced during the welding of the second layer.

L Burn through frequently occur during weld repairs, especially when the repair cavity is at the root depth. I

Visual inspection should always be performed, if possible, to confirm bum through.


Concavity

I-ION:

RADIOGRAPHIC APPEARANCE:

CAUSE!

REMARKS/SPECIAL CONSIDERATIONS:


Crack crater

DEFINITION: A linear rupture of metal under stress.

b , ~ ~ o ~ ~ ~ ~ ~IRANCE: Generally a star shaped indication with irregular, feathery? twisting lines of darker density oriented within a

weld crater. The discontinuity is usually shallow, therefore, the indication may not be as pronounced as indications ~UUU~GC.I from other types of cracking.

' Impr01 B Not ad - T

CAUSES: 4 )f the welding arc by abruptly removing the arc. 4 meters of the welding procedure.

incomplete fillmg 01 ule weld crater.

REMAP be emp crater cr .-. -- 3: -

I 2ONSIDERATIONS: It is to hasized that although the discontinuity and resulting radiographic indication is generally star

shaped, acking does not always take this shape. Random raaographic indications from crater cracking may be oriented in any direction to the weld axis.


Crack, longitudinal (shown in the root)

DEFINITION: A linear rupture of metal under stress.

RADIOGRAPHIC APPEARANCE: Irregularly shaped, feathery, twisting lines of darker density

oriented along the axis of the weld.

CAUSES: Improper fit-up of joint. Contamination of base material. Violation of the welding procedures.

REMARKS/SPECIAL CONSIDERATIONS: Longitudinal cracks can occur throughout the weld; in the centerline,

fusion lines and in the root. Cracking can, at times, be difficult to detect due to the geometric

principles of the radiographic technique.

Crack, transverse

DEFINITION: A linear rwture of metal under stress.

u &IDIOGRAPHIC APPEARANCE: Irregularly shaped, feathery, twisting lines of darker density

oriented perpendicular to the axis of the weld. Transverse cracks are generally tight discontinuities, therefore producing subtle indications on the radiograph.

CAUSES: Transverse cracks are generally the result of longitudinal shrinkage

strains acting on weld metal of low ductility. Most commonly found in weld joints having a high degree of restraint.

REMARKSISPECIAL CONSIDERATIONS: Cracks may be limited in size and completely within the weld metal,

but may also propagate fiom the weld metal into the adjacent heat affected zone.

Orientation and subtleness of the discontinuity can, at times, be difficult to detect due to the geometric principles of the radiographic technique.

Cracking indications can be masked in the as-welded condition.

\v

Inspector's Handbook 7-3 1

Crater pits

indicatia subtle to

DEFINITION: An approximately circular surface condition extending into the weld in an irregular manner.

e RADIOGRAPHIC APPEARANCE:

%e indication will appear as a circular dot with darker density, similar to porosity, in the root area of lble insert welds. However, due to the irregular nature of discontinuity, the edge of the indication is usually

I~UL a5 uefined as porosity. The irregularity of the discontintinuity can produce a "halo" effect on the edge of the guishing a crater pit fiom porosity. The radiographic indication from crater pits can range fiom nced, depending on the severity of the pit.

CAUSE Impr01

The in Porosi

- xr:--.-1 . A"- * Additi confiinn;

~n, distin I pronom

S : per ten nination of the welding arc. lhering to the parameters of the welding procedure.

REMARKSISPECLAL CONSIDERATIONS: s from crater pits can be misinterpreted as porosity. ccur anywhere in the weld, while crater pits occur in the weld root area.

vlq11n~ mspecrion should always performed, if possible to confirm crater pits. onal radiography, e.g. putting the indication in the sidewall or profile view, may be employed to assist in ation of the discontinuity.


Incomplete fusion of a consumable insert

DEFINITION: Tncomplete melting of the consumable insert without fusion and bonding to the base metal along one or

\c/ F :s of the consumable insert.

