8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
1/26
Operator’s views of current status andfuture research - H2S Cracking
John Martin
BP Exploration
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
2/26
Sour Service (H2S Cracking)
• Definition:-
− ISO 15156
‘Exposure to oilfield environments that contain H2S
and can cause cracking of materials by themechanisms addressed by ISO 15156 Part 1’
• Mechanisms in ISO 15156
−SSC, HIC, SOHIC, SZC, SCC, GHSC
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
3/26
Generation of Hydrogen by Corrosion Processes
Fe2+
Fe – 2e
2H++2e =H.+H
.=H2
H.
H.+H
.=H2
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
4/26
Hydrogen Entry Mechanism
• Atomic Hydrogen is generated by the corrosionprocess
• Generally H• + H• = H2
• However HS- poisons the combination.
• H• enters the steel matrix
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
5/26
Cracking in sour service
H
HHH
H
Higher Strength Steels YS > 500 MPa Low Strength Steels YS < 550 MPa
Applied Stress No Applied Stress
H2
H2
H2 H+
S2-Fe2+
H
H
FeS Film
Metal Matrix
pH 2S
pH
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
6/26
Sulphide Stress Cracking (SSC)
• Cracking involving corrosion and tensile stress in the
presence of water and H2S
• Hydrogen embrittlement mechanism in carbon steel
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
7/26
Low Alloy Steel Grades (API 5CT/ISO11960)
Strength
(ksi)
Grade
(ISO 11960
except *) Min. Yield Max. Yield Min. Tensile
H40 40 80 60 Yes
J55 55 80 75 Yes
K55 55 80 95 Yes
M65 65 85 85 Yes
C90 90 105 100 No (?)
L80 80 95 95 Yes
C95 95 110 105 No (?)
P110 110 140 125 No (?)
C110* 110 120 115 Mild Only
Q125 125 150 135 No (Type 1 (?))
T95 95 110 105 Yes
N80 80 110 100 No (?)
C125* 125 140 130 Very Mild Only
H2S
Resistant
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
8/26
Domain Diagram for C110
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
9/26
Low Alloy Steel Grades (API 5L/ISO3183)
Strength
(ksi)
Grade
(* new
additions)Min. Yield Max. Yield Min. Tensile
B 35 65 60 Yes
X42 42 72 60 Yes
X46 46 76 63 Yes
X60 60 82 75 Yes
X56 56 79 71 Yes
X65 65 87 78 Yes
X80 80 140 125 No (?)
X90* 90 112 101 No (?)
X100* 100 122 110 No (?)
X70 70 92 83 Yes
X52 52 77 67 Yes
X120* 120 152 133 No (?)
H2S
Resistant
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
10/26
Hydrogen Induced Cracking (HIC)
• Cracking that occurs when atomic hydrogen diffuses into steel and
combines to form molecular hydrogen at discontinuities• Also called Hydrogen Pressure Induced Cracking (HPIC); Blister
cracking; Stepwise cracking (SWC)30” seam welded API 5LX 60 sourcrude oil pipeline, failed 1972 during
commissioning. Abu Dhabi
Also called “step-wise
cracking”
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
11/26
HIC and Related Mechanisms in ISO15156/NACEHIC and Related Mechanisms in ISO15156/NACEMRMR--01750175
““The equipment user shall consider HIC/SWCThe equipment user shall consider HIC/SWC
as defined in ISO 15156as defined in ISO 15156--1/NACE MR1/NACE MR--01750175when evaluating flatwhen evaluating flat--rolled carbon steelrolled carbon steel
products for sour service environmentsproducts for sour service environments
containing even trace amounts of Hcontaining even trace amounts of H22SS””
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
12/26
Preliminary proposal for HIC severity regions
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
13/26
CRA Grades (ISO 13680 except *)
Type Category
(Cr-Ni-Mo)
Maximum Available SMYS
(ksi)
13-0-0* (e.g. L80 13Cr) 90
25-7-3+N 125
27-31-4 140
21-42-3 125
25-50-6 140
20-54-9+17Fe 140
22-50-7 140
13-4-1* 110
Martensitic Stainless Steel
13-5-2 110
22-5-3+N 125
Super Duplex Stainless Steel 25-7-4 + 2W +N 125
Austenitic Stainless Steel
25-32-3 140
Austenitic Ni Al loys
15-60-16 +4W 140
Duplex Stainless Steel
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
14/26
13Cr/4Ni/1Mo alloy – SSC Failure
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
15/26
SSC Failure of Downhole Tubular String
• HP/HT Gas Producer – 45mmscf/d, 50ppm H2S and 8.7mol%CO2.(0.5psia H
2S, pH 3.5).
