Deflagration and Detonation Flame Arresters

Stanley S. Grossel Process Safety and Design, Inc.

CENTER FOR CHEMICAL PROCESS SAFETY of the

American Institute of Chemical Engineers 3 Park Avenue, New York, New York I001 6-5991

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Deflagration and Detonation Flame Arresters

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Deflagration and Detonation Flame Arresters

Stanley S. Grossel Process Safety and Design, Inc.

CENTER FOR CHEMICAL PROCESS SAFETY of the

American Institute of Chemical Engineers 3 Park Avenue, New York, New York I001 6-5991

Copyright 0 2002 knerican Institute of Chemical Engineers 3 Park Avenue New York, N..w York 10016-5991

All rights resewed. N o part of this publication niay be reprodtlced, stored i n a retrieval system, or transmitted in any forni or by any means, electronic, mechanical, photocopying, recording, or othcr- wise without the prior permission of the copyright owner.

Library of Congress Cataloging-in-Publication Data

ISBN 0-8 169-079 1-9 Publication nunibcr G-64

I t is sincerely hoped that the inlbrniation presented in Iliis voluine will lei111 t o ;in even more impressive salety record lor the entire industry; however, tlie American Institute olChemical Engineers, its consultants, C ( Y S Suhconi- niittce memhen, their employers, atid their emplcryers' ollicers antl directors cliscleim making or giving m y warranties or representations, exlxess or implied. inclucling wi th respect t o litness. intended purpose. use oI nier- chantability anillor correctness or accuracy of the content o l the inloriii;itioii presented in this tlocumcnt. As bc~ween ( I ) American Institute ol(:hemical Engineers, i ts consiiltants, ( X I ' S Siilxwnniittee menihers, their employers. their employers' olliccrs and directors antl (2) the user 0 1 th is clocuinent, the user accepts any legal liability or rcspmsihility wh;itsoever Tor tlie coiise- cpcnces of its use or misuse.

This book is available at a special discount when ordered in bulk quantities. For information, contact the Center for Chemical Process Safety at the address shown above.

Contents

Preface Acknowledgments Acronyms and Abbreviations

2 History and State-of-the Art

2.1. Historical Development of Flame Arresters

2.2. Case Histories of Successful and Unsuccessful Applications of Flame Arresters 2.2.1. Successful Applications 2.2.2. Unsuccessful Applications

xi

xiii

xv

5

7 7 8 V

1 Introduction

1.1. Intended Audience 1

1.2. Why This Book Was Written 1

1.3. What Is Covered in This Book 2

1.4. What the Reader Should Learn from This Book 3

1.5. Units of Measure 3

vi Con tents

10 10 11 11 12

2.3. Evolution of Standards and Codes 2.3.1, United States 2.3.2. Canada 2.3.3. United Kingdom 2.3.4. Europe and International

Tradeoffs and Conflicts 2.4. Safety Concerns and Environmental Regulations:

2.5. References

3 Overview of Deflagration and Detonation Prevention and Protection Practices

3.1. Introduction

3.2. Deflagration and Detonation Flame Arresters

3.3. Deflagration Venting

3.4. Oxidant Concentration Reduction

3.5. Combustible Concentration Reduction

3.6. Deflagration Suppression

3.7. Deflagration Pressure Containment

3.8. Equipment and Piping Isolation

3.9. References

13

1 4

17

17

2 8

3 0

35

36

40

40

46

4 Overview of Combustion and Flame Propagation Phenomena Related to DDAs

4.1. Introduction to the Chemistry and Physics of Flame Propagation 4. I. I. Combustion Chemistry and Thermodynamics 4.1.2. Flammability Characteristics 4.1.3. Decomposition Flames

4.2.1. Burning Velocity and Flame Speed 4.2.2. Flame Acceleration and Deflagration-to-Detonation

4.2.3. Detonations

4.2. Dynamics of Flame Propagation

Transition (DDT)