I he axis I

n elonge eld. The

RADIOGRAPHIC APPEARANCE: i unifom ~ted band or localized bad of lighter density in the center of the weld image, oriented along

1 of the w L width of the band appears approximately equal to the diameter of the consumable insert.

material The in

material is not fu

CAUSE Impro!

cation n - - . The indi lay appear in the following ways The indcation rnav aDpear with both edges straight with abrupt density transitions fiom the insert area to the base

I area. TI rites lack of filling or blending to the base metal, with both sides of the insert not fused. I dication pear with one edge having a smooth, gradual density transition fiom the insert area to the base material area and the other edge straight with an abrupt density transition fiom the insert area to the base

lis indicates the former edge is blended with firsion into the adjacent base metal and the latter edge area. ll sed.

of the ,

S: ~ f i t UP weld joint.

Using too low a welding current. Using too fast of a travel speed. An incorrect torch angle. An improper motion or weaving technique of the torch.

REMARKS/SPECIAL CONSIDERATIONS: b 8 Visual inspection should always be performed, where possible, to confirm incomplete fusion of the insert, when

viewed on radiographs.


Lack of fusion

DEFINITION: Lack of complete fusion of some portion of the metal in a weld

joint with the adjacent metal. The adjacent metal may be either base metal or previously deposited weld metal. When the discontinuity occurs between a weld bead and the adjacent base metal, the term "lack of sidewall h ion" is often used, does not occur in the root.

RADIOGRAPHIC APPEARANCE: Irregularly edged, or straight and irregularly edged lines of

darker density oriented along the axis of the weld. If lack 6f fusion occurs between weld beads, both edges of the indication may be irregular as they indicate the weld puddle not fusing to the contour of the previously deposited weld beads. If the lack of fusion occurs between a weld bead and base metal, one edge of the indication will be straight, as it indicates the weld puddle not fusing to the prepared base meal. Sometimes the lines are interspersed with darker density spots, of varying shapes, indicating voids resulting from the lack of fusion.

CAUSES: mcient welding current to melt the adjacent metal. Too fast a welding speed of travel will not allow for fusion to the

adjacent metal. Too fast a welding current to melt the adjacent metal. Improper torch or electrode angle may prohibit melting of the adjacent metal.

. Improper placement of weld passes may cause a sharp valley to fonn. Lack of proper access to the face of weld joint. - -

Tightly adhering oxides resulting from improper cleaning of items to be welded.

REMARKS/SPECIAL CONSIDERATIONS: Lack of fusion on the under bead side of the weld, lying in a horizontal plane, tends to be undetectable but often

the sides of lack of fusion lines tend to curl out of the horizontal plane and are recorded on the radiograph. - - A distinguishing characteristic between lack of fusion and incomplete penetration is that lack of h i o n can occur

anywhere in the weld and incomplete penetration occurs at the weld root.


Lack of penetration (left - nonnal fit-up, right - mismatch)

DEFINITION: Lack of penetration of the weld through the thickness of the joint or penetration which is less than

k specified.

straightr incompl

GRAPHIC APPEARANCE: Straight, fine edged lines of darker density oriented along the axis of the weld in the area of the root. The less of both edges of the indication's image and location in the center of the weld image help to distinguish ete penetration from lack of fusion.

CAUSE Insuff

- I---- - r-- In bot

cause a Joints

elding current or to fast travel speed. - Irnnroya wren or electrode angle to melt the root land. h backing ring joints and joints to be welded from both sides, improper placement of initial weld pass may sharp valley to form at the root weld.

from both sides, insufficient removal of the backside prior to welding.

s atthe7 on can b

weld roc e promi

REMARKSISPECIAL CONSIDERATIONS: ~t and is always straight, as it is a RT indication of the actual weld joint preparation. The nent or subtle depending on the severity of the discontinuity.


Melt through -.

