Valve selection handbook: engineering fundamentals for selecting manual valves, check valves, pressure relief valves, and rupture discs

337 Pages·1999·16.6 MB·English

by  R. W. Zappe

V A L V E

S E L E C T I O N
H A N D B O O K

F O U R T H
E D I T I O N

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V A L V E

S E L E C T I O N
H A N D B O O K

F O U R T H E D I T I O N

Engineering fundamentals for selecting manual valves,
check valves, pressure relief valves, and rupture discs

R. W. Z A P P E

Gulf Professional Publishing
an imprint of Butterworth-Heinemann

To
Henry Hanke
in memory

Valve Selection Handbook
Fourth Edition

Copyright © 1981, 1987, 1991,1999 by Elsevier Science. All rights reserved.
Printed in the United States of America. This book, or parts thereof, may not be
reproduced in any form without permission of the publisher.

Originally published by Gulf Publishing Company,
Houston, TX.

For information, please contact:
Manager of Special Sales
Elsevier Science
200 Wheeler Road
Burlington, MA 01803-2041
Tel: [phone]
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For information on all Gulf Professional Publishing titles available, contact our
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1 0 9 8 7 6 5 4 3 2

Library of Congress Cataloging-in-Publication Data

Zappe, R. W., 1912-
Valve selection handbook / R. W. Zappe, —4th ed.
p.
cm.
Includes bibliographical references and index.
ISBN 0-88415-886-1
1.
Valves—Handbooks, manuals, etc. I. Title.
TS277.Z37
1998
621.8'4—dc21
98-36482
CIP

Printed on Acid-Free Paper (oo)

The information, opinions and recommendations in this book are based on the author's
experience and review of the most current knowledge and technology, and are offered
solely as guidance on the selection of valves for the process industries. While every care
has been taken in compiling and publishing this work, neither the author nor the publisher
can accept any liability for the actions of those who apply the information herein.

CONTENTS

Preface, xii

1 Introduction
1
Fundamentals, 1. Manual Valves, 2. Check Valves, 2.
Pressure Relief Valves, 2. Rupture Discs, 3. Units of
Measurements, 3. Identification of Valve Size and
Pressure Class, 4. Standards, 4.

2 Fundamentals
5

Fluid Tightness of Valves, 5
Valve Seals, 5. Leakage Criterion, 5. Proving Fluid
Tightness, 6.

Sealing Mechanism, 8
Sealability Against Liquids, 8. Scalability Against Gases, 9.
Mechanism for Closing Leakage Passages, 10.

Valve Seatings, 11
Metal Seatings, 11. Sealing with Sealants, 13.
Soft Seatings, 13.

v

Gaskets, 14
Flat Metallic Gaskets, 14. Compressed Asbestos Fiber
Gaskets, 15. Gaskets of Exfoliated Graphite, 16.
Spiral Wound Gaskets, 17. Gasket Blowout, 19.

Valve Stem Seals, 20
Compression Packings, 20. Lip-Type Packings, 24.
Squeeze-Type Packings, 25. Thrust Packings, 26.
Diaphragm Valve Stem Seals, 26

Flow Through Valves, 27
Resistance Coefficient £, 27. Flow Coefficient Cv, 32.
Flow Coefficient Kv, 33. Flow Coefficient Av, 34.
Interrelationships Between Resistance and Row Coefficients, 35.
Relationship Between Resistance Coefficient and Valve
Opening Position, 35. Cavitation of Valves, 37. Waterhammer
from Valve Operation, 39. Attenuation of Valve Noise, 43.

3 Manual Valves
45

Functions of Manual Valves, 45

Grouping of Valves by Method of Flow Regulation, 45

Selection of Valves, 47
Valves for Stopping and Starting Flow, 47. Valves for Control
of Flow Rate, 47. Valves for Diverting Flow, 47. Valves for
Fluids with Solids in Suspension, 47. Valve End Connections,
48. Standards Pertaining to Valve Ends, 49. Valve Ratings, 49.
Valve Selection Chart, 50.

