structural analysis and design of process equipment

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 I 7 I E E - E t - --1t. . ,';i:::: -.r,..-'-;;,r&. .r/C* N*w York Chichester STRUCTURAL ANALYSIS AND DESIGN OF PROCESS EQUIPMENT Mqon H. Jowod Nooter Corporation St. Louis, M issouri Jomes R. Fqrr Babcock & Wilco.r Company Barberton, Ohio A Wiley-lnterscience Publicqtion JOHN WILEY & SONS Brisbone Toronto Singopore

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I

E

STRUCTURAL ANALYSIS AND DESIGN OF PROCESS EQUIPMENT

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Mqon H. JowodNooter Corporation St. Louis, M issouri

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Jomes R. Fqrr Babcock & Wilco.r CompanyBarberton, Ohio

7

A Wiley-lnterscience Publicqtion

I

JOHN WILEY & SONS

.r/C*

N*w York

Chichester

Brisbone Toronto

Singopore

To Our Wives, Dixie and Barbara

Copyright

O

1984 by

hhn Wilev & Sons, IncCanada

All righis reserve{]. Publishcd simultaneously in

Reproduction or transiation ()f any part oi this work hcyond that permitted by Secton 107 or 108 of ihe It)?6 linited States Copyrighl Act wrthout lhe permrssron ,,1 rlr .i't)\rfi!hl owner is unl.rwlul Requests iot | ,"' ,1,,, !,, lrrrhcr infomati,)n sbould be addrcssed lo L , , I'1 t,.,rlrjitrrl. John Wil'v & Sons, lnc '! |

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PREFACEWe wrote this book to serve three purposes. The first purpose is to provide structural and mechanical engineers associated with the petrochemical industry a reference book for the analysis and design of process equipment. The second is to give graduate engineering students a concise introduction to the theory of plates and shells and its industrial applications, The third purpose is to aid process engineers in understanding the background of some of the design equations in the ASME Boiler and hessure Vessel Code. Section VIII. The topics presented are separated into four parts. Part 1 is intended to familiarize the designer with some of the common "tools of the hade." Chapter I details the history ofpressure vessels and various applicable codes from around the world. Chapter 2 discusses design specifications furnished in purchasing process equipment as well as in various applicable codes. Chapter 3 establishes the strength criteria used in different codes and the theoretical background needed in developing design equations in subsequent chapters. Chapter 4 includes different materials of construction and toughness considerations. Part 2 is divided into three chapters outlining the basic theory of plates and shells. Chapter 5 develops the membrane and bending theories of cylindricalshells. Chapter 6 discusses various approximate theories for analyzing heads and transition sections, and Chapter 7 derives the equations for circular and rectangular plates subjected to various loading and support conditions. These three chapters form the basis from which most of the design equations are derived in the other chapters. Part 3, which consists of flve chapters, details the design and analysis of components. Chapters 8 and 9 derive the design equations established by the ASME Code, VI[-l and -2, for cylindrical shells as well as heads and transition sections. Chapter 10 discusses gaskets, bolts, and flange design. Chapter ll presents openings and their reinforcement; Chapter l2 develops design equations

tor support systems.Part 4 outlines the design and analysisof some specialized process equipment. Chapter 13 describes the design of flat bottom tanks; Chapter 14 derives the

ftitActcquations for analyzing hest transfer equipment. Chapter l5 describes the theory of thick cylindrical shells in high-pressure applications. Chapter l6 discusses the stress analysis of tall vessels. Chapter 17 outlines the procedure of the ASME Code, VI[-l, for designing rectangular presswe vessels. To simplify the use of this book as a reference, each chapter is written so that it stands on its own as much as possible. Thus, each chapter with design or other mathematical equations is written using terminology frequently used in industry for that particular type of equipment or component discussed in the pertinent chapter. Accordingly, a summary of nomenclature appears at the end of most of the chapters in which mathematical expressions are given. In using this book as a textbook for plates and shells, Chapters 3, 5,6 md7 form the basis for establishing the basic theory. Instructors can select other chapters to supplement the theory according to the background and needs of the graduate engineer.

ACKNOWLEDGMENTSWe are indebted to many people and organizations for their help in preparing this

In deriving the background of some of the equations given in the ASME Boiler and Pressure Vessel Code, attention was focused on Section VIII, Divisions1 and

2. Although these same equations do occur in other sections of the

ASME Code, such as the Power and Heating Boilers, no consideration is given in this book regarding other sections unless specifically stated'MAAN JAWADJAMES FARRSaint Louit, Missouri

Barberton, OhioSeptember 1983

book. A special thanks is given to the Nooter Corporation for generous support rluring the preparation of the manuscript. Also a special thanks is given to the American Society of Mechanical Engineers for supplying many of the illustrations used in this book and also to the American Petroleum Institute and the Tubular Exchangers Manufacturers Association. We also give thanks to Messrs. W. D. Doty, G. Hays, G. G. Karcher, T. W. [,odes, H. S. Olinger, and R. F. O'Neill for reviewing the manuscript, and to Mr. W. H. Schawacker for supplying many of the photographs. We would also like to extend our appreciation to Mrs' Y. Batteast for typing portions of the manuscript.

M. J.

CONTENTSPART I BACKGROUND AND BASIC CONSIDERATIONS Hisiory ond Orgonizotion of CodesUse of Process Vessels and Equipment United History of Pressure Vessel Codes in theStates Pressure Organization of the ASME Boiler and

Chopter I

3 4

l.l1.2 1.3

Vessel Code

1.4 1.5 1.6

for Pressure Organization of the ANSI B31 Code Piping Standards Some Other Pressure Vessel Codes and in tie United States Worldwide Pressure Vessel CodesReferences

8

9 'r0

BibliograPhY

lll314 14

Chopter 22.1

Selection of Vessel, Specificotions' Reports, ond Allowoble Slresses Selection of VesselWhich Pressure Vessel Code Is Used Design Specifications and Purchase Orders Special Design Requlrements Design RePons and Calculatjons Materials' SPecifi cations

2.2 2.3 2.4 2.5 2.6

l5 l5 t616

CONTINT!

CONTENTS Dcsign Data tbr Ncw MaterialsFactors of Safety

xlll

2.7 2.8 2.9 2.10

't717

Allowable Tensile Stresses in the ASME Code Allowable Extemal Pressure Stress and Axial Compressive Stress in the ASME Boiler and Pressure Vessel Code

t7

4.5.2 4.5.3 4.5.44.6 4.7

l922 22

'l'heory ol' Brittle Fracture Hydrostatic Testing Factors Influencing Brittle Fracture Hydrogen Embrittlement Nonmetallic VesselsReferences

Allowable Stresses in the ASME Code for Pressure Piping B31 2.12 Allowable Stress in Other Codes of the World2.11References

Bibliography

70 74 75 76 77 78 79

26

PART 2

ANAIYSIS OF COMPONENTSSlress in Cylindricol Shells

8l8384 92 96 lO7I 14

Chopter 33.1

Strength Theories, Design Criierio, ond Design EquotionsStrength Theories

Chopfer 5 29305.1

5.2

3.2 3.3 3.4 3.5 3.6

Design Criteria Design Equations Stress-Strain Relationships Strain-Defl ection EquationsForce-Stress Expressions References

3l33 33 35 39 42

5.3

Pressure Discontinuity Analysis 5.2.1 Long Cylinders 5.2.2 Short Cylinders Buckling of Cylindrical ShellsStress Due to Intemal

5.3.1 5.3.2 5.3.35.4

Bibliography

43

Uniform Pressure Applied to Sides Only 114 Uniform Pressure Applied to Sides and Ends 116 Pressure on Ends Only lr8119

Thermal Stress

Chopter 44.1

Moteriqls of ConstructionMaterial Selection 4,l.l Corrosion

4546 46 49 52 53 53 3J 56 56 60

5.4.1 5.4.2 5.4.3

4.1.24.1

Uniform Change in Temperature Gradient in Axial Direchon Gradient in Radial Direction NomenclatureReferences

124 127 r30137

Strength

4.2

Material Cost Nonferrous Alloys 4.2.1 Aluminum Alloys

.3

r38139

Bibliography

4.3 4.4 4.5

4.2.2 Copper and Copper Alloys 4.2.3 Nickel and High-Nickel Alloys 4.2,4 Titanfum and Zirconium AlloysFerrous Alloys Heat Treating of Steels

Chopter6.

6I

Anolysis of Formed Heods ond TronsitionSectionsHemispherical Heads 6.1 . Various Loading Conditions 6.1.2 Discontinuity Analysis 6.1.3 Thermal Stress

141142 146

I

6l63 68

r52158

Brittle Fracture 4.5. I ASME Presssure Vessel Criteria

6.1.4

Buckling Strength

159

xiv

CONTENTSCONTENTS

xv

6.2 6.3 6.4

Ellipsoidal Heads Torispherical Heads Conical Heads

163

Chopier 99.1

167

Design of Formed Heods ond Tronsifion SeclionsIntroduction

243244247 249

r68169172

6.4.1 6.4.2 6.4.3

Unbalanced Forces at Cone{o-Cylinder

9.2 9.3

Junction

Discontinuity Analysis Cones Under Extemal Pressure NomenclatureReferences

175 178 'r80

Bibliography

t8t183184184 193

9.4

Chopter 77.1

Stress in Flot PlotesIntroduction

7.2 7.3 7.4

Circular PlatesRectangular Plates

ASME Equations for Hemispherical Head Design ASME Design Equations for Ellipsoidal and Flanged and Dished Heads 9.3.1 Ellipsoidal and Torispherical Heads under External Pressure ASME Equations for Conical Head Design 9.4.1 ASME Simplification of Discontinuity Analysis due to Intemal Pressure 9.4.2 Conical Shells under External Pressure 9.4.3 ASME Simplification of Discontinuity Analysis due to External PressureNomenclatureReferences

255 256 256 26r261

Circular Plates on Elastic Foundation NomenclatureReferences

197

Bibliography

200 201 201

Bibliography

265 266 267

Chopter

l0

Bfind Flonges, Cover Ploles, ond Flonges 269

l0.lPART 3 Chopter DESIGN OF COMPONENTSDesign of Cylindricol ShellsASME Design Equations Evaluation of Discontinuity Stresses ASME hocedure for Extemal Pressure Design Design of Stiffening Rings Allowable Gaps in Stiffening Rings Out-of-Roundness of Cylindrical Shells under External Pressure Design for Axial Compression NomenclatureReferences

IntroductionCircular Flat Plates and Heads with UniformLoading

270274 276

203205206 208 218 226 23r 235 238 240 240241

ro.2 r0.3

8

ASME Code Formula for Circular Flat Headsand Covers

8.1 8.2 8.3 8.4 8.5 8.6 8.7

10,4 10,5 10.61O.7

Comparison of Theory and ASME Code Formula

for Circular Flat Heads and Covers without BoltingBolted Flanged Connections Contact FacingsGaskets

278 278 279281

Bibliography

10.7.1 Rubber O-Rings 10.7.2 Metallic O- and C-Rings 10.7.3 Compressed Asbestos Gaskets 10.7.4 Flat Metal Gaskets 10.7.5 Spiral-Wound Gaskets

281281

282 283 285

CONTENTS

CONTENTS

xvii

1O.7.6 10.7.7 10.7.8

Jacketed Gaskets

Metal Ring GasketsHigh-Pressure Gaskets

10.7.9

Lens Ring Gaskets '10.7. Delta Gaskets 10.7.1I Double-Cone Gaskets

I0

I0.7. l2 Gasket Design 10.8 Bolting Design 10.9 Blind Flanges 10. 10 Bolted Flanged Connections with Ring-TypeGaskets

285 285 285 286 287 288 290292

I I.5 I 1.6

Ligament Efficiency of Openings in Fatieue Evaluation of Nozzles under InternalPressure

Shells

387

1t.7

Extemal Loadings

Local Stresses in the Shell or Head I 1.7.2 Stresses in the Nozzle Nomenclature11

.7.1

392 394 394407 415 416 417

References

294 298 307 310317

Bibliography

Chopter

l2

Vessel SupportsIntroduction

421422 423 434 438 442 443 449 456 456 457

I 10. l2 10. l3 10, l4l0.l

Reverse Flanges

12.1

Full-Face Gasket Flange Flange Calculation Sheets

12.2

FlatFace Flange with Metal-to-Metal Contact Outside of the Bolt Circle 10.15 Spherically Dished CoversNomenclature References

Bibliography

317 324 330 332 332

12.3 12.4 12.5 12.6

Skirt and Base Ring Design 12.2.1 Anchor Chair Design Design of Support Legs Lug-SupportedVessels Ring GirdersSaddle Supports

NomenclatureReferences

Bibliography

Chopter I I

Openings, Nozzles, ond Externol [oodingsGeneralStresses and Loadings at Openings

335336 338 343 346 349 359 368 379383

ll.lI 1.2 I 1.3'|

PART

4 l3

THEORY

AND DESIGN OF

SPECIAL

EQUIPMENT

459461462 462 462 470 476 482 487 490 496 496

1.4

Theory of Reinforced Openings Reinforcement Limits I I .4. Reinforcement Rules for ASME.

