International Conference on Hydrogen Safety "Enabling Progress and Opportunities" September 12 -14, 2011 San Francisco, California-USA Quantifying the hydrogen embrittlement of pipeline steels for safety considerations (#186) L. Briottet, I. Moro, P. Lemoine CEA, LITEN, DTBH/LCTA, F-38054 Grenoble, France LITEN/DTBH/LCTA Sept. 14, 2011 1
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/LCTA ICHS 2011 Sept. 14, 2011 2
Approach • API grade X 80 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/LCTA ICHS 2011 Sept. 14, 2011 3
Monotonic loading Tensile test Up to 35 MPa H 2 Disk pressure Test (ISO 11114 -4 method A) PHe / PH 2 LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 4
Fracture mechanics / Dynamic loading Compact Tensile Single Edge Notch Tensile specimen Initial crack Monotonic loading Fracture toughness Cyclic loading Fatigue Crack Growth Up to 35 MPa H 2 LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 5
Fracture mechanics / Static loading Wedge Opening Load - Static loading (ISO 11114 -4 method C) Loading conditions Air Inert gas H 2 AL 30 MPa H 2 LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 6
High-strength steel grade API X 80 F 914. 4 mm x e 12. 7 mm w% C Mn Si P S Fe 0. 075 1. 86 0. 35 0. 015 <0. 003 Bal. Pearlite alignments Ferrite + pearlite LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 7
Monotonic loading – Main results Tensile tests • No influence on s 0. 2 or UTS • Strain rate ductility • P (up to ~10 MPa) ductility Disk pressure tests PHe / PH 2 ~ 2 LITEN/DTBH/LCTA • Efficient empirical criteria for seamless bottles • Not based on an understanding of the HE mechanisms How to use it for other applications? ICHS 2011 Sept. 14, 2011 8
Fracture mechanics – Main results WOL - Static loading – 30 MPa • Several K • Precracking in air or H 2 • No crack propagation after 1000 hr Toughness – Monotonic loading - 30 MPa • 220 k. J/m² (N 2) 15 k. J/m² (H 2) LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 9
Fracture mechanics – Main results Fatigue Crack growth – Cyclic loading - 30 MPa H 2 - 0. 1 Hz FCG air • FCG x 10 • Significant effect even at low P LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 10
Some possible HE indices definition 0% no effect 100 % maximum effect Tensile elongation Toughness FCG rate Disk pressure test WOL crack length And more …… LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 11
Damage analysis Tensile test Disk pressure test Quasi-cleavage External cracks Toughness test Same ao Same final COD LITEN/DTBH/LCTA Ductile H 2 inlet ICHS 2011 Sept. 14, 2011 12
Embrittlement index X 80 HS steel Fracture mechanics Continuum mechanics Static loading Cyclic Monotonic loading Necessary to provide guidelines to select the appropriate test LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 13
HE mechanisms ? Tensile tests with atmosphere switches High kinetic for • HE reversibility • HE occurrence Tensile tests under H 2 pressure : HE not due to trapped H in the bulk HE caused by surface / sub surface H populations è Are the same H populations involved depending on the loading conditions ? èTests on pre-charged specimens or under cathodic charging ? LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 14
Ensure transferability from lab-scale tests to structure Transferability Numerical simulations + experimental validations 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 CNRS-GDF SUEZ Up to 1 m diameter Defects - Fatigue crack propagation - Welds LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 15
Conclusions • Many ways to quantify HE under hydrogen pressure • HE susceptibility measures strongly depend on : ü Testing environment (in-situ, P, …) ü Presence of defects (crack, weld) ü Static / dynamic loading ü Monotonic / cyclic loading • Difficult to fit lab-scale tests with in-service conditions ü Improve knowledge on HE mechanisms to define the appropriate tests to select materials Ê Group tests with the same HE features Ê Propose appropriate methods for a given application Input for international codes and rules adapted to future hydrogen infrastructures applications LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 16
Thank you for your attention CEA / LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011 17
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