Globe Valves, 51
Valve Body Patterns, 52. Valve Seatings, 57. Connection of
Disc to Stem, 60. Inside and Outside Stem Screw, 60. Bonnet
Joints, 61. Stuffing Boxes and Back Seating, 62. Direction of
Flow Through Globe Valves, 64. Standards Pertaining to
Globe Valves, 64. Applications, 65.

Piston Valves, 65
Construction, 65. Standards Pertaining to Piston Valves, 69.
Applications, 69.

VI

Parallel Gate Valves, 69
Conventional Parallel Gate Valves, 70. Conduit Gate Valves,
74. Valve Bypass, 77. Pressure-Equalizing Connection, 77.
Standards Pertaining to Parallel Gate Valves, 79.
Applications, 79.

Wedge Gate Valves, 79
Variations of Wedge Design, 82. Connection of Wedge to
Stem, 86. Wedge Guide Design, 86. Valve Bypass, 87.
Pressure-Equalizing Connection, 87. Case Study of Wedge
Gate Valve Failure, 88. Standards Pertaining to Wedge Gate
Valves, 88. Applications, 90.

Plug Valves, 90
Cylindrical Plug Valves, 92. Taper Plug Valves, 95. Antistatic
Device, 98. Plug Valves for Fire Exposure, 98. Multiport
Configuration, 98. Face-to-Face Dimensions and Valve
Patterns, 99. Standards Pertaining to Plug Valves, 100.
Applications, 100.

Ball Valves, 101
Seat Materials for Ball Valves, 101. Seating Designs, 102.
Pressure-Equalizing Connection, 106. Antistatic Device, 108.
Ball Valves for Fire Exposure, 109. Multiport Configuration,
109. Ball Valves for Cryogenic Service, 110. Variations of
Body Construction, 110. Face-to-Face Dimensions, 110.
Standards Pertaining to Ball Valves, 112. Applications, 112.

Butterfly Valves, 112
Seating Designs, 114. Butterfly Valves for Fire Exposure, 126.
Body Configurations, 126. Torque Characteristic of Butterfly
Valves, 126. Standards Pertaining to Butterfly Valves, 129.
Applications, 129.

Pinch Valves, 130
Open and Enclosed Pinch Valves, 130. Flow Control with
Mechanically Pinched Valves, 132. Flow Control with Fluid-
Pressure Operated Pinch Valves, 132. Valve Body, 133.
Limitations, 134. Standards Pertaining to Pinch Valves, 134.
Applications, 135.

VII

Diaphragm Valves, 135
Weir-Type Diaphragm Valves, 136. Straight-Through
Diaphragm Valves, 137. Construction Materials, 138.
Valve Pressure/Temperature Relationships, 139. Valve Flow
Characteristics, 139. Operational Limitations, 139. Standards
Pertaining to Diaphragm Valves, 140. Applications, 140.

Stainless Steel Valves, 141
Corrosion-Resistant Alloys, 141. Crevice Corrosion, 141.
Galling of Valve Parts, 141. Light-Weight Valve
Constructions, 142. Standards Pertaining to Stainless
Steel Valves, 142.

4 Check Valves
143

Function of Check Valves, 143
Grouping of Check Valves, 143. Operation of Check Valves,
149. Assessment of Check Valves for Fast Closing, 151.
Application of Mathematics to the Operation of Check
Valves, 151.

Design of Check Valves, 152
Lift Check Valves, 152. Swing Check Valves, 153. Tilting-
Disc Check Valves, 154. Diaphragm Check Valves, 155.
Dashpots, 156.

Selection of Check Valves, 157
Check Valves for Incompressible Fluids, 157. Check Valves for
Compressible Fluids, 157. Standards Pertaining to Check
Valves, 157.