Chopter

Flot Bottom TonksIntroduction

I

Section Section

IVIII, Division I

13.1 13.2

I I .4.2 Reinforcement Rules for ASME,

API 650 Tanks 13.2.1 Roof Design

l

l.4.3.4.4

II I

L4.5

Reinforcement Rules for ASME, Section VIII, Division 2 Reinforcement Rules for ANSUASME 831. I Reinforcement Rules for ANSI/ASME83 t.3

13.2.2 13.2.3

Shell Design Annular Plates

13.3 13.4

API 620 Tanks 13.3. I Allowable Stress CriteriaI

3.3.2

Compression Rings

ANSI 896.1 Aluminum Tanks13.4.

I

Design Rules

xviii

CONTENTS

coNTENrs

13.5

AWWA Standard D100References BibliograPhY

498 499 499

16.4 16.5

Dynamic Analysis from Wind Effects Vessel Under Intemal Pressure OnlyI

6.3.2

577581

Vessel Under Internal Pressure and ExtemalLoading

Chopter

14

Heql Tronsfer EquipmeniTYPes

501502 505 508 514 519 523 523 527 533537

-

16,6 Vessel Under External Pressure Only 16.7 Vessel Under External Pressure and ExternalLoadingReferences

585 588591

l4.l14.2

of Heat Exchangers TEMA Design of Tubesheets in U-TubeExchangers

14.314.4

in U-Tube Theoretical Analysis of TubesheetsExchangers Equations for Background of the ASME Design Tubesheets in U-Tube Exchangers Theoretical Analysis of Fixed Tubesheets

Bibliography

593 593

Chopter

17

Vessels

of Noncirculor Cross Section

595596601 601

14.5 14.6

TEMA Fixed Tubesheet Design l4'6'l Local Equivalent Pressure

17,1 17.2 17.3 17.417.5

Types of Vessels Rules in Codes

Openings

Section

in

Vessels with Noncircular Cross

l4'6'214'6'3

General Equivalent Pressure

Ligament Efficiency

Relationship Between Local and Equivalent Pressure

Openings

for

Constant Diameter601

14.7

ExPansion Joints

NomenclatureReferences BibliograPhY

537

17,617.7 17.8 17.9

538 539 Pressure

Chopfer

15

Vessels

for High

541541

t7.to

15.l15.2 15.3 15.4

Basic EquationsPres$essing of Solid Wall Vessels Layered Vessels Prestressing of Layered Vessels

543547

Ligament Efficiency for Multidiameter Openings Subject to Membrane Stress Ligament Efficiency for Multidiameter Openings Subject to Bending Stress Design Methods and Allowable Stresses Basic Equations Equations in the ASME Code, VIII-I Design of Noncircular Vessels in Other Codes I 7. 10. I Method in Swedish Pressure Vessel

603 606 610 612 619 626 627 630 633 633

Code

Nomenclature

Biblio$aphY

558 562 563

Rules References BibliographyAPPENDICES

I 7.

10.2

Design by Lloyd's Register of Shipping

Chopter

16

Toll VesselsDesignConsiderations Earthquake Loading

565566567

635

l6.l16.2 16.3

Wind Loading 16.3'1 Bxternal Forces from Wind Loading

573 573

A B Appendix CAppendix Appendix

Guide to Various Sample of Heat Exchanger Speciflcation Sample of an API Specification

Codes

636

Sheet Sheet

U6648

II

CONIENTS

D E Appendix FAppendix Appendix Appendix

Sample of a Pressure Vessel Design Data Sheet Sample of Various Materials for Process Equipment

652 668

Required DataSection

for Material Approval in the ASME675

VIII

Code

G

-

Procedure for Providing Data for Code Charts for Extemal Pressure Design

Appendix Appendix Appendix

H I J Appendix KAppendix

Corrosion Charts Various ASME Design Equations Joint Efficiency Factors Simplified Curves for Extemal Loading on CylindricalShells

678 683 686 689 698

PART

L

Conversion Tables

BACKGROUND

INDEX

AND BASICCONSIDERATIONS

CHAPTER

HISTORY AND ORGANIZATION OF CODES

-OtD 2

TIMERS [(lop) Courtesy Bobcock & Witcox Compony, (bol|or,) (

iuroly

,",r,,, , ,"r,,,,r,,,1

-Y

HISTORY AND ORGANIZATION OF CODES

I.I

USE OF PROCESS VESSELS AND EQUIPMENT

'I'hroughout the world, the use of process equipment has expanded considerably. ln the petroleum industry, process vessels are used at all stages of processing oil. At the beginning of the cycle, they are used to store crude oil Many different types of these vessels process the crude oil into oil and gasoline for the consurner. The vessels store petroleum at tank farms after processing and, finally, scrvc to hold the gasoline in service stations fol the consumer's use. The use of Droccss vessels in the chemical business is equally extensive. Process vessels are uscd everywhere. Prcssure vessels are made in all sizes and shapes. The smaller ones may be no larger than a fraction of an inch in diameter, whereas the larger vessels may be 150 ft or more in diameter. Some are buried in the ground or deep in the occan; most are positioned on the ground or supported on platforms; and some lctually are found in storage tanks and hydraulic units in aircraft The internal pressure to which process equipment is designed is as varied as thc size and shape. Intemal pressure may be as low as I in water gage pressure to as high as 300,000 psi or more. The usual range of pressure for monoblock

construction is about 15 to about 5000 psi, although there are many vessels designed for pressures below and above that range. The ASME Boiler and Itcssure Code, Section VIII, Division t*, specifies a range of intemal pressure liom 15 psi at the bottom to no upper limit; however, at an intemal pressure abovc 3000 psi, the ASME Code, VIII-I, requires that special design considcrations may be necessary.r However, any pressure vessel that meets all the rrquircrncnts of the ASME Codc. regardless of the intemal or external design prcssuro. rnay slill bc acccptcd by thc authorized inspector and stamped by the nrlrnrllclurcr with thc ASMI'l ('rxlc syrttbol. Some other pressure equlpment, srrch as Al'l'' sl(nagc t Dks. rrriry bc dcsigned and contain no more intemal pf('ssur( llriur lhitl gcncrirlc(l l)y lllc sllllic hcird of fluid contained in the tank.

I,2

HISIORY OF PRISSURE VESSET CODES IN THT UNITED STATES

llrt(,rt1lr llr( lrlr' lS(X):, ;rrrrl lrrtlv ltX)O\. (\l)losiotls in boilers and pressure vcsscls rlcrc lr({tr{nt /\ lrrctrllx lrorlt t trplosiott tlrr thc Mississippi River :,1{rlrlx);rt .\rtlt,ttt,t.t '\1rrrl .'/ lStr5. rcsttllctl itt thc boat's sinking within 20 r,l r rrtrr,,tr,rlrlrl r.trltttttr'rl un,rl)irl( (l rrrlo tlrc clrr'ly 1900s. In 1905, a destructive , rlrl,,.r,,rr (,1 .r lr, lrlr( l!,rl(-r rrr ir sllrr'' lltellrly in Brockton, Massachusetts (Fig. I l r. l rlllrl ''Il rr ,'r'l( . rrrlrrr, rl l l / otlrcls. and did Xi400,000 in property damage

nrnrt(.\,rr,l tlrrr|..rtlr,,l |')l)ilr,(,llr(r\JtoittlllrotrtcaliertheCivilWar.Thistype

'1,' rlL, r,\r \'.Alt r,rl, \'lll l,rrrrl VIII .'. rsrrrie(l lo (lcscribc thc ASME Boilcr and I'rcsstrrc Vi....tl(,trit ,, l',," \'ftl ffl\, r'r l. /,,,'r.vt( V, rfry'.r, and l)ivisitttl2, Alk'r'ttttiK |tttll li'r /!,11r,, l,\

\, /,

l.l Firerub boiler explosion in sho focrory in Brockron, Md!3ochuseits in 1905. (Courlesy Horrford St@m Boiler Inrpection ond Insurdn.e Co., Horrford, Cr.)Fisure

6irr dcalh,

HISIORY AND ORGANT/N rION Of CODTS

].4

ORGANIZATION OF THT ANSI 83

]

CODI] IOR PRISST'RE

PIPINO

7

the ANSI/ASME Boiler and pressure Vessel Code have been established as the legal requirements in 47 of the 50 states in the United Str,", ,,",f in all the prwinces of Canada. Also, in many other countries of the worlti, the ASME

2, Alternatiye Rules for pressure Vessels. The ANSUASME Boiler and pressure Vessel Code is issued by the American Society of Mechanical Engineers with approval by the American'National Stan_ dards lnshtute (ANSI) as an ANSI/ASME document. One or morc sections

, sure Vessels, and another new part was issued, which was Seciion VI II, Division

Unfired Pressure Vessel Code, Section VIII. This continued until the 196g edition. At that time, the original code became Section VIII, Oivislon I pres_

vessel codes existed. In 1951, the last API_ASME Code ;as issued as a separare document.a In 1952, the two codes were consolidated into one code_the ASME

In 1911, Colonel E. D. Meier, the president of-the American Society of Mechanical Engineers, established a committee to write a set of rules tbr the design and construction of boilers and pressure vessels. On February 13, 1915, the first ASME Boiler Code was issuid. It was entitled ,,Boiler Construction Code, 1914 Edition." This was the beginning of the various sechons of the ASME Boiler and Pressure Vessel Code, which ultimately became Section 1, Power Boilers.3 The first ASME Code for pressure vessels was issued as ,,Rules fbr the ^ construction ofUnfired Pressure Vessels,', Section VIII, 1925 edition. The rules applied to vessels over 6 in. in diameter, voiume ove. 1.5 ft3, and pressure over 30 psi. In December 1931, a Joint API_ASME Committee wis ibrmed to develop an unfired pressure vessel code for the petroleum indusiry. .l.he first edition was issued in 1934. For the next 17 years,iwo separate unfiied pre;sure

clrusctt$ governor directed the fbrmation of a Board of Boiler Rules. The first set of rules for the design and construction of boilers was approved in Massachusetts on August 30, l9O7 . This code was three pages long-!-

Irr l(X)(r, l'r.llre'cx;rkrsi.rr irr . rlrr)c llrel.ry i'l,yrrrr. Massirclrrtsc.s, r.cs.ltcd injrlry, a|ld cxtcnsivc propcrty darragc. Aticr this accidcnr, the Massa_

T

cqUipl c|l{ irrrtl ir;lrlielrliorr; olllcrs fctalc lo sl)ccilic Illillcliltls all(l tlrclll{xls l()f ()l applicatiOn rn(l cot)trol ol cclt'tiprnctrt; lnd tlthcrs rclate ttt care !lnd inspoctioll 'l'hc tirllowing sections specifically relate to boiler and installed cquipnrctrt.pressure vessel design and constructlon:

Section Section

I.