51 52 56 59

60 60

64 66

Contents

4.3. Ignition and Quenching

4.4. Theoretical Basis for Flame Arrester Design and Operation

4.5 References

5 Deflagration and Detonation Flame Arrester Technology

5.1. Where Flame Arresters May Be Needed

5.2. Types of Flame Arresters 5.2.1. Introduction 5.2.2. Crimped Metal Ribbon 5.2.3. Parallel Plate 5.2.4. Expanded Metal Cartridge 5.2.5. Perforated Plate 5.2.6. Wire Gauze 5.2.7. Sintered Metal 5.2.8. Ceramic Balls 5.2.9. Metal Shot 5.2.10. Hydraulic (Liquid Seal) Flame Arrester 5.2.11. Packed Bed Flame Arrester 5.2.12. Velocity Flame Stopper 5.2.13. High Velocity Vent Valve 5.2.14. Conservation Vent Valves as Flame Arresters

5.3.1. Classification According to NEC Groups and MESGs 5.3.2. Reactions and Combustion Dynamics of Fast-Burning Gases 5.3.3. Flame Propagation Direction

5.3. Selection and Design Criteria/Considerations

vii

71

73

73

77

78 78 78 81 82 83 84 85 85 86 87 95 96 97 98

98 98

104 105

5.3.4. Quenching Diameter, Quenching Length, and Flame Velocity 105 5.3.5. Burnback Resistance 113 5.3.6. Pressure Drop Limitations 114 5.3.7. Fouling and Plugging Potential and Protection 115 5.3.8. Unwanted Phases 116 5.3.9. Material Selection Requirements 116 5.3.10. Special Design Options 117 5.3.1 1. System Constraints 117 5.3.12. Mixture Composition 118

119 5.3.13. Operating Temperature and Pressure

viii Con tents

5.3.14. Ignition Location 5.3.15. Changes in Pipe Diameter 5.3.16. Location and Orientation 5.3.1 7. Reliability 5.3.18. Monitoring and Instrumentation 5.3.19. Inspection and Maintenance Requirements

5.4. Special Applications 5.4.1. Hydrogen 5,4.2. Acetylene 5.4.3. Ethylene Oxide

5.5. Information That Should Be Provided to Manufacturers

5.6. References

6 Installation in Process Systems

6.1. Design Considerations with Respect to Other

6.2. Piping and Flame Arrester System Design Considerations

6.3. Maintaining Reliability

6.4. Optimum Location in System

6.5. Supports for Static and Dynamic Forces

6.6. References

System Components

7 Inspection and Maintenance of Flame Arresters

7.1. Need and Importance of Maintenance

7.2. Mechanical Integrity Issues 7.2.1. Inspection 7.2.2. Current Maintenance Practices 7.2.3. Documentation and Verification of Flame Arrester

Maintenance

7.3. Training and Competence Issues for Operating and

7.4. On-Stream Isolation and Switching of Parallel Spares

Maintenance Personnel

120 124 125 126 127 128

128 129 130 131

131

132

139

140

142

142

143

146

147

147 148 149

150

150

150

Contents

7.5. Check List for inspection

7.6. References

ix

151

151

8 Regulations, Codes, and Standards

8.1. Regulations, Codes, and Standards Summaries 8.1.1. United States 8.1.2. Canada 8.1.3. United Kingdom 8.1.4. Europe and International

