Quantifying the hydrogen embrittlement of pipeline steels for safety considerations ( #186)

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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

International Conference on Hydrogen Safety

"Enabling Progress and Opportunities"

September 12-14, 2011

San Francisco, California-USA

2LITEN/DTBH/LCTA ICHS 2011 Sept. 14, 2011

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


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


Monotonic loading

Up to 35 MPa H2

Tensile test

Disk pressureTest

(ISO 11114-4 method A)

PHe / PH2


Cyclic loadingFatigue Crack Growth

Fracture mechanics / Dynamic loading

Up to 35 MPa H2

Compact Tensile

Monotonic loadingFracture toughness

Single Edge Notch Tensile specimen

Initial crack


ALAir

Inert gas

Loading conditions

H2

30 MPa H2

Fracture mechanics / Static loading

Wedge Opening Load - Static loading(ISO 11114-4 method C)


High-strength steel grade API X80

C Mn Si P S Fe

0.075 1.86 0.35 0.015 <0.003 Bal.

Ferrite + pearlite Pearlite alignments

914.4 mm x e12.7 mm

w%


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?PHe / PH2 ~ 2

Disk pressure tests


Fracture mechanics – Main results

• Several K• Precracking in air or H2

• No crack propagation after 1000 hr

• 220 kJ/m² (N2) 15 kJ/m² (H2)

WOL - Static loading – 30 MPa

Toughness – Monotonic loading - 30 MPa


Fracture mechanics – Main results

Fatigue Crack growth – Cyclic loading - 30 MPa

• FCG x 10• Significant effect even at low P

H2 - 0.1 Hz

air FCG


Some possible HE indices definition

100 %maximum effect

100(%)2

22

NF

HF

NF

TEE

EEI

100(%)2

22

N

HN

JJ

JJI

100/1(%)2

HHeFCG dnda

dndaI

1001

1100(%)2

EHe

HHe

DPT IP

PPI

100)(

(%) 2

o

HWOL

aW

aI

Tensile elongation

Toughness

FCG rate

Disk pressure test

WOL crack length

0 % no effect

And more ……


Damage analysis

Tensile test

Quasi-cleavage External cracks

Same ao

Same final COD

Toughness testH2 inlet

Quasi-cleavage Ductile

Disk pressure test

H2 inlet


0

10

20

30

40

50

60

70

80

90

100

Fatigue CrackGrowth

Toughness WOL TensileElongation

Disk

Em

bri

ttle

men

t in

dex

(%

)

Fracture mechanics Continuum mechanics

Cyclic Monotonic loading

Static loading

Embrittlement index

Necessary to provide guidelines to select the appropriate test

X80 HS steel


Tensile tests with atmosphere switches

Tensile tests under H2 pressure :HE not due to trapped H in the bulkHE 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 ?

0

200

400

600

800

0 1 2 3Axial displacement (mm)

F/S

0 (

MP

a)N2

H2

0

200

400

600

800

0 1 2 3Axial displacement (mm)

F/S

0 (

MP

a)N2

H2

N2/H2

H2/N2

High kinetic for

• HE reversibility

• HE occurrence


Developing a test facility for full scale pipeline section up to 30 MPa H2 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


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


Thank you for your attention

CEA / LITEN

Quantifying the hydrogen embrittlement of pipeline steels for safety considerations ( #186)

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