Power Boilers (one volume)

III

Division DivisionCode

N-47 Section IV,Section

Case

1. 2.

Nuclear Power Plant Components (7 volumes)Concrete Reactor Vessels dnd Containment (one volume) Class I Components in Elevated Temperature Service (tn Nuclear Code Case book) Heating Boilers (one volume) Pressure Vessels (one volume) Alternative Rules for Pressure Vessels (one volume) Fiberglass-Reinforced Plastic Pressure Vessels (one volume)

VIII

Division DivisionSection

1. 2.

X.

of

Boiler and Pressure Vessel Code is used to construct boilcrs arrc pressurevessels.

In the United States most piping systems are built to the ANSI/ASME Code P.ressure Piping B3l . There are a number of different piping couc sectrons for different types of systems. The piping section that i" ,ir".i tiu. boiiers in combination with Section I of the ASME Boiler and pressure Vcsscl (ixle is the fo1!-o1er Piping, 831.1.5 The piping secrion thar is olicn uscrt with !o09 -Cheniical Section VIII, Division I , is the code for piant and lretnricLrrrr t{clinery Piping, 831.3.6 for

A new edition of the ASME Boiler and Pressure Vessel Code is issued on July I every three years and new addenda are issued every six months on January I and July l. A new edition incorporates all the changes made by the addenda to the previous edition; it does not incorporate, however, anything new beyond that coniained in the previous addenda except for some editorial corections or a change in the numbering system. The new edition of the code becomes mandatory when it appears. The addenda are permissive at the date of issuance and become mandatory six months after that date. Code CasesT are also issued periodically after each code meeting They contain permissive rules for materials and special constructions that have not been sufficiently developed to place them in the code itself. Finally, there are the Code Interpretations8 which are issued every six months These are in the form of questions and replies that further explain items in the code that have beenmisunderstood.

I.4

ORGANIZATION OF THE ANSI

83I

CODE TOR

PRESSURE PIPING

I,3

VESSET CODE

ORGANIZATION OF THE ASME BOILER AND

PRESSURE

The ASME Boiler ancl pressure Vessel Code is clivided into many sectrons, divisions, parts, and subparts. Some ofthese sections relat",u ro"lrti. tina of

"

In the United States the most frequently used design rules for pressure piping are the ANSI 83l Code for Pressure Piping. This code is divided into many sections for different kinds of piping applications Some sections are related to specific sections of the ASME Boiler and Pressure Vessel code as follows:

HISTORY AND ORGANIZATION OF CODES

I.6

WORLDWIDE PRESSURE VESSEI

CODES

q

R!1.1.

Power Piping (which is related to Section I) F.31.2. Fuet Gas Piping (which may be related to Section VIII) 831.3. Chemical Plant an(l Petoleum Refnery Piping (which may be related to Section VIII) R31.4. Liquitl Petroleum Transporting Prping (which may be related to Section VIII) 831.5. Refrigeration Piping (which may be related to Section VIII) 831.7, Nuclear Power Piping (which has been discontinued and incorporated into Section III) B31,8. Gas Transmission and Distribution Piping Systems (which may berelated to Section

bular Exchanger Manufacturer's Association, New york. Standnrds of the Expqnsion Joint Manufacturers Associ(ltion, 4th ed. , Exoan_ sion Joint Manufacturer's Association, New york.

Stanlarh of Tubular Exchanger Manufacturers Association, 6th ed.,

Tu_

I.6

WORI-DWIDE PRESSURE VESSEL CODES

VIII)

The ANSI B31 Piping Code Committee prepares and issues new editions and addenda with addenda dates that correspond with the ASME Boiler and Pressure Vessel Code and addenda. However, the issue dates and mandatory dates do not always correspond with each other.

Pressure Vessel Code, which is used worldwide, many other pressure vessel codes have been legally adopted in various countries. Difficulty often occurs when vessels are designed in one colntry, built in another country, and installed in still a different country. With this worldwide construction this is often the case. The following list is a partial summary of some of the various codes used in

In addition to the ASME Boiler and

different countries:

Australia.SOME OTHER PRESSURE VESSEL CODES AND STANDARDS IN THE UNITED STATES

I.5

Australian Code for Boilers and Pressure Vessels, SAA Boiler Code (Series AS 1200): AS 1210, Unf.red Pressure Vessels and Class 1 H, pressare Vessels of Advanced Design and Constuction, Standards Association of Australia. Belgium.Code

In addition to the ANSVASME Boiler and Pressure Vessel Code and the ANSI B31 Code for Pressure Piping, many other codes and standards are commonly used for the design of process vessels in the United States. Some of them are:ANSUAPI Standard 620. "Recommended Rules for Design and Construction of Large, Welded, Low-Pressure Storage Tanks," American Petroleum Institute (API), Washington, D.C. ANSVAPI Standard 650. "Welded Steel Tanks for Oil Storage," American Petroleum Institute, Washington, D.C. ANSI-AWWA Standard D100. "Water Steel Tanks for Water Storage"' American Water Works Association (AWWA), Denver, Colorado'

Standard Institute (IBN), Brussels, Belgium,

for

Good Practice

for

the Construction of Pressure Vessels, Belgian

France.Constructton Code Calculation Rules for Unfred pressure Vessels, Syndicat National de la Chaudronnerie et de la Tuyauterie Industrie e (SNCT), paris, France. Germany.

ANSVAWWA Standard D101. "Inspecting and Repairing Steel Water Tanks, Standpipes, Reservoirs, and Elevated Tanks, for Water Storage," American Water Works Association, Denver, Colorado. ANSI 896.1. "specification for Welded Aluminum-Alloy Field Erected Storagc Tanks," American National Standards Institute, New York' lll, (A4. Standartl for Conk ner Assemblies.lor I'P-Gas, 4th ed, Underwlitcrs Laboratories. Nolthbrook, Illinois.

A.D. Merkblatt Code, Carl Heymanns Verlag KG, Koln/Berlin, Federal Republic of Germany.haly. Itqlian Pressure Vessel Code, National Association for Combustion Control (ANCC), Milan, Iraly.

t0

HISTORY AND ORGANTZATION OF CODES

BIBTIOGRAPHY

,ltpun.Japan Associution. Tokyo, Japan. Juyuu'ts-t' Standarrl, Construction of pressure Vessels,JIS B g24j, published "- - e' 'J' Y' by the Jupan Srandards Association. Tokyo, Japan. Jap,ayle High pressure Gas Control Law, Ministry of International

llpressure

,lqnnt'st' l)tt,.t,rurt Vt,l;scl Code. Ministry of Labor, published by lJoilcr

8.

ASME Boiler and Vessel Code, _fu terpretations, (isstred every six months), Amedcan Society of Mechanial Engineers, New york.

BIBTIOGMPHY' Steel Tanks for

1i1,1,".t":,ry.Jibtished by rhe rnstitution for tngtneering, Tokyo, Japan.Netherlands.

sffi

riigi;;Jrr*" c", "r

Trade

Liquid Stoege', in Steel plate Engifieerin| Data, Vol. and Sreel lnslirute, Washingron, D.C.

l,

1976 ed., American

Iron

f,:|;:#i:"*-eSweden.

vessets. Dienst voor het stoomwezen, The Hague, the

Swedish Pressure Vessel Code,-Tryckkarls kommissioner, the Swedish pres-

sure Vessel Commission, Stockholm, Sweden.

United Kingdom.

British Code 85.5500, British Standards Institution, London, England. More complete details. discussions of factors of safety. and applications the codes mentioned are given in Section 2.7. e summ,lry

which.ar.e appticable for ihe various,.reqrl;il around the world is given in Appendix

A.

;'r#J

of of iti. p_ug.upt, # ,ti .o0., ur.o

REFERENCES

f. 2.

l. ASME Boiler and pressure Vesset Code, Section_|, power Boileru, ANSTASME BPV_I, nlll*,*n Sociery of Mechanicat Engrneers. New york, 1983. _ Liq.uids and Gases, 5th ed., " lilHy3,::ff '.{iX::#l#f#*y:::k-!y1951.gmeers and American petroleum Institute, ^Pa'r:teu! New york,

"R""",*";;;'R';:"i."iiirT"firi,"ffilffi;TiJi:i,*Li.;, j::::"[iJ:** tanks," ANsr,/Apr srd. 620,;.;;;";-;;;;;; i,i.tr"iot", wu,r,ing_ .;:Apr srandard 620,

ASME Boiler and pressure Uo*] ANSVASME BpV-Vm_1, Americar

"aT.:

,:".,,:n. Unr, Division

l,

pressure Vessets,

S, 6. 7'

ol

ASME Code for hessure pipinq BJl.Mechanicar Engineers,

Socicty

ASME Code for hessure pioins B3l, g!t:m:cal. ptant and petroleunt Refinery piping, 83t.3. American Siciety of Mechanical ;;C;;, ;u;;"lo.k,r,,*0. ^NSvASME A_SME Boije-r and hessure vesser code, cases, Boirers antr pre,rrrre y$dh, American

Niw-york, 73l;;"'0"'ANSL/ASME

B31

l'

American societv

of lvlechanicaj En8incers, Ncw -cod? york,

19g3.

CHAPTE

R

2

SELECTION OF VESSEL, SPECI FICATIONS, REPORTS,

AND ALLOWABLE STRESSES

l3

l4

SttECTlON OF VESSIL, SPECIFICAIl()N".

rtlr",lrr'., nND

ALLOWABLE STRESSES

2.4

SPECIAL DESIGN REQUIREMENTS

l5

2.1

SELECTION OF VTSSI

I

2.3

DESIGN SPECIFICATIONS AND PURCHASE ORDERS

Although nrlrrly lttr l t. ,,'rrlrl,rt, 1,, llr( \( lL'clion of pressure vessels, the two basic r.r;rrirr.rrfrrt,, tlr,rt ,rll,, t tlr, ,( [.r lion are safety and economics. Many it(.Drs i||r. r rr,,rrI r,,l rr,tr,r', rrrrrtcrials' availability, corrosion resistance, lrltllrrl,, rrr, rrl,tlr r11, . .rr,l rrrrrgnitudes of loadings, location of installation rr, lr,lprl, ( rnl I,r.r,l'rt' ,"r,t r.rrr'(lrquake loading, location of fabrication_(shoD "r 1., l,lr t", rrr,,r ,,t \i.,,s(.1 installation, and availability of labor supply at therrt, rrr, r, ,r'.rrr1' rrsc of special pressure vessel in the petrochemical and other rl, , rtr. ;rvrilability of the proper materials is fast becomrng a maJor 1,r,,t,1,,,' I lr(. nrost usual material for vessels is carbon steel. Many other special_ r,,, l r r,rr{ rlls iLre also being used for corrosion resistance or the abilily ro conmln rrr,lrr

\l

field.

wrthout degradation of the material's properties. Substitution of materials lent and cladding and coatings are used extensively. The design engineer rrrrrst lrc in communication with the process engineer in order that all materials rrsctl will contribute to the overall integrity of the vessel. For those vessels that rctluire field assentbly in contrast to those that can be built in the shop, proper (luality assurancc must be established for acceptable welding regardless;f ihe adverse condilions under which the vessel is made_ provisions must be estab_ lished for ftrrliography, stress relieving, and other operations required in the.r tlrrrr Ir'. I x (.vl

For thost. vcssels that will operate in climates where low temperatures are encounlcr((l r)f contain fluids operating irt low temperatures, special care must be takc rr Ir crrsure impact resistance of the materials at low timperatures. Toohlirirr tlrs l,r()l)crty, the vessel may require a special high-alloy steel, nonferrous rrrirlcrirrl, rrr some special heat treatment.