8.2. Comparison of Various Flame Arrester Standards and Codes

8.3. Standards and Codes in Preparation

8.4. References

153 153 158 159 160

162

165

165

9 Illustrative Examples, Calculations, and Guidelines for DDA Selection

9.1. Introduction 167

9.2. Example 1-Protective Measures for a Vent Manifold System 167

9.3. Example 2-Sizing of an End-of-Line Deflagration Flame Arrester 169

9.4. Example 34alculation of Limiting Oxidant Concentration (LOCI 172

9.5 Example Ma lcu la t i on of the LFL and UFL of Mixtures 172

9.6. Example 54alculation of the MESG of Mixtures 173

9.7. Determination If a DDT Can Occur 175

9.8. Typical Locations in Process Systems 175

9.9. List of Steps in the Selection of a DDA or Other Flame Propagation Control Method 176

9.10. References 177

10 Summary

10.1. Status of DDA Technology 179

X

10.2. Recommended Practices

10.3. Why Flame Arresters Fail

10.4. Future Technology Development

10.5. References

Contents

181

182

182

184

Appendix A Flame Arrester Specification Sheet for Manufacturer Quotation 185

Appendix B List of Flame Arrester Manufacturers

Appendix C UL and FM Listings and Approvals

Appendix D Suggested Additional Reading

Glossary

Index

187

191

193

197

209

Preface

The Center for Chemical Process Safety (CCPS) was established in 1985 by the American Institute of Chemical Engineers for the express purpose of assisting industry in avoiding or mitigating catastrophic chemical acci- dents. To achieve this goal, CCPS has focused its work on four areas:

Establishing and publishing the latest scientific, engineering, and management practices for prevention and mitigation of incidents involving toxic, flammable, and/or reactive material Encouraging the use of such information by dissemination through publications, seminars, symposia, and continuing education pro- grams for engineers Advancing the state of the art in engineering practices and technical management through research in prevention and mitigation of cata- strophic events Developing and encouraging the use of undergraduate engineering curricula that will improve the safety knowledge and consciousness of engineers

Despite precautions, unwanted combustion can occur in process piping and vessels. This practical book offers safety guidelines for the design, instal- lation, maintenance and inspection of flame arrester systems to provide pro- tection against deflagrations and detonations propagating through process equipment, piping and especially vent manifold systems. The combustion and explosion phenomenon is discussed as it relates to selection, installation and maintenance of deflagration and detonation flame arresters. Other

xi

xii Preface

methods to prevent these propagating flames such as venting, pressure containment, oxidant reduction, combustible concentration reduction, deflagration suppression, and equipment and piping isolation are also briefly discussed. Anumber ofworked examples are given to illustrate var- ious aspects of the design of these systems.

Acknowledgments

This book could not have written without the assistance of many people and organizations that shared their expertise and experience with me, and I would like to acknowledge help from the following people:

The work on the project was supervised by the CCPS Engineering Practices Subcommittee whose members provided appreciable input from their own expertise and experience. The CCPS Subcommittee was chaired by R. Walz (ABB Lummus Global) and included (in alphabetical order): L. G. Britton (Union CarbiddDow), C. A. Dafft (Rohm and Haas), H. L. Febo, Jr. (FM Global), R. P. Gale (Solutia), H. G. Curry (Procter & Gamble), P. N. Lodal (Eastman Chemical), G. Myers (US. Department of Energy), J. L. Owen (duPont), G. A. Peters (Air Products 8c Chemicals), S. A. Rogers (Honeywell), W. A. Thornberg (Industrial Risk Insurers), and A. Torres (Eastman Kodak).

John A. Davenport was the CCPS staff liaison and was responsible for the overall administration of the project.

I would like to thank Dr. Geraint 0. Thomas (Centre for Explosion Studies, Department of Physics, University of Wales, Aberystwyth, UK) for offering to write Chapter 4. He prepared the first draft, but due to a sabbat- ical in Japan and other research commitments, he was unable to write the revisions. However, he did make constructive comments and suggestions on the revisions that I wrote. ln addition, I would like to thank the follow- ing other individuals who provided me with technical data and other assis- tance based on their knowledge of flame arresters and combustion science and technology: G. Binks (IMI Amal), R. Butler (Enardo). K. Chatrathi

