Pressure Vessel Design Handbook

1 BEDNAR e-u m:u cnm -en Glen Zc ::c:u »m z< em men oen om ".- r i B! CE ISBN 0-89464-S03-X IIII m ~lr l PRESSURE VESSEL DESIGN HANDBOOK SECOND EDmON PRESSURE VESSEL DESIGN HANDBOOK PRESSURE VESSEL DESIGN HANDBOOK Second Edition Henry H Bednar, P.E TECHNIP ITALY S.p.A BIBLIOTECA (~3.6.~) INVENTARIO NQ 4.~.~Q KRIEGER PUBLISHING COMPANY MALABAR, FLORIDA Preface to Second Edition Second Edition 1986 Reprint Edition 1991 Printed and Published by KRIEGER PUBLISHING COMPANY KRmGER DRIVE MALABAR, FLORIDA 32950 Copyright IC> 1986 by Van Nostrand Reinhold Company, Inc Reprinted by Arrangement All rights reserved No part of this book may be reproduced in any form or by any means, electronic or mechanical, including information storage and retrieval systems without permission in writing from the publisher No liability is assumed with respect to the use o/the information contained herein Printed in the United States of America Library of Congress Cataloging-in-Publication Data Bednar, Henry H Pressure vessel design handbook / Henry H Bednar cm p Reprint Originally published: 2nd ed New York: Van Nostrand Reinhold, cl986 Includes bibliographical references and index ISBN 0-89464-503-X (lib bdg : acid-free paper) Pressure vessels Design and construction Handbooks, manuals, etc Title TA660.T34B44 1990 68I'.76041 dc20 90-5043 CIP 10 In revising the fIrst edition the intent has been to improve the handbook as a reference book by enlarging its scope The stress analysis of pressure vessels has been greatly enhanced in accuracy by numerical methods These methods represent a great addition to the analytical techniques available to a stress analyst Therefore, chapter 12 describing the most important numerical methods with illustrative examples has been added Throughout the text new material and new illustrative examples have also been added The writer believes that any technical book in which the theory is not clarifIed by illustrative examples, can be of little use to a practicing designer engineer Also some typographical errors have been corrected It should be kept in mind that practical engineering is not an absolute exact science There are too many variable factors and unknown quantities so that only a reasonable estimate of forces and stresses can be made, particularly in more involved problems Almost all problems in engineering practice not have a single-value answer, and usually they require a comparison of alternatives for solution Therefore, no defInite rules can be given for deciding how to proceed in every case, and the rules laid down cannot be applied inflexibly The designer must be guided by his former experience and his best personal judgment since he bears the fmal responsibility for the adequacy of the design The writer would like to extend his gratitude to all readers who offered constructive comments, particularly to Dr A S Tooth of University of Strathclyde, Glasgow, Scotland for his comments on the stresses in shells at saddle sUl'ports HENRY H BEDNAR Preface to First Edition This handbook has been prepared as a practical aid for engineers who are engaged in the design of pressure vessels- Design of pressure vessels has to be done in accord with specific codes which give the formulas and rules for satisfactory and safe construction of the main vessel components However, the codes leave it up to the designer to choose what methods he will use to solve many design problems; in this way, he is not prevented from using the latest accepted engineering analytical procedures Efficiency in design work is based on many factors, including scientific training, sound engineering judgment, familiarity with empirical data, knowledge of design codes and standards, experience gained over the years, and available technical information Much of the technical information currently used in the design of pressure vessels is scattered among many publications and is not available in the standard textbooks on the strength of materials This book covers most of the procedures required in practical vessel design Solutions to the design problems are based on references given here, and have been proven by long-time use; examples are presented as they are encountered in practice Unfortunately, exact analytical solutions for a number of problems are not known at the present time and practical compromises have to be made Most engineering offices have developed their own vessel calculation procedures, most of them computerized However, it is hoped that this book will provide the designer with alternative economical design techniques, will contribute to his better understanding of the design methods in use, and will be convenient when hand computations or verifications of computer-generated results have to be made No particular system of notation has been adopted Usually the sy~bols as they appear in particular technical sources are used and defined as they occur Only the most important references are given for more detailed study It is assumed that the reader has a working knowledge of the ASME Boiler and Pressure Vessel Code, Section VIII, Pressure Vessels, Division The writer wishes to express his appreciation to the societies and companies for permission to use their published material_ Finally, the writer also wishes to express his thanks to the editorial and production staff of the Publisher for their contribution to a successful completion of this book HENRY H BEDNAR Contents PREFACE TO FIRST EDITIONlv PREFACE TO SECOND EDITION I vii DESIGN LOADS/! 