Material Selection - Salinity problems.
Material Selection - Salinity problems.
(OP)
Good day.
I'm a newly graduated engineer and I work in the Oil & Gas industry in Denmark. I have been tasked with performing a material selection for an offshore oil facility in the North Sea. As part of this assignment I have access to the predicted flow parameters and I must admit that the salt content predicted have me stumped somewhat.
My question is; Are the materials I have specified as options acceptable for the service?
My two material options are.
- Inconel 625 cladded Carbon Steel
- Super Duplex stainless steel
The process parameters are;
Pressure: 780 Bar (Before PSV, 150 Bar after)
Temperature: 160 deg C
mol%CO2: 0.1-0.2
ppm H2S: <5
Total Dissolved Solids: 106868 mg/L
Chlorite content: 64830 mg/L
Density of formation water is about 1077.2 g/cm3
I look forward to hearing any thoughts on the subject.
Kind regards.
- Klaus Truelsen
I'm a newly graduated engineer and I work in the Oil & Gas industry in Denmark. I have been tasked with performing a material selection for an offshore oil facility in the North Sea. As part of this assignment I have access to the predicted flow parameters and I must admit that the salt content predicted have me stumped somewhat.
My question is; Are the materials I have specified as options acceptable for the service?
My two material options are.
- Inconel 625 cladded Carbon Steel
- Super Duplex stainless steel
The process parameters are;
Pressure: 780 Bar (Before PSV, 150 Bar after)
Temperature: 160 deg C
mol%CO2: 0.1-0.2
ppm H2S: <5
Total Dissolved Solids: 106868 mg/L
Chlorite content: 64830 mg/L
Density of formation water is about 1077.2 g/cm3
I look forward to hearing any thoughts on the subject.
Kind regards.
- Klaus Truelsen





RE: Material Selection - Salinity problems.
NORSOK standards
http:
DNV standards and recommended practices
http:
RE: Material Selection - Salinity problems.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Material Selection - Salinity problems.
The materials in question is to be used for process piping in the meantioned process parameters.
I have performed a CO2 corrosino rate prediction based on the C. de Waard model and im predicting 4-4,5 mm/year corrosion based on this. This is unacceptable for the use of carbon steel.
From here on the two material options are primarily based on the temperature and the salinity of the FEED.
I hope this cleares up my situation.
- Klaus Truelsen
RE: Material Selection - Salinity problems.
In my opinion as a first impression the two alternatives 625+CS or Super duplex are acceptable.
there are some guidelines that you can use to select your materials:
A Guideline To The Successful Use Of Duplex Stainless Steels For Flowlines
http://www
Selection guidelines for corrosion resistant alloys in the oil and ...
http://www.stainless-steel-world.net/pdf/10073.pdf
and also you can use the NACE / ISO.
other factors that you've to consider and that you've to exclude are the presence of elemental sulphur, but i think taht with your H2S pression in shloud not be present, and also the presence oxygen.
S
Corrosion Prevention & Corrosion Control
RE: Material Selection - Salinity problems.
I'll be reading you'r references as well as taking a look at NORSOK M-001 again. From the process information i have available elemental sulphur will not be a problem, neither will the H2S partial pressure (even before the PSV)
- Klaus Truelsen
RE: Material Selection - Salinity problems.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Material Selection - Salinity problems.
I haev rechecket the ISO 15156/NACE H2S limitations and the 5 ppm H2S will result in sour service at 760 Bar but within the allowable limitations for Super Duplex SS.
I have specifyed NORSOK M-501 paint codes as to avoid SCC problems and as of now no insulation will be used.
Based on "http://www.stainless-steel-world.net/pdf/10073.pdf" Duples steel will be acceptable in reguards to the salinity contenth of the streem.
right now my primary worry is that the mixture of salinity and potential sour service at a later time will be problematic.
Thanks for you'r help to all of you.
- Klaus Truelsen