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 SAE J2579 focuses on safety qualification of vessel in Compressed Hydrogen Storage System of FCVs Receptacle with check Excess flow Fill Check Valve Full System Isolation High Pressure Regulator Low Pressure Regulator Service Defuel Shufoff Container Isolation Valve PRV PRV PRD vent Containment Vessel Hydrogen Fuel Handling System Compressed Hydrogen Storage System • 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) Safety qualification of vessel must consider hydrogen embrittlement of metal components Hydrogen embrittlement accelerates fatigue cracking a crack in H2 crack in N2 Nf = Ninitiation + Ngrowth Number of pressure cycles, N Dp H2 H2 H2 H2 H2 H2 a H2 Barthélémy, 1st 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/dN = C(DK)m Dp engineering analysis a t Ri Ro performance testing pressure Dp Nf Number of pressure cycles, N • Design qualification in SAE standards based on performance testing Vessel safety qualification in SAE J2579 is based on performance testing Pneumatic test (H2) Hydraulic test Expected-Service Performance Verification Test Durability Performance Verification Test BP0 <20% 180%NWP a 5% cy +50C 5% cy -40C 40%cy 15-25C +55oC > 30 hrs b Leak / Permeation > 30 hrs 5% cy -40Ca 5% cy +50Cb 40%cy 15-25Cc +55oC Leak / Permeation Proof Pressure 150% NWP 500 cy = light duty 1000 cy = heavy duty a Fuel/defuel cycles @-40oC with initial system equilibration @ -40oC, 5 cycles with +20oC fuel; 5 cycles with <-35oC fuel b Fuel/defuel cycles @+50oC with initial system equilibration @+50oC, 5 cycles with <-35oC fuel c Fuel/defuel cycles @15-25oC with service (maintenance) defuel rate, 50 cycles 150% NWP 125%NWP 80%NWP Chemicals Drop time b c Damage 125%NWP 115%NWP 80%NWP chemical exposure Pressure  Pressure  180%NWP a burst Burst Proof Pressure BP0 <20% 48 hr time N cycles 15C-25C N cycles •3500 cycles passenger light-duty • 7000 cycles commercial, heavy-duty M cycles • 1000 cycles passenger light-duty • 2000 cycles commercial, heavy-duty 10 cycles 15-25oC 1000 hr +85oC M cycles +85oC, 95%RH M cycles -40oC Residual Strength • These performance tests do not evaluate “durability” under H2 gas pressure cycling, i.e., hydrogen embrittlement Logic flow for addressing hydrogen embrittlement through performance testing in SAE J2579 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J2579 Appendix B.2.3) NO YES Vessel qualified using existing expectedservice (pneumatic) and durability (hydraulic) performance tests (SAE J2579 Section 5.2.2) YES Metals in vessel meet acceptance criteria from materials testing in H2? (SAE J2579 Appendix C.15) NO 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) • Recent activity focused on Appendix C.14 and Appendix C.15 Logic flow for addressing hydrogen embrittlement through performance testing in SAE J2579 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J2579 Appendix B.2.3) NO YES Vessel qualified using existing expectedservice (pneumatic) and durability (hydraulic) performance tests (SAE J2579 Section 5.2.2) YES Metals in vessel meet acceptance criteria from materials testing in H2? (SAE J2579 Appendix C.15) NO 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) • 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 H2 H2 H2 H2 H2 H2 OR HH H H H H • Issues addressed: – Acceptance criterion established as RAH2/RAair > 0.7 RA – Test conducted in H2 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) H2 – Acceptance criterion, e.g., Nf(H2)/Nf(air) ~ 1 air cycles to failure (Nf ~ Ninitiation) Appendix C.15 materials test: “long crack” growth test load H2 H2 H2 H2 H 2 H2 H H H H2 • Issues addressed: – Load-cycle frequency a – Test temperature(s) da/dN H2 air DK – Acceptance criterion? Load-cycle frequency must be specified for fatigue tests conducted in H2 gas A.H. Priest, British Steel, 1983 Magnitude of accelerated fatigue cracking in H2 gas depends on load-cycle frequency Logic flow for addressing hydrogen embrittlement through performance testing in SAE J2579 Metals in vessel are 6061 Al or high-nickel 316 stainless steel? (SAE J2579 Appendix B.2.3) NO YES Vessel qualified using existing expectedservice (pneumatic) and durability (hydraulic) performance tests (SAE J2579 Section 5.2.2) YES Metals in vessel meet acceptance criteria from materials testing in H2? (SAE J2579 Appendix C.15) NO 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) • Performance test in Appendix C.14 evaluates design-specific hydrogen compatibility Performance test in Appendix C.14 intended to account for H2-accelerated fatigue cracking Dp H2 filler material H2 H2 a H2 H2 H2 H2 • Issues addressed: – Pressure-cycle profile – Test temperature H2 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 J2579 Appendix B.2.3 • SAE J2579 Appendix C.15 • SAE J2579 Appendix C.14 USA GM Sandia National Laboratories Europe Adam Opel BMW Robert Bosch Linde 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