NSS 1740.16 National Aeronautics and Space Administration SAFETY STANDARD FOR HYDROGEN AND HYDROGEN SYSTEMS Guidelines for Hydrogen System Design, Materials Selection, Operations, Storage, and Transportation Office of Safety and Mission Assurance Washington, DC 20546 PREFACE This safety standard establishes a uniform Agency process for hydrogen system design, materials selection, operation, storage, and transportation. This standard contains minimum guidelines applicable to NASA Headquarters and all NASA Field Centers. Centers are encouraged to assess their individual programs and develop additional requirements as needed. “Shalls” and “musts” denote requirements mandated in other documents and in widespread use in the aerospace industry. This standard is issued in loose-leaf form and will be revised by change pages. Comments and questions concerning the contents of this publication should be referred to the National Aeronautics and Space Administration Headquarters, Director, Safety and Risk Management Division, Office of the Associate for Safety and Mission Assurance, Washington, DC 20546. Frederick D. Gregory Effective Date: Feb.12, 1997 Associate Administrator for Safety and Mission Assurance i ACKNOWLEDGMENTS The NASA Hydrogen Safety Handbook originally was prepared by Paul M. Ordin, Consulting Engineer, with the support of the Planning Research Corporation. The support of the NASA Hydrogen-Oxygen Safety Standards Review Committee in providing technical monitoring of the standard is acknowledged. The committee included the following members: William J. Brown (Chairman) NASA Lewis Research Center Cleveland, OH Harold Beeson NASA Johnson Space Center White Sands Test Facility Las Cruces, NM Mike Pedley NASA Johnson Space Center Houston, TX Dennis Griffin NASA Marshall Space Flight Center Alabama Coleman J. Bryan NASA Kennedy Space Center Florida Wayne A. Thomas NASA Lewis Research Center Cleveland, OH Wayne R. Frazier NASA Headquarters Washington, DC The special contributions provided by Grace Ordin are noted. Also acknowledged are the contributions provided by Carol A. Vidoli and, particularly, William J. Brown of NASA Lewis Research Center for their aid in reviewing, organizing, and editing this handbook; Fred Edeskuty of Los Alamos National Laboratory for information on slush hydrogen, and William Price of Vitro Corporation for his revision. This revision was prepared and edited by personnel at the NASA Johnson Space Center White Sands Test Facility. This document was extensively reviewed by experts at the various NASA centers, and their comments and suggections were instrumental in making the manual as complete and accurate as possible. The expertise of these professionals in the area of hydrogen system hazards, materials, selection, design, and operation is gratefully acknowledged. iii ABOUT THIS DOCUMENT This document and its companion document, Safety Standard for Oxygen and Oxygen Systems (NSS 1740.15 1996), are identified as Tier 2 Standards and Technical Requirements in the NASA Safety and Documentation Tree (NHB 1700.1 1993). The information presented is intended as a reference to hydrogen design and practice and not as an