2.?

WHICH PRESSURE VESSEL CODE IS USED?

'l lrc lrrst consideration must be whether or not there is a pressute vessel law at llrc lo( irt ion of the installation. If there is, the applicable iodes are stated in the l:rw. ll thc jurisdiction has adopted the ASME Code, Section VIII, the decision rrrly bc narowed down to selecting whether Division I or Division 2 is used. I'here are many opinions regarding the use of Division I versus Division 2, but the "bottom line" is economics. In the article ,.ASME pressure_Vessel Code: Which Division to Choose?",r the authors have listed a number of factors for consideration. Division uses approximate formulas, charts, and graphs in simple calculations. Division 2, on the other hand, uses a complex methocl of fbrmulas, charts, and design-by-analysis which must be describcd in ir stress report. Sometimes so many additional requirements are addcd lo tltc rriuirnum specifications of a Division I vessel that it might bc rnorc ccorrorrrir.rrl to supply lu I)ivision 2 vcssel and lake advantage of thc highcr itlL)rvrl)l(. strrsscs.

.

Currently, the only pressure vessel code, exclusive of the ASME Code, III-lNB, Nuclear Vessels, which specifically requires formal design specifications as part of the code requirements is the ASME Code, VIII-2, Alternative Rules for Pressure Vessels. This code requires a User's Design Specification to be prepared and certified by a registered professional engineer experienced in pressure vessel design. This certification by the professional engineer is given on the ASME Manufacturer's Data Report, Form A- 1. The manufacturer is responsible for retaining the User's Design Specification for five years. For other codes and standards, design specifications and design requirements are not well defined. For the ASME Code, VIII-1, there is no specific statement that any design specifications are required. The only indication of some sort of design specifications is the list of minimum loadings in UG-22 that is considered for all construction . Sectron l, Power Eoilers, is less definitive on what loadings are necessary to consider and what shall be included in a design specification or purchase order. PG-22 of Section I states that loadings that cause stresses to go higher than 107o above those stresses caused by internal design pressure shall be considered. The Manufacturer's Data Report, Form U-1 for the ASME Code, V I-1, requires many items to be listed, which means that most of the basic design information must be given in a design specification or purchase order. Although some codes help the purchaser regarding what data are needed for inclusion in the design specifications, this is usually done by mutual agreement between the purchaser and the manufacturer. "For those process vessels that do not have a "suggested" list of items in design requirements and specifications as part of code requirements, it is necessary to establish them in the purchase order or contract agreement. The contract information is supplied by the purchaser or user with the manufacturer's help as to what is needed and what shall be considered. Some design standards help the user and manufacturer by offering fill-in forms that specifically list the requirements for designing a process vessel. Design specification forms for a heat exchanger built to the standards of the Tubular Manufacturers Associationz are given in Appendix B and lor an API Srandard 650 Storage Tanki are given in Appendix C. It is always necessary to maintain a document containing design speciflcations so that a permanent record is kept for reference. Often on a large process vessel, some loadings from attached or supported equipment are not known until after the job has started.

I

2.4

SPECIAL DESIGN REOUIREMENTS

In addition to the standard information required on all units, such as designpressure, design temperature, geometry, and size, many other items of infbrmation are necessary and must be recorded. The (xrrrosion and erosion amounts arc

16l,

sfl,tcTtoN Ot Vtssll, st,tctt tcaTtoNs, RfpoRTs, AND AU-OWABLErrrrrl rr srrrtirlrlt.

STRTSSES

2.9

ATLOWABLE TENSITE STRESSES IN THE

ASMI

CODE

17

lyl)c (,l lllrirl tlrrrl

lx' *,u,.,,

will

rcqltitc(l slx\.ili(.rk.sigrr tlctaiis. Supported position, vertical or honzontat, and s[pl)oll lor.rrtiorrs rlusl bc listed as well as any iocal loads from supported crltip,rc,t rrrrtl piping. Site locatiorr is given so that wind, *o*, una lcquircntcots ctrn lre determined. Impact loads and cyclic "u.tnquut" requirements are alsoinclurlcd.

r'irlcri.l uld method of protection are to be noted. The lrc t,0|llainctl, such as lethal, must be noted because ofthe

may be recertified to an SA or SB specification for an ASME certified vessel. Depending upon the contract specifications, permissible materials for construction are given in lists such as that shown in Appendix E.

2.7

DESIGN DATA FOR NEW MATERIALS

allowable stresses vary with the type of loadinls.

spccilications state whether or not certain loadings

thc ASME Code, VIII-2, a statement as to whether or not a tatigue according.to AD_160 is given. rf u rutilu" analysis is :::'.r,:::'.-"111r'llo cycles and rc(lurrc(t. lhe specitlc loadings will be given. In addiiion, the design

lirr

ire

sustained or transrent. The

2.5

DESIGN REPORTS AND CATCULATIONS

(raclutl

U-2(g) or other design formulas. The pressure vessel design sheets should contain basic design and materials data and at least the basic calculations of pressure parts as given in the design formulas and procedures in the applicable onT.nd1d_fg. a simple vessel, an example of calculation sheets rs given :_od^. depicts only those calculations that are required ll ilp"yiT D. This example and for construction. for the Authorized Inspector Other vessels may requre rnuch more extensive calculations depending upon the complexity and con_greements.

lations. These calculaiions are prepared and certified by a registered professional engrneer experienced in pressure vessel design. As with the Usir,s Design Specification, the Manufacturer's Design Report is mandatory and the certification reported on the Manufactu.".i Datu Repo.t. This is kept on file by the manufacturer for five years. - For vessels not requidng design reports, the manufacturer has available for the- Authorized Inspector's review those necessary calculations for satisfying

T:,1YE ,C"1.. .VII.2. requires a formal design report with rhe assumptions rn.the User's Design Specification incorporated in the stress analysis calcu_

When design data, such as allowable stresses, are requested for a new material, that is, one not presently in the code, extensive information must be supplied to the Code Committee for evaluation. The ASME Code Committee lists this information to develop allowable stresses, strength data, and other required properties for accepting a new material into the code. Each section of the code contains an appendix listing these requirements such as the one for the ASME Code, VIII-I, in Appendix F. The code also provides data to establish extemal pressure charts for new materials; this is given to those who want to establish new external pressure charts. The required information is given in Appendix G. It is the person's responsibility requesting the addirion to supply all the data needed to establish those properties required in the code.

2.8

FACTORS OF SAFETY

In order to provide a margin of safety between exact formulas, which are based on complex theories and various modes of failure , and the actual design formulas used for setting the minimum required thicknesses and the stress levels, a factor of safety (FS) is applied to various materials' properties that are used to set the allowable stress values. The factors of safety are directly related to the theories and modes of failure, the specific design criteria of each code, and the extent to x.hich various levels of actual stresses are determined and evaluated.

2.9

ALLOWABTE TENSILE STRESSES IN THE ASME CODE

2.6

MATTRIALS' SPECIFICATIONS

As previously discussed, the basis for setting the allowable stress values or the design stress intensity values is directly related to many different factors depending upon the section of the code used. The criteria for setting allowable tensile stresses for each section of the ASME Boiler and Pressure Vessel Codeare as follows: For Section I, Power Boilers, the ASME Code, YIll-l , Pressure Vessels, and Section III, Division 1, Subsections NC, ND, and NE, except for bolting whose strength has been enhanced by heat treatment, the factors used to set the allowable tensile stresses are summarized below. At temperatures in the tensile strength and yield strength range, the least of:

All crxles itnd standards have materials, specifications and requirements de_ sclibirrg whirl rrralcrials are permissible. Those material, tirut *"i"r_rtt"O *itt ir sp(.( rli( ((xlc arc cither listed or limited to the ones that have aliowable stress vrrlrrts liivcrr. l)upcnding upon the code or standard, permitted rnatenas tor a pirrtit rrliu plxt.ss vcsscl are limited. For instan"., Jin ljll (lcsif nirrior crr bc uscd in ASME Boiler and piersir" V"rr"i-Cot an se or "rnr,_"_ SI) specifications are the same B specifi:]:lil...Y:::,:t flltlotl rr lltc ASIM ::l',t Stirrrtlirltls a On specific instances, certain materiais that Itttvc lrt'rr rr.rlrril( r'r'r(r to sonrc other spccification, such as the DIN standard..

o;i.;";;,

l:,lf

u';;;,

1. j of the specified minimum tensile strength. 2. j of the tensile strength at remperarure. 3. ! of the specified minimum yield strength.

I8

SEI.TCTIONr{

OI

VESSEL, SPECITICATIONS, REPORTS,

AND AttOWABtE

STRESSES

2.IO

ALLOWABLE EXTERNAI PRESSURE STRESS AND AXIAI.

STRESS

I9

4.

ol thc yicld strength at temperature (except as noted below where 90Zo is uscd).

following: (1) | of the specified minimum yield strength and (2) j of the yieldstrength at temperature.stresses is much more simple:

At temperatures ip the creep and rupture strength range, the least of:

For Section IV, Heating Boilers, the criterion for setting the allowable (1) I /5 of the specified minimum tensile strength.

l, 2. 3.,_

hours.

l00qa of the average stress to produce a creep rate of 0.0l per l000 hours (l7o in 105 hour). 67Ea of the average stress to produce rupture at the end of 100,000 hours. 80Vo of the rninimum stress to produce rupture at the end of 100,000

ALTOWABLE EXTERNAL PRESSURE STRESS AND AXIAL COMPRESSIVE STRESS IN THE ASME BOILER AND PRESSURE VESSEL CODE

2.IO

allowable stresses, higher allowable stresses are permitted for austenitic stainless steels and nickel-alloy materi-als where gleater deformation is not objectionable.

In the temperature range in which tensile strength or yield shength sets themay be increased to

spicified minimum yield strength is still maintained. For the ASME Code, VIII-I, bolting material whose slrength has been en_ hanced by heat treatment or strain hardening have the addition; criteria of (l) j of the specified minimum tensile strength and (2) t of the specified minimum yield strength. For the ASME Code, VIII-2, and Section III, Division 1, Subsection NB and NC-3200 of Subsection NC, the factor used to set the design stress intensity values for all materials except bolting is the least of:

!9h:l*,the criterion of I yield strength at lemperature 9oVo,yield strengthat temperature. However, the factor

!

