Addressing Hydrogen Embrittlement in the SAE J 2579

Addressing Hydrogen Embrittlement in the SAE J 2579 Fuel Cell Vehicle Tank Standard Brian Somerday Sandia National Laboratories Livermore, CA, USA Christine Sloane. Solutions, LLC Kewadin, MI, USA International Conference on Hydrogen Safety ICHS 2011 San Francisco, CA, USA September 14, 2011 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC 04 -94 AL 85000

SAE J 2579 focuses on safety qualification of vessel in Compressed Hydrogen Storage System of FCVs • Compressed Hydrogen Storage System (CHSS) boundary defined by interfaces that isolate stored high pressure H 2 • All containment vessel designs include metal components (e. g. , composite vessels have boss and liner)

Safety qualification of vessel must consider hydrogen embrittlement of metal components Hydrogen embrittlement accelerates fatigue cracking a crack in H 2 crack in N 2 Nf = Ninitiation + Ngrowth Number of pressure cycles, N Dp H 2 H 2 H 2 a H 2 Barthélémy, 1 st ESSHS, 2006

Vessel safety qualification typically conducted by either engineering analysis or performance testing stress analysis: DK = Dp[f(a, t , Ro, Ri)] crack growth law: da/d. N = C(DK)m Dp a t Ro engineering analysis Ri performance testing pressure Dp Nf Number of pressure cycles, N • Design qualification in SAE standards based on performance testing

Vessel safety qualification in SAE J 2579 is based on performance testing Pneumatic test (H 2) Hydraulic test Durability Performance Verification Test • These performance tests do not evaluate “durability” under H 2 gas pressure cycling, i. e. , hydrogen embrittlement

Logic flow for addressing hydrogen embrittlement through performance testing in SAE J 2579 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J 2579 Appendix B. 2. 3) NO YES Vessel qualified using existing expectedservice (pneumatic) and durability (hydraulic) performance tests (SAE J 2579 Section 5. 2. 2) YES Metals in vessel meet acceptance criteria from materials testing in H 2? (SAE J 2579 Appendix C. 15) NO Vessel qualified using existing performance tests (SAE J 2579 Section 5. 2. 2) AND new (more extreme) H 2 gas cycling test (SAE J 2579 Appendix C. 14) • Recent activity focused on Appendix C. 14 and Appendix C. 15

Logic flow for addressing hydrogen embrittlement through performance testing in SAE J 2579 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J 2579 Appendix B. 2. 3) NO YES Vessel qualified using existing expectedservice (pneumatic) and durability (hydraulic) performance tests (SAE J 2579 Section 5. 2. 2) YES Metals in vessel meet acceptance criteria from materials testing in H 2? (SAE J 2579 Appendix C. 15) NO Vessel qualified using existing performance tests (SAE J 2579 Section 5. 2. 2) AND new (more extreme) H 2 gas cycling test (SAE J 2579 Appendix C. 14) • Tests in Appendix C. 15 determine whether material has unrestricted (i. e. , not design specific) hydrogen compatibility

Appendix C. 15 materials test: slow strain rate tensile test H 2 H 2 H 2 OR HH H H • Issues addressed: – Acceptance criterion established as RAH 2/RAair > 0. 7 RA – Test conducted in H 2 gas or with “precharged” H – Test temperature(s)

Appendix C. 15 materials test: fatigue crack initiation test • Issues addressed: – R ratio, i. e. , ratio of Smin to Smax – Stress-cycle frequency (f) stress (S) – Test temperature(s) H 2 – Acceptance criterion, e. g. , Nf(H 2)/Nf(air) ~ 1 air cycles to failure (Nf ~ Ninitiation)

Appendix C. 15 materials test: “long crack” growth test • Issues addressed: – Load-cycle frequency – Test temperature(s) da/d. N H 2 air DK – Acceptance criterion?

Load-cycle frequency must be specified for fatigue tests conducted in H 2 gas A. H. Priest, British Steel, 1983 Magnitude of accelerated fatigue cracking in H 2 gas depends on load-cycle frequency

Logic flow for addressing hydrogen embrittlement through performance testing in SAE J 2579 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J 2579 Appendix B. 2. 3) NO YES Vessel qualified using existing expectedservice (pneumatic) and durability (hydraulic) performance tests (SAE J 2579 Section 5. 2. 2) YES Metals in vessel meet acceptance criteria from materials testing in H 2? (SAE J 2579 Appendix C. 15) NO Vessel qualified using existing performance tests (SAE J 2579 Section 5. 2. 2) AND new (more extreme) H 2 gas cycling test (SAE J 2579 Appendix C. 14) • Performance test in Appendix C. 14 evaluates design-specific hydrogen compatibility

Performance test in Appendix C. 14 intended to account for H 2 -accelerated fatigue cracking Dp H 2 filler material H 2 a H 2 H 2 • Issues addressed: – Pressure-cycle profile – Test temperature H 2 pressure rise time > 5 min hold time > 2 min 125% NWP 2 MPa Number of pressure cycles, N – Number of cycles

SAE working group on hydrogen embrittlement represents international effort Japan JARI AIST/HYDROGENIUS • SAE J 2579 Appendix B. 2. 3 • SAE J 2579 Appendix C. 15 • SAE J 2579 Appendix C. 14 USA GM Sandia National Laboratories Europe Adam Opel BMW Robert Bosch Linde

Summary • Vehicle tank standard SAE J 2579 describes safety qualification for Compressed Hydrogen Storage System • Safety qualification based on performance testing – Hydraulic long-term durability test does not account for hydrogen embrittlement • New tests developed for SAE J 2579 to evaluate hydrogen compatibility of vessel designs – Material-level testing determines whether material has unrestricted (i. e. , not design specific) hydrogen compatibility – Component-level testing evaluates design-specific hydrogen compatibility