The Safety Relief Valve Handbook: Design and Use of Process Safety Valves to ASME and International Codes and Standards (Butterworth-Heinemann IChemE)

The Safety Valve Handbook is a professional reference for design, process, instrumentation, plant and maintenance engineers who work with fluid flow and transportation systems in the process industries, which covers the chemical, oil and gas, water, paper and pulp, food and bio products and energy sectors. It meets the need of engineers who have responsibilities for specifying, installing, inspecting or maintaining safety valves and flow control systems. It will also be an important reference for process safety and loss prevention engineers, environmental engineers, and plant and process designers who need to understand the operation of safety valves in a wider equipment or plant design context. • No other publication is dedicated to safety valves or to the extensive codes and standards that govern their installation and use. A single source means users save time in searching for specific information about safety valves. • The Safety Valve Handbook contains all of the vital technical and standards information relating to safety valves used in the process industry for positive pressure applications. • Explains technical issues of safety valve operation in detail, including identification of benefits and pitfalls of current valve technologies. • Enables informed and creative decision making in the selection and use of safety valves. • The Handbook is unique in addressing both US and European codes: - covers all devices subject to the ASME VIII and European PED (pressure equipment directive) codes; - covers the safety valve recommendations of the API (American Petroleum Institute); - covers the safety valve recommendations of the European Normalisation Committees; - covers the latest NACE and ATEX codes; - enables readers to interpret and understand codes in practice. • Extensive and detailed illustrations and graphics provide clear guidance and explanation of technical material, in order to help users of a wide range of experience and background (as those in this field tend to have) to understand these devices and their applications. • Covers calculating valves for two-phase flow according to the new Omega 9 method and highlights the safety difference between this and the traditional method. • Covers selection and new testing method for cryogenic applications (LNG) for which there are currently no codes available and which is a booming industry worldwide. • Provides full explanation of the principles of different valve types available on the market, providing a selection guide for safety of the process and economic cost. • Extensive glossary and terminology to aid readers’ ability to understand documentation, literature, maintenance and operating manuals. • Accompanying website provides an online valve selection and codes guide. 77122_fm 1 Front Matter 1 Acknowledgements -1 Preface -1 Table of Contents -1 Appendix Section: Relevant Tables and References -1 Index -1 77122_pref 3 Front Matter -1 Preface 3 Table of Contents -1 Appendix Section: Relevant Tables and References -1 Index -1 77122_ack 6 Front Matter -1 Acknowledgements 6 Table of Contents -1 Appendix Section: Relevant Tables and References -1 Index -1 77122_toc 7 Front Matter -1 Acknowledgements -1 Preface -1 Table of Contents 7 1. History -1 1.1 Acronyms, Abbreviations -1 2. Overpressure Protection -1 2.1 General Definition of an SRV -1 2.2 Where Do SRVs Fit in the Process? -1 2.3 Where Do SRVs Act within the Process? -1 2.4 Causes of Overpressure -1 2.4.1 Blocked Discharge -1 2.4.2 Fire Case -1 2.4.2.1 Sizing for Vaporizing Liquids (Wetted Vessels) -1 2.4.2.2 Sizing for Vessels Containing Gases and Vapours Only (Unwetted Vessels) -1 2.4.3 Thermal Expansion -1 2.4.4 Runaway Reaction -1 2.4.5 Tube Rupture in Heat Exchangers -1 2.5 Determine Overpressure Protection Requirements -1 2.6 Overpressure Relief Devices -1 2.7 Risk Assessment and Reduction -1 3. Terminology -1 3.1 Testing -1 3.2 Type of Devices -1 3.2.1 Reclosing Pressure-Relieving Devices -1 3.2.2 Non-Reclosing Pressure Relief Device -1 3.3 Dimensional Terms -1 3.4 Operational Terms -1 3.5 Component Terms -1 3.6 Clarification of the Terms: Set Pressure, Overpressure, Accumulation, MAWP and Design Pressure -1 3.6.1 PED versus ASME -1 3.6.1.1 Overpressure versus Accumulation -1 3.6.1.2 ASME VIII on Accumulation -1 3.6.1.3 Multiple Valves -1 3.6.1.4 PED on Accumulation -1 3.6.1.5 All Cases Except Fire -1 3.6.1.6 Fire Case Only -1 3.6.1.7 Fired Vessels, Boilers -1 3.6.1.8 Practical Applications -1 3.6.1.9 Conclusion -1 4. Codes and Standards -1 4.1 Overview Operational Requirements -1 4.2 ASME and API Codes and Standards - Clarifications -1 4.2.1 National Board Approval -1 4.2.2 Main Paragraph Excerpts from ASME VIII -1 4.2.3 Main Excerpts from American Petroleum Institute Recommended Practices Related to Safety Relief Valves -1 4.2.3.1 Gas -1 4.2.3.2 Steam -1 4.2.3.3 Water -1 4.3 NACE -1 4.4 PED 97/23/EC (Pressure Equipment Directive) - CEN -1 4.5 ATEX -1 4.5.1 European ATEX Guidelines -1 5. Design Fundamentals -1 5.1 Construction Materials -1 5.2 Direct Spring-Operated SRVs -1 5.2.1 Introduction -1 5.2.2 Functionality -1 5.2.3 General Design -1 5.2.4 Design of Main Assemblies -1 5.2.4.1 Cap Design and Styles -1 5.2.4.2 Bonnet Parts -1 5.2.4.3 Non-Wetted Parts in the Body -1 5.2.4.4 Bellows -1 5.2.4.5 Wetted Parts -1 5.2.5 Design Differences -1 5.2.5.1 Disc Designs -1 5.2.5.2 Nozzle/Body Design -1 5.2.5.3 Disc Holder Designs -1 5.2.6 Types of Spring-Operated SRVs -1 5.2.6.1 Thermal Relief Valves -1 5.2.6.2 Conventional Spring-Operated SRV -1 5.2.6.3 Open Bonnet Spring-Operated SRV -1 5.2.6.4 Balanced Bellows Spring-Operated SRV -1 5.2.6.5 High-Performance Resilient-Seated SV -1 5.2.6.6 Balanced Piston SRV -1 5.2.6.7 Designs Out of Forged Blocks - Block Design -1 5.2.6.8 Controlled Safety Pressure Relief System -1 5.3 Pilot-Operated Safety Relief Valves -1 5.3.1 Introduction -1 5.3.2 Functionality -1 5.3.3 Types of POSRV -1 5.3.3.1 Low Pressure Diaphragm Type -1 5.3.3.2 Snap (Pop) Action High-Pressure POSRVs -1 5.3.3.3 Modulating Action High-Pressure POSRVs -1 5.3.3.4 Special Features of POSRVs -1 5.3.4 Summary -1 5.4 DIN Design -1 5.5 Non-Reclosing Pressure Relief Devices -1 5.5.1 Summary -1 6. Installation -1 6.1 Inlet and Outlet Piping -1 6.1.1 Calculating Piping Losses -1 6.1.1.1 Inlet Losses due to Entrance Effects -1 6.1.1.2 Inlet Losses due to Piping -1 6.1.1.3 Pressure Drop Effect due to Upstream Devices -1 6.1.2 Calculating Outlet Piping -1 6.2 Location of Installed SRVs -1 6.3 Reaction Forces and Bracing -1 6.4 Temperature Transmission -1 6.5 Installation Guidelines -1 7. Sizing and Selection -1 7.1 Introduction -1 7.2 Gas and Vapour Sizing -1 7.3 Steam Sizing (Sonic Flow) -1 7.4 Steam Sizing - per ASME Section I -1 7.5 Liquid Sizing -1 7.5.1 Combination Devices -1 7.6 Two-Phase and Flashing Flow -1 7.6.1 Some Basics -1 7.6.2 Two-Phase Liquid/Vapour Flow -1 7.6.2.1 Omega -1 7.6.2.2 Omega 9 -1 7.6.3 Two-Phase System with Flashing or Non-Condensable Gas -1 7.6.3.1 Determine Omega -1 7.6.3.2 Determining the Critical Conditions -1 7.6.3.3 Determining the Mass Flux -1 7.6.4 Subcooled Liquid Flashing -1 7.6.4.1 Determine Omega -1 7.6.4.2 Determining the Subcooling Region -1 7.6.5 Two-Phase System with Flashing and Non-Condensable Gas -1 7.6.5.1 Determine Omega -1 7.6.5.2 Determining the Critical Conditions -1 7.6.5.3 Determining the Mass Flux -1 7.6.5.4 Determination of the Required Areas of the SRV -1 7.6.5.5 Determination of Omega 9 -1 8. Noise -1 8.1 Risk of Damage to Hearing -1 8.2 Planning an Accident -1 8.3 Noise from the SRV, Open Vent and Associated Pipe -1 8.4 Noise Calculations -1 8.5 Conclusions -1 9. Safety Relief Valve Selection -1 9.1 Seat Tightness -1 9.2 Blowdown -1 9.3 