Compatibility of Metallic Materials with Hydrogen...Gaseous hydrogen embrittlement The world leader...

FIRST EUROPEAN SUMMER SCHOOL FIRST EUROPEAN SUMMER SCHOOL ON HYDROGEN SAFETY ON HYDROGEN SAFETY

BELFAST BELFAST –– AUGUST 15AUGUST 15--2424THTH, 2006 , 2006

Compatibility of Metallic Materials with Hydrogen

Hervé Barthélémy

2The world leader in industrial and medical gases

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

1. GENERALITIES

2. REPORTED ACCIDENTS AND INCIDENTS ON HYDROGEN EQUIPMENT

3. TEST METHODS

4. PARAMETERS AFFECTING HYDROGEN EMBRITTLEMENT OF STEELS- Environment, Material and Design


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

5. HYDROGEN EMBRITTLEMENT OF OTHER MATERIALS

6. HYDROGEN ATTACK

7. CONCLUSION - RECOMMENDATION


1.GENERALITIES

Internal hydrogen embrittlement

External hydrogen embrittlement


1.GENERALITIES

1 - COMBINED STATE :

Hydrogen attack

2 - IN METALLIC SOLUTION :

Gaseous hydrogen embrittlement


1.GENERALITIES

Important parameter : THE TEMPERATURE

T < 200°C Hydrogen embrittlement

T ≥ 200°C Hydrogen attack


Reversible phenomenaTransport of H2 by the dislocations

CRITICAL CONCENTRATION

AND DECOHESION

ENERGY

1.GENERALITIES

H2 traps


2.REPORTED ACCIDENTS AND INCIDENTS

FAILURE OF A HYDROGEN TRANSPORT

VESSEL IN 1980



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


3.TEST METHODS

Static (delayed rupture test)

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


3.TEST METHODS

Specimens for compact tension test


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

10-820 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


3.TEST METHODS

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

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


3.TEST METHODS

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 (σm) of

the corresponding pressure vessels

σm (MPa)

I


3.TEST METHODS

Fatigue test - Principle


3.TEST METHODS

Fatigue test - Pressure cycle


3.TEST METHODS

Fatigue tests, versus ∆ P curvesnN2nH2

0

1

2

3

4

5

6

4 5 6 7 8 9 10 11 12 13

Delta P (MPa)

Cr-Mo STEELPure H2H2 + 300 ppm O2F 0.07 Hertz

nN2nH2


3.TEST METHODS

Fatigue test Principle to detect fatigue crack initiation


TESTS CHARACTERISTICSType of hydrogen embrittlement and transport modeType of hydrogen embrittlement and transport mode

LOCATION OF HYDROGENTESTS TRANSPORT MODE

Disk rupture test External Dislocations

F % test External + Internal Diffusion + Dislocation

Hollow tensile specimen test External Dislocations

Fracture mechanics tests External Dislocations

P.E.S. test External Dislocations

Tubular specimen test External Dislocations

Cathodic charging test External Diffusion


Practical point of viewPractical point of viewTESTS CHARACTERISTICS

TESTSSPECIMEN

(Size-complexity)CELL

(Size-complexity)COMPLEMENTARY

EQUIPMENT NEEDED

Disk rupture test Small size and very simpleSmall size and very simple

Hydrogen compressor and high pressure vessel

Tensile machine

Fatigue tensile machine for fatigue test only

--

Large hydrogen source at high pressure

Electrochemical equipment

(potentiostat)

Tensile test Relatively small size Large size

Fracture mechanics test

Relatively large size and complex

Very large size and complex

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

Average size

Tubular specimen test

Large size and complex No cell necessary

Cathodic charging test

Small size and simple

Small size and very simple


TESTS CHARACTERISTICSInterpretation of resultsInterpretation of results

PRACTICAL DATA TO

PREDICT IN SERVICE

PERFORMANCE

POSSIBILITY OF RANKING

MATERIALS

SELECTION OF MATERIALS –

EXISTING CRITERIA

TESTS SENSIBILITYTESTS

YesPHe/PH2 Fatigue life

Treshold stress

- KIH- Crack growth

rate

- KIH

Critical hydrogen concentration

Yes/No

No, but maximum allowable KIH could

be defined

No

No

No

Disk rupture High sensitivity Possible

Tensile test Good/Poor sensitivity Possible/Difficult

Fracture mechanics

Good sensitivity Possible

P.E.S. test Poor sensitivity Difficult

Tubular specimen test

Good sensitivity Difficult

Cathodic charging

Good sensitivity

Possible but difficult in practice


4. PARAMETERS AFFECTING HYDROGEN EMBRITTLEMENT OF STEELS

4.1. Environment

4.2. Material

4.3. Design and surface conditions


4.1. Environment or “operating conditions”

Hydrogen purity

Hydrogen pressure

Temperature

Stresses and strains

Time of exposure



Hydrogen purity

Influence of oxygen contamination



Influence of H2S contamination

Hydrogen purity



Hydrogen pressure

Influence of H2S partial pressure for AISI 321 steel



Temperature

Influence of temperature - Principle



Temperature

Influence of temperature for some stainless steels



Hydrogen purity

Hydrogen pressure

Temperature

Stresses and strains

Time of exposure


4.2. Material

Microstructure

Chemical composition

Heat treatment and mechanical properties

Welding

Cold working

Inclusion


4.2. Material



4.2. Material

Welding

4.22.01.91.9 Embrittlement index

25 %8 %2.5 %0 %

(No weld)Ferrite content


4.2. Material

Microstructure

Chemical composition


Welding

Cold working

Inclusion


4.3. Design and surface conditions

Stress level

Stress concentration

Surface defects


4.3. Design and surface conditionsStress concentration

Crack initiation on a geometrical discontinuity


4.3. Design and surface conditionsSurface defects

FAILURE OF A HYDROGEN

TRANSPORT VESSEL IN 1983. HYDROGEN

CRACK INITIATED ON INTERNAL

CORROSION PITS


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 MATERIALS3) Materials known to be very sensitive to HE :

Ni and high Ni alloysTi and Ti alloys

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

Non compatible material can be used at limited stress level


6. HYDROGEN ATTACKMain parameters summarized on the « Nelson curves » :

Influence of P, T, Cr and MoTi and W have also a beneficial effectC, Al, Ni and Mn (excess) have adetrimental effect

Other parameters :

Heat treatment

Stress level, welding procedure


6. HYDROGEN ATTACK

Nelson curves

Legend :Surface decarburizationInternal decarburization(Hydrogen attack)


7. CONCLUSION - RECOMMENDATION1) The influence of the different parameters shall

be addressed.



be addressed.2) To safely use materials in presence of

hydrogen, an internal specification shall cover the following :




hydrogen, an internal specification shall cover the following :• The « scope », i.e. the hydrogen pressure,

the temperature and the hydrogen purity





the temperature and the hydrogen purity• The material, i.e. the mechanical properties,

chemical composition and heat treatment






chemical composition and heat treatment• The stress level of the equipment






chemical composition and heat treatment• The stress level of the equipment• The surface defects and quality of finishing






chemical composition and heat treatment• The stress level of the equipment• The surface defects and quality of finishing• And the welding procedure, if any

Compatibility of Metallic Materials with Hydrogen...Gaseous hydrogen embrittlement The world leader...

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