international conference on hydrogen safety s. sebastian – spain september 11-13 th, 2007 hervé...

INTERNATIONAL CONFERENCE INTERNATIONAL CONFERENCE ON HYDROGEN SAFETY ON HYDROGEN SAFETY S. SEBASTIAN – SPAINS. SEBASTIAN – SPAIN

SEPTEMBER 11-13SEPTEMBER 11-13THTH, 2007, 2007

Hervé Barthélémy

Compatibility of Metallic Materials with Hydrogen

Review of the Present Knowledge

2The world leader in industrial and medical gases

1. INTRODUCTION

2. REPORTED ACCIDENTS AND INCIDENTS ON HYDROGEN EQUIPMENT

3. TEST METHODS

Compatibility of Metallic Materials with Hydrogen – Review of the present knowledge

4. PARAMETERS AFFECTING HYDROGEN EMBRITTLEMENT OF STEELS

- Environment, Design and Material


Compatibility of Metallic Materials with Hydrogen – Review of the present knowledge

5. HYDROGEN EMBRITTLEMENT OF OTHER MATERIALS

7. CONCLUSION - RECOMMENDATION

6. HYDROGEN ATTACK


Internal hydrogen

embrittlement

External hydrogen

embrittlement

1.GENERALITIES


2 - IN METALLIC SOLUTION :

1.GENERALITIES

Hydrogen attack

Gaseous hydrogen embrittlement

1 - COMBINED STATE :


T 200°C Hydrogen embrittlement

Important parameter : THE TEMPERATURE

1.GENERALITIES

T 200°C Hydrogen attack


Reversible phenomena Transport of H2 by the dislocations

CRITICAL CONCENTRATION

AND DECOHESION

ENERGY

1.GENERALITIES

H2 traps


FAILURE OF A HYDROGEN TRANSPORT

VESSEL IN 1980

2.REPORTED ACCIDENTS AND INCIDENTS


FAILURE OF A HYDROGEN

TRANSPORT VESSEL IN 1983. HYDROGEN

CRACK INITIATED ON INTERNAL

CORROSION PITS



HYDROGEN CYLINDER BURSTS INTERGRANULAR CRACK



VIOLENT RUPTURE OF A HYDROGEN STORAGE VESSEL



H2 VESSEL. HYDROGEN CRACK ON STAINLESS STEEL PIPING



Static (delayed rupture test)

3.TEST METHODS

Constant strain rate

Fatigue

Dynamic


3.TEST METHODS

Fracture mechanic (CT, WOL, …)

Tensile test

Disk test

Other mechanical test (semi-finished products)

Test methods to evaluate hydrogenpermeation and trapping


3.TEST METHODS

Fracture mechanics test with WOL type specimen

1. Vessel head2. Specimen3. O-rings4. Vessel bottom5. Gas inlet – Gas outlet6. Torque shaft7. Load cell8. Instrumentation feed through9. Crack opening displacement

gauge10. Knife11. Axis12. Load application


Specimens for compact tension test

3.TEST METHODS


3.TEST METHODS

Air Liquide/CTE equipment to perform fracture mechanic test under HP hydrogen

(up to 1 000 bar)


3.TEST METHODS

Influence of hydrogen pressure (300, 150, 100 and 50 bar) - Crack growth rate versus K curves

10-4

10-5

10-6

10-7

10-8

20 25 30


3.TEST METHODS

X

152 bar

41 bar

1 bar

165 bar

H2

N2

K, MPa Vm

Influence of hydrogen pressure

by British Steel

10-2

10-3

10-4

10-5

10 20 30 40 60 80 100

dadN

mm/cycle


Tensile specimen for hydrogen tests (hollow tensile specimen) (can also be performed with specimens cathodically charged or with tensile spencimens in

a high pressure cell)

3.TEST METHODS


I = (% RAN - % RAH) / % RAN

I = Embrittlement index

RAN = Reduction of area without H2

RAH = Reduction of area with H2

3.TEST METHODS


3.TEST METHODS

Cell for delayed rupture test with Pseudo Elliptic Specimen

Pseudo EllipticSpecimen


3.TEST METHODS

Tubular specimen for hydrogen assisted fatigue tests

Inner notches with elongationmeasurement

strip


Disk testing method – Rupture cell for embedded disk-specimen

1. Upper flange2. Bolt Hole3. High-strength steel ring4. Disk5. O-ring seal6. Lower flange7. Gas inlet

3.TEST METHODS


Example of a disk rupture test curve

3.TEST METHODS


Hydrogen embrittlement indexes (I) of reference materials versus maximum wall stresses (m) of

the corresponding pressure vessels

m (MPa)

I

3.TEST METHODS


Fatigue test - Principle

3.TEST METHODS


Fatigue test - Pressure cycle

3.TEST METHODS


Fatigue tests, versus P curvesnN2

nH2

0

1

2

3

4

5

6

4 5 6 7 8 9 10 11 12 13

Delta P (MPa)