Service Temperature -1 9.4 Weight and/or Height -1 9.5 Backpressure -1 9.6 Orifice Size - Sizing -1 9.7 Two-Phase Flow -1 9.8 Type of Fluid -1 9.9 Reciprocating Compressors -1 9.10 Liquid -1 9.11 Materials -1 10. Maintenance and Testing -1 10.1 Maintenance Frequency and Cost -1 10.1.1 Introduction -1 10.1.2 Maintenance Cost -1 10.1.3 Maintenance Frequency -1 10.1.3.1 Rationale -1 10.1.3.2 Factors Affecting Selection of an Inspection Grading -1 10.1.3.3 Inspection Grade Awards Guidelines -1 10.1.3.4 Inspection Requirements and Reporting -1 10.1.3.5 Inspection Intervals and Survey Requirements -1 10.2 Transportation and Dirt -1 10.2.1 Preinstallation Handling and Testing of Pressure Relief Valves -1 10.3 Troubleshooting SRVs -1 10.3.1 Seat Leakage -1 10.3.2 Chatter -1 10.3.3 Premature Opening -1 10.3.4 Valve Will Not Open -1 10.3.5 Valve Opens above Set Pressure -1 10.3.6 Valve Does Not Reclose -1 10.3.7 Bellows Failure -1 10.3.7.1 Mechanical Failure -1 10.3.7.2 Fatigue Failure -1 10.3.7.3 Corrosion Failure -1 10.3.8 Springs -1 10.4 Testing -1 10.4.1 In situ Testing of Spring-Operated SRVs -1 10.4.2 In situ Testing of Pilot-Operated SVs -1 10.5 Maintenance Procedure -1 11. Cryogenic Applications -1 11.1 Thermal Relief -1 11.2 Process -1 11.2.1 Conventional Spring-Operated SRVs on Cryogenic Service -1 11.2.2 Balanced Bellows Spring-Loaded SRVs on Cryogenic Service -1 11.2.3 POSRV on Cryogenic Service -1 11.2.3.1 Considerations for POSRVs on LNG and Cryogenic Applications -1 11.3 Testing for Cryogenic Service -1 11.3.1 The 'Submerged Test' -1 11.3.2 The 'Boil-off Test' -1 11.4 Conclusion -1 12. Specifying Safety Relief Valves -1 12.1 Summary of Overall Requirements -1 12.2 Materials -1 12.3 Design -1 12.4 Identification -1 12.5 Inspection and Testing -1 12.6 Preparation for Shipment -1 13. Non-Conformance of Existing Pressure Relief Systems -1 13.1 No Relief Device Present -1 13.1.1 External Fire (33%) -1 13.1.2 Multiple Scenarios (23%) -1 13.1.3 Blocked Outlet (16%) -1 13.1.4 Thermal Relief (16%) -1 13.1.5 Tube Rupture (7%) -1 13.1.6 Others (4%) -1 13.1.7 Control Valve Failure (1%) -1 13.2 Under/Oversized Safety Valves -1 13.2.1 External Fire (38%) -1 13.2.2 Blocked Outlet (16%) -1 13.2.3 Tube Rupture (13%) -1 13.2.4 Multiple Scenarios (12%) -1 13.2.5 Control Valve Failure (10%) -1 13.2.6 Others (9%) -1 13.2.7 Loss of Condensing (2%) -1 13.3 Improper Installation -1 13.3.1 Outlet Pressure Drop Too High (43%) -1 13.3.2 Inlet Pressure Drop Too High (36%) -1 13.3.3 Blocked Relief Pathway (9%) -1 13.3.4 Set Pressure Too High (8%) -1 13.3.5 Others (4%) -1 13.4 What Can Go Wrong in the Process Scenarios -1 Appendix Section: Relevant Tables and References -1 A. Comparisons between the Safety Valves Sizing Formulas -1 A.1 Gas Flows -1 A.2 Critical (Choked) Flows -1 A.3 Subcritical Flows -1 A.4 Liquid Flows -1 B. Backpressure Correction Factors -1 C. Compressibility Factors -1 D. Ratio of Specific Heats k and Coefficient C -1 E. Capacity Correction Factor for Superheat, K_sh -1 F. Capacity Correction Factor for High Pressure Steam, K_n -1 G. Capacity Correction Factor for Viscosity, K_v -1 H. Allowable Operating, Working, Relief, Set and Blowdown Pressures -1 I. Codes and Standards Organizations -1 J. API 526 Data Sheet Recommendation -1 K. Generic Sizing Program -1 L. Worldwide Codes and Standards (Most Common) -1 M. Properties of Common Gases -1 N. Relevant Conversion Factors -1 Index -1 A -1 B -1 C -1 D -1 E -1 F -1 G -1 H -1 I -1 K -1 L -1 M -1 N -1 O -1 P -1 R -1 S -1 T -1 V -1 W -1 77122_01 13 Front Matter -1 Table of Contents -1 1. History 13 1.1 Acronyms, Abbreviations 17 Appendix Section: Relevant Tables and References -1 Index -1 77122_02 18 Front Matter -1 Table of Contents -1 2. Overpressure Protection 18 2.1 General Definition of an SRV 18 2.2 Where Do SRVs Fit in the Process? 18 2.3 Where Do SRVs Act within the Process? 