DEFINITION: A convex or concave irregularity on the s&ce of a backing ring

or strip, through hole.

fbsed root or adjacent base metal resulting from fusing comple a localized region but without development of a void or open

RADIOGRAPHIC APPEARANCE: A localized area, usually rounded, and generally found at the

center of the weld image. The density of the indication appears lighter when the discontinuity is convex and darker when the discontinuity is concave.

CAUSES: Using a weld current higher than allowed by the welding procedure. Improperly preparing the tungsten electrode tip. Using too slow a welding speed of travel will cause overheating. Improper fit up of the weld joint (unacceptable root gap).

REMARKS/SPECIAL, CONSIDERATIONS: The entire thickness of metal is melted or re-melted and deforms, m

hole or void develops as with a burn through. Melt through most often occurs during the welding of the root pass,

although it is possible for this discontinuity to be introduced during the welding of the second layer. Visual inspection should always be performed, if possible, to confirm melt through.

u


Offset (misalignment/rnismatch, shown with LOP)

DEFINITION:

'L Lateral misalignment of two butt joint members of equal thickness.

RADIOGRAPHIC APPEARANCE: Offset on piping weld joints can appear on the film in different

ways. The radiographic image is dependent upon the orientation of the offset to the beam of radiation. When the offset condition is parallel to the beam of radiation, the offset image may appear as an abrupt density change, generally half m y across the width of the weld image. When the offset condition is perpendicular to the beam of radiation, and the entire image of the item is on the film, the offset image will appear in the sidewall or profile view, as lateral misalignment of the members with a high-low effect of the pipes' ID and OD.

CAUSES: Improper fit-up or fixturing may cause the members to be offset.

Improper welding block sequencing on the root pass.

REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be performed to c o n f i i questionable offset conditions when viewed on

radiographs.


Oxidation

DEFINITION: A condition resulting from partial or complete lack of purge of a surface which is heated during weldiv

resulting in formation of oxide on the surface. This condition may range from slight oxidation through the u formation of heavy black scale to the extreme of a very rough surface having a rough crystalline appearance.

OGRAPHIC APPEARANCE: Highly irregular, low density area, with a wrinkled or sugared appearance in the center of the weld image.

The condition may extend for the entire circumference of the weld when there is a complete loss of purge. The condition may only be localized, in one or more areas of the weld, occurring whenever the purge is partially interrupted.

CAUSES: *, Loss of internal purge gas resulting in an unshielded molten weld puddle on the ID.

High oxygen content in purge gas or path. Moisture in the area of the weld, due to inadequate drying of the purge path, leakage, etc ...

REMARKSISPECIAL CONSIDERATIONS: A visual inspection should always be performed, if possible, to confirm oxidation. Oxidation generally occurs during the flowing of the weld root. However, this condition may occur during

welding if there is a degree of root reflow, loss of purge, or moisture present. Oxidation frequently occurs during weld repairs.

Overlap (re-entrant angle)

DEFINITION: The protrusion of weld metal beyond the weld toes or weld root.

sidewall at the fu:

phic im2 r is not ; -. .&+L .. d -

or profi sion line

" ,~IOGRAPHIC APPEARANCE: 3verlap conditions on the OD of piping butt weld joints should be an extremely m e occurrence in as much

i ;factory VT and other surface inspections, such as PT or MT are required prior to RT. However, overlap on ult: mternal weld surface consumable insert piping weld butt joints can appear on the film in different ways. The I ige is dependent upon the orientation of the overlap to the beam of radiation. When the overlap

located in the sidewall or profile view, the overlap image will appear consistent with that of C u l ~ v c n l r v WIU~ an abrunt density change at the fusion line of the weld root image. When the offset image is in the ! it will appear as roll over of the weld root reinforcement with an unsatisfactory blending i weld root image.

- I

le view, :ofthe\

S: I ow of a welding speed.

.roo low or too hi& of a welding current. M e angle. ect torch

- I or elecl

REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be performed, where possible, to confm questionable root surface conditions

when viewed on radiographs.