xiii

xiv Acknowledgments

(Fike), D. Crow1 (Michigan Technological University), J. DePasquale (ESAB), F. Destro (Western Enterprises), D. Dickerman (Praxair), J. Gorman (Varec), R. Guile (Western Enterprises), W. Howard (Consul- tant), D. Kirby (Union Carbide/Dow), K. Lapp (Westech), D. Long (IMI Amal), V. Mendoza (NAO), F. Nichols (retired from ICI), E. Patenaude (Westech), T. Piotrowski (Protectoseal), D. Pritchard (HSE), N. Roussakis (HAD Combustion and Chemicals), A. Schneider (U.S. Coast Guard), R. Schwab (Consultant), R. Schwartz (John Zink), R. Shepherd (Tornado Flare Systems), V. Smolensky (NAO), W. Stevenson (Cv Technology), J. Straitz I11 (NAO), M. Wauben (SchuF USA), D. Wechsler (Union Car- bide/Dow), and R. White (Southwest Research Institute).

CCPS also gratefully acknowledges the comments and suggestions submitted by the following peer reviewers:

Geoff Binks Michael Davies Randy Freeman Margaret Gregson Ken Lapp Vadim Smolensky Geraint 0. Thomas Anthony Thompson Matt Wauben Donald White, Jr. Jan Windhorst

IMI A m 1 Limited Braunschweiger Flammenjlter GmbH ABS Group Inc. Health and Safe9 Executive (UK) Westech Industrial Ltd. NAO Inc. University of Wales, UK Monsanto Company SchuF (USA), Inc. Flair Nova Chemicals, Ltd.

Lastly, I would like to express my appreciation to Syl Turicchi (former manager) and Jack Weaver (Director) of the CCPS staff for their support and guidance.

AIT API ASTM ATEX BAM BSI CART CFR CGA CEN CJ CMR CSA DDA DDT DMA ESD FM FMRC ft/sec HSE

Acronyms and Abbreviations

Autoignition Temperature American Petroleum Institute American Society for Testing and Materials Atmospheres Explosibles (European Protection Standard) Bundesanstalt fur Materialprufung British Standards Institute Calculated Adiabatic Reaction Temperature Congressional Federal Register Compressed Gas Association ComitC EuropCean de Normalisation Chapman Jouguet Crimped Metal Ribbon Canadian Standards Association Deflagration and Detonation Arrester Deflagration-to-Detonation Transition Detonation Momentum Attenuator Emergency Shutdown Factory Mutual Factory Mutual Research Corporation feet per second Health and Safety Executive (UK)

xv

xvi

IChemE IEC IMO IR LEL LFL LOC MESG M IC MIE MOC mts NAS NEC NFPA NMAB OSHA PTB RED UEL UFL UK UL uv USCG voc

Acronyms and Abbreviations

Institution of Chemical Engineers (UK) International Electrotechnical Commission International Maritime Organization Infrared Lower Explosive Limit Lower Flammable Limit Limiting Oxidant Concentration Maximum Experimental Safe Gap Minimum Igniting Current Minimum Ignition Energy Maximum Oxidant Concentration meters per second National Academy of Sciences National Electrical Code National Fire Protection Association National Materials Advisory Board Occupational Safety and Health Administration Physikalische-Technische Bundesanstalt Restricted End Deflagration Upper Explosive Limit Upper Flammable Limit United Kingdom Underwriters Laboratories Ultraviolet United States Coast Guard Volatile Organic Compounds

1

Introduction

1.1. Intended Audience

This “concept book” is intended for use by chemical engineers and other technical personnel involved in the design, operation, and maintenance of facilities and equipment where deflagration and detonation arresters (DDAs) may be required. These people are usually technically competent individuals who are aware of, but not experts in, combustion phenomena. The facilities where such devices may be needed include chemical plants, petrochemical plants, petroleum refineries, pharmaceutical plants, spe- cialty chemical plants, storage tank farms, loading and unloading facilities, and pipelines.

