pressure vessel training module

8/13/2019 Pressure Vessel Training Module

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DOCUMENTTITLE

:PRESSURE VESSEL TRAINING MODULE

DOCUMENT NO. : PV-100REVISION : 0 (Mar-2010)


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PRESSURE VESSEL TRAINING MODULERevision 0 (Mar-2010)

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Table of Contents

1. Purpose .................................................................................................................................... 2 2. Vessels Supports ..................................................................................................................... 2

Horizontal Vessels Saddle Supports ........................................................................................ 3 Vertical Vessels .......................................................................................................................... 4 3. Data Sheet Preparation ............................................................................................................ 7 4. ASME Code, Section VIII, Division 1 Vs. Division 2 ......................................................... 12 5. Materials ............................................................................................................................... 13

Carbon Steel .............................................................................................................................. 13 Carbon-Moly Steel (Low Alloy Steel For High Temperature) ................................................. 14 Chrome-Moly Steel (Low Alloy Steel For High Temperature)................................................ 15 Low Alloy Steel For Low Temperature .................................................................................... 16 Stainless Steel (High Alloy Steel) ............................................................................................. 16

Nonferrous Alloys ..................................................................................................................... 19 Material Selection ..................................................................................................................... 21

6. MDMT .................................................................................................................................. 25 Definition of Brittle Fracture .................................................................................................... 25 Impact Test Exemption per UCS-66 ......................................................................................... 26 Impact Test Exemption per UCS-66.1 ...................................................................................... 29

7. Radiography .......................................................................................................................... 34 Spot Radiography ...................................................................................................................... 34 Full Radiography ...................................................................................................................... 34

8. PWHT By Service Conditions .............................................................................................. 35 9. Nozzle Connections .............................................................................................................. 36 10. Type of Hydrotest .............................................................................................................. 39


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1. PurposeTo prepare Mechanical Pressure Vessel Data Sheet, the originator shall havepressure vessel design experience and shall ensure the work is both accurate andcomplete. The purpose of this Standard is to provide knowledge to originators forpreparation of the Mechanical Pressure Vessel Data Sheet.

This Practice covers an overview of the ASME Division 1 and 2, two aspects ofmaterials selection for pressure vessels which are selection for the serviceconditions and selection for MDMT & design temperature. This practice also coversinformation about radiography & PWHT requirements and nozzle type selection.

2. Vessels SupportsPressure vessels are normally supported by one of the following methods (SeeFigure 1):

Skirts

Support legs Support lugs Ring girders Saddles

Fig. 1 Typical Vessel Supports


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Horizontal Vessels Saddle SupportsHorizontal vessels are typically supported on two saddles. The design methods ofsupports for horizontal vessels are based on L. P. Zicks analysis presented in1951. Material of vessel saddle shall be A283 Gr. C and reinforcing plates directlywelded to shell shall be of the same material as the vessel shell.

The distance between the head tangent line and the center line of the saddleshould in no case be more than 20% of the tangent-to-tangent length, L. One endof the horizontal vessel typically contains a sliding support to facilitate thermalexpansion. The minimum contact angle suggested by the ASME Code is 120,except for very small vessels.

Fig. 2 Horizontal Vessels on Saddle Supports


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Vertical VesselsVertical vessels may be supported by skirts, legs or lugs. In general, verticalvessels are skirt-supported when the vessel diameter exceeds about 4'-0 or whenthe shell height to diameter ratio exceeds about 3.

Vertical Vessel Support Legs Leg-supported vessels are normally lightweight, and the legs provide easyaccess to the bottom of the vessel. Legs may be made of angle, U-channel, H-beam or pipe and the number of legs may be 3, 4 or more depending on thevessel diameter. Material of support legs shall be structural steel A36 orfabricated from either A283 Gr. C or A285 Gr. C. Legs longer than about 7 feet(2.1m) should be cross braced. Do not use legs where high vibration, shock orcyclic service is anticipated in the vessels. Legs length will be decided by pipingdesigner.

Fig. 3 Vertical Vessel on Leg Support

Vertical Vessel Lug Supports

Vessels supported on lugs commonly located in structure. Two or four lugs are

commonly used. The lug itself may have two gussets and a top plate. Reinforcingplate may be used to stiffening the shell. Material of support lugs shall bestructural steel A283 Gr. C or A285 Gr. C. If local stress on shell at lug locationexceed allowable one, use ring-girder type. Lug support elevation will be decidedby piping designer.


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Fig. 4 Vertical Vessel on Lug Support

Vertical Vessel Ring-Girder

Sometime ring girder which consist of upper and lower ring are added on the lugswhich have the advantage of supporting torsional and bending moments resulting

from the transfer of loads from the vessel wall to the supports.

Fig. 5 Vertical Vessel Ring-Girder Support

Vertical Vessel Skirts

When supported on skirts, the corroded centerline of skirt plate shall coincidewith the corroded centerline of bottom shell plate, rounded off to the nearest 1/16"(1.5mm). Minimum thickness for carbon steel skirt shall be 1/4" (6mm). For headthicknesses 1" (25mm) and greater, the skirt thickness shall be no less than 1/4of the thickness of the part to which it is attached, except that the skirt thicknessneed not exceed 1-1/2" (38mm) in satisfying this requirement. No corrosionallowance is required for skirt and base rings, unless otherwise required by clientspecifications, etc. Skirt shall be straight type when height to inside diameter ratiois less than 18 and shall be flare when height to inside diameter ratio is greaterthan or equal to 18. Skirt height will be decided by piping designer.


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Fig. 6 Vertical Vessel on Skirt Support


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3. Data Sheet PreparationThe Vessel Drawing/Data Sheet is prepared in conjunction with project specificationsuitable for obtaining comprehensive bids and subsequent purchase of pressurevessels. The engineer shall have pressure vessel design experience and shallensure the work is both accurate and complete and shall avoid supplyinginformation that is not needed.

Below is a sample of pressure vessel data sheet that can be modified according toproject requirements. This section provides guidance for completion of eachnumbered line on the Data Sheet as below.

