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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)
5 | API, 2018 Exploration and Production Winter Standards Meeting
FAILURES EXPERIMENTAL FINAL REMARKSTHEORY
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
6 | API, 2018 Exploration and Production Winter Standards Meeting
FAILURES EXPERIMENTAL FINAL REMARKSTHEORY
7 | API, 2018 Exploration and Production Winter Standards Meeting
FAILURES EXPERIMENTAL FINAL REMARKSTHEORY
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
8 | API, 2018 Exploration and Production Winter Standards Meeting
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
FAILURES EXPERIMENTAL FINAL REMARKSTHEORY
What is Hydrogen Embrittlement?
9 | API, 2018 Exploration and Production Winter Standards Meeting
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
10 | API, 2018 Exploration and Production Winter Standards Meeting
H2 (hydrogen gas)
2H+ + 2e-
2H+ (atomic hydrogen)
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
How Hydrogen Embrittlement Happens in Fasteners
Manufacturing Process In Service Environment
CATHODICOVER
PROTECTION
GALVANICCOUPLING
CORROSIONFORMING
MACHININGHEAT TREATMENT
PICKLINGPHOSPHATE
PLATING
11 | API, 2018 Exploration and Production Winter Standards Meeting
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
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.
12 | API, 2018 Exploration and Production Winter Standards Meeting
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
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.
13 | API, 2018 Exploration and Production Winter Standards Meeting
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
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)
14 | API, 2018 Exploration and Production Winter Standards Meeting
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+
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
15 | API, 2018 Exploration and Production Winter Standards Meeting
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
API 20 EASTM B994 SC18 CLASS1
Galvanic Coupling
Manufacturing Process In Service Environment
API 20 EASTM B994 SC18 CLASS1ASTM F519
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
THEORY EXPERIMENTAL FINAL REMARKSFAILURES
-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
17 | API, 2018 Exploration and Production Winter Standards Meeting
• 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
18 | API, 2018 Exploration and Production Winter Standards Meeting
Potential Current Corrosion resistance
Hydrogen production
Zinc
Zinc-Nickel
Nickel-Cobalt
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
CATHODICOVER
PROTECTION
GALVANICCOUPLING
CORROSION
API 20 EASTM B994 SC18 CLASS1
Cathodic Overprotection
Manufacturing Process In Service Environment
API 20 EASTM B994 SC18 CLASS1ASTM F519
FORMINGMACHINING
HEAT TREATMENT
PICKLINGPHOSPHATE
PLATING
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
19 | API, 2018 Exploration and Production Winter Standards Meeting
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.
20 | API, 2018 Exploration and Production Winter Standards Meeting
Anode Cathode
Cathodic overprotection to -1.2 V vs Ag/AgCl
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
Nickel-Cobalt: Hydrogen Embrittlement Test for Cathodic Protection
21 | API, 2018 Exploration and Production Winter Standards Meeting
• 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
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
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
22 | API, 2018 Exploration and Production Winter Standards Meeting
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
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
Charging Side3.5% wt NaCl1.0 mA/cm2
Exit Side0.1 N NaOH+0.3 V vs Ag/AgCl
Permeation: How Hydrogen Penetrates Steel
23 | API, 2018 Exploration and Production Winter Standards Meeting
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
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
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
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.
25 | API, 2018 Exploration and Production Winter Standards Meeting
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
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.
26 | API, 2018 Exploration and Production Winter Standards Meeting
EXPERIMENTALTHEORY FINAL REMARKSFAILURES
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.
27 | API, 2018 Exploration and Production Winter Standards Meeting
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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