Inspector's Harrdbook 7-39

Porosity (right - clustered porosity, bottom left - distributed porosity, bottom right - aligned porosity in the root)

DEFJNITION: Gas pockets or voids in weld metal.

RADIOGRAPHIC APPEARANCE: Usually spherically shaped areas of darker density and may be

scattered throughout single pass welds or throughout several passes of multiple pass welds. Although usually spherical in shape, porosity may also occur as nonspherical pockets and appear on the radiograph as elongated voids, sometimes referred to as "piping or wormhole porosity". The density of the indication varies directly with the diameter or magnitude of the pore.

CAUSES: Faulty welding techniques such as using too long an arc with the

SMAW process. Improper cleaning of the weld joint.

REMARKSISPECIAL CONSIDERATIONS: None.


Root razorback condition

DEFINITION: An oxide membrane, gray in color, with a sharp ridge or peak and ribs fi.om the peak to the edge giving it a

L 'ierringbone effect. Also known as "reverse center line crease."

RADIOGRAPHIC APPEARANCE: The image of root razorback is consistent with that of convexity with an associated herringbone appearance

and sharp peak at the center. The lightest density of the image is in the center and is dependent upon the height of peaked condition. The density of the image gradually increases as the condition blends into the base metal.

CAUSES: Moisture in the area of the weld. Moisture in the purge gas.

REMARKSISPECIAL CONSIDERATIONS: This is one of the most common root surface defects encountered when welding NiCu and Ni-C-r-Fe. Visual inspection should always be performed, where possible, to confm root razorback condition when viewed

on radiographs.


Root surface centerline crease

DEFINITION: An intermittent or continuous peripheral centerline concavity fonned on the root surface.

I 4

RADIOGRAPHIC APPEARANCE: The image of centerline crease is consistent with that of concavity with an associated herringbone

appearance. If the crease has a notch or a questionable blending condition at the center, the image will crease oriented along the axis of the weld.

CAUSES: Thick cover pass over a consumable insert that had minor concavity. Excessive welding current.

REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be preformed, where possible to confm questionable centerline crease when

viewed on radiograph. Approved workmanship sample radiographs may be employed to evaluate centerline crease when a visual

inspection is not possible.

Inspector9s Handbook

Root surface concavity

DEFINITION: A depression on the root surface of the weld, which may be due to

L/ -pvity, internal purge or shrinkage.

RADIOGRAPHIC APPEARANCE: The image of concavity may appear as intermittent elliptical areas

or elongated bands of darker film density oriented along the axis of the weld in the center of the weld image. The width of the image is consistent with the weld root width. The darkest density of the concavity's image is generally in the center and is dependent up6n the depth of the concavity. The density of the image gradually decreases as the concavity blends into the base metal.

CAUSES: . Improper fit up of the weld joint.

Using too high of a'welding current, too slow of a travel speed, or extremely high purge gas flow rate.

REMARKSISPECIAL CONSIDERATIONS: Visual inspection should always be preformed, where possible to

confirm questionable concavity when viewed on radiograph.


Root surface convexity

I TION: Reinforcement of tk root surface of a butt- ksed type weld.

I 4

RADIOGRAPHIC APPEARANCE: The image of convexity may appear as intermittent elliptical areas or elongated bands of lighter film

density oriented along the axis of the weld in the center of the weld image. The widthof the image is consistent with the weld root width. The lightest density of the convexity's image is generally in the center and is dependent upon the height of the convexity blends into the base metal.

CAUSES: Using to low or high of a welding currert. Using too slow travel speed when welding.

REMARKS/SPECIAL CONSIDERATIONS: Visual inspection should always be performed, when possible, to confirm questionable convexity when viewed

on radiographs.

Slag,

DEFINITION: Non-metallic solid material entrapped in weld metal or

b'ptween weld metal and base metal. . 2 RADIOGRAPHIC APPEARANCE:

Well defined, irregularly shaped, uniformly darker density areas usually elongated along the axis of the weld.