Within the ASME Boiler Code, simplified methods are given to determine the maximum allowable external pressure and the maximum allowable axial compressive stress on a cylindrical shell without having to resort to complex analytical solutions. Various geometric values are contained in the geometry chart, whereas materials' properties are used to develop the materials charts. Allowable stresses in the materials charts are based on the followine criteria For cylindrical shells under external pressure, the least of:

l. 2, 3. 4.

33Vo 33Va 67Vo

of the critical buckling stress with a factor of 807o for tolerance. of the specified minimum yield strength and yield strength at tem-

perature.

of the average stress to produce a creep rate of 0.01%/1000 hours (17ol 100,000 hours).

1. i of the specified minimum tensile strength. 2. ] of the tensile strength at remperarure. 3. of the specified minimum yield strength. 4. J of the yielded strength at temperature except as noted in the tbllowing.2

OI:

-

IOOVo of the allowable stress in tension. For spheres and spherical portions of heads under extemal pressure, the least

paragraph.

l. 2. 3. 4. l. 2. 3. 4.

of the critical buckling stress with a factor of 607o for tolerance. 25Va of the specified minimum yield strength and yield strength at tem25Eo

perature.

design by Appendix 4 of the ASMII (ixlc. VIII_2, and by Division -l , Slbsdition NB ancl NC-32(X) ot' Sutiscc.riirn IrtC. the crilcria lirr setting bolting design stress intcnsity vitlucs urc thc lesscr of theSectirrn

maintained. There are two criteria for setting bolting design stress intensity values in the ASME Code, VIII-2. For design by Appendix 3, the criteria are the same as for the ASME Code, VI -1, because these values are used for the tlcsign of bolts

Higher design stress intensity values are permitted for austenitic stainless steels and nickel-alloy materils where greater deformation is not objectionable. In this_ case, the criterion of J yield strength at temperature may be increased to as high as 90Vo yield strength at temperature or any value beiween and gOVo ! yield strength at temperatue depending upon the acceptable amount of deformation. However, the factor of j specified minimum yield strength is still

507o of the average stress to produce a creep rate of 0.017o/1000 hours

(17ol100,000 hours). IOOVo of the allowable stress in tension.

For cylindrical shells under axial compression, the least259o50Vo

ol

of the critical buckling stress with a factor of 5OVo for tolerance. of the specified minimum yield strength and yield strength at temof the average stress to produce a creep rate of 0.017o/1000 hrs

perature.1007o(

for flangjs.

III,

Ior

l7ol 100,000 hours).

ljQVo of the allowable stress in tension.

o

t)

;ta

rrtt|tla\o cr \o

;6 ;5 ;6 -iA-i-l

Ed

0rt5

tItl tt||l ttltl.oP.ocotoNONa{:

.9

oo@

o

ltltitll

t-. F- a\o \o \o tr \o -i -i .l ^'

g -g Fq,

eq

rl||tls3ss5ssii>;h\>.o..).o.i66+

.i "i -; .-'

g

' =x

tF

6E '< ri 6O.

. o6;

.;T tE

i; = l0),2AEo

----!-

3(D,/t)and for elastic or plastic region

(8.6)

(D./t ;P

Example 8.4. The length of a cylindrical shell is 15 ft, outside diameter l0 ft, and is constructed of carbon steel with minimum yield strength of 36,000 psi. The shell is subjected to an extemal pressure of 10 psi. Find (a) the required thickness using ASME factor of safety and (b) the required thickness using a factor of safety of 2.0.

lO),

.t4B,t = 3(D./t)

Solution.

(a) Assume

where A = factor

determined from Fig. 8.10 and is equal to e", Then

t

:

6 rn.

: D, :BEq

factor determined from Fig. 8.11outside diameter of cylinder

= P=r

modulus of elasticity allowable extemal pressure thickness of cylinder

4:zzo t '-p_(2x0.009_l-8..1!Z?

D.

L=1.2s

:

From Fig. 8.10, factor A = 0.00018. From Fig. 8.11, modulus of elasticity ar room temperature is 29,000,000 psi. Hence, from Eq. 8.6

D,/t values less than 10, ASME uses a variable factor of safety that ranges from 3.0 for values of D"/t = 10 to a factor of safety of 2.0 for values of D"/t = 4-O. This reduction occurs because for very thick cylinders, bucklingForceases to be a consideration and the allowable values in tension and comoression

x

106)

(3)(32u)

:

r0.9

psi o.K.

are about the same . Hence, for D"f

t 30 Jegrees, it is rhe largerof0

.5

\/ffi

or e.73xte)

+

2.5t0)

For Fig. ll.15d, it is the targer of (0.5

\/r^I, +

or (2.57., +

t)

In both expressions above, t" is not to exceed 1.5[ or 1.7317 where I7 = width of added reinforcing pad.For all cases, the terms and definitions are:

*=0

slope offset distance (in.)

: amgle from vertical I' : vertical length of tapered section r^=r+0.57:Metal Availablz for Reinforcement The metal available for reinforcement is obtained from the following within the limits established:areas

l. 2. 3. 4.

Excess vessel wall thickness

1LtFigur

Excess nozzle wall thickness which penetration welds

is integral or

attached

by full_ll.l5Deioil! for limir of rinlorcmonr normol to vesrel woll. (Courtesy Anericon Soci6ty of

Weld metal in fillet weldsPad attachment welds (where permitted)

,i..honi.ol

Enginis: From Fis. AD-5,{0.1 of the ASME Code, Vlll-2.)

371

OPININOS, NOZZTES. AND EXTIRNAI IOADINOS

I

I.4

REINFORCEMENT

TIMITS

373

Pads (where permitted) 6.

Required Area of Reintorcement The required minimum area of reinforcement

Metal from items 2, 3, and 4 meets the following:l(aR

4.,

is

-

o.ilTl

use specified comer radii.

Edge+o-edge of openings

-

2.5

\/Fi.

1.5.

Design is within the following dimensional limits:

which siue. : o.ozt | ; = ;* = 0.034 I = 0.9D = 0.9(a1.75) = 37 575 in. t = O.OLLL = O.o2l(37 .575) = 0.789 in.;use 1.O-in. thickness

LimitD/td/D

Formed Heads Cylinders 10-200and Spheres

t

Using AD-201(a) of the ASME Code, VtrI-2, the minimum requiredthickness of the nozzle is

l0-2500.50 max.

d/\/Dt

0.33 max. 0.80 max.

Ps

700x21,600

0.80 max.

-

0.5P

-

4 0.700

= 0.132

in.;

use 1{ in. thickness

374

oP!N|NOS, NOZZ|tS, AND [XT!RNA| TOAD|NOS

v.x.r 416, Nod.r

bl A.inlo.d.r Zar. Li'ir

ltll2l

Lc-

OSas

li / RPI3R

fo. nozrld in cylin l.ic.l.h.thLa

'

128

k./ 213|Bh/a+g.'tIh.dt

for notrl.3 in

(3) Th. c.ni.r or l. or L, i! .r llr. ionct!.. ot rh. ourrldr rorl.clr ol th! .hdl r.d .02116 of rhicknt.r, ...nd a',

.Cylindric.l Sh.llr

{a)

unilorm rhictn!3r

.on3id.r!d.31.

l. condrudioff whr. th. .o.. bosfthry p.$6 rhrollh mll r.gh.nr, th! .on. born.Lry m.y !a o.l, through !h. thi.ln'.i

lll H.lch.d'..3 r.pr .nt !{.il.blc rlinlorc.hanrr..,a..l2l M?r.l .1.. whhin rh. ronc bou..hry, in |rc.$ ot tha.raa bV ri. inr.rildion ot th. b.!ic rh.[r, rh.l ba conrida.ad .! conrrabutin! ro th. ..qut.rl &.., Ar, Th! b.jc th.[!.,r drtimd .r h.vi.g iniid. r.di!! ,, thictn rt a, inrkt! r..liv. ,,torhcd l3l Th. .vriltbl. r.'nldc.rn.nt .rx,4. ih.|tl b. .r t..tr .qo.l to I,/2 on ..ch rid. ol rh. norrlaornr.r ti...nd in rvaw d.m co.r.iniq rh. nor2l..tir.

rr|

=

o.ltro 0.5.rh. tfEer ot r.41thertre

nrr

'

>

\/A;l./21

o.

tn

))

or tl0

tz,sr otl.,/E7i6li,z] or lol9oltn targe. of I t - JitEil x 1.41 \,6

-

l0l90,1

x

" end0' A, = 8.834 in.,

(h)

Reinforcement available in shell with two-thftds limit:

1.

A' =

(l -

0.728r(2

x

8.315

-

12)

=

1.259 in.2

(i)

Total reinforcement with two-thftds limit is

2. 3. d/D < 0.25. 4. Standard fittings of extra heavy or Class 3000 rating.Limitations.and 90 deerees.

Connections made from fittings that have a standard pressure/temperature rating established. d^:2-in. NPS with tn6 > Schedule 160 pipe.

At = At + Aa + An A,

=

1.259

+ 4.972 + 5.912 =

t2.O4O in.z

Angle between branch and run or nozzle and shell is between 45

= lz.MO > A, = 5.922 in.2

3t0

optt{r],tot, NoTztlt, aND txrrRNAl loADlNos

r

r.4

RHNFORCIMINI

llMlt3

3tl

Notatlons and Dsnnltlons. (Sce Fig. 11.20)

a = angle between nozzle and shell (degrees) D, = outside diameter of run or header (in.) d1 = (D" - 27,) /sin o(in.) dz = horizontal limit of each side of centerline, which is the T, + T, + 0.5/, but not more than D, (in.) 1 = perpndicular limit : 2.54 + t, (in.)Required Area of Reinlorcement

larger of dy or

The lotal cross-sectional area of reinforcement required for any plane through the

center of an opening is given by

A,:which for

l.o7t^hdlz

-

sin d)

(rr.29,

a

:

90' is

A,Avoi.lable Area of Reinforcement

= l.o1t*dl

(1 1.30)

The total area available for reinforcement is the sum 45 where each area is determined as follows:

ofAl + A2 + A3 + A4 +(11.31)

Ar=(2dz-d)(7,*t,,t) . zl(n - t'h) A1 ---------1-=

sm(I

(rr.32)

A3

==

area

of fillet welds

t, T; -TN ^N N' f fislr6F.di6d 6lnro6m..t.r!. a6. at -.rc6wdl l. h.!d.

I

Aa : A5 Reinlorcement Zone

arca of reinforcing rings, pads, and so on.

area of saddles a i jml[mt l@'B3l lAr.!A3

a& ar.

A4 45

-

rilld

*ld dll'tin

ncor In rin!, prd. or Ini.s.l dinro,c.d.nr tNol! {2ll

The limits of reinforcement are formed by a parallelogram with sides of d2 on each side of the nozzle centerline and an altitude of Z perpendicular to the shellsurface.

Au

A2

-.rcF

wttl in

br.nch

- m'ttt

td'!t doc

tun

I I .20 Dimnlions ond not'otions for ANSI/ASME Ensinosru, From Fis. 1O'1.3.1D of ASMBANSI B3l'l )

(Coud$v Americon Socitv of rnchonicol

2.Multiple OpeningsThe following should be applied:

Try to limit centerline spacing tobetween oPenings.

1

54"

with at least 50% of

area

l.

