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Influence of electroplated coatings on Hydrogen Embrittlementof low-alloy steel for subsea applications.Electrochemical and Mechanical analysis.

Omar RosasDoxsteel Fasteners

2018 Exploration and Production Winter Standards Meeting

San Antonio, TX, January 23, 2018

Jim BurkJ.D. Burk and Associates

OUTLINE

• Failures: Introducing four hydrogen embrittlement case studies

• Theory: How hydrogen embrittlement happens and how it affects operations

• Experimental: Hydrogen embrittlement affecting bolts when using different coatings

• Final Remarks

Offshore Industry Failures

• Hydrogen Embrittlement failures are catastrophic in nature

• Hydrogen embrittlement failures in drilling equipment lead to significant safety and environmental risks

• Failures have significant economic consequences

• Failures occur mostly in a subsea environment

Dual Derrick Operations

FAILURES EXPERIMENTAL FINAL REMARKS

3 | API, 2018 Exploration and Production Winter Standards Meeting

THEORY

Buoyed Joints

54"

Slick Joints, 15(No Buoyancy)21"

LMRP

JointLength

75'PIN

#40

BOX

#39

Bolts

Inserts

Failure 1: Drilling Riser Connection (2003)

Bottom - 6,034’ Below Sea Level

Joint #1

Joint #77

77 joints

total

Failures

between

Joints

39, 40

Riser parted at 3,200 ft below sea level between joints 39 & 40

FAILURES EXPERIMENTAL FINAL REMARKSTHEORY

Failure 2: Lower Marine Riser Package (2012)



Failure 3: Blow Out Preventer (BOP) Flange Bolt Failure (2014)

• Flange bolting plated with zinc is missing where cracking occurs in stud threads

• High hardness in excess of HRC 34

• Arrows point at areas with consumed sacrificial coating





Failure 4: Bay Bridge Failure

• San Francisco Bay Area Bridge Failure

• High strength bolting

• (ASTM A490 39 HRC Maximum)

• Hot Dip Galvanized Zinc

• Bridge closed for repairs

• Long and costly repairs

• Offshore and on land

Efforts to address Hydrogen Embrittlement on bolting


2003

May

2012

Dec.

2013 2014 July

July

Fall 2015

Fall

2016 2017

Failure 1 Failure 2

Failure 3

BSEE QC-FIT Report

API Forms Bolting

Task Force

Zinc prohibitionFrom API

Bolting Task Force to BSEE

(TGR-3)

BSEE accepts recommendation

and TGRs

API 20E Rewritten

& Reissued

Failure 1 Presentation at Joint ASM/NACE

Meeting

Failure 1Presented

at IADC

API SCs assigned TGRs from CSOEM and SCs work


What is Hydrogen Embrittlement?


THEORY EXPERIMENTAL FINAL REMARKSFAILURES

Stress

Environment

Material

Susceptibility

Bolt load from

torqueing

Hydrogen

Hydrogen

Embrittlement

• Hydrogen embrittlement is the mortal enemy of fasteners.

• It causes metals to become brittle and fracture easily.

• Caused by tensile stress, material susceptibility to hydrogen, and corrosive environments.

High hardness

Hydrogen Embrittlement in Action

• Positively-charged hydrogen breaks out of water molecules and is attracted to metal

• Hydrogen atoms enter the metal through high-stress areas

• Hydrogen interacts with iron atoms to weaken and embrittle the metal


H2 (hydrogen gas)

2H+ + 2e-

2H+ (atomic hydrogen)


How Hydrogen Embrittlement Happens in Fasteners

Manufacturing Process In Service Environment

CATHODICOVER

PROTECTION

GALVANICCOUPLING

CORROSIONFORMING

MACHININGHEAT TREATMENT

PICKLINGPHOSPHATE

PLATING



API 20 EASTM B994 SC18 CLASS1ASTM F519

Evaluation of Hydrogen embrittlement in bolting

ASTM F519: No failure after 200 hours at 75% NTS. It evaluates IHE

ASTM 1940: Specifically related to fasteners. It evaluates IHE

ASTM 2660: Effect of residual hydrogen in the steel as a result of processing. It evaluates mainly EHE

ASTM 1624: Tests in air to investigate IHE. Tests in 3.5% NaCl and cathodic polarization to investigate EHE.



Electrochemical Approach to Hydrogen Embrittlement

• Every material possesses a Potential and delivers a Current

• Potential = Corrosion energy The higher the potential, the more resistant to corrosion.

• Current = How reactive a material is to its environment

The higher the current, the more hydrogen will be produced.

• The Protection Potential = the potential value (-0.85 V vs Ag/AgCl) where no electrons are exchanged between a material and its environment due to corrosion reactions

Potential Values equal or more negative produce hydrogen.



The Protection Potential

Fe++ Fe++

Fe++

Fe++

Fe++

Hydrogen EmbrittlementAnodic Stress

Corrosion Cracking

Anodic ReactionFe = Fe++ + 2e-

Potential (Volts-Ag/AgCl) Scale

Seawater Corrosion

H

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-1.2-1.1-1-0.9-0.8-0.7-0.6-0.5

200 ksi (44HRC)

175 ksi (40HRC)

150 ksi (38HRC)

125 ksi (32 HRC)


Norm

aliz

ed C

rack

Gro

wth

Rate

v

Cathodic Reaction2H+ + 2e- = H2

SeawaterHydrolysis

HH

H

H

H

H

H+H+

H+

H+

H+H+




API 20 EASTM B994 SC18 CLASS1

Galvanic Coupling



CATHODICOVER

PROTECTION

GALVANICCOUPLING

CORROSIONFORMING

MACHININGHEAT TREATMENT

PICKLINGPHOSPHATE

PLATING

• More negative potential increases the risk of hydrogen embrittlement.

