kukuh soerowidjojo - experience of qualification test of cra material
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NACE International East Asia Pacific Rim Area Conference & Expo 2014 September 2 – 4, 2014 Nusa Dua Convention Center Nusa Dua, Bali, Indonesia
JAKARTASECTION
Experience of Qualification Test of CRA Material
UNS N08028 (alloy 28) for Down Hole Tubular in
Sour Gas Well Application
Paper No: P30
Kukuh Soerowidjojo
Sandvik Materials Technology
Tuesday, September 16,
2014
2014 NACE EAP Conference & Expo
Outline
Objective
Background - Trend of field development
environment
Text book and past experience approach
Laboratory test
Result and discussion
Conclusion
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Objective
Qualifying UNS N08028 (Alloy 28) grade for
sour service in the given well conditions by
standard SSC/SCC corrosion test ISO 7539-1,
ISO 7539-3 (“U” bend) and ISO 7539-4 (tensile)
methods.
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Background
Increasing challenges:
HPHT fields
Sour fields
Deeper water
Shale gas field
Designated well conditions
Test temperature : 150oC (302oF)
CO2 partial pressure : 41 Bar (594.65 psi)
H2S partial pressure : 5.5 Bar (79.77 psi)
Chlorides : 75,000 mg/l (as NaCl)
Bicarbonate : 0.1% (as sodium bicarbonate)
pH at temperature * : 3.75 – 4.25
Total pressure at temp. 54 Bar (783.20 psi) – including 7.5 bar (108.78 psi)
vapour pressure.
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Environment limitation for CRA’s
NACE MR175
ISO 13680 – API 5CRA
Plotted reference conditions
Test conditions for the diagram: 1000 psi CO2 5% and 15% chlorides Stressed to 100% of yield strength at test temperature
Temperature: 150oC (302oF)
CO2 partial pressure: 41 Bar (594.65 psi)
H2S partial pressure: 5.5 Bar (79.77 psi)
Chlorides: 75,000 mg/l (as NaCl)
Bicarbonate: 0.1% (as sodium bicarbonate)
pH at temperature * 3.75 – 4.25
Total pressure at temp. 54 Bar (783.20 psi) – including 7.5 bar (108.78 psi) vapour pressure.
Client’s field conditions
Sour corrosion tests - ISO 7539-1
Constant load varies from 0.8 – 1.0 x actual
yield strength
Critical observations:
•pH (before and after
test)
•Oxygen content (before
and after test)
•Load is applied on
actual yield strength at
test temperature
“U” BEND SPECIMEN ISO 7539-3 TENSILE SPECIMEN ISO 7539-4
13
Test methods
“U” BEND SPECIMEN ISO 7539-3 TENSILE SPECIMEN ISO 7539-4
14
Observation results
No cracks are observed in the test specimens, neither “U” bends nor tensile specimens
Discussion
Literature study was very helpful to direct and funneling down the
options of materials to be selected.
ISO 7539 is a good alternative to NACE TM 0177 to test the
material in sour environment.
Stress level could be increased up to 100% of yield strength to
increase the severity of the test conditions
It is very important to get oxygen level in the test solution as low as
possible.
Oxygen content in the test solution is very important to be kept as
low as possible.
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Conclusion
Laboratory test confirmed the material selected i.e. UNS
N08028 (Alloy 28) through text book and NACE MR
0175 should resistant to sulfide stress cracking / stress
corrosion cracking risk introduced by the given
environment.
UNS N08028 (Alloy 28) PSL2 was considered qualified
to be used in the project.
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JAKARTASECTION
THANK YOU
9/16/2014 2014 NACE EAP Conference & Expo 17
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