Overlapping area shall be counted only one time.

a design Example 11.11 A steam pipe has a 24-in' inside diameter with of 14,500 psi at the design temoressul of Z5OO psi and an allowable stress of pera$re. A branch ptpe wtrn an rnside diameter of 8 in connects at an angle

980

OPININO!. NOZZ[!S, AND IXTIRNAI toADlNos

|

1,4

RflNloRclMlt{T tl,ulTs

lu

Notatlone and Deffnltlons. (See Fig. 11.20)

a = angle between nozzle and shell (degrees) D" = outside diameter of run or header (in') dy = (D. - 24,)/sin o(in.) dz = horizontal limit of each side of centedine, which is the T, + T, + 0.5d, but not more than D, (in.) 1, : perpendicular limit = 2.5T^ + te (in.)Required Area of Reinforcement

larger of d1 or

The total cross-sectional area of reinforcement re4uired for any plane tbrough the center of an opening is given bY

A,which for

=

l.o7t,,hdt(2

-

sin d)

(1r.29)

a=

90o is

A,Avaihble Area of Reinforcenent

= l.olt*dr

(11.30)

The total area available for reinforcement is the sum 45 where each area is determined as follows:

ofAl + A2 + & +

+

^

At=Qlz-d)(T"-t*)Ar = -_---:-sln aA3

(11.31)

;r I

t,

.

zL\T,

-

t*)

(rr.32)

= a'.ea of fillet welds A+ = nrea of reinforcing rings, pads, and so on. A5 = arca of saddles

-TrNvFr.diDdorntor6n.nr.n!iaa..!43-lilltt'|'!ldm'itl Nv 4llD!l!II' eor aa - nrot in ri.s, p.d, or l.t trl a6. a1 -.'..sEll i. h..rL N' dinror.m.nr lNoa {2,1 l@' atle a5 _htnt innddttdd!run aE 42 -.r6.Mlt an bEnch f (Court$y Americon Socitv oI ttchonicol Figur. I I.20 Dimaffions ond nolotions for ANSVASME B3l lEnsimrs. From Fig. 104.3.1D of ASME/ANSI

Reintorcement Zone The limits of reinforcement are formed by a parallelogram with sides of d2 on cach side of the nozzle centerline and an altitude ofl perpendicular to the shellsurl'rce.

B3l'l

)

2.

Try to limit centerline spacing tobetween opemngs.

l 54"

with at least 5070 of

area

Mulliple OpeningsThc folkrwing should be aPPlied:

l.

Ovcrlapping area shall be counted only one time'

a design Example 11.11 A steam Plpe has a 24-in' inside diameter with psi and an-ailowable stress of 14,500 psi at the design tem-"r.ui" of 2500 ;;;;;.; ;;-.fi pipe with an inside diameter of 8 in' connects at an angle of

?82so that

OPININOS, NOZZITS, AND EXTERNAI. TOADINGS

I

I.4

REINFORCEMENT

IIMITS

383

o = 75'.'l'hoE

=

br&nch is &ttached by a lull-penctrutit)n wcld that is radiographed 1.0. Determine the thickness and reintbrcement requirements.

requirement: l7-in. OD ring x 0 75 in thick Nozzle attached to shell and pad by full-penetration welds'Pad

I

SolutinnProblem

l.

Determine the minimum required thickness of the run pipe as follows:

PR t', = Sf=-06p 2. t*=

25oo

x tr

=

2.308 in.: use

4

:

ll.lllfthenozzlewereattachedattt=g}",whatthicknessisrequiredfor the pad, if anY?Answer: I in. thickIPad

2.5 in.

Determine the minimum required thickness of the branch pipe as follows:

I.4.5

Reinforcemenl Rules for ANSI/ASME 83l '3

Pr _ oSt, Sn A,:

2500

x

4.0

=

0.769 in.: use 4,

=

2.0 in.

3. 4, 5.

Area required for reinforcement according to Eq. 11.29 is

Plant and The reinforcement requirements for ANSI/ASME B31 3, Chemical are similar to the requirements for ANSVASME Petroleum Refinery Piping, connections' S31. t and for Section Vtri, Dini.ion 1. Rules are given for branch

oi no""l"., which are attached to run piping, or headers' Differing ftom other

1.07(2.308\(8X2

-

sin 75')

:

29.43s't.z

,"info.""."ntshown in

Horizontal limits of reinforcement are the larger of

minimum requiled thickness of the branch piping piping' The area "ul"ulations anJ tne tun piping is measured on the outside thickness of the is the remainder of the piping's nominal thickness as available foi riiniorcement, the

Fig. 11.21.

d=8in. or 4+ nI r = 2.5 + 2.O + 4 = 8.5in.;ined.

use8.5in.

Limilations of GeomewThe angle between the nozzle and header is restricted to those intersections where tle acute intersection angle B is equal to 45" or more'

Perpendicular limit of reinforcement is as follows: Assume a 0.75 in. thick pad is added and attached by full penetration welds that are exam-

L = O'75 in'

Limitalion When No Reinforcement Calculatians Are Required0.75

L=

2.s7i,

+ t" =

2.5(2)

+

:

5.75 in.

6.

Area available for reinforcement is

1. 2. 3.

Ar

:

(2x8.5

-

8X2.5

-

2.308)

=

2.880

in.,

Standard fittings that have pressure/temperature ratings determined' < O'25 and a Standard fittings not exceeding 2-in. NPS that have d/D lb or more. pressure rating of 2000 Integrally reinforced connections that have been proved adequate by tests, calculations, and use.

4, =

2(5.75\(2

sln /J-

:-o

7691

=

14.656

n.,

Nomenclature

A, = (0.5)'z= 0.250 in.'?

ra = (2x8.5 - 8 - 4)(0.75) : 3.750 in., A, = At * A2 + A3 + Ac = 21.536 n.' > A, =Shell requirement: 24-:lr.. ID x 2.5 in. thick Nozzle requirement: 8-in. ID x 2.0 in. thick

4 = opening size in run or header (in') dz : horizontal limit on one side measured from the centedine of the open20.430 in.2

ing (in.)

l+ :

vertical limit perpendicular to header surface (in')acute angle at intersection (degrees)

Fillet weld requirements: 2 with 0.5 in. legs

F:,,, =

required thickness of header (in.)

I

L4 RllNrgRcltllllr I Llmlrt

g--t:6

Requireil Area of Reinforcement At For intemal Pressure,'o

Ar = ttdrQFor extemal Pressure'

-

sin F)

(1 1.33)

E

. thd(z - sin ar: -----T- B)Horizontal 1but not more than

(11.34)

3E

\,

Limits.

of the The horizontal limits on each side of the centerline

nozzle is the larger of

6!l

t2 ic

'6-

t;i.ie:IaEg'E

d1 or T1+4+05dID1,.

lI

:;e

12 fa , .z .-'

E *E E

t\ d" t 'E

t,o o o,s

$ig E iE,ei e 'Eq

$*c

5 oalo)

"a t s E ; t : Ec d --=: gE E\ I *HE 3.8 E E$ :E r ; E *,t..tc 3b: s E ; EE 5 !6

:H fr 6 -e; H R H {lrF. e; a 5 E --:-\ E9 d o o { lasg.E ".9 +E

E 3.3 t

>-:-e

e F

o.g

x

6fr igg'EiEiiiEs ;$H; E FBa ! L' ll.,l I l. $E 'EE ri .EE BflgESF.3 FE.E

A;EI iEf I - .eE E EEFsggg4t3

o p412

EEEI F

Eg?A

1t1

ollt{lt{ol, f{ollt|t,Tobb

AND

rxil${

r KTAD|NO3

NO'rltNCtATURt

4lt

ll,llf)

Strcr-Rongr RrductlonFactor,

Focl,oru (

7.

Determine allowable stress range

S,r:

Cycles, rV 7000 and less Over 7000 to 14,000

/

/Se

=

0.8 for 20,000 cycles

1.0

Over 14,000 to 22,000 Over 22,m fi 45,ONOver 45,0m

b

100,000

Over 100,000Courtgoy American Societygioeers.

0.9 0.8 0.7 0.6 0.5 of Mchanical En-

= 0.8[1.25(17,500 + 12,000) Ss < S,{ design is acceptable.Problpm

-

3760]

=

26,490 psi

11.1E An 8-in. NPS Schedule

160 branch pipe is attached to a 16-in. NPS pipe. The design pressure is 2000 psi, the allowable Schedule 160 run stress cold is S, = 17.5 ksi, and the allowable sfress at design temperature is 12.0 ksi. The maximum allowable torsional moment is 450,000 in.-lb. The pipe is designed for 10,000 cycles. Maximum

2.

Data at juncture from Table 11.6: 1.312 n=4 __ 5.719 =n,r"n R, u:H=z.qo n-'-

allowable bending moments are set as equal, ff rounded up to the next even 1(X) in.lb, what is the value of M. md Mi2

Answer: M. = Mr = 331,400 in.-lb

t = o.75i" + i = o.7s(2.$) + 0.25 = 2.053. Determine torsional stess:

(

s,=E=ffi=*oo.t4.Determine the bending shess:

NOMENCTATURE

Individual nomenclature is used throughout Chapter 11 and usually noted close to where used. The following gives some general nomenclature:

Sa=

2.05

x

600,000),

+

(2.40

x

900,000

122.6

:

20,770 psi

p, or P = intemal(psi)F"

design prcssure or maximum allowable working pressure

5.

Determine the stess range:

s"

- !*|14

=

\/Ao,nTT4@ - 2t,t7o psi3760 psi

nM6OT

: := =

extemally applied axial force (lb) extemally applied horizontal force (lb) extemally applied bending moment (in.-lb)total local stess at opening (psi) allowable tensile stress (psi) inside diameter of shell (in.)

6.

Determine sustained longitudinal stress:

sL: ezu) nl4i:

sD

: :

4

t6

OPTNINOS, NOZZtTS. AND TXTTRNAT I.OADINGS

BIBI.IOGRAPHY

417

d

=

insidc dianrctcr

ol nozzle (in.)

:=r,T^

inside radius of opening (in.)distance from center of opening to point being examined (in.),l

"strcsscs liorl Radial Loads aDd Lxlonl l MoDrcnls in Cylintlrical I'r'cssttrc Vcs scls," Wtltlint: Journal, Vol. 34, Rcsearch Supplcncnt, pp 601ts-617s, 1955 "Computation of the Sbesses ftom Local Loads in Sphcrical Prcssurc Vcsscls or -, Pressure vessel Heads," Wewing Research Council, Bulletin No. 34, New York, March14.

:= = =

nominal thickness of shell (in.) nominal thickness of nozzle (in.)

minimum required thickness of shell (in.) minimum required thickness of nozzle (in.)17.

"Local Stresses irr Spherical Shells from Radial or Moment Loadings," Weklirg Joumal, Vol. 36, Research Supplement, pp. 24ls-243s, 1957. "Sresses in a Spherical vessel from Radial l,oads Acting on a Pipe," weldinS -, Research Council, Bulletin No. 49, New Yo*, April 1959 "Stresses in a Spherical Vessel from Extemal Moments Acting on a Pipe," ibid , pp

195't. -,

-,

3t-62."Influence of a Reinforcing Pad on the Stresses in a Spherical Vessel -, l-oading," ibid., pp. 63-?3.under Local

, "stresses in Spherical Vessels from Local Loads Transfe.red by ^ Pipe," Weditq Research Council, No,50, pp. 1-9, May 1959. , "Additional Data on Stresses in Cylindrical Shells under Local Loading," ibid., pp.

-, -

l0-50.

REFERENCES

1. 2. 3. 4, 5. 6, 7. E. qlll.