Construction Code Corrosive Service Yes NoPressure Vessel Specification Cyclic Service Yes NoDesign Pressure psig Other Special ServiceDesign Temperature oF Code Stamp Yes NoMin. Design Metal Temperature (MDMT) oF MIGAS Certificate Yes NoOperating Pressure psig MAWP BasisOperating Temperature oF Impact Test Yes NoRadiography Full PWHT Yes No

Corrosion Allowance in HydrotestLiquid Specific Gravity Painting SpecificationLiquid Level in Yes, thk: in SG:

NoWind Design Code Yes, thk: in SG:

Basic Wind Speed mile/hr NoExposure

Importance Factor Internal Ladder Seismic Design Code Insulation Clips Top davit

Seismic Zone Fireproofing Clips Cathodic PotectionSoil Profile Pipe Support Clips Name Plate

Earthing Lugs / Boss Lifting Lugs Tailing Lugs

Insulation(By Others)

DESIGN DATA

Spot Per Code

Calculated Dsg Press.Per Code

Platform / Ladder Clips

Fireproofing(By Others)

ACCESSORIES

DESIGN DATAConstruction Code: ASME VIII Div 1 or 2, PD5500, etc (see sec. 4 of this document) Pressure Vessel Specification: document number of pressure vessel specificationDesign Pressure: see the value in the process data sheetDesign Temperature: see the value in the process data sheetMin. Design Metal Temperature (MDMT): see the value in the process data sheetOperating Pressure: see the value in the process data sheetOperating Temperature: see the value in the process data sheetRadiography: see sec. 7 of this documentCorrosion Allowance: see the value in the process data sheetLiquid Specific Gravity: see the value in the process data sheetLiquid Level: see the HIGHEST liquid level in the process data sheetWind Design Code: see project specification (for example: ASCE 02, UBC 97, etc)

Basic Wind Speed: see project specificationExposure: see project specificationImportance Factor: see project specification

Seismic Design Code: see project specification (example: UBC 97, etc)

Seismic Zone: see project specificationSoil Profile: see project specification

Corrosive Service: see process data sheetCyclic Service: see process data sheetOther Special Service: see process data sheetCode Stamp: see process data sheetMIGAS Certificate: Yes only for Oil & Gas projectMAWP Basis: calculated, if no specified in the project specificationImpact Test: Per Code, if no specified in process data sheet (also see sec. 6 of this document)PWHT: Per Code, if no specified in process data sheet (also see sec. 8 of this document) Hydrotest: see project specification (also see sec.10 of this document)


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Painting Specification: : document number of painting specificationInsulation: see process data sheet or PIDFireproofing: see process data sheet

ACCESSORIESPlatform / Ladder Clips: generally is requiredInsulation Clips: yes, if insulation is requiredFireproofing Clips: yes, if fireproofing is requiredPipe Support Clips: generally is requiredEarthing Lugs / Boss: generally is requiredLifting Lugs: generally is requiredTailing Lugs : Yes, for skirt vertical vesselInternal Ladder: generally is requiredTop davit: generally is required for skirt vertical vessel which has internal traysCathodic Potection: see process data sheetName Plate: generally is required

Head And Shell InternalCladding thk: in ExternalReinf. Pads Internal

Pipe External

Plate RemovableForgings Non-RemovableFittingsSupportsExternal Welded Parts

Empty lbOperating lbFull of Water lb

NOZZLE

NOTES

Remark

Boltings

Internals

Gaskets

Description

ESTIMATED WEIGHT

Mark QtySize(in)

Rating

Nozzle/Manhole

Necks

MATERIAL SPECIFICATIONS

Moment (lbf-ft)Shear (lbf)WindEarthquake

FlangeType

Proj.(in)

SHEAR & MOMENT AT BASE (OPERATING)

MATERIAL SPECIFICATIONS (see sec. 5 of this document)Head and Shell: see process data sheet (for example: SA516-70, SA240-316, etc)Cladding: see process data sheet (for example: SS316L, thk 3mm)Reinf. Pads : same material as shell and head (for example: SA516-70, SA240-316, etc)Nozzle/Manhole Necks: same generic material as head/shell (for example: SA106-B, SA312-TP316L, etc)Forgings: same generic material as head/shell (for example: SA105, SA182-F316L, etc)Fittings: same generic material as head/shell (for example: SA234-WPB, SA403-WP316L, etc)Supports: generally use SA283-CExternal Welded Parts: same material as shell and head (for example: SA516-70, SA240-316, etc)Gasket

Internal: fill up if the vessel has internal removable parts (example PTFE)External: see piping material specification (for example: 316 SS spiral wound 4.5t non-asbestosfilled CS OR / 316 SS IR, etc)


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BoltingInternal: fill up if the vessel has internal removable parts (example SA193-B8M/SA194-B8M)External: see piping material specification (for example: SA193-B7/SA194-2H)

InternalRemovable: such as trays, demister, etc, generally made from Stainless Steel (SS316, SS304,etc)Non removable: its mean the internal parts that welded to inside of vessel. The material same asshell/head (SA516-70, SA516-60, SA240-316, etc).

ESTIMATED WEIGHTEmpty: its mean fabrication weight without removable internals, insulation, fireproofing &platform/ladder.Operating: weight of empty plus operating liquidFull of water: weight of vessel complete with internal, insulation, etc plus water test.

SHEAR & MOMENT AT BASE:Fill up calculated shear & moment due to wind & seismic base on standard ASCE, UBC, etc asrequired by project specification. It can be leave it, and let vendor to fill up.

NOZZLENozzle data shall be filled up base on information in the process data sheet. (see also sec. 9 of thisdocument)

NOTESGeneral notes should be added as necessary to support, clarify, add information, or to give directionnot otherwise provided .


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Company Logo

Page of1 Client : Title :2 Project : Tag Number :3 Location : No. Required :4

Project No. : Doc. No. : Rev :56 Construction Code Corrosive Service See proc. dt sht Yes No7 Pressure Vessel Specification Cyclic Service See proc. dt sht Yes No8 Design Pressure psig Other Special Service9 Design Temperature oF Code Stamp See proj. spec. Yes No

10 Min. Design Metal Temperature (MDMT) oF MIGAS Certificate See proj. spec. Yes No11 Operating Pressure psig MAWP Basis See proj. spec.12 Operating Temperature oF Impact Test See Section 4 Yes No13 Radiography See section 5 Full PWHT See Section64 Yes No14 Corrosion Allowance in Hydrotest15 Liquid Specific Gravity Not less than 1 Painting Specification16 Liquid Level Use the highest liquid level in Yes, thk: in SG:17 No Insulation: see proc. dt sht or PID18 Wind Design Code Yes, thk: in SG:19 Basic Wind Speed mile/hr No check to process safety20 Exposure21 Importance Factor Internal Ladder 22 Seismic Design Code Insulation Clips Top davit23 Seismic Zone Fireproofing Clips Cathodic Potection24 Soil Profile Pipe Support Clips Name Plate25 Blast Pressure psi Earthing Lugs / Boss26 g Lifting Lugs27 g Tailing Lugs28 MATERIAL SPECIFICATIONS (See process data sht & section 3)29 Head And Shell Internal See piping material30 Cladding thk: in External See piping material31 Reinf. Pads Internal See piping material32 Pipe External See piping material33 Plate Removable34 Forgings Non-Removable35 Fittings36 Supports37 External Welded Parts to be the same as head & shell38

39 Empty lb40 Operating lb41 Full of Water lb42 NOZZLE (See process dt sht & sec. 743

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See process data shtSee project spec.