5 Pressure Relief Valves
158

Principal Types of Pressure Relief Valves, 158

Terminology, 160
Pressure Relief Valves, 160. Dimensional Characteristics, 162.
System Characteristics, 162. Device Characteristics, 163.

VIII

Direct-Loaded Pressure Relief Valves, 165
Review, 165. Safety Valves, 168. Safety Relief Valves, 171.
Liquid Relief Valves, 177. Vacuum Relief Valves, 180.
Direct-Loaded Pressure Relief Valves with Auxiliary
Actuator, 182. Oscillation Dampers, 188. Certification of
Valve Performance, 190. Force/Lift Diagrams as an Aid for
Predicting the Operational Behavior of Spring-Loaded
Pressure Relief Valves, 191. Secondary Back Pressure from
Flow-Through Valve Body, 198. Verification of Operating
Data of Spring-Loaded Pressure Relief Valves Prior to and
after Installation, 200

Pilot-Operated Pressure Relief Valves, 202
Pilot-Operated Pressure Relief Valves with Direct-Acting
Pilot, 202. Stable Operation of Valves with On/Off Pilots, 209.
Pilot-Operated Pressure Relief Valves with Indirect-Acting
Pilot, 211.

Rupture Discs
214
Terminology, 215. Application of Rupture Discs, 216.
Limitations of Rupture Discs in Liquid Systems, 218.
Construction Materials of Rupture Discs, 218. Temperature
and Burst Pressure Relationships, 220. Heat Shields, 221.
Rupture Disc Application Parameters, 221.

Metal Rupture Discs, 223
Tension-Loaded Types, 223. Compression-Loaded Types, 230.
Graphite Rupture Discs, 239. Rupture Disc Holders, 242.
Clean-Sweep Assembly, 244. Quick-Change Housings, 244.
Accessories, 246. Double Disc Assemblies, 246. Selecting
Rupture Discs, 248. Rupture Disc Device in Combination
with Pressure Relief Valve, 249. Explosion Vent Panels, 252.
Reordering Rupture Discs, 254. User's Responsibility, 255.

IX

7 Sizing Pressure Relief Devices
256

Sizing of Pressure Relief Valves Gas, Vapor, Steam, 260
Sizing Equations for Gas and Vapor other than Steam, 261.
Sizing Equations for Dry Saturated Steam, 264.

Sizing Equations for Liquids Flow, 267
Influence of Inlet Pressure Loss on Valve Discharge
Capacity, 269

Sizing of Inlet Piping to Pressure Relief Valves, 271

Sizing of Discharge Piping of Pressure Relief Valves, 272
Sizing of Rupture Discs, 274. Rupture Disc Sizing for
Nonviolent Pressure Excursions, 274. Sizing Equations for
Gas or Vapor, 275. Rupture Disc Sizing for Violent Pressure
Excursions in Low-Strength Containers, 277.

APPENDIX A ASME Code Safety Valve Rules
279

APPENDIX B Properties of Fluids
283

APPENDIX C Standards Pertaining to Valves
290

APPENDIX D International System of Units (S.I.)
299

References
317

Index
321

x

PREFACE

Valves are the controlling elements in fluid flow and pressure systems.
Like many other engineering components, they have developed over
some three centuries from primitive arrangements into a wide range of
engineered units satisfying a great variety of industrial needs.
The wide range of valve types available is gratifying to the user
because the probability is high that a valve exists that matches the appli-
cation. But because of the apparently innumerable alternatives, the user
must have the knowledge and skill to analyze each application and deter-
mine the factors on which the valve can be selected. He or she must also
have sufficient knowledge of valve types and their construction to make
the best selection from those available.
Reference manuals on valves are readily available. But few books, if
any, discuss the engineering fundamentals or provide in-depth informa-
tion about the factors on which the selection should be made.
This book is the result of a lifelong study of design and application of
valves, and it guides the user on the selection of valves by analyzing
valve use and construction. The book is meant to be a reference for prac-
ticing engineers and students, but it may also be of interest to manufac-
turers of valves, statutory authorities, and others. The book discusses
manual valves, check valves, pressure relief valves and rupture discs.
Revisions in the fourth edition include a full rewriting of the chapters
on pressure relief valves and rupture discs. These revisions take full
account of current U.S. practice and the emerging European standards.
I wish to express my thanks to the numerous individuals and compa-
nies who over the years freely offered their advice and gave permission