19 2.4 Causes of Overpressure 20 2.4.1 Blocked Discharge 20 2.4.2 Fire Case 21 2.4.2.1 Sizing for Vaporizing Liquids (Wetted Vessels) 22 2.4.2.2 Sizing for Vessels Containing Gases and Vapours Only (Unwetted Vessels) 27 2.4.3 Thermal Expansion 29 2.4.4 Runaway Reaction 30 2.4.5 Tube Rupture in Heat Exchangers 30 2.5 Determine Overpressure Protection Requirements 31 2.6 Overpressure Relief Devices 33 2.7 Risk Assessment and Reduction 36 Appendix Section: Relevant Tables and References -1 Index -1 77122_03 39 Front Matter -1 Table of Contents -1 3. Terminology 39 3.1 Testing 39 3.2 Type of Devices 41 3.2.1 Reclosing Pressure-Relieving Devices 41 3.2.2 Non-Reclosing Pressure Relief Device 42 3.3 Dimensional Terms 43 3.4 Operational Terms 45 3.5 Component Terms 51 3.6 Clarification of the Terms: Set Pressure, Overpressure, Accumulation, MAWP and Design Pressure 54 3.6.1 PED versus ASME 58 3.6.1.1 Overpressure versus Accumulation 59 3.6.1.2 ASME VIII on Accumulation 59 3.6.1.3 Multiple Valves 59 3.6.1.4 PED on Accumulation 60 3.6.1.5 All Cases Except Fire 61 3.6.1.6 Fire Case Only 63 3.6.1.7 Fired Vessels, Boilers 63 3.6.1.8 Practical Applications 63 3.6.1.9 Conclusion 63 Appendix Section: Relevant Tables and References -1 Index -1 77122_04 65 Front Matter -1 Table of Contents -1 4. Codes and Standards 65 4.1 Overview Operational Requirements 68 4.2 ASME and API Codes and Standards - Clarifications 68 4.2.1 National Board Approval 69 4.2.2 Main Paragraph Excerpts from ASME VIII 70 4.2.3 Main Excerpts from American Petroleum Institute Recommended Practices Related to Safety Relief Valves 76 4.2.3.1 Gas 78 4.2.3.2 Steam 79 4.2.3.3 Water 79 4.3 NACE 80 4.4 PED 97/23/EC (Pressure Equipment Directive) - CEN 83 4.5 ATEX 87 4.5.1 European ATEX Guidelines 87 Appendix Section: Relevant Tables and References -1 Index -1 77122_05 90 Front Matter -1 Table of Contents -1 5. Design Fundamentals 90 5.1 Construction Materials 91 5.2 Direct Spring-Operated SRVs 91 5.2.1 Introduction 91 5.2.2 Functionality 92 5.2.3 General Design 97 5.2.4 Design of Main Assemblies 101 5.2.4.1 Cap Design and Styles 101 5.2.4.2 Bonnet Parts 104 5.2.4.3 Non-Wetted Parts in the Body 105 5.2.4.4 Bellows 106 5.2.4.5 Wetted Parts 107 5.2.5 Design Differences 108 5.2.5.1 Disc Designs 108 5.2.5.2 Nozzle/Body Design 108 5.2.5.3 Disc Holder Designs 110 5.2.6 Types of Spring-Operated SRVs 111 5.2.6.1 Thermal Relief Valves 111 5.2.6.2 Conventional Spring-Operated SRV 112 5.2.6.3 Open Bonnet Spring-Operated SRV 113 5.2.6.4 Balanced Bellows Spring-Operated SRV 113 5.2.6.5 High-Performance Resilient-Seated SV 114 5.2.6.6 Balanced Piston SRV 119 5.2.6.7 Designs Out of Forged Blocks - Block Design 119 5.2.6.8 Controlled Safety Pressure Relief System 120 5.3 Pilot-Operated Safety Relief Valves 122 5.3.1 Introduction 122 5.3.2 Functionality 123 5.3.3 Types of POSRV 124 5.3.3.1 Low Pressure Diaphragm Type 125 5.3.3.2 Snap (Pop) Action High-Pressure POSRVs 125 5.3.3.3 Modulating Action High-Pressure POSRVs 127 5.3.3.4 Special Features of POSRVs 128 5.3.4 Summary 134 5.4 DIN Design 135 5.5 Non-Reclosing Pressure Relief Devices 136 5.5.1 Summary 140 Appendix Section: Relevant Tables and References -1 Index -1 77122_06 141 Front Matter -1 Table of Contents -1 6. Installation 141 6.1 Inlet and Outlet Piping 141 6.1.1 Calculating Piping Losses 151 6.1.1.1 Inlet Losses due to Entrance Effects 153 6.1.1.2 Inlet Losses due to Piping 154 6.1.1.3 Pressure Drop Effect due to Upstream Devices 155 6.1.2 Calculating Outlet Piping 156 6.2 Location of Installed SRVs 159 6.3 Reaction Forces and Bracing 159 6.4 Temperature Transmission 163 6.5 Installation Guidelines 163 Appendix Section: Relevant Tables and References -1 Index -1 77122_07 170 Front Matter -1 Table of Contents -1 7. Sizing and Selection 170 7.1 Introduction 170 7.2 Gas and Vapour Sizing 174 7.3 Steam Sizing (Sonic Flow) 177 7.4 Steam Sizing - per ASME Section I 179 7.5 Liquid Sizing 181 7.5.1 Combination Devices 182 7.6 Two-Phase and Flashing Flow 