Sour Oil Corrosion?

[MechEng176]

Hi,

Wanted to pick peoples minds on Sour oils corrosion potential for Carbon Steel(CS) pipe. I know H2S can mess up CS and so can sour oil (no H2S, just >0.5% Sulphur content). But sour oil is only a threat when it is at high temperatures (200-500C) right? Am I right in saying that if the oil is at 10-20C, then amount of corrosion is pretty much negligible?

Thanks!

 

[SJones]

It depends which damage mechanisms apply in the environment. The one that leaps out is sulphidation, which is an elevated temperature mechanism. Try getting hold of API RP 571 and searching through for 'sulfur,' some more sulphur related damage mechanisms could become apparent for specific applications.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

If you are dealing with an intermediate product that is fully dry, then there is little risk at lower temperatures.
But if during a shutdown you allow humid air into the system all hell can break loose.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[racookpe1978]

I don't know the fluids enough, but isn't ANY water trapped in the pipe with the sour oil/sour gas even more corrosive over time?

 

[OGMetEngr]

The risk at near ambient temperatures is that of cracking due to H2S. Sulfide stress cracking (SSC) and hydrogen induced cracking (HIC) can occur depending on chemistry and strength/hardness. I recommend taking a look at NACE MR0175 if there is any risk of water in the system. Also if the pipe is manufactured from plate, depending on sulfur level, HIC risk may be high

 

[OGMetEngr]

Also if the pipe is manufactured from plate, depending on sulfur level, HIC risk may be high

To clarify, I mean sulfur in the chemical composition of the steel. Take a look at NACE MR0175/ISO15156-2 section 8 for an explanation.

 

[TD2K]

I'd expect carbon steel to be used for oil piping at 10 to 20C. Piping in refineries for crude oil and products are usually carbon steel up to about 400F to 500F (equipment is different of course). Above 400F to 500F depending on the fluid, you start looking at chrome alloys or stainless steels.

One coker expansion job where I did all the OSBL piping between the new coker unit and other units were all carbon steel for the utility streams, coker feed and product streams, amine, caustic and even the sour gas from the amine regenerators over to the sulfur units.