authorizing document. The words “shall” and “must” are used in this document to indicate a mandatory requirement, and the authority for the requirement is given. The words “should” and “will” are used to indicate a recommendation or that which is advised but not mandatory. The information is arranged in an easy-to-use format. The reader will find the following useful to note: · A numbered outline format is used so information can be readily found and easily cited. · An index is provided in Appendix H to assist the reader in locating information on a particular topic. · Acronyms are defined when introduced, and a tabulation of acronyms used in the document is provided in Appendix F. · The figures and tables referenced in the text are located in the appendices. · All sources are referenced so the user can verify original sources as deemed necessary. References cited in the main body of the text can be found in Chapter 10, and references introduced in an appendix is cited in that appendix. The latest revisions of codes, standards, and NASA directives should be used when those referenced are superseded. · The International System of Units (SI) is used for primary units, and US Customary units are given in parentheses following the SI units. Some of the tables and figures contain only one set of units. v TABLE OF CONTENTS Paragraph Page CHAPTER 1: BASIC HYDROGEN SAFETY GUIDELINES 100 SCOPE 1-1 101 INTRODUCTION 1-1 102 APPLICABLE DOCUMENTS 1-5 103 PERSONNEL TRAINING 1-5 104 USE OF INHERENT SAFETY FEATURES 1-7 105 CONTROLS 1-9 106 FAIL-SAFE DESIGN 1-10 107 SAFETY 1-10 108 WAIVER PROVISIONS 1-11 CHAPTER 2: PROPERTIES AND HAZARDS OF HYDROGEN 200 TYPICAL PROPERTIES 2-1 201 TYPES OF HAZARDS 2-3 202 FLAMMABILITY AND IGNITION OF HYDROGEN 2-14 203 DETONATION 2-24 204 CHARACTERISTIC PROPERTIES OF GH2 2-29 205 CHARACTERISTIC PROPERTIES OF LH2 2-35 206 CHARACTERISTIC PROPERTIES OF SLH2 2-36 CHAPTER 3: MATERIALS FOR HYDROGEN SERVICE 300 CONSIDERATIONS FOR MATERIALS SELECTION 3-1 301 HYDROGEN EMBRITTLEMENT 3-7 302 THERMAL CONSIDERATIONS IN MATERIALS SELECTION 3-11 CHAPTER 4: HYDROGEN FACILITIES 400 SAFETY POLICY 4-1 401 SAFETY REVIEWS 4-2 402 GENERAL FACILITY GUIDELINES 4-6 vii TABLE OF CONTENTS (continued) Paragraph Page 403 BUILDINGS AND TEST CHAMBERS 4-12 404 CONTROL ROOMS 4-18 405 LOCATION AND QUANTITY-DISTANCE GUIDELINES 4-19 406 EXCLUSION AREAS 4-29 407 PROTECTION OF HYDROGEN SYSTEMS AND SURROUNDINGS 4-32 408 FIRE PROTECTION 4-36 409 DOCUMENTATION, TAGGING, AND LABELING OF STORAGE VESSELS, PIPING, AND COMPONENTS 4-39 410 INSTRUMENTATION AND MONITORING 4-42 411 EXAMINATION, INSPECTION, AND RECERTIFICATION 4-46 CHAPTER 5: HYDROGEN STORAGE VESSELS, PIPING, AND COMPONENTS 500 GENERAL REQUIREMENTS 5-1 501 STORAGE VESSELS 5-3 502 PIPING SYSTEMS 5-15 503 COMPONENTS 5-25 504 OVERPRESSURE PROTECTION OF STORAGE VESSELS AND PIPING SYSTEMS 5-43 505 HYDROGEN VENT AND FLARE SYSTEMS 5-49 506 CONTAMINATION 5-55 507 VACUUM SYSTEM 5-60 CHAPTER 6: HYDROGEN AND HYDROGEN FIRE DETECTION 600 HYDROGEN DETECTION 6-1 601 HYDROGEN FIRE DETECTION SYSTEMS 6-9 CHAPTER 7: OPERATING PROCEDURES 700 GENERAL POLICY 7-1 viii TABLE OF CONTENTS (continued) Paragraph Page 701 STORAGE AND TRANSFER