XI

to use their material in this book. Because the list of the contributors is
long, I trust I will be forgiven to mention only a few names:
My thanks go to the late Frank Hazel of Worcester Controls for his con-
tribution to the field of manual valves; in the field of pressure relief valves
to Jurgen Stolte and the late Alfred Kreuz of Sempell A.G.; Manfred
Holfelder of Bopp & Reuther G.m.b.H.; and Mr. Gary B. Emerson of
Anderson, Greenwood & Co. In the field of rupture discs, my thanks to
Tom A. LaPointe, formerly of Continental Disc Corporation, and G. W.
Brodie, formerly a consultant to Marston Palmer Limited.

R. W. Zappe

XII

1

INTRODUCTION

Valves are the components in a fluid flow or pressure system that regu-
late either the flow or the pressure of the fluid. This duty may involve
stopping and starting flow, controlling flow rate, diverting flow, prevent-
ing back flow, controlling pressure, or relieving pressure.
These duties are performed by adjusting the position of the closure
member in the valve. This may be done either manually or automatically.
Manual operation also includes the operation of the valve by means of a
manually controlled power operator. The valves discussed here are man-
ually operated valves for stopping and starting flow, controlling flow
rate, and diverting flow; and automatically operated valves for prevent-
ing back flow and relieving pressure. The manually operated valves are
referred to as manual valves, while valves for the prevention of back
flow and the relief of pressure are referred to as check valves and pres-
sure relief valves, respectively.
Rupture discs are non-reclosing pressure-relieving devices which ful-
fill a duty similar to pressure relief valves.

Fundamentals

Sealing performance and flow characteristics are important aspects in
valve selection. An understanding of these aspects is helpful and often
essential in the selection of the correct valve. Chapter 2 deals with the
fundamentals of valve seals and flow through valves.

1

2
Valve Selection Handbook

The discussion on valve seals begins with the definition of fluid tight-
ness, followed by a description of the sealing mechanism and the design
of seat seals, gasketed seals, and stem seals. The subject of flow through
valves covers pressure loss, cavitation, waterhammer, and attenuation of
valve noise.

Manual Valves

Manual valves are divided into four groups according to the way the
closure member moves onto the seat. Each valve group consists of a
number of distinct types of valves that, in turn, are made in numerous
variations.
The way the closure member moves onto the seat gives a particular
group or type of valve a typical flow-control characteristic. This flow-
control characteristic has been used to establish a preliminary chart for
the selection of valves. The final valve selection may be made from the
description of the various types of valves and their variations that follow
that chart.
Note: For literature on control valves, refer to footnote on page 4 of
this book.

Check Valves

The many types of check valves are also divided into four groups
according to the way the closure member moves onto the seat.
The basic duty of these valves is to prevent back flow. However, the
valves should also close fast enough to prevent the formation of a signifi-
cant reverse-flow velocity, which on sudden shut-off, may introduce an
undesirably high surge pressure and/or cause heavy slamming of the clo-
sure member against the seat. In addition, the closure member should
remain stable in the open valve position.
Chapter 4, on check valves, describes the design and operating charac-
teristics of these valves and discusses the criteria upon which check
valves should be selected.

Pressure Relief Valves

Pressure relief valves are divided into two major groups: direct-acting
pressure relief valves that are actuated directly by the pressure of the sys-
tem fluid, and pilot-operated pressure relief valves in which a pilot con-