SHEAR & MOMENT AT BASE (OPERATING)

WindEarthquake

FlangeType

Proj.(in)

Roughly estimated

Roughly estimatedRoughly estimated

Moment (lbf-ft)by vendor by vendor

by vendor by vendor

Shear (lbf)

Nozzle/ManholeNecks

TransportationLoad

Horiz. Accelerations See project specificationSee project specificationVert. Accelerations

See sec. 1

See process data shtSee process data sht

See project specificationSee project specification

Refer to project specification

See process data sht

Fireproofing(By Others)

ACCESSORIES

See project specification

See project specificationSee project specificationSee project specification

Dsg Press.Per Code

Platform / Ladder Clips


See project spec.

See project specificationSee project specification




Insulation(By Others)

DESIGN DATA

PRESSURE VESSELDATA SHEET

R e v

i s i o n

Spot

See process dt sht

Per Code

Calculated

Mark Qty Size(in)

Rating Remark

Boltings

Internals

Gaskets

Description

to be the same as cladding if any,otherwise same as head / shell

ESTIMATED WEIGHT


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SKETCHSketch shall be consistent with the following items:- Establish a reference line for tail dimensions. Use a head tangent line or face of flange if vessel hasa flanged end.- Show supports.- Show location of legs, lugs, clips, etc.- Identify and locate needed internal details. Provide only enough detail to describe the item- Locate support saddles including dimension from head tangents to center line of the saddles,elevation from the vessel centerline to the bottom of the base plate, and elevation from grade, ifavailable. Identify which saddle will have slotted mounting holes and whether a slide plate isrequired.- Provide the skirt height dimension from the bottom of the base plate to the head tangent.

Company Logo

1 Client : Title :2 Project : Tag Number :3 Location : No. Required :4 Project No. : Doc. No. : Rev : 05

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SKECTH

PRESSURE VESSELDATA SHEET

R e v

i s i o n


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4. ASME Code, Section VIII, Division 1 Vs. Division 2Pressure vessels may be designed to meet the requirements of either Division 1 orDivision 2 of Section VIII of the ASME Code.

Division 1 is based on the maximum-stress theory of failure, one of the mostconservative methods available. It is the most frequently used Code in the world,and provides the most economic design and construction for the majority of vesselsused in the petroleum industry.

Division 2 was developed to take advantage of the technological advancementsmade in design methods, materials, and nondestructive examination. Division 2vessels will consequently have thinner walls than Division 1 vessels for the samedesign conditions but more expensive in design and inspection cost. However, thisthickness reduction results in lower materials costs, lower foundation costs, andlower shipping and erection costs. And for some cases, Division 2 can be moreeconomical, when the reduction in material and fabrication costs exceeds theincrease in design and inspection costs.

The selection of Division 1 or Division 2 shall be based on both design andeconomic considerations. The following are the Rules of Thumb for application of

ASME Section VIII, Division 2: When the required thickness according to ASME Section VIII Division 1 basis

of a vessel exceeds 2 inches (50 mm) irrespective of the design pressure &materials.

When the fabricated weight of the vessel excluding the internal & externalweight exceeds 100 tons according to ASME Section VIII Division 1 basis.

When the design pressure exceeds 3000 psig (20.68 Mpa), the ASME SectionVIII Division 2 shall be applied. (See U-1 (d) of ASME Section VIII, Division 1for Scope of Division 1).

When vessels operating in cyclic service.

For application of Division 2 rules, consult an experienced pressure vessel engineer. A feature of Division 2 is that the purchaser must provide the vessel vendor withUSER'S DESIGN SPECIFICATION that states all intended operating conditions andloadings for the service life of the vessel. This information should constitute thebasis for selecting materials and designing, fabricating and inspecting the vessel asrequired including the method of supporting the vessel.

The purchaser must evaluate the intended operating conditions to determinewhether or not a fatigue analysis is required (per AD-160, ASME VIII, Div.2) and if itis required, to provide enough information so that an analysis can be carried out.The process engineer will note on the Process Data Sheets which vessels may beconsidered potentially to be in "cyclic" service and attach sufficient data on theplanned operating conditions to permit the mechanical engineer to evaluate theneed for fatigue analysis. Appendix 5 (Mandatory) of Division 2, Design based onfatigue analysis, provides the method of design for cyclic loading.


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The USER'S DESIGN SPECIFICATION must be certified by a registeredprofessional engineer experienced in pressure vessel design. Sample of USER'SDESIGN SPECIFICATION is in the attachment 2.

The vessel vendor is required to prepare a MANUFACTURER'S DESIGN REPORTestablishing the conformance with the rules of Division 2 for the design conditionsspecified in the Users Design Specification. This conformance should also becertified by a registered professional engineer.

5. MaterialsIn general, selection of vessel materials shall be base on service conditions andMDMT/design temperature. Vessel materials usually are specified in the processdata sheets in generic name, by nominal composition or by trade name. In themechanical data sheets, these generic materials shall be designated in the

ASME/ASTM materials. ASME specifications have the same numerical designationas the ASTM specifications, but are preceded by SA instead of A (e.g., SA516-70).

ASME specifications shall be in accordance with ASME Section II, Part A.

Carbon SteelCarbon steels for pressure vessels have a nominal composition of iron with about1% manganese and up to 0.35% carbon. Some limitations of carbon steels are asfollows: Brittle Fracture. Carbon steels may be susceptible to brittle fracture at

normal ambient temperatures. Hydrogen Attack. Carbon steel will suffer hydrogen attack at elevated

temperature in high pressure hydrogen.

Graphitization . Welded carbon steel is limited to 800F maximum to preventgraphitization. Graphitization is the formation of graphite, primarily in weldheat-affected zones, from the decomposition of iron carbides. This will causethe failure of even a small load or strains.

Stress Corrosion Cracking (SCC). As-welded or cold-worked carbon steel issusceptible to stress corrosion cracking in caustic, nitrate, carbonate, aminesolutions and in anhydrous ammonia. Stress relief is required to preventfailures.

Sulfide Stress Cracking (SSC). High strength steel and hard welds in steelin aqueous solutions containing H2S are susceptible to sudden non-ductilefailures. Wet H2S is defined as service conditions of at least 50 ppm of H2S

dissolved in a liquid water phase. PWHT, controlling maximum strength andhardness is generally sufficient to prevent cracking.

