Funded by FCH JU (Grant agreement No. 256823) 1 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 1 Chapter E: Hydrogen embrittlement and permeation

Funded by FCH JU (Grant agreement No. 256823)

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© HyFacts Project 2012/13CONFIDENTIAL – NOT FOR PUBLIC USE

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Chapter E: Hydrogen embrittlement and permeation

Belfast – January 25, 2013Hervé Barthélémy – Air Liquide


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1. INTRODUCTION - GENERALITIES

2. REPORTED ACCIDENTS AND INCIDENTS ON HYDROGEN EQUIPMENT

3. TEST METHODS

HYDROGEN EMBRITTLMENT AND PERMEATION

4. PERMEATION TESTS


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6. HYDROGEN EMBRITTLEMENT OF OTHER MATERIALS

8. CONCLUSION - RECOMMENDATION

7. HYDROGEN ATTACK

HYDROGEN EMBRITTLMENT AND PERMEATION

5. PARAMETERS AFFECTING HYDROGEN EMBRITTLEMENT OF STEELS

- Environment, Design and Material


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Internal hydrogen

embrittlement

External hydrogen

embrittlement

1. GENERALITIES


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2 - IN METALLIC SOLUTION :

Hydrogen attack

Gaseous hydrogen embrittlement

1 - COMBINED STATE :

1. GENERALITIES


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6 T 200°C Hydrogen embrittlement

Important parameter : THE TEMPERATURE

T 200°C Hydrogen attack

1. GENERALITIES


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Reversible phenomena Transport of H2 by

the dislocations

CRITICAL CONCENTRATION

AND DECOHESION

ENERGY

H2 traps

1. GENERALITIES


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FAILURE OF A HYDROGEN TRANSPORT

VESSEL IN 1980

2. REPORTED ACCIDENTS AND INCIDENTS


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FAILURE OF A HYDROGEN

TRANSPORT VESSEL IN 1983. HYDROGEN

CRACK INITIATED ON INTERNAL

CORROSION PITS



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102. REPORTED ACCIDENTS

AND INCIDENTS

HYDROGEN CYLINDER BURSTS INTERGRANULAR CRACK


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VIOLENT RUPTURE OF A HYDROGEN STORAGE VESSEL



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H2 VESSEL. HYDROGEN CRACK ON STAINLESS STEEL PIPING



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Static (delayed rupture test)

3. TEST METHODS

Constant strain rate

Fatigue

Dynamic


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Fracture mechanic (CT, WOL, …)

Tensile test

Disk test

Other mechanical test (semi-finished products)

Test methods to evaluate hydrogenpermeation and trapping

3. TEST METHODS


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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


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Specimens for compact tension test

3. TEST METHODS


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3. TEST METHODS

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

(up to 1 000 bar)


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10-4

10-5

10-6

10-7

10-8

20 25 30

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

3. TEST METHODS


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K, MPa Vm

Influence of hydrogen pressure

by British Steel

X

152 bar

41 bar

1 bar

165 bar

H2

N2

10-2

10-3

10-4

10-5

10 20 30 40 60 80 100

dadN

mm/cycle

3. TEST METHODS

N2


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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


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

I = Embrittlement index

RAN = Reduction of area without H2

RAH = Reduction of area with H2

3. TEST METHODS


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Cell for delayed rupture test with Pseudo Elliptic Specimen

Pseudo EllipticSpecimen

3. TEST METHODS


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Tubular specimen for hydrogen assisted fatigue tests

Inner notches with elongationmeasurement

strip

3. TEST METHODS


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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


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3. TEST METHODS

Example of a disk rupture test

curve


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3. TEST METHODSI

m (MPa)

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

pressure vessels


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Fatigue test - Principle

3. TEST METHODS


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Fatigue test - Pressure cycle

3. TEST METHODS


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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


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3. TEST METHODS

Fatigue test Principle to detect fatigue crack initiation


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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

External Dislocations

P.E.S. test External Dislocations

Tubular specimen test External Dislocations

Cathodic charging test External Diffusion

TESTS CHARACTERISTICS


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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 test Relatively 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 testLarge size and complex

No cell necessaryLarge hydrogen source at high pressure

Cathodic charging test Small size and simpleSmall size and very simple

Electrochemical equipment (potentiostat)



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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 sensitivity Difficult No - KIH

Cathodic

chargingGood sensitivity

Possible but difficult in practice

NoCritical hydrogen concentration



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4. PERMEATION TESTS

4.1. Definition

4.2. Important parameter: temperature


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4.1. Definition

• Permeability is the result of gas solution and gas diffusion

• Permeability coefficient is defined as follows :

Pe = S × D.