182 7.6.1 Some Basics 184 7.6.2 Two-Phase Liquid/Vapour Flow 186 7.6.2.1 Omega 187 7.6.2.2 Omega 9 187 7.6.3 Two-Phase System with Flashing or Non-Condensable Gas 188 7.6.3.1 Determine Omega 189 7.6.3.2 Determining the Critical Conditions 190 7.6.3.3 Determining the Mass Flux 190 7.6.4 Subcooled Liquid Flashing 190 7.6.4.1 Determine Omega 191 7.6.4.2 Determining the Subcooling Region 191 7.6.5 Two-Phase System with Flashing and Non-Condensable Gas 193 7.6.5.1 Determine Omega 193 7.6.5.2 Determining the Critical Conditions 193 7.6.5.3 Determining the Mass Flux 194 7.6.5.4 Determination of the Required Areas of the SRV 196 7.6.5.5 Determination of Omega 9 198 Appendix Section: Relevant Tables and References -1 Index -1 77122_08 202 Front Matter -1 Table of Contents -1 8. Noise 202 8.1 Risk of Damage to Hearing 207 8.2 Planning an Accident 212 8.3 Noise from the SRV, Open Vent and Associated Pipe 212 8.4 Noise Calculations 213 8.5 Conclusions 216 Appendix Section: Relevant Tables and References -1 Index -1 77122_09 219 Front Matter -1 Table of Contents -1 9. Safety Relief Valve Selection 219 9.1 Seat Tightness 219 9.2 Blowdown 220 9.3 Service Temperature 220 9.4 Weight and/or Height 221 9.5 Backpressure 221 9.6 Orifice Size - Sizing 224 9.7 Two-Phase Flow 224 9.8 Type of Fluid 225 9.9 Reciprocating Compressors 225 9.10 Liquid 226 9.11 Materials 227 Appendix Section: Relevant Tables and References -1 Index -1 77122_10 229 Front Matter -1 Table of Contents -1 10. Maintenance and Testing 229 10.1 Maintenance Frequency and Cost 229 10.1.1 Introduction 229 10.1.2 Maintenance Cost 230 10.1.3 Maintenance Frequency 232 10.1.3.1 Rationale 232 10.1.3.2 Factors Affecting Selection of an Inspection Grading 233 10.1.3.3 Inspection Grade Awards Guidelines 233 10.1.3.4 Inspection Requirements and Reporting 235 10.1.3.5 Inspection Intervals and Survey Requirements 236 10.2 Transportation and Dirt 236 10.2.1 Preinstallation Handling and Testing of Pressure Relief Valves 237 10.3 Troubleshooting SRVs 238 10.3.1 Seat Leakage 239 10.3.2 Chatter 241 10.3.3 Premature Opening 243 10.3.4 Valve Will Not Open 244 10.3.5 Valve Opens above Set Pressure 244 10.3.6 Valve Does Not Reclose 244 10.3.7 Bellows Failure 244 10.3.7.1 Mechanical Failure 245 10.3.7.2 Fatigue Failure 246 10.3.7.3 Corrosion Failure 246 10.3.8 Springs 247 10.4 Testing 248 10.4.1 In situ Testing of Spring-Operated SRVs 250 10.4.2 In situ Testing of Pilot-Operated SVs 252 10.5 Maintenance Procedure 253 Appendix Section: Relevant Tables and References -1 Index -1 77122_11 261 Front Matter -1 Table of Contents -1 11. Cryogenic Applications 261 11.1 Thermal Relief 263 11.2 Process 263 11.2.1 Conventional Spring-Operated SRVs on Cryogenic Service 264 11.2.2 Balanced Bellows Spring-Loaded SRVs on Cryogenic Service 264 11.2.3 POSRV on Cryogenic Service 266 11.2.3.1 Considerations for POSRVs on LNG and Cryogenic Applications 266 11.3 Testing for Cryogenic Service 268 11.3.1 The 'Submerged Test' 268 11.3.2 The 'Boil-off Test' 269 11.4 Conclusion 270 Appendix Section: Relevant Tables and References -1 Index -1 77122_12 271 Front Matter -1 Table of Contents -1 12. Specifying Safety Relief Valves 271 12.1 Summary of Overall Requirements 271 12.2 Materials 272 12.3 Design 273 12.4 Identification 274 12.5 Inspection and Testing 275 12.6 Preparation for Shipment 275 Appendix Section: Relevant Tables and References -1 Index -1 77122_13 277 Front Matter -1 Table of Contents -1 13. Non-Conformance of Existing Pressure Relief Systems 277 13.1 No Relief Device Present 281 13.1.1 External Fire (33%) 281 13.1.2 Multiple Scenarios (23%) 282 13.1.3 Blocked Outlet (16%) 282 13.1.4 Thermal Relief (16%) 282 13.1.5 Tube Rupture (7%) 282 13.1.6 Others (4%) 283 13.1.7 Control Valve Failure (1%) 283 13.2 Under/Oversized Safety Valves 283 13.2.1 External Fire (38%) 283 13.2.2 Blocked Outlet (16%) 284 13.2.3 Tube Rupture (13%) 284 13.2.4 Multiple Scenarios (12%) 284 13.2.5 