Hydrogen-Induced Cracking. Some low strength carbon steels may besusceptible to hydrogen-induced cracking (HIC) in wet services containingH2S. Postweld heat treatment may also be beneficial to prevent cracking.

There are 3 types of carbon steel:


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1. Non-Killed Carbon Steel , such as A283 all grade & A36. These materials arenot acceptable for pressure parts.

2. Semi-Killed Carbon Steel , such as A285 all grade. These materials areacceptable for pressure parts with nominal thickness not greater than 1 inches(25 mm) and minimum design temperature not less than 30 oF (-1.11 oC).Note:Semi-killed Carbon Steel per ASME SEC.II SA-6/SA-6M para.3.7 - Incompletely deoxidizedsteel containing oxygen to form enough carbon monoxide during solidification to offsetsolidification shrinkage.

3. Killed Carbon Steel , such as A515 all grade, A516 all grade, A106 all gradeand A105. These materials are acceptable for pressure parts for all nominalthickness with minimum design temperature not less than -50 oF (-46 oC) butmay be to be normalized or impact tested depending on the thickness (seeUCS-66 of ASME VIII, div.1).Note:Killed Steel per ASME SEC.II SA-6/SA-6M para.3.9 - Steel deoxidized, either by addition ofstrong deoxidizing agents or by vacuum treatment, to reduce oxygen content to such a levelthat no reaction occurs between carbon and oxygen during solidification.

Common ASTM/ASME carbon steel materials:

Plate for pressure parts: A285-C, A515-60 / 70, A516-60 / 70Plate for non pressure parts: A36, A283-B / C, A285-B / CPipe: A106-B, A333-1 / 3 / 6Tube: A179, A214, A334-1 / 3Forging for ANSI flange: A105, A350-LF2 / LF3Forging for body/cover flange & tubesheet: A266-2 / 4, A765-I / II / IIIWelded fittings: A234-WPB, A420-WPL3

Carbon-Moly Steel (Low Alloy Steel For High Temperature)Carbon-moly steel is similar to carbon steel but with 0.5% molybdenum (C-1/2Mo) added which improves the steels high temperature strength andgraphitization resistance. Some limitations of C-1/2Mo are as follows:

Brittle Fracture . Unless made to fine-grain practice and normalized, carbon-moly steels may have poor toughness (increased susceptibility to brittlefracture).

Hydrogen Attack. Carbon-moly steel cannot be relied upon to resisthydrogen attack.

Graphitization . Carbon-moly is resistant to a maximum service temperatureof 850F.

Stress Corrosion Cracking. Same as for carbon steel. Sulfide Stress Cracking. Same as for carbon steel.

Common ASTM/ASME Carbon-Moly (C-1/2Mo) Steel materials:

Plate: A204-BPipe: A335-P1


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Tube: A209-T1Forging: A182-F1Welded fittings: A234-WP1

Chrome-Moly Steel (Low Alloy Steel For High Temperature)

Chrome-moly low alloy steels are similar to carbon steel but with chromium andmolybdenum added. Typical grades are 1 Cr- Mo, 1 Cr- Mo, and 2 Cr-1Mo. The characteristics are:

Better resistance to hydrogen attack. Better high temperature strength. Chrome-moly steels do not graphitize. More difficult to fabricate. Require control of preheat for welding. Require postweld heat treatment for all welded construction.

Some limitations of Chrome-Moly steels are as follows: Brittle Fracture. Chrome-moly steels become susceptible to brittle fracture at

low temperatures and above about 650F embrittle in service. The 2 Cr-1Mo steels are particularly susceptible, but 1 Cr- Mo and 1 Cr- Mo mayalso be susceptible.

Hydrogen Attack. Resistance to hydrogen attack is dependent on thechromium and molybdenum contents in the steel. Resistance improves withincreased alloy content.

Stress Corrosion Cracking. Same as for carbon steel. Sulfide Stress Cracking. Same as for carbon steel.

Common ASTM/ASME Chrome-Moly Steel materials:Plate 1 Cr- Mo: A387-12 Class 1 or 2Plate 1 Cr- Mo: A387-11 Class 1 or 2Plate 2 Cr-1 Mo: A387-22 Class 1 or 2Note:Class 2 is Normalized and Tempered, allowable stress is higher than class1.Pipe 1 Cr- Mo: A335-P12Pipe 1 Cr- Mo: A335-P11Pipe 2 Cr-1 Mo: A335-P22Tube 1 Cr- Mo: A213-T12Tube 1 Cr- Mo: A213-T11Tube 2 Cr-1 Mo: A213-T22Forging 1 Cr- Mo: A182-F12Forging 1 Cr- Mo: A182-F11Forging 2 Cr-1 Mo: A182-F22Welded fittings 1 Cr- Mo: A234-WP12

Welded fittings 1 Cr- Mo: A234-WP11Welded fittings 2 Cr-1 Mo: A234-WP22


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Low Alloy Steel For Low TemperatureTo improve toughness of carbon steel at low temperature, Nickel is added toimprove embrittle fracture due to its strong contact force (anti-tearing poperty).However, this material is difficult for welding. If available suppliers do not havesuccessful experience with this material, austenitic stainless steel is a better

choice.

Common ASTM/ASME Nickel steel materials:

Plate 2- Ni: A203-A / BPlate 3- Ni: A203-D / EPlate 9 Ni: A353Pipe 2- Ni: A333-7Pipe 3- Ni: A333-2Plate 9 Ni: A333-8Forging 2- Ni: -Forging 3- Ni: A350-LF3

Forging 9 Ni: A522-IWelded fittings: -

Stainless Steel (High Alloy Steel)Stainless steels are corrosion-resistant steels that contain at least 10.5%chromium. Chromium is unique in that it forms a passive layer on the steelsurface that provides protection from corrosion. Stainless steels are classified aseither austenitic, ferritic, martensitic, or duplex depending on their microstructure.

3.5.1 Austenitic Stainless Steels (3xx series) have an austenite structuresimilar to the high temperature structure of carbon steel. In general,the3xx series are ironchromiumnickel alloys that contain 1626%chromium and 622% nickel. The characteristics of austenitic stainlesssteels are: Nonhardenable by heat treatment. Nonmagnetic. Weldable. Excellent low-temperature toughness, Can be used for both cladding and solid wall construction.

Some limitations of Austenitic stainless steels are as follows: Chloride stress corrosion cracking of austenitic stainless steels

can occur in aqueous solutions containing chloride ions. Cracking ismost severe where the chloride ion concentration is high, the solutionis hot, the pH is neutral or low, and especially where evaporationbuilds up deposits on the stainless steel.