' Impr01 between -

Slag is roods. T

-- -

- too low welding 3n. nx bead +La L,,,

per inter

.--- ,---

(

unproper 111-up, sucn as maequate bevel of the joint sides. Using a weldin ~t for the size of electrode. Faulty : techniq 1 as wrong electrode position or

orientatic I znt causing sharp valleys or undercutting 1

mpro] slag from the surface.

r a bypr hus, slag

placemt is.

kg currer ues sucl

pass clel

oduct of g inclusi~ . a,... a,.,

'the bur^ OnS are i .. ... +I...-.

REMARKSISY~CIAL CUNSIOERATIONS: ning of the flux covering on welding asociated with the SMAW process.

Slag hlulw~v~la w -UJ ull~rlghout the weld, in the center of the welcl-in fusion lines and in the r&t.

'v

Inspectds Handbook

Tungsten inclusion

DEFINITION: Metallic tungsten inclusions in the weld deposit.

RADIOGRAPHIC APPEARANCE: Irregularly shaped spots of low film density areas, usually

random in size and location. They are solid or liquid bits of tungsten electrode from the TIG welding process that drop or are melted from the electrode and become entrapped in the weld puddle. Tungsten inclusions appear as low or light density areas on the radiograph because of the differences of radiographic absorption between the inclusion and surrounding metal. sten en is dnwr radi6graphically then the surrounding metal and therefore absorbs more radiation. This, in turn, allows fewer rays to reach the film.

CAUSES: Overheating the tungsten electrode due to excessive current for the

particular electrode size. DpfPctive tungsten electrode (flaking of particles).

ing the tungsten molten puddle. into the --*-

m Dipp

REMARKSISPECIAL CONSIDERATIONS: None.

Undercut

.tl

he base I

DEFINITION: An intermittent or continuous groove on the external surface of metal along the edge of the weld.

51 kAuluGWHlc MY~ARANCE:

a irregular, elongated area of darker density oriented along the extamdl h i o n line of the weld image to the base metal.

using 8 using

rrn

filler me An inc

too long excessiv . .'a

cxccsslve welding current. t an arc length will result in a gouging effect. I ,e welding speed of travel.

w nen uslng me GTAW process, adding an -cient amount of

ectrode angle can cause a gouging effect.

acceptar Visual

ice Visu i inspect:

inspec ion shou . .

REMARKS/SPECIAL CONSIDERATIONS: External undercut is readily revealed and dispositioned upon

:tion. Id always be performed to confirm questionable

extema unaercut wnen viewed on radiographs.

- Inspector's Handbook 7-47

Undercut, root - DEFINITION:

An intennittent or continuous groove in the internal surface of the base metal, backing ring/strip along the edge of the root of the weld.

)GRAPHIC APPEARANCE: An irregular, elongated area of darker density oriented along the

lnternai h i o n line of the weld image to the base metal.

filler m

mproper la up of the weld joint. Excessive current during welding When using the GTAW process, adding an insufficient amount of

incorrect electrode angle can cause a gouging effect.

Radic based c . .

KEMARKS/SPECIAL CONSIDERATIONS: evaluation of root undercut in backing ring joints can be

nanship sample radiographs as well as the use of slotted

7-48 ImyectoISs Handbook

Weld splatter

DEFINITION: . In arc welding, the metal particles expelled during welding which do not form a part of the weld.

iL/ , RADIOGRAPHIC APPEARANCE:

Small, rounded areas of lighter density generally found adjacent to the edge of the weld image on the base metal.

CAUSES: There will be some weld spatter when using the SMAW process. However, long arcing is a factor. Lack of concentricity or damage to the electrode flux.

REMARKS/SPECIAL CONSIDERATIONS: Weld splatter is most commonly found when the SMAW welding process is employed. Weld spatter is generally revealed and dispositioned upon acceptance Visual inspection. However, weld spatter

may occur from another welding operation in the area after the acceptance VTPT inspections and prior to the RT.


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