• Permeation in polymers is a molecular permeation


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The permeability coefficient is defined as the product of the diffusion and solubility coefficients of the gas for this material. When Henry’s law is satisfied, the flow at steady state, for a given temperature, is given by:

e

PPe

e

PPDSJ VM

. J: flow of molecules going through a surface A, at steady state (permeability flow rate)

e: thickness of the samplePM: partial pressure of the gas on

the upstream sidePV: partial pressure of the gas on

the downstream sidePe: permeability coefficient of the

gas

4.1. Definition

AP M

P V

e

J

P M

P V

e

J

P M

P V

P M

P V

e

J

e2<<A


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))(

exp()(RT

PEaPPePe • According to Arrhenius

4.2. Important parameter: Temperature

• Permeability investigated mainly for elastomer and plastic materials

• Hydrogen permeability of metals is several order of magnitude lower than permeability of polymers


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38PERMEATION CELL BY GASEOUS CHARGING

1. Reference electrode (S.C.E.)

2. Argon (inlet)3. Argon (outlet)4. Auxiliary electrode (Pt)

5. Teflon cell6. Disk (working electrode)

58 mm and e = 0,75 mm


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39PERMEATION TEST BY CATHODIC CHARGING - PRINCIPLE

1. Battery 2. Recorder3. Potentiostat4. Reference electrodes5. Solution6. Auxiliary electrodes (Pt)

7. Membrane8. Charging solution


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40PERMEATION AND DEGASSING CURVES - PRINCIPLE

1. Hydrogen flow 2. Theorical curve (with D0)

3. 2nd permeation4. Stop in charging5. Calculation6. 2nd permeation7. Beginning8. 1st permeation9. Beginning (charging)


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5. PARAMETERS AFFECTING HYDROGEN EMBRITTLEMENT OF STEELS

5.1. Environment

5.2. Material

5.3. Design and surface conditions


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Hydrogen purity

Hydrogen pressure

Temperature

Stresses and strains

Time of exposure

5.1. Environment or “operating conditions”


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Influence of oxygen contamination

Hydrogen purity



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Influence of H2S contamination

Hydrogen purity



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Hydrogen pressure


Influence of H2S partial pressure for AISI 321 steel


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Influence of temperature - Principle

Temperature



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Influence of temperature for some stainless steels

Temperature



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Hydrogen purity

Hydrogen pressure

Temperature

Stresses and strains

Time of exposure



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Microstructure

Chemical composition

Heat treatment and mechanical properties

Welding

Cold working

Inclusion

5.2. Material


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5.2. Material


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Welding

5.2. Material

4.22.01.91.9 Embrittlement index

25 %8 %2.5 %0 %

(No weld)Ferrite content

4.22.01.91.9 Embrittlement index

25 %8 %2.5 %0 %

(No weld)Ferrite content


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Microstructure

Chemical composition


Welding

Cold working

Inclusion

5.2. Material


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Stress level

Stress concentration

Surface defects



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Crack initiation on a geometrical discontinuity




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Crack initiation on a geometrical discontinuity




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FAILURE OF A HYDROGEN

TRANSPORT VESSEL IN 1983. HYDROGEN

CRACK INITIATED ON INTERNAL

CORROSION PITS

Surface defects



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576. 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


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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 EMBRITTLEMENT OF OTHER MATERIALS


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Nelson curves

Legend :Surface decarburizationInternal decarburization(Hydrogen attack)

7. HYDROGEN ATTACK


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7. HYDROGEN ATTACK

Ti and W have also a beneficial effect

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

Heat treatment

Stress level, welding procedure

In addition to parameters summarized on the « Nelson curves » (influence of P, T, Cr and Mo):

Other parameters :


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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

• And the welding procedure, if any

8. CONCLUSION - RECOMMENDATION

Documents

Funded by FCH JU (Grant agreement No. 256823) 1 © HyFacts Project 2012/13 CONFIDENTIAL – NOT FOR PUBLIC USE 1 Chapter E: Hydrogen embrittlement and permeation