Recommendations to prevent chloride stress corrosion crackinginclude:


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1. Do not select solid wall austenitic stainless steelconstruction for hot and aqueous chloride services. Ifstainless steel is required, used as clad construction.

2. Where no other economical material is available, vesselsmade of solid austenitic stainless steel should be PWHT(See section 5)

Sulfur-derived acids can cause polythionic acid stress corrosioncracking of austenitic stainless steels. These acids commonlydevelop during shutdowns by the oxidation of iron sulfide scale in thepresence of moisture and oxygen. Usually polythionic acid cracking isprevented by using the chemically stabilized or extra low carbongrades of stainless steel and avoiding harmful heat treatments.

Common ASTM/ASME Austenitic stainless steel materials:

Plate: A240-304, 304L, 316, 316L, 321, 347Pipe: A312-TP304, 304L, 316, 316L, 321, 347

Tube: A213-TP304, 304L, 316, 316L, 321, 347Forging: A182-F304, 304L, 316, 316L, 321, 347Forging for body/cover flange & tubesheet: A336-F304, 304L, 316, 316L,321, 347Welded fittings: A403-WP304, 304L, 316, 316L, 321, 347Note:

Any type austenitic SS forgings with notes G7 of ASME 1A are not recommended for theflanges, blind flange, tubesheet or any applications which can cause leakage.

There are many compositional variations of austenitic stainless steelsteels. The following list summarizes these variations which frequentlyused for pressure vessels material: 304 Popular 188 stainless steel, lower C than 302 304L Low-carbon 304 for improved corrosion resistance 304LN Low-carbon 304 with nitrogen added for strength 304H Higher carbon 304 304Cu Copper added for improved cold working 304N Nitrogen added for strength 309 High Cr and Ni for heat resistance 309S Lower carbon 309 309Cb Niobium (columbium) added 310 Higher Cr and Ni than 309 for improved heat resistance 310S Lower carbon 310 310Cb Niobium (columbium) added 316 Mo added for improved corrosion resistance 316L Lower C for improved corrosion resistance and weldability 316LN Lower C and higher nitrogen (for strength) 316H Higher carbon 316 316N Nitrogen added for strength 316Ti Titanium added 316Cb Niobium (columbium) added 317 Higher Cr and Mo for improved corrosion resistance 317L Low-carbon 317 for improved weldability


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321 Titanium added to minimize Cr carbide precipitation 347 Nb and Ta added to minimize Cr carbide precipitation 347H Higher carbon 347 348 Ta and Co added for restricted nuclear applications 348H Higher carbon 348

3.5.2 Ferritic Stainless Steels (4xx series) have a ferrite structure similar tothe low temperature structure of carbon steel. The ferritic stainless steelsare basically ironchromium alloys with chromium ranging from 10.5 to27%. The characteristics are: Nonhardenable with heat treatment. Magnetic. Poor Weldability Their use in pressure vessel is primarily as cladding.Some limitations of Ferritic stainless steels are as follows: Embrittle in 750F to 900F Service. Straight chromium stainless

steels, such as the ferritic (Types 405 and 430) and martensitic types(Type 410), containing 13% or more chromium can embrittle duringexposure to temperatures in the 750F to 900F range. Prevent thisproblem by not using chromium stainless steels for solid wallconstruction of pressure vessels.

Common ASTM/ASME Ferritic stainless steel materials:

Plate: A240-405 and 430Pipe: N/ATube: A268-TP405 and 430

Forging: N/AWelded fittings: N/A

There are fewer variations of ferritic stainless steels than austeniticstainless steels. The ferritic stainless steels are listed below: 405 Low Cr with Al added 430 General-purpose ferritic stainless steel

3.5.3 Martensitic Stainless Steels (13Cr) Martensitic stainless steels containadded carbon, which expands the gamma loop to allow higher chromiumcontents to be used. Because they can be heat treated, the martensiticstainless steels generally have higher strength than the austenitic andferritic stainless steels. The characteristics are: Can be hardened with heat treatment. Magnetic. Poor Weldability Their use in pressure vessel is primarily as cladding.Some limitations of Martensitic stainless steels are as follows:


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Sulfide Stress Cracking. The martensitic stainless steels areespecially susceptible to sulfide stress cracking. This cracking isprevented by controlling weld strength and hardness.

Embrittle in 750F to 900F Service. Straight chromium stainlesssteels, such as the ferritic (Types 405 and 430) and martensitic types(Type 410), containing 13% or more chromium can embrittle duringexposure to temperatures in the 750F to 900F range. Prevent thisproblem by not using chromium stainless steels for solid wallconstruction of pressure vessels.

Common ASTM/ASME Martensitic stainless steel materials:

Plate: A240-410Pipe: N/ATube: A268-TP410Forging: N/AWelded fittings: N/A

3.5.4 Duplex Stainless Steels have structures of roughly 50% austenite and50% ferrite (22Cr-5Ni-3Mo-1N). There are many more duplex stainlesssteels that have priority compositions and trade. The corrosioncharacteristics of these duplex stainless steels are similar to austeniticstainless steels. However, they have higher strength and better resistanceto stresscorrosion cracking than austenitic stainless steels.Note:Stress Corrosion Cracking (SCC): Cracking of metal produced by the combined action ofcorrosion and tensile stress (residual or applied). Nonhardenable with heat treatment. Weldable. Can be used for both cladding and solid wall construction.Common ASTM/ASME Duplex stainless steel materials:

Plate: A240-S31803Pipe: A790-S31803Tube: A789-S31803Forging: A182-F51Welded fittings: N/A

The two grades most frequently used for pressure vessels are 2205 (UNSS31803) and 2507 (UNS 32750). Zenon 100 (UNS S32760), 2507, and255 (UNS S32550) have sufficient chloride pitting resistance for seawater

service.Nonferrous Alloys

Nonferrous alloys are designated in the ASME Code by the prefix SB.Two classes of alloys occasionally considered are discussed in thissection, nickel alloys and titanium alloys. NickelChromiumIron Alloys

Nickel and high-nickel alloys have excellent corrosion resistance andare used in high-temperature applications in corrosive environments.


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Inconel alloy 600 and 625 is a standard engineering material for use inseverely corrosive environments at high temperatures up to 2150 oF(1177 oC) and also resistant to chloride-ion stress-corrosion crackingand corrosion by high-purity water. Fabricating and weldability aregenerally good with proper precautions.

Fig. 7 represents some compositional modifications of nickel and itsalloys to produce special properties.