This book will also be of use to process hazard analysis (PHA) team members and process safety and loss prevention specialists.

1.2. Why This Book Was Written

There is a need in many chemical processes for protection against propa- gation of unwanted combustion phenomena such as deflagrations and det- onations (including decomposition flames) in process equipment, piping, and especially vent manifold systems (vapor collection systems).

1

2 1. introduction

There are different ways, both passive and active, to provide this desired protection against deflagrations and detonations. Methods include DDAs, venting, pressure containment, oxidant concentration reduction (inerting and fuel enrichment), combustibles concentration reduction (ventilation or air dilution), deflagration suppression, and equipment and piping isolation. These are discussed in more detail in Chapter 3.

This book makes reference to flame arresters, deflagration flame arresters, and detonation flame arresters. “Flame arresters” is the generic term for both deflagration and detonation flame arresters. Deflagration flame arresters are used when a flame only propagates at subsonic velocity, whereas detonation arresters are used when a flame can propagate at all velocities including supersonic velocities.

One of the major reasons that this book was written is that nonspecial- ist chemical engineers know little about DDAs. Although DDAs have been specified and installed For many years, quite often they have failed because the wrong type of flame arrester was specified, or it was improperly installed, or inadequate inspection and maintenance were provided.

It is intended that this book will foster effective understanding, appli- cation and operation of DDAs by providing current knowledge on their principles of operation, selection, installation, and maintenance methods.

1.3. What Is Covered in This Book

This book covers many aspects of DDA design, selection, specification, installation, and maintenance. It explains how various types of flame arresters differ, how they are constructed, and how they work. It also describes when a flame arrester is an effective solution for mitigation of deflagrations and detonations, and other means of protection (e.g., oxi- dant concentration reduction) that may be used. It also briefly covers some aspects of dust deflagration protection.

Chapter 2 is a general discussion of the historical development of DDAs, and an overview of the applicable standards and codes is presented.

An overview of various prevention and protection methods against deflagrations and detonations is presented in Chapter 3.

Chapter 4 presents an overview ofcombustion and explosion phenom- ena as this is vital to the understanding of the conditions under which a DDA must function.

Chapter 5 is a comprehensive discussion of DDA technology, covering the various types of DDAs used in the chemical process industries, as well as selection and design considerations and criteria. Detailed information is

1.5. Units of Measure 3

presented on how to select a DDA for various operating conditions and applications (e.g., deflagration versus detonation conditions, end-OF-line versus inline, vent manifold/vapor recovery systems). During the descrip- tion and discussion of various types of DDAs, some application examples are presented.

Subsequent chapters cover installation considerations (Chapter 6), inspection and maintenance practices (Chapter 7), regulations, standards, and codes, including certification test protocols (Chapter 8) , and some illustrative examples (Chapter 9). Chapter 10 provides a summary of the present state-of-the-art and what other information and research is needed, followed by appendixes, a glossary, and suggested additional reading.

This book does not provide specific recommendations For maritime operations (e.g., ship and barge loading and unloading). The require- ments For these are covered in the U.S. Coast Guard regulations, which are outlined in Section 2.3.1 and in Chapter 8.

1.4. What the Reader Should Learn from This Book

After reading this book the reader should

1. be aware that it is not possible to design flame arresters From basic

2. be more conversant with deflagration and detonation phenomena

3. know when a flame arrester is an effective solution For combustion

4. be able to select an appropriate flame arrester and have it properly

5 . know what needs to be done to keep a DDA Functional; 6. be able to work with and ask the proper questions of “experts” and

theory;

in process equipment and vent manifold systems;

hazards;

installed;

manufacturers.

1.5. Units of Measure

The equations given in subsequent chapters are presented as they appear in the original reference source. Some may have mixed units (English and metric) and, therefore, the numerical constants are not dimensionless.