• Below the water stability region, hydrogen is produced

• Nickel-Cobalt will not cause hydrogen embrittlement. Zinc does.

• Zinc will produce hydrogen gas and atomic hydrogen.

Thermodynamics of Hydrogen Production

Water Stability Region

16 |

Fe3+

Fe

Ni-Co

Zn-Ni

Zn

Fe3+

Fe2+

Fe

Fe2O3

FeO

Pote

ntial (V

) vs

SH

E


-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

-5 -4 -3 -2 -1 0 1 2

BareSteel

NickelCobalt

Zinc

ZincNickel

Electrochemical Performance of Different Metallic Coatings

• As negative potentials decrease more hydrogen is produced

• A higher current creates more hydrogen discharge

Pote

ntial (V

vs

Ag/A

gCl)

Log | current | (mA)

EXPERIMENTALTHEORY FINAL REMARKSFAILURES


• Zinc and Zinc-Nickel have a very low potential and delivers a very high current, so it is very reactive and its cathodic current will produce hydrogen.

• Nickel-Cobalt has a high potential and delivers a very low current, so it reacts very slowly and is resistant to corrosion.

Summary of electrochemical performance


Potential Current Corrosion resistance

Hydrogen production

Zinc

Zinc-Nickel

Nickel-Cobalt


CATHODICOVER

PROTECTION

GALVANICCOUPLING

CORROSION

API 20 EASTM B994 SC18 CLASS1

Cathodic Overprotection



FORMINGMACHINING

HEAT TREATMENT

PICKLINGPHOSPHATE

PLATING



Cathodic protection (overprotection)

• Cathodic Protection charges metals with current to prevent corrosion.

• Too much current accelerates hydrogen production, putting fasteners at risk of hydrogen embrittlement. This is easy to do by accident due to the design of cathodic protection.

• Coatings must protect fasteners from accidental cathodic overprotection.

• Cathodic charging was used for hydrogen production tests, hydrogen permeation tests, and the effect of cathodic protection on the mechanical strength of coupons.


Anode Cathode

Cathodic overprotection to -1.2 V vs Ag/AgCl


Nickel-Cobalt: Hydrogen Embrittlement Test for Cathodic Protection


• Notched tensile samples (49 HRC) were subject to cathodic overprotection of -1.0 V vs Ag/AgCl in 3.5%wt NaCl.

• Tensile tests to break the samples were performed after 30 days of polarization.

Bare Steel Nickel-CobaltZinc coating


Tensile Tests with Cathodic Protection• Nickel-Cobalt plating has a

minimal effect on a fastener’s mechanical performance.

• Cathodic overprotection has no effect on mechanical performance with Nickel-Cobalt plating.

• Nickel-Cobalt protects fasteners under stress from hydrogen.

Bare Steel


249.73

Zn CoatingNi-Co

120.87

181.38

92.09

230.43235.07

Without Cathodic Protection With Cathodic Protection

Zn-Ni Coating

252.73

97.43


Charging Side3.5% wt NaCl1.0 mA/cm2

Exit Side0.1 N NaOH+0.3 V vs Ag/AgCl

Permeation: How Hydrogen Penetrates Steel



Hydrogen Permeation Cell Testing

Ar Gas

Test Solution

Charging Cell

Pt (AE)

Salt Bridge

Potentiostat

RE (Ag/AgCl)

Saturated KCl1N-NaOH

Ni-Co Zinc Zn-Ni


Hydrogen Production on different coatings

• 1 mA/cm2 was applied during 12 hours in a 3.5wt% NaClacidified to pH=3

• Hydrogen was collected and quantified

• Nickel-Cobalt produced the least amount of hydrogen compared to the other coatings.



0

1

2

3

4

5

6

7

Zn Zn-Ni Ni-Co

Hyd

roge

n P

rod

uct

ion

(m

L/cm

2)

Hydrogen Permeation Cell Testing: Results ASTM G148

• Zn showed the highest hydrogen permeation

• Ni-Co exhibited the lowest hydrogen permeation, one order of magnitude less than Zn-Ni and two orders of magnitude of Zn

• Despite the high hydrogen production on the Zn-Ni, Zn had a higher permeation.



1.4 E -10

1.0 E -11

2.6 E -12

1.10E-14

2.11E-13

4.11E-13

6.11E-13

8.11E-13

1.01E-12

1.21E-12

1.41E-12

1.61E-12

Zn Zn-Ni Ni-Co

HYd

roge

n P

erm

eati

on

(m

ol/

cm s

)

Final Remarks

• Materials selection plays a crucial role regarding hydrogen embrittlement susceptibility.

• Nickel-Cobalt will not produce hydrogen even with high cathodic overprotection, Zn and Zn-Ni will do.

• Eliminating one of the elements from the catastrophic Venn diagram, may eliminate the risk of hydrogen embrittlement.

• Nickel-Cobalt protects from external sources of hydrogen in the field.


FINAL REMARKSTHEORY EXPERIMENTAL

Bolt load from

torqueing

FAILURES

Stress

Environment

Material

Susceptibility

Hydrogen

High hardness

Question & AnswerAny questions?

Thank you all

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