Titanium Alloys.These are used infrequently for pressure vessels and used usually as

cladding. Welding is difficult, requiring very clean conditions, so fieldrepairs are not practical.

Unalloyed titanium is highly resistant to the corrosion normallyassociated with many natural environments, including seawater.Titanium exposed continuously to seawater for about 18 years hasundergone only superficial discoloration.


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Material SelectionTable 1 illustrates pressure vessel materials typically selected for serviceenvironments. This table is not suitable for final materials selection, but only forinitial investigation. For a given service environment, materials selection shouldbe made with consideration for both corrosion rates and other potential

deterioration mechanisms, such as stress corrosion cracking and hydrogendamage.

When stainless steel or a more highly alloyed material is required, it is oftenpreferable to use a carbon or low alloy steel clad with a thin layer of the highalloy material. Clad plate is usually less expensive than solid alloy plate unlessthe thickness of the vessel is less than 1/2 inch. Clad plate is also preferredbecause it is less likely to develop through-wall stress corrosion cracks than solidalloy.

CLAD PLATE: A composite plate consisting of two or more metals permanently and integrallybonded over their entire intersurface by rolling under heat and pressure.


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TABLE 1. MATERIAL SELECTION FOR SERVICE ENVIRONMENTS


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From PVM-500 Materials, Chevron Manuals

NOTES:

(1) Carbon steel. Grades commonly used for pressure vessel plates are SA285 GradeC, SA515 Grade 70 and SA516 Grade 70. Choice will be determined by minimumdesign metal temperature and thickness.

(2) Clad carbon steel. Carbon steel clad with 12% Cr steel is covered by SpecificationSA263. We usually designate a base metal plate (carbon steel per note 1 above)and the cladding as Type 405 or Type 410S.

(3) Low alloy steels. 1 Cr- Mo steel is covered by SA387 Grade 11 (plate) andSA182/336 F11 (forgings). 2 Cr-1 Mo steel is covered by SA387 Grade 22 (plate)and SA182/336 F22 (forgings).

(4) Carbon or low alloy steel clad with Type 321 or 347 stainless steel. These plates arecovered by SA264 for roll band cladding. Base metal plate is designated per notes 1or 3 above. If forgings are used for shell components or if shell plates are thick, theywill be weld overlay clad rather than roll band clad. Base metal will be designatedper notes 1 and 3 above.

Table 2 illustrates suitable materials base on temperature range. Any materiallisted for a colder temperature range may be used in a warmer temperaturerange depending the suitable of the material due to the vessel contain as pertable 1. For example, A240-304 may be used in the temperature range of 33Fto 775F.


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TABLE 2 MATERIAL SELECTION FOR DESIGN TEMPERATURECompo-nent

Design Temperature oF-425to-321

-320to-151

-150to-51

-50to-21

-20to4

5to32

33to775

776to875

876to1000

1001to1100

1101to1500

>1500

Plate A240-

304,304L,316,316L,347

A353

orA240-304,304L,316,316L,347

A203-

D orA240-304,304L,316,316L,347

A516-

55, 60to meetSA20

A516

AllGrade

A516

AllGrade

A285-

C (min60 oF)orA516AllGrade

A204-

B

A387-

11, 12

A387-

22

A240-

347H orB424(incoloy825)

B443

(Inco-nel625)

Pipe A312-TP304,304L,316,316L,347

A333-8 orA312-TP304,304L,316,316L,347

A333-3 orA312-TP304,304L,316,316L,347

A333-1, 6 orA106-B

A333-1, 6 orA106-B

A106-B

A106-B

A335-P1

A335-P11,P12

A335-P22

A312-TP347HorB423(incoloy825)

B444(Inco-nel625)

Tube A249/

A213-TP304,304L,316,316L,347

A334-

8 orA249/A213-TP304,304L,316,316L,347

A334-

3 orA249/A213-TP304,304L,316,316L,347

A334-

1 orA179orA214

A179

orA214

A179

orA214

A179

orA214

A209-

T1

A209-

T11,T12

A209-

T22

A213-

TP347HorB163(incoloy825)

B444

(Inco-nel625)

ForgingsANSIFlange

A182-F304,304L,316,316L,347

A522-IorA182-F304,304L,316,316L,347

A350-LF3orA182-F304,304L,316,316L,347

A350-LF2

A105 A105 A105 A182-F1

A182-F11,F12

A182-F22

A182-F347HorB564(incoloy825)

B564(Inco-nel625)

ForgingsnonANSI

A336-F304,304L,316,316L,347

A522-IorA336-F304,304L,316,316L,347

A765-IIIorA336-F304,304L,316,316L,347

A765-I, II

A765-I, II

A765-I, II

A765-I, II

A336-F1

A336-F11,F12

A336-F22

A336-F347HorB564(incoloy825)

B564(Inco-nel625)

Fittings A403-WP304,304L,316,316L,347

A420-WPL8orA403-WP304,304L,316,316L,347

A420-WPL3 orA403-WP304,304L,316,316L,347

A420-WPL6

A243-WPB

A243-WPB

A243-WPB

A234-WP1

A234-WP11,WP12

A234-WP22

A403-WP347H

B366(Inco-nel625)


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6. MDMT

Definition of Brittle Fracture

Brittle fracture can occur in ferritic steels, such as carbon, carbon- moly,chrome-moly, and 400 series stainless steels, within the normal atmospherictemperature range. Most occur during hydrotest rather than in operation. Thematerial property Brittleness indicates that the material is prone to failurewithout deformation.

Toughness is the ability of a material to absorb energy by yielding (plasticdeformation) prior to failure. Toughness depends on a materials ductility andstrength. Toughness therefore indicates the materials ability to resist brittlefracture.

The fracture toughness of a particular material decreases with increasingsection thickness for two reasons:

1. It is metallurgically more difficult to obtain good toughness properties asthickness increases.

2. Thicker sections produce greater constraint ahead of the notch due to atriaxial state-of-stress.

To prevent brittle fracture, use tough materials. Toughness is a physicalproperty of materials that primarily characterizes their resistance to brittlefracture, depending on temperature, loading rate, and thickness.

Sufficiently tough steels are selected by one of the following:


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1. Using materials selection curves, or impact exemption curves (see Fig.UCS-66 of ASME VIII div.1).

2. Using steels that have been Charpy V-Notch (CVN) impact tested to Coderequirements.

Using steels selected from the ASME Code impact test exemption curves ishighly preferred. Impact tests increase materials costs substantially andcomplicate delivery.