Cr-Mo STEELPure H2

H2 + 300 ppm O2

F 0.07 Hertz

nN2

nH2

3.TEST METHODS


Fatigue test Principle to detect fatigue crack initiation

3.TEST METHODS


Type of hydrogen embrittlement and transport modeType of hydrogen embrittlement and transport mode

TESTSLOCATION OF

HYDROGENTRANSPORT MODE

Disk rupture test External Dislocations

F % test External + Internal Diffusion + Dislocation

Hollow tensile specimen test

External Dislocations

Fracture mechanics tests


P.E.S. test External Dislocations

Tubular specimen test


Cathodic charging test

External Diffusion

TESTS CHARACTERISTICS


Practical point of viewPractical point of view

TESTSSPECIMEN

(Size-complexity)

CELL

(Size-complexity)

COMPLEMENTARY

EQUIPMENT NEEDED

Disk rupture testSmall size and very simple

Small size and very simple

Hydrogen compressor and high pressure vessel

Tensile testRelatively small size

Large size Tensile machine

Fracture mechanics test

Relatively large size and complex

Very large size and complex

Fatigue tensile machine for fatigue test only

P.E.S. testAverage size and very easy to take from a pipeline

Average size --

Tubular specimen test

Large size and complex

No cell necessaryLarge hydrogen source at high pressure

Cathodic charging test

Small size and simple

Small size and very simple

Electrochemical equipment (potentiostat)



Interpretation of resultsInterpretation of results

TESTSTESTS

SENSIBILITY

POSSIBILITY OF RANKING

MATERIALS

SELECTION OF MATERIALS –

EXISTING CRITERIA

PRACTICAL DATA TO

PREDICT IN SERVICE

PERFORMANCE

Disk rupture High sensitivity Possible

Yes

PHe/PH2 Fatigue life

Tensile testGood/Poor sensitivity

Possible/Difficult Yes/No Treshold stress

Fracture mechanics

Good sensitivity

PossibleNo, but maximum

allowable KIH could be defined

- KIH

- Crack growth rate

P.E.S. test Poor sensitivity Difficult No

Tubular

specimen testGood

sensitivityDifficult No - KIH

Cathodic

chargingGood

sensitivityPossible but

difficult in practiceNo

Critical hydrogen concentration



4. PARAMETERS AFFECTING HYDROGEN EMBRITTLEMENT OF STEELS

4.1. Environment

4.2. Material

4.3. Design and surface conditions


Hydrogen purity

Hydrogen pressure

Temperature

Stresses and strains

Time of exposure

4.1. Environment or “operating conditions”


Influence of oxygen contamination


Hydrogen purity


Influence of H2S contamination

Hydrogen purity



Influence of H2S partial pressure for AISI 321 steel


Hydrogen pressure


Influence of temperature - Principle

Temperature



Influence of temperature for some stainless steels


Temperature


Hydrogen purity

Hydrogen pressure

Temperature

Stresses and strains

Time of exposure



Microstructure

Chemical composition

Heat treatment and mechanical properties

Welding

Cold working

Inclusion

4.2. Material



4.2. Material


4.2. Material

Welding

4.22.01.91.9 Embrittlement index

25 %8 %2.5 %0 %

(No weld)Ferrite content


Microstructure

Chemical composition


Welding

Cold working

Inclusion

4.2. Material


Stress level

Stress concentration

Surface defects



Crack initiation on a geometrical discontinuity




FAILURE OF A HYDROGEN

TRANSPORT VESSEL IN 1983. HYDROGEN

CRACK INITIATED ON INTERNAL

CORROSION PITS


Surface defects


5.HYDROGEN EMBRITTLEMENT OF OTHER MATERIALS

1) All metallic materials present a certain degree of sensitive to HE

2) Materials which can be used

Brass and copper alloys

Aluminium and aluminium alloys

Cu-Be


5.HYDROGEN EMBRITTLEMENT OF OTHER MATERIALS

3) Materials known to be very sensitive to HE :

4) Steels : HE sensitivity depend on exact chemical composition, heat or mechanicaltreatment, microstructure, impurities and strength

Ni and high Ni alloys

Ti and Ti alloys

Non compatible material can be used at limited stress level


6. HYDROGEN ATTACK

Influence of P, T, Cr and Mo

Ti and W have also a beneficial effect

C, Al, Ni and Mn (excess) have adetrimental effect

Heat treatment

Stress level, welding procedure

Main parameters summarized on the « Nelson curves » :

Other parameters :


6. HYDROGEN ATTACK

Nelson curves

Legend :Surface decarburizationInternal decarburization(Hydrogen attack)


1) The influence of the different parameters shallbe addressed.




2) To safely use materials in presence of hydrogen, an internal specification shall cover the following :





• The « scope », i.e. the hydrogen pressure, the temperature and the hydrogen purity






• The material, i.e. the mechanical properties, chemical composition and heat treatment







• The stress level of the equipment








• The surface defects and quality of finishing








• The surface defects and quality of finishing

• And the welding procedure, if any


international conference on hydrogen safety s. sebastian – spain september 11-13 th, 2007 hervé...

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