'ASME Boiler and Pressure Vessel Code," ANSVASME BPV, American Society of Mechanical Enginee$, New York, 1983. 'ANSI/ASME Code for Pressure Piping Mechanical Engineers, New York, 1980.

B3l" ANSI/ASME 831,

American Society of

BIBLIOGRAPHY

Harvey, J. F., Theory and Design of Modern Pressure Vessels, 2nd ed., Van Nostland Reinhold, hincton, N.J., 1974.Rodabaugh, E. C., and R. C. Gwaltney, "Inside Versus Outside Reinforcing of Nozzles in Spherical Shells with Pressure Loading," Phase Report 117-7, January 1974, BattelleColumbus Inboratory, Columbus, Ohio.Rodabaugh, E. C., "Proposed Altemate Rules for Use in ASME Codes," Phase Report 117-3, August 1969, Battelle-Columbus Laboratory, Columbus, Ohio, Rules and Regulations

Ellyin, F., "An Experimental Study of Elasto-Plastic Response of Branch-Pipe Tee Connections Subjected to lntemal hessure, Extemal Couples, and Combined lrading," wRC BulletinNo 230, Welding Research Council, New York, September 1977.Ellyin, F., "Elastic Stresses NearAttachmentsa Skewed

Hole in

a FIat Plate and

in Shells," WRC 8llrrerln No. 153, Welding

Applications to Oblique Nozzle Research Council, New York,

l98l.

for

the Classifcatior

o/SiDJ, Lloyd's Register of Shipping, Irndon,

August 1970.

Sterling, F. W ,, Marine E gi eers Handbook, McCtraw-Hill, New York, 1920. Porowski, J. S., W, J. O'Donnell, and J. R. Fan, "Limit Design of Perforated Cylindrical Shells per ASME Code," Jounal of Pressure Vessel Technology, Vol. 99, Sedes J, No. 4,November 197?.

Ellyin F., "Experimental Investigation of Limit lnads of Nozzles in Cylinddcal Vessels"' wRc BulletinNo.2lg, welding Research Council, New York, September 1976 Eringen, A. C., A. K. Naghdi, S. S. Mahmood, C. C. Thiel, and T. Ariman, "Stress Concentrations in Two Normatly Intersecting Cylindrical Shells Subject to lntemal hessure," WRC Bulletin No. 139, welding Research Council, New York, April 1969. Fidler, R., "A Photoelastic Analysis of Oblique Cylinder In&fiections Subjected to Intemal Ptesslure," WRC Bulletin No. 153, Welding Research Council, New York, August 1970. Findlay, G. E. and J. spenc, "Bending ofPipe Bends with Elliptic Cross Sections," I/Rc B!.rletin No. 164, Welding Research Council, New York, August 1971. Gwaltney, R. C., and J. M. Corum, "An Analytical Study of Inside and Outside Compact Reinforcement for Radial Nozzles in Spherical Sheus," ORNL 4732, June 1974, Oak Ridge National Laboratory, Oak Ridge, Tenn.

Wichman, K. R., A. G. Hopper, and J. L. Mershon, "Local Stresses in Spherical and Cylindrical Shells due to Extemal lradings," Welding Research Council, Bulletin No. 107, Ncw York, August 1965.

Bijlaad, P. P., "Shesses from Local Loadings in Cylindrical I.\ME, Vol. 77. pp. 805-816. 1955.

Pressure Vessels," T/ans.

ll. _,

vol.

"Stresses ftom Radial Loads in Cylindrical Pressue Vessels," Welding .loutnal, 33, Research Supplement, pp. 6l5s-623s, 1954.

al!

oPlNtt{ot, t{ozz[3, aNo rxTaRNAt r,oAotNos"ARcvlcw dnd llvlluution of Computcr Program6 for thc Analysis of Strcsscs in MtC BulletinNo. 108, Wclding Research Couocil, New York, SeptemberSellcrB. F.,

BIEIIOORAPHY 4I9"A Note onthe Conelation of Photoelestic and Stcel Model Data for Nozzlc Con' Cylindrical Shells," WRC Blt eri, No l39, Welding Resealch Council, Ncw

Kruus, H.,

PrcBsun Vc$scls," 1965.

ne.tions in

teveD, M. M., "Photoelastic Determination of the Sftesses at Oblique Openings in Plates and Shells," WftC Bunettu No. 153, Welding Resea.ch Council, New York, August 1970.

teven, M. M., "Phoioelastic Determination of thc Shesses in Reinforced Openings in hessure Vessels," WRC Bulletirr No. ll3, Welding Resea.ch Council, New York, April 1 6. Lind, N. C., A. N. Sherboume, F. Ellyin, and J. Dainora, "Plastic Tests of Two Branch-pipe Connections," lyRC trrrerir No. 164, Welditrg Research Council, New York, August 1971. Marwell, R. L., atrd R. W. Holland, 'collaps Test of a Thin-Walled Cylin&ical Pressue Vesscl with Radially Attached Nozzle," WRC Bulletin No. 230, Welding Research CouDcil, New

Yo!k, April 1969. Taylor, C. E,, and N. C. Lind, "Photolastic Study of the Stresses neat Operdngs in hcssure Vessels," WRC Burkr,t No. ll3, Welding Resea.ch Council, New York, April 1966' Tso, F. K. W., J. w. Bryson, R. A weed, and S. E. Moore' "Stress Analysis of Cylindrical Pressure Vessels with Closely Spaced Nozzles by the Fhit Element Melhod"'in Vol l' Stres! Analysis of vessels with Two Closely Spaced Nozzles under Intemlrl Pressure'

oRNL/NUIiEG-18/vl, November 1977, Oak Ridge National Laboratory, oak Ridge, Tenn'

Yort, September

1977.

Mershon, J. L. , "Intetpretive Repoit orr Obliqle Nozzle Connections in hessure Vessel Heads and Shells udder Ifternal Pres$ur ading," WXC Sarr?rrn No. 153, Welding Research Council,

t

New Yort, August 1970. Mershon J. L., "Preliminary Evaluation of PVRC Photoelastic Test Data on Reinforced Openings in Pressur Vessels," WRC Bullain No. I13, Welding Research Council, New York, April1966.

Raju, P. P., '"Tbre-Dimensional Finite Element Analysis of 45" Lateral Model | (tl/D = 0.08, D/T = lO, under External i&Plarc MomeDt lrading," TR-3984-2, Teledyne Enginedng Services, Waltham. Mass. December 1980. Raju, P. P,, "Three-Dimensional Finite Element Analysis of 45"I-ateral Modelz(d/D :0.5, D/f : n) under Intrtral hessur and Extemal in-Plane Moment Loading," TR-3984-1, Tlcdyne Engineeriry Services, Waltham, Mass., December 1980. Raju, P, P., "Tbree-Dimensional Finite Element Analysis of 45" Lareral Model l(d/D = 0.08, D/T = lO) under Internal Pressure and Extemal in-Plane Moment Loadings," TR-3X9-1, revisd A, Teledyne Engineering Services, Waltham, Mass., January 1980. Riley, W, F., "Experime al Detennination of Stress Disributioni in Thin-Walled Cylindrical and Spherical Pressure Vessls wilh Ciltula. Nozzles," WRC BulletinNo. 108, Welding Research Council, New York, September 1965. Rodabaugh, E. C., "Elastic Stesses in Nozzles iD Pressue Vessels with Intemal Pressue Loaditr8," Phas Repoft ll7-1, April 1969, Battelle-Colubus Laboratory, Columbus, Ohio. Rodabaugh, E. C., "Review of Service Experietrc atrd Test Data on q)ening$ in Pressure Vessels with Non-I egral ReiDforcidg," WRC Bulletin No. 166, Weldiog Research Council, New York, October 1971. Rodabaugh, E. C. , and R. C. Gwahiey, 'Additional Data on Elastic Stresses in Nozzles in Pre$sulE Vessels with Intemal Pressure loading," Phase Report ll7-2, December 1971, BattelleColumbus kboratory, Columbus, Ohio. Rodabaugh, E. C,, aDd R. C. cwaltoey, "Elastic Stsesses at Reinforced Nozzles ir Spherical Shells with Pressur and Moment Loadiog," Phase Report ll?-gR, September 1976, BattelleColumbus Iaboratory, Columbus, Ohio. Rodabaugh, E, C,, and S. E. Moore, "Evaluation of the Plastic Characte.istics of Piping hoducts in Relation to ASME Code Cdteiia," NUREC/CR-0261 ORNI-/Sub-2913/8, Oak Ridge National Inboratory, Oak Ridge, TeIm., July 1978. Schroeder, J., K. R. Srinivasaiah, and P, Graham, "Analysis of Test Data on Bmnch Connections Exposd to Intemal Pressure and/or Extemal Coluples," WRC Bulk,n No. 200, WeldingResearch Council. New

l

York. Novembr 1974.

Schoeder,

and P, Tugcu, "Plastic Stability of Pipes and Tes Exposed to Extemal Couples," WRC Bullctin No, 238, Welding Research Couucil, New York, June 1978.

t.,

CHAPTER

12

VESSEL SUPPORTS

Ditfereni v$sel supporis. (Courresy of the Noofer Corporotion: St. touir, Mo.)

420

421

412

VISSfl" SUPPORTS

I2.2

SKIRT AND BASE RING DESIGN

I2.I 1. 2. 3. 4, 5.

INTRODUCTION

Process equipment is normally supported by one

of the following methods:

Skirts Support legs Support lugs

a;.

Ring girdersSaddles

Most vertical vessels are supported by skirts, as shown in Fig. 12.Ic. Skirts are-economical because they generally transfer the loads from the vessel by shear action. They also hansfer the loads to the foundation through anchor bolts and bearing plates. I*g-supported vessels are normally lightweight and the legs provide easy access to the bottom of the vessel. An economic design is shown in Fig. 12. lb, where the legs attach directly to the vessel and the loads are transferredby shear action.

I.'igure 12. lc shows an alternate design where the lcgs irLre attached to lugs that in tum are welded to the vessel. The bending stiffness of the shell and its ability to resist the moments adequately, must be considered. The cross-bracing ol the legs may be needed to minimize lateral and torsional movements. Vessels supported by ring girders, (Fig. 12.1d), are usually placed within a structural frame. The ring girder has the advantage of supporting torsional and bending moments resulting from the transfer of loads from the vessel wall to the supports. Horizontal vessels, (Fig. l2.le), Ne normally supported by saddles. Stiffening rings may be required if the shell is too thin to transfer the loads to the saddles. The problem of thermal expansion must also be considered.

I2,2

SKIRT AND BASE RING DESIGN

Design of the skirt consists of first determining the dead weight of the vessel W and bending moment M due to wind and earthquake forces (see Chapter I 6) . Thestress

in the skirt is then determined from(f =

-w^

Mc -+I

(r2.r)10. Hence, the area A and the

In most practical applications, the ratio moment of inertia I is exPressed as

R/t )2rRtrR3 t

A

: I:

and the equation for the stress in a skirt becomes

(a) Sklrt

(b)

Leg

(c) L!s

,where

=

#'#,

0z.z)

o:= M=W

axial stress in skirt weight of vesselmoment due to wind or earthquake forces radius of skirt

R

:

r = thickness of skirt (d)Rins Gl

rderFigur

(e) l2.lVessel supporrs.

Because the compressive stress is larger than the tensile stress,Saddtes

it

usually

controls the skirt design and is kept below the skirt's allowable axial compressive stress as given by Eq. 8.15.