Impact Test Exemption per UCS-66Figure UCS-66 shall be used to establish impact testing exemptions forcarbon and low alloy steels listed in Part UCS. If a minimum design metaltemperature and thickness combination is on or above the curve, impacttesting is not required by the rules of ASME VIII Div.1.


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NORMALIZE

Heating iron-base alloys to approximately 100 oF above the critical temperaturerange followed by cooling to below that range in still air at ordinary temperature.

The normalizing process is commonly applied to steel articles of heavy section torefine the grain. For example SA516 plate with thickness over 40 mm shall benormalized. Under 40 mm, the plates may be ordered normalized or stress relieved,or both.


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For example:

1 nominal thickness of not normalized A516-60 is required MDMT at20 oF. To decide this material is required impact test or not, just go to fig.UCS-66.

Not normalized A516-60 is in Curve C, from this curve in Fig. UCS-66, theMDMT for the nominal thickness of 1 is -5 oF. Due to -5 oF is colder thanthe required MDMT of 20 oF, and then impact test is not required.

Each component such as head, shell, nozzle, flange, tubesheet, flat cover etc,shall be evaluated for impact test requirements based on its individualmaterial classification, and the warmest MDMT used as the MDMT for thevessel. The thickness is defined as below:

1) For butt joints other than those in flat heads and tubesheets, the nominalthickness of the thickest welded joint.

2) For corner, fillet, and lap welded joints, the thinner of the parts joined.3) For flat heads or tubesheets, the larger of the thickness from 2) above or

the flat component thickness divided by 4.4) For castings, the largest nominal thickness.5) For flat nonwelded parts, such as bolted flanges, tubesheets, and flat

heads, the thickness of the flat component divided by 4.6) For a nonwelded dished head, the greater of the flat flange thickness

divided by 4 or the minimum thickness of the dished portion.

According to UCS-66, impact tested material shall be used for the following:

1) If the governing thickness at any welded joint exceeds 4 inches and theMDMT is colder than 120 oF.

2) If the governing thickness of the non-welded part exceeds 6 inches andthe MDMT is colder than 120 oF.

3) Materials with specified minimum yield strength greater than 65000 psimust be impact tested.

4) If the MDMT is colder than -55 oF and the thickness ratio in Fig. UCS-66.1is greater than 0.35.

No impact test is required for:

1) ASME/ANSI B16.5 or B16.47 flanges if the MDMT is -20 oF or warmer.2) If the thickness is less than 0.10 inch (2.5mm) and the MDMT is -55 oF or

warmer.3) The materials listed in Fig. UG-84.1 need not be impact tested if the

MDMT is no more than 5 oF colder than the specification impact test

temperature.4) If the MDMT is colder than -55 oF but no colder than -155 oF and thethickness ratio in Fig. UCS-66.1 is equal to or less than 0.35.

Impact Test Exemption per UCS-66.1Fig. UCS-66.1 may be used to reduce the MDMT of vessels if the definedratio is less than one but not less than 0.35. The resulting MDMT may not becolder than -55 oF except as may result from the UCS-68(c) rule. UCS-68(c) isdefined as below:


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The following example illustrates the use of the flow chart in Fig. UCS-66.2.Say, the required MDMT is -10 oF.

Due to the adjusted MDMT is colder than therequired MDMT (-17 oF < -10 oF), then theabove material is exemption from impacttest.

If impact testing is indicated by UCS-66, check the following to see if it can beavoided:

1. Try to Normalized the material. This is cheaper than impact testing.

2. If normalized does not help, see if a reduction per Fig. UCS-66.1 & 2 isapplicable.

3. PWHT in accordance with UCS-68 (c) can give a 30 oF (17 oC) reduction ofMDMT. PWHT may also be cheaper than impact tests.


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7. RadiographyThere are 3 basic levels of radiography - None, Spot, and Full. The minimumacceptable level of radiography for oil & gas industry is Spot. Generally, FullRadiography is required for all pressure vessels in offshore project.

For the typical double butt weld in a vessel, spot radiography has a joint efficiency of85% and full radiography has a joint efficiency of 100%. In full radiography, 100% ofthe weld is examined and in spot radiography, typically min. 6 inches (150 mm) ofweld in every 50 feet (15 m) are examined (See UW-52).

It is possible to mix the types of radiography on a single vessel for the some of theeconomic reasoning. According to UG-116 (e) a vessel is stamped RT 1, RT 2, RT3, or RT 4 to indicate how it was radiographed:

1. RT 1 Full radiography of the entire vessel.

2. RT 2 Mix between full & spot radiography. In shells, longitudinal stresses(carried by circumferential welds) are typically half of circumferential stresses(carried by longitudinal welds).Basically, RT 2 allows you to fully radiograph only the longitudinal welds andto spot radiograph the circumferential one. This can result in a shell thicknessequivalent to RT-1.

3. RT 3 Spot radiography of the entire vessel.

4. RT 4 fully radiograph one part of a vessel, and spot radiography for theremainder.For example, a carbon steel tower with different thickness. If the lowersection has a thickness 34 mm and the top thickness is 30 mm, the thicknessis necessary for mandatory per code to fully radiograph the lower section, butspot radiography for the top one.

Spot RadiographySpot radiography is permitted for the following:

1. Vessel is not containing lethal substances.

2. Vessel carbon steel with thickness less than 1.25 inches (32 mm).

3. Vessel stainless steel with thickness less than 1.5 inches (38 mm).

4. Vessel thickness is controlled by external design pressure.

5. Unfired steam boiler with internal design pressure less than 50 psig.

Full RadiographyFull radiography is mandatory as per Code for the following:

1. Vessels containing lethal substances. See UW-2(a).

2. Unfired steam boilers with design pressure exceeding 50 psig.

3. All butt welds joined by electrogas welding with any single pass greater than1 (38 mm) and all butt welds joined by electroslag welding.


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4. Final closure of vessels (Ultrasonic examination when the construction doesnot permit radiographs).