Control Valve Failure (10%) 284 13.2.6 Others (9%) 284 13.2.7 Loss of Condensing (2%) 285 13.3 Improper Installation 285 13.3.1 Outlet Pressure Drop Too High (43%) 285 13.3.2 Inlet Pressure Drop Too High (36%) 286 13.3.3 Blocked Relief Pathway (9%) 287 13.3.4 Set Pressure Too High (8%) 287 13.3.5 Others (4%) 287 13.4 What Can Go Wrong in the Process Scenarios 288 Appendix Section: Relevant Tables and References -1 Index -1 77122_apdx 292 Front Matter -1 Table of Contents -1 Appendix Section: Relevant Tables and References 292 A. Comparisons between the Safety Valves Sizing Formulas 292 A.1 Gas Flows 292 A.2 Critical (Choked) Flows 294 A.3 Subcritical Flows 294 A.4 Liquid Flows 295 B. Backpressure Correction Factors 296 C. Compressibility Factors 298 D. Ratio of Specific Heats k and Coefficient C 299 E. Capacity Correction Factor for Superheat, K_sh 300 F. Capacity Correction Factor for High Pressure Steam, K_n 301 G. Capacity Correction Factor for Viscosity, K_v 302 H. Allowable Operating, Working, Relief, Set and Blowdown Pressures 304 I. Codes and Standards Organizations 305 J. API 526 Data Sheet Recommendation 307 K. Generic Sizing Program 309 L. Worldwide Codes and Standards (Most Common) 310 M. Properties of Common Gases 311 N. Relevant Conversion Factors 313 Index -1 77122_fr 317 Front Matter -1 Table of Contents -1 Appendix Section: Relevant Tables and References -1 Index -1 77122_indx 319 Front Matter -1 Table of Contents -1 Appendix Section: Relevant Tables and References -1 Index 319 A 319 B 319 C 320 D 321 E 322 F 322 G 322 H 323 I 323 K 323 L 323 M 324 N 324 O 325 P 326 R 327 S 328 T 329 V 330 W 330 Front Matter......Page 1 Appendix Section: Relevant Tables and References......Page 0 Preface......Page 3 Acknowledgements......Page 6 Table of Contents......Page 7 1. History......Page 13 1.1 Acronyms, Abbreviations......Page 17 2.2 Where Do SRVs Fit in the Process?......Page 18 2.3 Where Do SRVs Act within the Process?......Page 19 2.4.1 Blocked Discharge......Page 20 2.4.2 Fire Case......Page 21 2.4.2.1 Sizing for Vaporizing Liquids (Wetted Vessels)......Page 22 2.4.2.2 Sizing for Vessels Containing Gases and Vapours Only (Unwetted Vessels)......Page 27 2.4.3 Thermal Expansion......Page 29 2.4.5 Tube Rupture in Heat Exchangers......Page 30 2.5 Determine Overpressure Protection Requirements......Page 31 2.6 Overpressure Relief Devices......Page 33 2.7 Risk Assessment and Reduction......Page 36 3.1 Testing......Page 39 3.2.1 Reclosing Pressure-Relieving Devices......Page 41 3.2.2 Non-Reclosing Pressure Relief Device......Page 42 3.3 Dimensional Terms......Page 43 3.4 Operational Terms......Page 45 3.5 Component Terms......Page 51 3.6 Clarification of the Terms: Set Pressure, Overpressure, Accumulation, MAWP and Design Pressure......Page 54 3.6.1 PED versus ASME......Page 58 3.6.1.3 Multiple Valves......Page 59 3.6.1.4 PED on Accumulation......Page 60 3.6.1.5 All Cases Except Fire......Page 61 3.6.1.9 Conclusion......Page 63 4. Codes and Standards......Page 65 4.2 ASME and API Codes and Standards - Clarifications......Page 68 4.2.1 National Board Approval......Page 69 4.2.2 Main Paragraph Excerpts from ASME VIII......Page 70 4.2.3 Main Excerpts from American Petroleum Institute Recommended Practices Related to Safety Relief Valves......Page 76 4.2.3.1 Gas......Page 78 4.2.3.3 Water......Page 79 4.3 NACE......Page 80 4.4 PED 97/23/EC (Pressure Equipment Directive) - CEN......Page 83 4.5.1 European ATEX Guidelines......Page 87 5. Design Fundamentals......Page 90 5.2.1 Introduction......Page 91 5.2.2 Functionality......Page 92 5.2.3 General Design......Page 97 5.2.4.1 Cap Design and Styles......Page 101 5.2.4.2 Bonnet Parts......Page 104 5.2.4.3 Non-Wetted Parts in the Body......Page 105 5.2.4.4 Bellows......Page 106 5.2.4.5 Wetted Parts......Page 107 5.2.5.2 Nozzle/Body Design......Page 108 5.2.5.3 Disc Holder Designs......Page 110 5.2.6.1 Thermal Relief Valves......Page 111 