1.1 Introduction II 1.2 Design Pressure 12 1.3 Design Temperature 13 1.4 Dead Loads 14 1.5 Wind Loads 15 1.6 Earthquake Loads I 13 1.7 Piping Loads/21 1.8 Combinations of the Design Loads 122 STRESS CATEGORIES AND DESIGN LIMIT STRESSES 124 2.1 Introduction 124 2.2 Allowable Stress Range for Self-Limiting Loads 125 2.3 General Design Criteria of ASME Pressure Vessel Code, Section VIII, Division 1/26 2.4 General Design Criteria of ASME Pressure Vessel Code, Section VIII, Division 2/29 2.5 Design Remarks 138 MEMBRANE STRESS ANALYSIS OF VESSEL SHELL COMPONENTS 139 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Introduction 139 Membrane Stress Analysis of Thin-Shell Elements 143 Cylindrical Shells 146 Spherical Shells and Hemispherical Heads 155 Semiellipsoidal Heads 159 Torispherical Heads 162 Conical Heads/66 Toroidal Shells 171 Design of Concentric Toriconical Reducers under Internal Pressure 173 ix CONTENTS x xl CONTENTS DESIGN OF TALL CYLINDRICAL SELF-SUPPORTING PROCESS COLUMNS/80 4.1 Introduction 180 4.2 Shell Thickness Required for a Combination {)f Design Loads 181 4.3 Support Skirts 185 4.4 Anchor Bolts/91 4.5 Wind-Induced Deflections of Tall Columns 1103 4.6 Wind-Induced Vibrations I 107 4.7 First Natural Period of Vibration 1121 4.8 Illustrative Example 1129 SUPPORTS FOR SHORT VERTICAL VESSELS 1143 5.1 Support Legs 1143 5.2 Support Lugs 1153 '6 DESIGN OF SADDLE SUPPORTS FOR LARGE HORIZONTAL CYLINDRICAL PRESSURE VESSELS/161 6.1 General Considerations 1161 6.2 Maximum Longitudinal Bending Stress in the Shell I 161 6.3 Maximum Shear Stresses in the Plane of the Saddle 1165 6.4 Circumferential Stress at the Horn of the Saddle 1169 6.5 Additional Stresses in a Head Used as a Stiffenerl172 6.6 Ring Compression in the Shell over the Saddle 1173 6.7 Design of Ring Stiffeners I 175 6.8 Design of Saddles 1177 LOCAL STRESSES IN SHELLS DUE TO LOADS ON ATTACHMENTS 1186 7.1 Introduction 1186 7.2 Reinforcement of Openings for Operating Pressure I 186 7.3 Spherical Shells or Heads with Attachments I 188 7.4 Cylindrical Shells with Attachments I 193 7.5 Design Considerations 1208 7.6 Line Loads/210 DISCONTINUITY STRESSES/217 8.1 Introduction 1217 8.2 Procedure for Computing Discontinuity Stresses by the Force Method/220 8.3 Cylindrical Shells/221 8.4 Hemispherical Heads/226 8.5 Semiellipsoidal and Torispherical Heads 1230 8.6 Conical Heads and Conical Reducers without Knuckles 1230 THERMAL STRESSES 1241 9.1 General Considerations/241 9.2 Basic Thermal Stress Equations/241 9.3 9.4 9.5 9.6 External Constraints 1242 Internal Constraints 1244 Thermal Stress Ratchet under Steady Mechanical Load / 254 Design Consideration 1256 10 WELD DESIGN/259 10.1 Introduction 1259 10.2 Groove Welds 1260 10.3 Fillet Welds 1264 10.4 Plug Welds 1277 10.5 Design Allowable Stresses for Welded 10ints/278 10.6 Stress Concentration Factors for Welds I 279 10.7 Defects and Nondestractive Examinations of Welds 1280 10.8 Welding Processes 1281 10.9 Weld Symbols 1283 11 SELECTION OF CONSTRUCTION MATERIALS 1284 11.1 General Considerations 1284 11.2 Noncorrosive Service 1285 11.3 Corrosive Service 1290 11.4 Bolting Materials 1293 11.5 Stainless Steels/296 11.6 Selection of Steels for Hydrogen Service 1306 11.7 Aluminum Alloys 1309 12 NUMERICAL METHODS FOR STRESS ANALYSIS OF AXISYMMETRIC SHELLS 1312 12.1 Introduction/312 12.2 Finite Element Analysis, (FEA) Displacement Method I 314 12.3 Finite Element Analysis, Force Method I 376 12.4 Method of Stepwise Integration 1380 12.5 Method of Finite Differences 1381 APPENDICES 1385 AI Wind, Earthquake and Lowest One-Day Mean Temperature Maps/ 387 A2 Geometric and Material Charts for Cylindrical Vessels 1389 A3 Skirt Base Details 1391 A4 Sliding Supports for Vertical and Horizontal Vesse1s/392 AS Glossary of Terms Relating to the Selection of Materials 1394 A6 Standard Specifications Pertaining to Materials 1404 A7 Flanges 1405 A8 Elementary Matrix Algebra 1410 A9 References/416 AlO Abbreviations and Symbols/423 INDEX I 429 PRESSURE VESSEL DESIGN HANDBOOK Design Loads 1.1 INTRODUCTION The forces applied to a vessel or its structural attachments are referred to as loads and, as in any mechanical design, the first requirement in vessel design is to determine the actual values of the loads and the conditions to which the vessel will be subjected in operation These are determined on the basis of past experience, design codes, calculations, or testing A design engineer should determine conditions and all pertaining data as thoroughly and accurately as possible, and be rather conservative The principal loads to be considered in the design of pressure vessels are: design pressure (internal or external), dead loads, wind loads, earthquake loads, temperature loads, piping loads, impact or cyclic loads Many different combinations of the above loadings are possible; the designer must select the most probable combination of simultaneous loads for im eco· nomical and safe design Generally, failures of pressure vessels can be traced to one of the following areas: material: improper selection for the service environment; defects, such as inclusions or laminations; inadequate quality control; design: incorrect design conditions; carelessly prepared engineering computations and specifications; oversimplified design computations in the absence of available correct analytical solutions; and inadequate shop testing; fabrication: improper or insufficient