INTERNATIONAL CONFERENCE ON HYDROGEN SAFETY September 8-10, 2005 – PISE - ITALY

1. INTERNATIONAL CONFERENCEON HYDROGEN SAFETYSeptember 8-10, 2005 – PISE - ITALY 230003_Barthélémy, H. and Allidières, L.,Gaseous hydrogen Refuelling Stations : Selection of Materials for Hydrogen HighPressure Fuelling Connectors

2. EXAMPLE OF FUELLING STATION FOR HYDROGEN VEHICLES

3. HYDROGEN EMBRITTLEMENT • Internal • External

4. HYDROGEN EMBRITTLEMENT 1 - COMBINED STATE : Hydrogen attack 2 - IN METALLIC SOLUTION : Gaseous hydrogen embrittlement

5. T  200°C Hydrogen embrittlement T  200°C Hydrogen attack HYDROGEN EMBRITTLEMENT • Important parameter : THE TEMPERATURE

6. GASEOUS HYDROGEN EMBRITTLEMENT(G H E) • Reversible phenomena • Transport of H2 by the dislocations H2 TRAPS – CRITICAL CONCENTRATION AND DECOHESION ENERGY

7. (GHE) – DIFFERENT TYPES OF TEST METHODS (1) • Static (delayed rupture test) • Dynamic Constant strain rate Fatigue

8. (GHE) – DIFFERENT TYPES OF TEST METHODS (2) • Fracture mechanic (CT, WOL, …) • Tensile test • Disk test • Other mechanical test (semi-finished products) • Test methods to evaluate hydrogen permeation and trapping

9. (GHE) – DIFFERENT TYPES OF TEST METHODS (3) Specimens for compact tension test

10. (GHE) – DIFFERENT TYPES OF TEST METHODS (4) • Can also be performed with specimens cathodically charged and with tensile specimens in a high pressure cell Tensile specimens for hydrogen tests (hollow tensile specimen)

11. (GHE) – DIFFERENT TYPES OF TEST METHODS (5) • I = (% RAN - % RAH) / % RAN • I = Embrittlement index • RAN = Reduction of area without H2 • RAH = Reduction of area without H2

12. (GHE) – DIFFERENT TYPES OF TEST METHODS (6) • Upper flange • Bolt Hole • High-strength steel ring • Disk • O-ring • Lower flange • Gas inlet Disk testing method – Rupture cell for embedded disk-specimen

13. EXAMPLE OF A DISK RUPTURE TEST CURVE

14. DISK TEST – EMBRITTLEMENT INDEX

15. I m (MPa) DISK TEST – EMBRITTLEMENT INDEX Thin wall cylinders Thick wall cylinders (Good H2 behaviour) Thin wall cylinders Thick wall cylinders (Bad H2 behaviour) Hydrogen embrittlement indexes (I) of reference materials versus maximum wall stresses (m) of the corresponding pressure vessels

16. DISK TEST – EMBRITTLEMENT INDEX Fatigue test - Principle

17. DISK TEST – EMBRITTLEMENT INDEX Fatigue test - Pressure cycle

18. nN2 nH2 FATIGUE TESTS, VERSUS  P CURVES 6 Cr - Mo STEEL Pure H 2 5 H + 300 ppm O 2 2 F 0,07 Hertz 4 3 2 1 Delta P (MPa) 0 4 5 6 7 8 9 10 11 12 13

19. Fatigue test Principle to detect fatigue crack initiation

20. TESTS CHARACTERISTICSType of hydrogen embrittlement and transport mode

21. TESTS CHARACTERISTICSPractical point of view

22. TESTS CHARACTERISTICSType of hydrogen embrittlement and transport mode

23. TEST RESULTS

24. EFFECT OF STEEL STABILITY () ON THE EMBRITTLEMENT INDEX (E.I.)

25. EFFECT OF MARTENSITE FORMED AT LOW TEMPERATURE AND CHEMICAL COMPOSITION

26. TEST RESULTS FOR A 1.4057 (x 7 CrNi 16-2) STEEL (HV ~ 500 HV)

27. SELECTION OF MATERIALS FOR FUELLING CONNECTORS • Hydrogen compatible materials for parts exposed to high pressure hydrogen • Non hydrogen compatible materials only for : • Material not exposed to hydrogen • Material used at a low enough stress • If a risk analysis shows that the failure has no consequence on the safe use • If the connector is only used for a short period (to be checked by fatigue test)

28. CONCLUSION The fuelling connector is a critical part for the dispensing line This equipment is exposed during service to very severe conditions We have indicated how to select the right materials (test methods and design considerations)