5.2.6.2 Conventional Spring-Operated SRV......Page 112 5.2.6.4 Balanced Bellows Spring-Operated SRV......Page 113 5.2.6.5 High-Performance Resilient-Seated SV......Page 114 5.2.6.7 Designs Out of Forged Blocks - Block Design......Page 119 5.2.6.8 Controlled Safety Pressure Relief System......Page 120 5.3.1 Introduction......Page 122 5.3.2 Functionality......Page 123 5.3.3 Types of POSRV......Page 124 5.3.3.2 Snap (Pop) Action High-Pressure POSRVs......Page 125 5.3.3.3 Modulating Action High-Pressure POSRVs......Page 127 5.3.3.4 Special Features of POSRVs......Page 128 5.3.4 Summary......Page 134 5.4 DIN Design......Page 135 5.5 Non-Reclosing Pressure Relief Devices......Page 136 5.5.1 Summary......Page 140 6.1 Inlet and Outlet Piping......Page 141 6.1.1 Calculating Piping Losses......Page 151 6.1.1.1 Inlet Losses due to Entrance Effects......Page 153 6.1.1.2 Inlet Losses due to Piping......Page 154 6.1.1.3 Pressure Drop Effect due to Upstream Devices......Page 155 6.1.2 Calculating Outlet Piping......Page 156 6.3 Reaction Forces and Bracing......Page 159 6.5 Installation Guidelines......Page 163 7.1 Introduction......Page 170 7.2 Gas and Vapour Sizing......Page 174 7.3 Steam Sizing (Sonic Flow)......Page 177 7.4 Steam Sizing - per ASME Section I......Page 179 7.5 Liquid Sizing......Page 181 7.6 Two-Phase and Flashing Flow......Page 182 7.6.1 Some Basics......Page 184 7.6.2 Two-Phase Liquid/Vapour Flow......Page 186 7.6.2.2 Omega 9......Page 187 7.6.3 Two-Phase System with Flashing or Non-Condensable Gas......Page 188 7.6.3.1 Determine Omega......Page 189 7.6.4 Subcooled Liquid Flashing......Page 190 7.6.4.2 Determining the Subcooling Region......Page 191 7.6.5.2 Determining the Critical Conditions......Page 193 7.6.5.3 Determining the Mass Flux......Page 194 7.6.5.4 Determination of the Required Areas of the SRV......Page 196 7.6.5.5 Determination of Omega 9......Page 198 8. Noise......Page 202 8.1 Risk of Damage to Hearing......Page 207 8.3 Noise from the SRV, Open Vent and Associated Pipe......Page 212 8.4 Noise Calculations......Page 213 8.5 Conclusions......Page 216 9.1 Seat Tightness......Page 219 9.3 Service Temperature......Page 220 9.5 Backpressure......Page 221 9.7 Two-Phase Flow......Page 224 9.9 Reciprocating Compressors......Page 225 9.10 Liquid......Page 226 9.11 Materials......Page 227 10.1.1 Introduction......Page 229 10.1.2 Maintenance Cost......Page 230 10.1.3.1 Rationale......Page 232 10.1.3.3 Inspection Grade Awards Guidelines......Page 233 10.1.3.4 Inspection Requirements and Reporting......Page 235 10.2 Transportation and Dirt......Page 236 10.2.1 Preinstallation Handling and Testing of Pressure Relief Valves......Page 237 10.3 Troubleshooting SRVs......Page 238 10.3.1 Seat Leakage......Page 239 10.3.2 Chatter......Page 241 10.3.3 Premature Opening......Page 243 10.3.7 Bellows Failure......Page 244 10.3.7.1 Mechanical Failure......Page 245 10.3.7.3 Corrosion Failure......Page 246 10.3.8 Springs......Page 247 10.4 Testing......Page 248 10.4.1 In situ Testing of Spring-Operated SRVs......Page 250 10.4.2 In situ Testing of Pilot-Operated SVs......Page 252 10.5 Maintenance Procedure......Page 253 11. Cryogenic Applications......Page 261 11.2 Process......Page 263 11.2.2 Balanced Bellows Spring-Loaded SRVs on Cryogenic Service......Page 264 11.2.3.1 Considerations for POSRVs on LNG and Cryogenic Applications......Page 266 11.3.1 The 'Submerged Test'......Page 268 11.3.2 The 'Boil-off Test'......Page 269 11.4 Conclusion......Page 270 12.1 Summary of Overall Requirements......Page 271 12.2 Materials......Page 272 12.3 Design......Page 273 12.4 Identification......Page 274 12.6 Preparation for Shipment......Page 275 13. Non-Conformance of Existing Pressure Relief Systems......Page 277 13.1.1 External Fire (33%)......Page 281 13.1.5 Tube Rupture (7%)......Page 282 13.2.1 External Fire (38%)......Page 283 13.2.6 Others (9%)......Page 284 13.3.1 Outlet Pressure Drop Too