5. Vessel for material with minimum nominal thickness as below:

P No. Material Descripion Full R.T.

perUCS-56 (2)

PWHT per

UCS-56 (1)

1 Group 1, 2 Carbon Steel: SA36, SA285-C, SA515/516-55, 50, 65, 70, SA455-I, II

> 1.25(32mm)

>= 1.5(38mm)

8 group 1, 2 Austenitic stainless steel: 304, 309, 310,316, 321, 347,

> 1.5(38mm)

N/A

9A/B group 1 Low alloy steel: 2 Ni (SA203-A, B) &3Ni (SA203-D, E)

> 5/8(16mm)

>= 5/8(16mm)

3 group 1 Low alloy steel: C-1/2Mo (SA204-B) > 3/4(19mm)

>= 5/8(16mm)

4 group 1 Low alloy steel: 1Cr-1/2Mo (SA387-12) &

1Cr-1/2Mo (SA387-11)

> 5/8

(16mm)

All

5 group 1 Low alloy steel: 2Cr-1Mo (SA387-22) All All

43 Inconel 600, 625 > 3/8 (10mm)

N/A

45 Incoloy 800, 825 > 3/8 (10mm)

N/A

Note:

1. PWHT may be required for nominal thickness less than table above if requiredby service condition.

2. For ASME VIII Div 2: All pressure welds require 100% RT regardless the

thickness.Full RT examination is recommended for the following conditions:

1. All butt welds in head where it is made from two or more pieces of plate, andthe head knuckle also should be visually inspected.

2. For service at low temperatures where undetected flaws could cause brittlefracture.

3. For service where cyclic pressures and/or temperatures are encountered andundetected flaws could initiate fatigue cracks.

8. PWHT By Service ConditionsThe need for PWHT other than Code requirements are depends on some serviceconditions as summarized below:

1. Carbon steel vessels should be PWHT in the following services regardless theshell thickness for resistance to various types of stress corrosion cracking(SCC): Sour (wet H2S) services, for resistance to sulfide SCC (also called

hydrogen embrittlement cracking).


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Ammonium nitrate and calcium nitrate above 110F, for resistance to nitrateSCC

Concentrated anhydrous ammonia at any temperature, for resistance toammonia SCC

Hydrofluoric acid at any temperature, for resistance to hydrogenembrittlement cracking Amines (DEA, MEA, MDEA, DIPA, etc.) at any temperature, for resistance to

amine SCC. Potassium carbonate at any temperature, for resistance to carbonate SCC FCC Fractionator overhead systems, for resistance to carbonate SCC

(Stress relief temperature should be increased to 11501250F for thisservice.)

2. Carbon steel vessels for boiler feedwater deaerators which use steam should bePWHT to avoid corrosion fatigue.

3. Carbon steel vessels in specific severe sour services where hydrogen blisteringand hydrogen induced cracking (HIC) have previously occurred (referred to asHIC services) should be PWHT.

4. Carbon steel and austenitic stainless vessels should be PWHT for resistance tocaustic stress corrosion cracking (also called caustic embrittlement) if above140F for concentrations from 1 wt% to 30 wt% caustic, and if above 110F forconcentrations greater than 30 wt%.

5. Vessels made from solid types 304L, 316L, 321 and 347 should be PWHT forresistance to chloride stress corrosion cracking, in case: Insulated vessels which operate continuously or intermittently above 150F. Un-insulated vessels which operate continuously or intermittently above

150F if they are in high-chloride environments. (Examples of some highchloride environments are: coastal locations and off-shore platforms with saltspray, locations with salt water fire spray systems, and process streams withhigh chloride contents)

Types 304 and 316 can not be used for resistance to chloride stress corrosioncracking due to PWHT will cause loss of corrosion resistance due to excessivesensitization at temperatures between 800F to 1500F.

9. Nozzle ConnectionsNormally, standard ASME B16.5 Pipe Flanges for nozzle diameter 24 and less or ASME B16.47 Series B Large Diameter Steel Flanges for nozzle diameter over24, are used for nozzle flange. Non standard flange such as girth flange for shelland tube heat exchanger shall be design as per Appendix 2 of ASME VIII division 1.When a standard flange is selected, no additional calculations are required.


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Fig. 8 Flange types

Slip-on flange is usually used for flange rating 150 psi and nozzle foratmospheric tank. Weld neck type shall be used for flange rating 300 psi andhigher. Flange types are shown in fig. 8.

Fig. 9 Flange facings

Raised face is generally used for flange rating 600 psi and lower, and o-ring isapplied for rating 900 psi and higher. Recessed face is commonly applied forconfined joint body flange in shell and tube heat exchanger.


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Self Reinforced (SR) / Forged Nozzles are recommended if meet one of thefollowing:

1. Flange rating 600 psi and higher.

2. Shell components over 2 inches (50 mm) thick.

3. Design temperatures over 650F.4. For low temperature service when CV-impact testing is required.

Set-on is usually applied for connection nozzle to header in air fin cooler. Set-inwith reinforcing pad is usually applied for connection nozzle to shell / head inpressure vessel for flange rating 150 psi and 300 psi.

Fig. 10 Nozzle types


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10. Type of HydrotestFor Division 1 the program provides three different ways to determine hydrotestpressure. For Division 2, the program provides two hydrotest options.

ASME UG-99 (b) Div. IThe hydrotest pressure will be 1.3 (1.5 pre 99 addenda) times the maximumallowable working pressure for the vessel multiplied by the lowest ratio of thestress value S for the test temperature to the stress value S for the designtemperature. This type of hydrotest is normally used for non-carbon steel vesselswhere the allowable stress changes with temperature starting even at asomewhat low temperature.

ASME UG-99 (c) Div. IThe hydrotest pressure will be determined by multiplying the minimum MAP by1.3 (1.5 pre 99 addenda) and reducing this value by the hydrostatic head on thatpart. The hydrostatic head will determined based on the dimensions of the

vessel and by the "projection fields" input farther on down in this section. Inaddition the hydrostatic test position will also be used to determine the headpressure.

ASME UG-99 (b) footnote 35 Div. 1The hydrotest pressure will be 1.3 (1.5 pre 99 addenda) times the stated designpressure for the entire vessel, multiplied by the lowest ratio of the stress valueSa for the test temperature to the stress value S for the design temperature.

ASME UG-100 Pneumatic TestThe test pressure will be 1.1 (1.25 pre 99 addenda) times the stated designpressure for the entire vessel, multiplied by the lowest ratio of the stress value

Sa for the test temperature to the stress value S for the design temperature.

ASME AT-300 Div. 2 Based on Vessel Design PressureThe hydrotest pressure will be 1.25 times the design pressure to be marked onthe vessel, multiplied by the lowest ratio of the stress intensity value Sm for thetest temperature to the stress intensity value Sm for the design temperature.This type of hydrotest is normally used for non-carbon steel vessels where theallowable stress changes with temperature starting even at a somewhat lowtemperature.

ASME AT-301 Div. 2 Based on Calculated Pressure A hydrostatic test based on a calculated pressure may be used by agreementbetween the user and the Manufacturer. The hydrostatic test pressure at the topof the vessel shall be the minimum of the test pressures calculated by multiplyingthe basis for calculated test pressure for each element by 1.25 and reducing thisvalue by the hydrostatic head on that element.

pressure vessel training module

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