VESSIt SUPPORTS

Atlcr the thickncss of the skirt r is determined, the next step is designing the anchor bolts. For a given number of bolts Nthe total bolt area can be expressed as NA where A is the area of one bolt. The moment of inertia of bolts about the vessel's neutral axis is I = NAR2/2.'fhtts, Eq. 12.1 is

Toble

12.2

Bolt Dimensions ond Cleorqnces Bolting DqtdNut Dimensions

Radial Edge Wrench Across Across Bolt Root Bolt No. of Size Thrcads Arca (in.'?) Flats Corners Spacing Distance Distance DiameterB

_-w2M ,where P = load/bolt17

N -NR

(r2.3)

:

arJ rr d 10 o1

weight of vessel

'

N = number ofbolts R = radius of bolt chcle

M=

bending moment

18 l* li 1"1 ll 1"2 28 2i8 2i8 2i8

;e

o.126 o.202 o.3020.419 0.551

zrr_6

0.9691.1'7 5

lil!2 L7

RE .t? 16a!!1

a,

r

tiz

ri7F,

1.383rr_6

1.589

rt

t5

L1L'

ra-

8 88

o.728 o.9291. 155

ri32

t.'796 2.002 2.209

zc

.16L1

2.4t62.622

3*lJ7

The maximum load/bolt is based on the allowable stress and conesponding area given in Table 12.1. The allowable stress depends on the type of boli fumished. Table 12.2 shows various properties and required dimensions for bolts with different diameters.

lt li

8 8 8 8

1.405 1.608 1.980

2.828 ^3-15Ja-

4J;

3.035 3.449

+7

12.1. Determine the required skirt thickness and the number of bolts needed in a vessel with an outside radius R = 7 .0 ft. IIJI empty weight Wr : 160 kips, weight of contents Wz: l4l;} kips, wind-bending momenr M : 1500 ft-kips and temperature = 300. F. Assume A307 bolts and useExampleFigure 8. 11 for the exiemal pressure chart.

2.304 2.652 3.4234.292

4

+izi^ I J-6 Lz ^3 ZEt)a,7

1!1Z

Ji

3.862 4.2't54.688 5.102 5.515

5.2596.37

+i5

SolutionSkirt design

3i8 v 3i8 3i8 48

Ontta=

.487

Ji

7i8

8.'749 10.108 11.566

5.928 6.341

'7L

lE8"1

oi

6.755

+i .ri

rtra

8j9

Lpt

t=

0.375 in. From Eq. 12.2,

Tqble

12. I

Bolt Type4307 4325 4449A.490

AllowableTensileStress (ksi)

Cross-Sectional Area

(in.')tr

20 40 40 54

/^ 0.9743\' t\" - -7rr- 1Nominal

Nominal Nominal 425

'l{'

is number of lhrcads/in.

lN

Vttilt luPlotTt

r2,2160

tKlnT aND

lA$

RINO

DIIION all

o= From Eq. 8.15,

+

1l|40

1500

x

12

2

r (84

-

0.37 5 / 2)(0.37 5\

r(83.813f(0.375)

10.28 ksi

bctwccn and/or r,esting on a group of piles, it can be assumed that fte intersction to that of a reinforced concrotc c-on"ret" is similar Uots, bie plaie, U"".. fn t"feoit g to Fig. 12.2, the following assumptions are made:

ttt

*d

1. 2.0.125

A:=Boh designLet

The contribution of the bolts on the compression side is negligible' The bolts on the tension side are assumed to act as a continuous ring width r", where r" is calculated from the equation

of

RJt0.001 I

,,=4 zrd12,100

(t2.4)

Hence, from Fig. 8.11,

A=

psi

OK

3.

The allowable stress of steel /" is taken from Table

l2'1'

N=

12 bolts. From Eq. 12.3,

I-oad/tntr:

- t2

l@+

2(15ooxl2)12(84)

:Frorn Table 12.1,area requlre{

22.4 kips

:=

ldW

22.4| .12

n.2

From Table 12.2

l|.-lln. diameter bolts

(N' =.S).

Thus from Table 12.1,

n." ^-- 0.9743." *u=Z1r.sD-1-): 1.23 nz > 1.12 OKactual shess

7)A = J1: l-25

:=

18.2 ksi

total furnished areaUse

12

x

1.23

:

14.8 in.'?

l-in. skirt with 12

-

l*-in. dianeter bolts.

I

Having established the nurnber and size of bolts, the next step is to calculate thc interaction between the base plate, anchor bolts, and supporting snuchre. If thc supporting structure is a steel ftame or foundation, then Eq. 12.3 is all that is necded for designing anchor bolts. On the other hand, if the foundation is deep

tigl!.o 12,2

lrt

v||||t turro$tTobb 12.3 Concntr ProprrflcrAllowableCompressive Stess (psi) Compressive Stress (psi) Modulus

I2.2

SKIRT AND

IA3:

RINO DTSION

429

1=,t"of Flasticity Gsi)

=W=t-2k

(12.6)

f" = o.4sfl25m3000

E.:

The total force T of the tensile area of the reinforcement can be determined bv sumrning forces on the tensile side of the neuhal axis which gives

57,WO\/n

Ei

1,t251,350 1,575 1,800

2,850,000 3,120,000 3,370,000 3,610,000

lt8

/8"

t09

3500,1000

'll /,r\( t r = f,t,l;l {r--= ll.,r. yl sin 7 + cos 7l I * \ | [; \z/ tr -1- sln 7 L\z / J)o|

"E, = 30 x

lf

psi.

, =r,^(1) *,The disance between

(r2.7)12

4.

6.

Concrete on the compression side is assumed to have a width t" that is the same as the width of the base plate. The allowable complessive stress of concretel is taken from Table 12.3. The ratio of the modulus of elasticity of steel to that of concrete is defined as n.

I

and the neutral axis expressed by

is

t"=4l 1.56 oK - 683(1) J. = .o;i = 25.55 cps f' > 2k 25.55 > 3.12 oKProblems

_(0.2)(40.331

tall vessel under internal pressure only, the primary additional considF|rli(nr to the intemal pressure is the effect of fluid pressure head and the dead ['rrl. 'lhis is especially important at the bottom of a vessel where the effects may r rrrubine. The fluid pressure head may occur only during hydrostatic testing of lh{' vcssel or it may be a continuing load occurring during operation ofthe vessel, lh' additional pressure caused by the ffuid head is calculated as follows:

l,or

",=Wwlrt

(16.ls)

lc

PJ

16.5 A tall vessel conshucted with a- cylindrical

Il7t'

= =

additional internal pressure effect from fluid pressure head (psi) height of fluid column above point (ft) density of fluid. lb/ftl

design of the vesset fouowing rh"

shell and flat closure ends i8 to be installed near Denver, Coloiado. Th" ffi;;#;;.or tlre cyfin_ drical shell is 8 ft, the nominal i.6't.l'Joo ,r," ,o"igr,, length from head weld seam b head i, izJ n.-rir" nut t"ua, are 6.0-in. nominal thickness. Wt at is tf,e totA fa*J*ioO

:

*rl.rhi"k;;j, *aJl""-

*d;irh";;i;rltili io."" u."O fo.Lateral wind force

Answer:

=

""a"r14,060 lb.

|l the fluid head exists in the vessel during operation, the value ofP7is added lhe intemal pressure when the minimum required thicknesses are set. At the ' lr(,ttom of tlte vessel, the stresses and minimum required thickness are set by the tirtrl pressure. It may be possible to decrease the thickness when the fluid head rllcct is decreased in a vessel where a variation in plate thicknesses is acceptrrblc.

16.6

What is the total lateral wi using the Uniform Buildinf,%tff;

*

the vessel given in hoblem 16'5

Ansu'er:

Laterul wind force

=

21,100 lb.

16'7

Many_design specifications requirea-minimum design wind speed of r00 mph. What is the total lateral^wlnd torce on the vessel in problem 16.5 based on a wind speed of 100 mph?

Answer:

Lateral wind force

=

21,390lb.

If the fluid head exists in the vessel only during the hydrostatic testing, the plirnary membrane stress frorn the combination of the hydrostatic test pressure rrrrtl the fluid head pressure may go as high as the yield strength of the vessel t|r terial at the 0est temperature. However, if the resulting minimum required tlrickness from the combination is indicated as more than that thickness required lrrr the normal design conditions, substitution of a pneumatic iest or a combination of hydrostatic/pneumatic test should be considered. In general, the minirnum required thickness of a vessel should never be set by the requirements of thc hydrostatic head unless it is impossible to test it any other way. Also, rcrnember tJlat a hydrostatic test may use fluids other than water if water causes rr rrroblem such as corrosion.

..7.

TAtl

Vt!!!ts

16.4

VESSCL UNDTR INTTRNAI PRESSURT

ONIY

583

vslrcr uur also lts weight to iffi:i;:lJ:,.:ji,# ffi #*'#liilT":lji ;iilliJi,l,,lj, ;ii il.;",l:ll,l be consi( cause tensile or -addttronal.loadings : locatton of the extemal supports sKrn tocation. "r# ,ii:e or s[Whether the ,t .ir", pressive sresses a"p""a, "uur.J.Un",t-,w

F'or u vcssel untjcr intcrnal pres

lrr hoth Eqs. 16.18 and 16.19, the dead load term may be either tension orq'orrrpression depending upon the plane being examined.

In general, above the rrrpport line, this term is compressive and the total longitudinal stress is the

. In th actual design, the minin circumrerentiaLsnesi;ffi

il

#l}1T3ffi:*|"**'or=PR _

is initiallv set by

rllllcrence between the intemal pressure effect and the dead load effect. When llris is below the support line, the terms are both tensile. For some arangements, thc condition without inlemal pressure may be more critical than when intemalprcssure is considered.

t

(16.1

.rr is positive, the actual stress is positive and the allowable stress is rlctcrmined from the allowable tensile stress tables. If the value of or is negative,lht: allowable stress is determined by the method that establishes the maximum rrllowable axial compressive stress in a cylindrical shell.

ll

From the equation

ter-s or sr', tte

in

IJG_Z7tct(l

'e;;#;"i:') sE=P(4+o'

of the ASME code,

vltr-I,

expressed

(r6.1

l{xample 16,6. For the vessel described in Example 16.1, determine the total kngitudinal stress in the cylindrical shell above and below the support line that : 15,000 psi. lN at the lower shell-to-head junction. The value of SE

where

= allowable tensile shess (psi) E = weld joint efficiency (E = I.0 for seamless) P = intemal design pressure (psi) R = inside radius (in.),S

,l{rrtttion. Assume the intemalJr,

pressure

is set by Eq. 16.17 for a value of

=

15,000 psi. Reananging the terms gives

sEt _ (t5,000)(0.5) 'p.=R + 0.6r (30) + 0.6(0.5) = )45 nci'l'he dead load of vessel above the support line is

t

:

rninimum required thickness (in.)

Using this equation, a lentative m. circumferential .*;.. Wil;;;"f"rmum required thickness is set based on tho thickness is determined, be necessary ro inci;" it may d;;f;:litequ.ired tluid head.as well as the intemal pressure. Based desigir ^thethe total lonsitudinal stress'is determined ";;;;;;:r

Shell Upper head

9,700815 10,515 lb

f.;;

il;;iil#;

l"nili,ill"t'""'',PR2t

'l'he longitudinal stress using Eq. 16.19 is

w rD^t

(16.18)

oL: ot:

+Q45)(*730O

wnere

ot:W

_n"\ 2x0.5 "'- I 30 110 psi

(lo.sls)a(60.5X0