• Completed with a mixture of L80-13Cr & CR13 95ksi 13/4/1 tubing.
• Packerless completion allowed produced fluid to contact tubing OD.
• Tubing failed via SSC at localised sites of cold work on the OD (slip andtong marks).
• Gas, water and sand flowed from the tubing bore to the annulus,resulting in significant erosion of both the tubing and casing.
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
16/26
Domain Diagram for Super 13Cr
pH
3.5
4.5
5.5
0.001 0.01 0.1 1.0
pH2S (bara)
Domain Diagram For The Sulphide Stress Cracking Limits
Of 95ksi Super 13Cr Alloys In High Chloride (120,000 ppm Cl-
) Waters
UNACCEPTABLE
ACCEPTA BLE
0.03bara
FURTHER ASSESSMENT REQUIRED
pH
3.5
4.5
5.5
0.001 0.01 0.1 1.0
pH2S (bara)
Domain Diagram For The Sulphide Stress Cracking Limits
Of 95ksi Super 13Cr Alloys In High Chloride (120,000 ppm Cl-
) Waters
UNACCEPTABLE
ACCEPTA BLE
0.03bara
FURTHER ASSESSMENT REQUIRED
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
17/26
Stress Corrosion Cracking (SCC)
• In the context of this talk relates to the SCC
mechanisms that are associated with ‘active pathdissolution’ mechanisms (e.g. chloride SCC) and not
hydrogen-related mechanisms already covered (SSC,
HIC, etc.)
• As such the focus is mainly corrosion-resistant alloys
such as austenitic stainless steels (e.g. AISI 316),
duplex stainless steels (mixed mode mechanism or
CSC) and some nickel alloys (e.g. alloy 825)
• Developing domain diagrams for welded constructions
(flowlines, manifolds, piping,vessels, etc.) similar tothose already developed for OCTG
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
18/26
Domain diagrams for CRA flowlines and risers
pH
Partial Pressure
H2S
Decrease chloride,
temperature?
Increase chloride,
temperature?
No cracking
Cracking
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
19/26
Effect of welding?
pH
Partial Pressure
H2S
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
20/26
Cracking of duplex stainless steel
SSC D i f 25C D l St i l St l (125k i SMYS)
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
21/26
SSC Domain for 25Cr Duplex Stainless Steel (125ksi SMYS)
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
22/26
Areas of active research
• Effect of environmental conditions on cracking of CRAs
−
Chloride− Temperature
− pH
−H2S
• Effect of material processing on cracking
− Welding
− Plastic strain
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
23/26
H2S Cracking (SSC, SCC and HIC)
Thank You
For
Your
Attention!
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
24/26
SOHIC
3.5
mm
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
25/26
SOHIC
• Current Test Methods
−NACE TM0103 – Plate steels
− OTI 95 635 – Linepipe
• No universally accepted test method available• Bodycote/TWI/Force JIP
− Aim – To develop a simple go/no go SOHIC test
method for pressure vessel steels and line pipe
8/20/2019 Bp-Operator’s Views of Current Status and Future Research -H2S Cracking
26/26
SOHIC
• SOHIC testing requires further development
−JIP Test Method (Test Method imposes simultaneoustwisting and bending on a flat specimen to generate
triaxial stress)
−Methods for assessing fittings
• Appropriate test methods need to be applied
• Test techniques need to be realistic such that goodmaterials are accepted and poor ones rejected