PROCEDURES 7-10 CHAPTER 8: TRANSPORTATION 800 GENERAL 8-1 801 TRANSPORT ON PUBLIC THOROUGHFARES 8-3 802 TRANSPORT ON SITE CONTROLLED THOROUGHFARE 8-6 803 TRANSPORTATION EMERGENCIES 8-10 CHAPTER 9: EMERGENCY PROCEDURES 900 GENERAL 9-1 902 TYPES OF EMERGENCIES 9-4 902 ASSISTANCE IN EMERGENCIES 9-10 903 FIRE SUPPRESSION 9-11 904 FIRST-AID PROCEDURES FOR CRYOGENIC-INDUCED INJURIES 9-15 905 SAFEGUARDS FOR ENTERING PERMIT-REQUIRED CONFINED SPACES 9-16 CHAPTER 10: REFERENCES APPENDIX A: TABLES AND FIGURES A-1 APPENDIX B: ASSESSMENT EXAMPLES B-1 APPENDIX C: SCALING LAWS, EXPLOSIONS, BLAST EFFECTS, AND FRAGMENTATION C-1 APPENDIX D: CODES, STANDARDS, AND NASA DIRECTIVES D-1 APPENDIX E: RELIEF DEVICES E-1 APPENDIX F: ABBREVIATIONS AND ACRONYMS F-1 APPENDIX G: GLOSSARY G-1 APPENDIX H: INDEX H-1 ix LIST OF FIGURES Figures Page A1.1 Equilibrium Percentage of Para-hydrogen vs. Temperature A-3 A1.2 Enthalpy of Normal Hydrogen Conversion A-4 A1.3 Vapor Pressure of Liquefied Para-hydrogen (TP to NBP) A-5 A1.4 Vapor Pressure of LH2 (NBP to CP) A-6 A1.5 Vapor of Normal and Para-hydrogen Below the Triple Point A-7 A1.6 Comparison of densities and bulk Fluid Heat Capacities for Slush, Triple-Point liquid, and NBP Liquid Para-hydrogen A-8 A1.7 Proposed Phase Diagram (P-T) for Solid Hydrogen at Various Otho-hydrogen Mole Fractions A-9 A1.8 Proposed Phase Diagram (V-T Plane) for Solid Normal Hydrogen A-10 A1.9 Specific Heat (Heat Capacity) of Saturated Solid Hydrogen A-11 A1.10 Melting Line from Triple Point to Critical Point Pressure for Para-hydrogen A-12 A2.1 Flammability Limits at a Pressure of 101.3 kPa (14.7 psia) and a Temperature of 298 K (77 °F) A-37 A2.2 Effects of N2, He, CO2, and H2O Diluents on Flammability Limits of Hydrogen in Air at 101.3 kPa (14.7 psia) A-38 A2.3 Effects of Halocarbon Inhibitors on Flammability Limits of Hydrogen-Oxygen Mixtures at a Pressures of 101.3 kPa (14.7 psia) and a Temperature of 298 K (77 °F) A-39 A2.4 Distance for Fireball Radiation Flux Induced Third Degree Burns per Amount of Fuel Burned at a Thermal Radiation Intensity of 134 kJ/m2 (11.8 Btu/ft2) A-40 A2.5 Radiation Intensity as a Function of Exposure Time or Escape Time A-41 x LIST OF FIGURES (continued) Figures Page A2.6 Variation in Distance from a Hydrogen Fire for a Thermal Radiation Exposure of 2 cal/cm2 for an Exposure Duration of 10 s A-42 A2.7 Minimum Dimensions of GH2-Air Mixtures for Detonation at 101.3 kPa (14.7 psia) and 298 K (77 °F) A-43 A2.8 Detonation Cell Widths for Hydrogen-Air Mixtures at 101.3 kPa (14.7 psia) A-44 A2.9 Minimum Initiation Energies for Direct Detonation of Hydrogen-Air Mixtures A-45 A4.1 Flame Dip as a Function of Stack Diameter an Hydrogen Flow A-65 A4.2 Blowout and Stable Flame Region A-66 A4.3 Flame Shape in Crosswinds A-67 A4.4 Minimum Flow Rate for Non-Stratified, Two Phase Hydrogen and Nitrogen Flow for Pipeline Fluid Qualities Below 95% and 98% A-68 A4.5 Liquid Hydrogen Flow Rate Limits to Avoid Excessive Cooldown Stresses in Thick-wall Piping Sections Such as Flanges for 304 SS and 6061 Al A-69 A4.6 Liquid Nitrogen Flow Rate Limits to Avoid Excessive Cooldown Stresses in Thick-wall Piping Sections Such as Flanges for 304 SS and