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robo5209 (Chemical) (OP)
15 Feb 08 5:07
i am checking on the maximum h2s partial pressure in the gas pipeline (wet gas) before the sulfite stress cracking begin to occur. is there any rule of thumb for the h2s partial pressure?


Thanks in advance.
BigInch (Petroleum)
15 Feb 08 6:43
The only data I've seen that I can recall now was based on concentration, partial pressures being that they vary considerably at different points along a pipeline for example, apparently wern't very interesting to study.

http://virtualpipeline.spaces.msn.com

"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

SJones (Petroleum)
15 Feb 08 9:30
For a carbon steel pipeline, ISO 15156 Parts 1 and 2 are what you need to be looking at and don't forget that sulphide stress cracking is not the only degradation mechanism to consider in H2S containing service.

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/

robo5209 (Chemical) (OP)
18 Feb 08 0:02
From the literature a found, stated that partial pressure for H2S is 0.05 psi and cannot exceed than this level for the corrosion environment begin to occur. It is reliable??

Thanks in advance for any comments .

Ezamy
gr2vessels (Mechanical)
18 Feb 08 2:07
robo,
The H2S partial pressure limits vary with the type of steel you are using in the given environment. For details refer to NACE MR 0175, I've seen 15 psi and above for carbon steel, etc...
BigInch (Petroleum)
18 Feb 08 4:45
0.05 partial pressure pretty much says you only have to have H2S in the stream.  Corrosion in an untreated gas gathering system with some H2O can be a big problem with H2S content at only 5 ppm.  But that's general corrosion, not specifically a stress cracking parameter.

http://virtualpipeline.spaces.msn.com

"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

robo5209 (Chemical) (OP)
18 Feb 08 10:26
Thank you for the information.
BigInch,gr2vessels & SJones.
Really appreciate it.


Cheers
SJones (Petroleum)
19 Feb 08 13:57
Don't forget HIC!

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/

Ashereng (Petroleum)
20 Feb 08 22:55
NACE MR-0175 also has a chart of to determine if SSC is going to be a problem/concern.

From memory, if under 750 ppm, it is based on partial pressure. If over 750 ppm, it is based on total pressure.

You should go through the NACE MR-01-75 document.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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