fabrication procedures; inadequate inspection; careless handling of special materials such as stainless steels; PRESSURE VESSEL DESIGN HANDBOOK DESIGN LOADS service: change of service conditions to more severe ones without adequate provision; inexperienced maintenance personnel; inadequate inspection for corrosion 1.2 DESIGN PRESSURE Design pressure is the pressure used to determine the minimum required thickness of each vessel shell component, and denotes the difference between the internal and the external pressures (usually the design and the atmospheric pres· sures-see Fig 1.1) It includes a suitable margin above the operating pressure (10 percent of operating pressure or 10 psi minimum) plus any static head of the operating liquid Minimum design pressure for a Code nonvacuum vessel is 15 psi For smaller design pressures the Code stamping is not required Vessels with negative gauge operating pressure are generally designed for full vacuum The maximum allowable working (operating) pressure is then, by the Code definition, the maximum gauge pressure permissible at the top of the compl!!ted vessel in its operating position at the designated temperature It is based on the nominal vessel thickness, exclusive of corrosion allowance, and the thickness required for other loads than pressure In most cases it will be equal or very close to the design pressure of the vessel components By the Code definition, the required thickness is the minimum vessel wall thickness as computed by the Code formulas, not including corrosion allowance; the design thickness is the minimum required thickness plus the corrosion allowance; the nominal thickness is the rounded-up design thickness as actually used in building the vessel from commercially available material If the nominal vessel thickness minus corrosion allowance is larger than the required thickness, either the design pressure or the corrosion allowance can be standard atm = 14.69 psia (pr) ga!ge ~ standard atmospheric ~ ~I l - absolute (psia) local atm o I negative (psigl (vacuum) absolute zero pressure (fldl vac'Jum) Fig 1.1 increased, or any excess thickness can be used as reinforcement of the nozzle openings in the vessel wall The vessel shell must be designed to withstand the most severe combination of coincident pressure and temperature under expected operating conditions The nominal stress in any part of the vessel as computed from the Code and standard engineering stress formulas, without consideration oflarge in~reases in stresses at the gross structural discontinuities, cannot exceed the Code allowable stress 1.3 DESIGN TEMPERATURE Design temperature is more a design environmental condition than a design load, since only a temperature change combined with some body restraint or certain temperature gradients will originate thermal stresses However, it is an important design condition that influences to a great degree the suitability of the selected material for construction Decrease in metal strength with rising temperature, increased brittleness with falling temperature, and the accompanying dimensional changes are just a few of the phenomena to be taken into account for the design The required Code design temperature is not less than the mean metal vessel wall temperature expected under operating conditions and computed by standard heat transfer formulas and, if possible, supplemented by actual measurements For most standard vessels the design temperature is the maximum temperature of the operating fluid plus 50°F as a safety margin, or the minimum temperature of the operating fluid, if the vessel is designed for low-temperature service (below -20°F) In large process vessels such as oil refinery vacuum towers the temperature of the operating fluid varies to a large degree, and zones with different design temperatures, based on expected calculated operating conditions, can be used for the design computations of the required thicknesses The design metal temperature for internally insulated vessels is determined by heat transfer computations, which should provide sufficient allowance to take care of the probable future increase in conductivity of the refractory d~e to gas, deterioration, coking, etc At a minimum, the designer should assume a conductivity for the internal insulating material 50-100 percent higher than that given by the manufacturer's data, depending on operating conditions A greater temperature margin should be used when external insulation is used as well The possibility of a loss of a sizable lining section and the required rupture time of the shell should also be considered Extensive temperature instrumentation of the vessel wall is usually provided For shut-down conditions the maximum design temperature for uninsulated vessels and the connecting piping will be the equilibrium temperature for metal objects, approximately 230°F for the torrid zone, 190°F for the temperate zone, and 150°F for the frigid zone .. .PRESSURE VESSEL DESIGN HANDBOOK PRESSURE VESSEL DESIGN HANDBOOK Second Edition Henry H Bednar, P.E TECHNIP ITALY S.p.A BIBLIOTECA... Minimum design pressure for a Code nonvacuum vessel is 15 psi For smaller design pressures the Code stamping is not required Vessels with negative gauge operating pressure are generally designed... center of gravity causes the vessel to deflect, since the inertia of the vessel mass restrains the vessel from moving simultane- 16 DESIGN LOADS PRESSURE VESSEL DESIGN HANDBOOK alL 'T2H I ! mode