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2

History and State-of-the Art

2.1. Historical Development of Flame Arresters

The forerunner of the present-day flame arrester is the miner’s safety lamp. In the early 1800s candles and oil lamps were used in coal mines and were responsible for many disastrous explosions. Sir Humphrey Davy was requested to find a solution to this problem, and in 1815 he presented a paper to the Royal Society of London entitled “On the Fire-Damp of Coal Mines, and on Methods of Lighting a Mine so as to Prevent its Explosion.” This resulted in the invention of the famous Davy lamp that uses a fine metal gauze as a flame arrester. He demonstrated that a metal gauze having about 28 openings per linear inch would cool the products of com- bustion so that a flame would not ignite flammable gas on the other side of the gauze. To avoid danger resulting from failure of a single gauze cylinder surrounding the flame, he found it necessary to use two concentric cylin- ders, one slightly smaller than the other. The lower edges were fitted snugly to the bowl containing the fuel, and the upper ends of the cylinders were covered by disks of similar gauze.

Also in 1815, but before Davy presented his first lamp to the public, George Stephenson (one of the pioneers in the development of the steam locomotive) quite independently was also working on a safe miner’s lamp. He discovered during his experiments that flame produced by a particular gas at a given concentration will not pass through a tube smaller than a cer- tain diameter. While most people have heard of Davy’s lamp (it seems that Sir Humphrey received all the credit), it was actually Stephenson’s discov-

5

6 2. History and State-of-the Art

ery that was extremely important, because it provided the basis for the con- cept of the “quenching distance,” which in turn led to the concept of “Maximum Experimental Safe Gap” (MESG). The MESG is extensively used today to classify gases and gas mixtures for the purpose of selecting flame arresters and electrical equipment. For further discussion of histori- cal developments, see Smiles (1975).

Flame arresters for chemical process equipment and flammable liquid containers have been available for over 120 years. A US patent was issued as early as 1878 for a “spark-arrester” (Allonas 1878), while another “spark-arrester” was patented in 1880 (Stewart 1880). Numerous US pat- ents have been issued for various designs of flame arresters, with one as recent as 1995 (Roussakis and Brooker 1995). In Germany, patents were issued in 1929 and 1939 for flame arresters that contained shock absorber internals upstream of the flame arrester elements. This innovation made them suitable as detonation arresters (Wauben 1999).

The crimped metal ribbon flame arrester element (see Chapter 5), which is used in both deflagration and detonation flame arresters, was the concept of Mr. Swan, an RAF Engineering Officer, who worked at the Royal Aircraft Establishment at Farnborough, England (Binks 1999). He needed a flame arrester for use during purging of gas bags of dirigibles, which then used flammable hydrogen rather than the inert helium used today. In this application it was used as a deflagration flame arrester, although it was also used as a detonation flame arrester for Group D and C gases (Group IIA and IIB in Europe). These classifications will be discussed in Section 5.3.1. Mr. Swan’s crimped metal ribbon arresters were licensed to IMI Amal in the UK and were first manufactured in the late 1910s or early 1920s. There were many applications for crimped metal ribbon flame arresters during World War I1 in aircraft and motor torpedo boat engines, but they were mostly used as deflagration flame arresters. Their wide- spread use in detonation flame arresters occurred after World War 11.

It was not until the 1950s that detonation flame arresters made of crimped metal ribbon elements were developed and began to be used more frequently (Binks 1999). The major impetus for the use of crimped metal ribbon detonation flame arresters in the US was the enactment of clean air legislation (Clean Air Act of 1990) which inadvertently created a safety problem by requiring reductions in volatile organic compound (VOC) emissions. To do this, manifolded vent systems (vapor collection systems) were increasingly installed in many chemical process industry plants which captured VOC vapors and transported them to suitable recov- ery, recycle, or destruction systems. This emission control requirement has led to the introduction of ignition risks, for example, from a flare or via spontaneous combustion of an activated carbon adsorber bed. Multiple