1 Quantifying the hydrogen embrittlement of pipeline steels for safety considerations ( #186) L. Briottet, I. Moro, P. Lemoine CEA,LITEN, DTBH/LCTA, F Grenoble, France LITEN/DTBH/LCTASept. 14, 2011 International Conference on Hydrogen Safety "Enabling Progress and Opportunities" September 12-14, 2011 San Francisco, California-USA

LITEN/DTBH/LCTAICHS 2011Sept. 14, Scope Development of a hydrogen pipeline delivery infrastructure  High initial capital cost No recognized international methods to choose materials - specific application - very different testing conditions - materials susceptibility to HE - improving safety coefficients for component design How to quantify Hydrogen Embrittlement under hydrogen gas pressure? French National Research Agency projects – CATHY-GDF, CESTAR

LITEN/DTBH/LCTAICHS 2011Sept. 14, Approach API grade X80 ferrito-pearlitic steel Various mechanical tests under hydrogen high pressure Many ways to quantify hydrogen embrittlement Comparison of some possible embrittlement indices Discussion

LITEN/DTBH/LCTAICHS 2011Sept. 14, Monotonic loading Up to 35 MPa H 2 Tensile test Disk pressure Test (ISO method A) P He / P H2

LITEN/DTBH/LCTAICHS 2011Sept. 14, Cyclic loading Fatigue Crack Growth Fracture mechanics / Dynamic loading Up to 35 MPa H 2 Compact Tensile Monotonic loading Fracture toughness Single Edge Notch Tensile specimen Initial crack

LITEN/DTBH/LCTAICHS 2011Sept. 14, AL Air Inert gas Loading conditions H2H2 30 MPa H 2 Fracture mechanics / Static loading Wedge Opening Load - Static loading (ISO method C)

LITEN/DTBH/LCTAICHS 2011Sept. 14, High-strength steel grade API X80 CMnSiPSFe <0.003Bal. Ferrite + pearlite Pearlite alignments  mm x e12.7 mm w%

LITEN/DTBH/LCTAICHS 2011Sept. 14, Monotonic loading – Main results No influence on  0.2 or UTS  Strain rate   ductility  P (up to ~10 MPa)   ductility Tensile tests Efficient empirical criteria for seamless bottles Not based on an understanding of the HE mechanisms  How to use it for other applications? P He / P H2 ~ 2 Disk pressure tests

LITEN/DTBH/LCTAICHS 2011Sept. 14, Fracture mechanics – Main results Several K Precracking in air or H 2 No crack propagation after 1000 hr 220 kJ/m² (N 2 )  15 kJ/m² (H 2 ) WOL - Static loading – 30 MPa Toughness – Monotonic loading - 30 MPa

LITEN/DTBH/LCTAICHS 2011Sept. 14, Fracture mechanics – Main results Fatigue Crack growth – Cyclic loading - 30 MPa FCG x 10 Significant effect even at low P H Hz air FCG

LITEN/DTBH/LCTAICHS 2011Sept. 14, Some possible HE indices definition 100 % maximum effect Tensile elongation Toughness FCG rate Disk pressure test WOL crack length 0 % no effect And more ……

LITEN/DTBH/LCTAICHS 2011Sept. 14, Damage analysis Tensile test Quasi-cleavage External cracks Same a o Same final COD Toughness test H 2 inlet Quasi-cleavageDuctile Disk pressure test H 2 inlet

LITEN/DTBH/LCTAICHS 2011Sept. 14, Fracture mechanicsContinuum mechanics CyclicMonotonic loading Static loading Embrittlement index  Necessary to provide guidelines to select the appropriate test X80 HS steel

LITEN/DTBH/LCTAICHS 2011Sept. 14, Tensile tests with atmosphere switches Tensile tests under H 2 pressure : HE not due to trapped H in the bulk HE caused by surface / sub surface H populations  Are the same H populations involved depending on the loading conditions ?  Tests on pre-charged specimens or under cathodic charging ? HE mechanisms ? High kinetic for HE reversibility HE occurrence

LITEN/DTBH/LCTAICHS 2011Sept. 14, Developing a test facility for full scale pipeline section up to 30 MPa H 2 pressure within the French ANR CATHY-GDF and CESTAR projects Ensure transferability from lab-scale tests to structure Transferability  Numerical simulations + experimental validations CNRS-GDF SUEZ Defects - Fatigue crack propagation - Welds Up to 1 m diameter

LITEN/DTBH/LCTAICHS 2011Sept. 14, Conclusions Many ways to quantify HE under hydrogen pressure HE susceptibility measures strongly depend on : Testing environment (in-situ, P, …) Presence of defects (crack, weld) Static / dynamic loading Monotonic / cyclic loading Difficult to fit lab-scale tests with in-service conditions Improve knowledge on HE mechanisms to define the appropriate tests to select materials  Group tests with the same HE features  Propose appropriate methods for a given application  Input for international codes and rules adapted to future hydrogen infrastructures applications

LITEN/DTBH/LCTAICHS 2011Sept. 14, Thank you for your attention CEA / LITEN