High (43%)......Page 285 13.3.2 Inlet Pressure Drop Too High (36%)......Page 286 13.3.5 Others (4%)......Page 287 13.4 What Can Go Wrong in the Process Scenarios......Page 288 A.1 Gas Flows......Page 292 A.3 Subcritical Flows......Page 294 A.4 Liquid Flows......Page 295 B. Backpressure Correction Factors......Page 296 C. Compressibility Factors......Page 298 D. Ratio of Specific Heats k and Coefficient C......Page 299 E. Capacity Correction Factor for Superheat, K_sh......Page 300 F. Capacity Correction Factor for High Pressure Steam, K_n......Page 301 G. Capacity Correction Factor for Viscosity, K_v......Page 302 H. Allowable Operating, Working, Relief, Set and Blowdown Pressures......Page 304 I. Codes and Standards Organizations......Page 305 J. API 526 Data Sheet Recommendation......Page 307 K. Generic Sizing Program......Page 309 L. Worldwide Codes and Standards (Most Common)......Page 310 M. Properties of Common Gases......Page 311 N. Relevant Conversion Factors......Page 313 77122_fr......Page 317 B......Page 319 C......Page 320 D......Page 321 G......Page 322 L......Page 323 N......Page 324 O......Page 325 P......Page 326 R......Page 327 S......Page 328 T......Page 329 W......Page 330 The Safety Valve Handbook is a professional reference for design, process, instrumentation, plant and maintenance engineers who work with fluid flow and transportation systems in the process industries, which covers the chemical, oil and gas, water, paper and pulp, food and bio products and energy sectors. It meets the need of engineers who have responsibilities for specifying, installing, inspecting or maintaining safety valves and flow control systems. It will also be an important reference for process safety and loss prevention engineers, environmental engineers, and plant and process designers who need to understand the operation of safety valves in a wider equipment or plant design context. No other publication is dedicated to safety valves or to the extensive codes and standards that govern their installation and use. A single source means users save time in searching for specific information about safety valves The Safety Valve Handbook contains all of the vital technical and standards information relating to safety valves used in the process industry for positive pressure applications. Explains technical issues of safety valve operation in detail, including identification of benefits and pitfalls of current valve technologies Enables informed and creative decision making in the selection and use of safety valves The Handbook is unique in addressing both US and European codes:- covers all devices subject to the ASME VIII and European PED (pressure equipment directive) codes;- covers the safety valve recommendations of the API (American Petroleum Institute);- covers the safety valve recommendations of the European Normalisation Committees;- covers the latest NACE and ATEX codes;- enables readers to interpret and understand codes in practice Extensive and detailed illustrations and graphics provide clear guidance and explanation of technical material, in order to help users of a wide range of experience and background (as those in this field tend to have) to understand these devices and their applications Covers calculating valves for two-phase flow according to the new Omega 9 method and highlights the safety difference between this and the traditional method Covers selection and new testing method for cryogenic applications (LNG) for which there are currently no codes available and which is a booming industry worldwide Provides full explanation of the principles of different valve types available on the market, providing a selection guide for safety of the process and economic cost Extensive glossary and terminology to aid readers'ability to understand documentation, literature, maintenance and operating manuals Accompanying website provides an online valve selection and codes guide.