Addressing Hydrogen Embrittlement in the SAE J2579 Fuel Cell Vehicle Tank Standard

1. Addressing Hydrogen Embrittlement in the SAE J2579 Fuel Cell Vehicle Tank Standard Brian Somerday Sandia National Laboratories Livermore, CA, USA Christine Sloane SloaneSolutions, 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-AC04-94AL85000

2. SAE J2579 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 H2 • All containment vessel designs include metal components (e.g., composite vessels have boss and liner)

3. Safety qualification of vessel must consider hydrogen embrittlement of metal components Hydrogen embrittlement accelerates fatigue cracking Dp H2 H2 H2 a H2 H2 H2 H2 a crack in H2 crack in N2 Nf = Ninitiation + Ngrowth Number of pressure cycles, N Barthélémy, 1st ESSHS, 2006

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

5. Vessel safety qualification in SAE J2579 is based on performance testing • These performance tests do not evaluate “durability” under H2 gas pressure cycling, i.e., hydrogen embrittlement Pneumatic test (H2) Hydraulic test Durability Performance Verification Test

6. Logic flow for addressing hydrogen embrittlement through performance testing in SAE J2579 • Recent activity focused on Appendix C.14 and Appendix C.15 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J2579 Appendix B.2.3) Metals in vessel meet acceptance criteria from materials testing in H2? (SAE J2579 Appendix C.15) NO NO YES YES Vessel qualified using existing expected-service (pneumatic) and durability (hydraulic) performance tests (SAE J2579 Section 5.2.2) Vessel qualified using existing performance tests (SAE J2579 Section 5.2.2) AND new (more extreme) H2 gas cycling test (SAE J2579 Appendix C.14)

7. Logic flow for addressing hydrogen embrittlement through performance testing in SAE J2579 • Tests in Appendix C.15 determine whether material has unrestricted (i.e., not design specific) hydrogen compatibility Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J2579 Appendix B.2.3) Metals in vessel meet acceptance criteria from materials testing in H2? (SAE J2579 Appendix C.15) NO NO YES YES Vessel qualified using existing expected-service (pneumatic) and durability (hydraulic) performance tests (SAE J2579 Section 5.2.2) Vessel qualified using existing performance tests (SAE J2579 Section 5.2.2) AND new (more extreme) H2 gas cycling test (SAE J2579 Appendix C.14)

8. Appendix C.15 materials test:slow strain rate tensile test • Issues addressed: • Acceptance criterion established as RAH2/RAair > 0.7 • Test conducted in H2 gas or with “precharged” H • Test temperature(s) H H2 H2 H OR H H2 H2 H H H2 H2 H RA

9. Appendix C.15 materials test:fatigue crack initiation test • Issues addressed: • R ratio, i.e., ratio of Smin to Smax • Stress-cycle frequency (f) • Test temperature(s) • Acceptance criterion, e.g., Nf(H2)/Nf(air) ~ 1 stress (S) H2 air cycles to failure (Nf ~ Ninitiation)

10. Appendix C.15 materials test:“long crack” growth test • Issues addressed: • Load-cycle frequency • Test temperature(s) • Acceptance criterion? da/dN H2 air DK

11. Load-cycle frequency must be specified for fatigue tests conducted in H2 gas Magnitude of accelerated fatigue cracking in H2 gas depends on load-cycle frequency A.H. Priest, British Steel, 1983

12. Logic flow for addressing hydrogen embrittlement through performance testing in SAE J2579 • Performance test in Appendix C.14 evaluates design-specific hydrogen compatibility Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J2579 Appendix B.2.3) Metals in vessel meet acceptance criteria from materials testing in H2? (SAE J2579 Appendix C.15) NO NO YES YES Vessel qualified using existing expected-service (pneumatic) and durability (hydraulic) performance tests (SAE J2579 Section 5.2.2) Vessel qualified using existing performance tests (SAE J2579 Section 5.2.2) AND new (more extreme) H2 gas cycling test (SAE J2579 Appendix C.14)

13. Dp H2 H2 filler material H2 H2 H2 H2 H2 Performance test in Appendix C.14 intended to account for H2-accelerated fatigue cracking • Issues addressed: • Pressure-cycle profile • Test temperature • Number of cycles a H2 pressure rise time > 5 min hold time > 2 min 125% NWP 2 MPa Number of pressure cycles, N

14. SAE working group on hydrogen embrittlement represents international effort • SAE J2579 Appendix B.2.3 • SAE J2579 Appendix C.15 • SAE J2579 Appendix C.14 Europe Adam Opel BMW Robert Bosch Linde Japan JARI AIST/HYDROGENIUS USA GM Sandia National Laboratories

15. Summary • Vehicle tank standard SAE J2579 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 J2579 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