Wet CO2 piping material

[Viewsonic]

I'm in the early stages of investigation on a project using CO2 for EOR. The CO2 may have some moisture initially, but when the oil is being extracted through the wells, there will be oil, gas, and water. Therefore, all the CO2 separating equipment will be exposed to wet CO2.

The options that I am considering for piping materials are coated carbon steel, and I'm investigating 304 and 316 SS. The information I've looked at is leaning towards using 316.

Is this a good choice for a piping material? The system will be seeing temperatures of up to 300 degrees F and pressures up to 2500 psig. The higher pressures will see separated and dry CO2 but the lower pressures will definitely see wet CO2.


Thanks in advance,
Viewsonic

 

[SJones]

When you say "piping material", it is assumed that you are referring to B31.3 piping rather than B31.4/8 pipelines. Think about the use of coated carbon steel in a piping system with all its branches elbows and fittings coupled with all the cutting and fitting that will occur during fabrication. From an integrity and constructability point of view, you will probably end up ruling out coated carbon steel as a continuous coating cannot be guaranteed. 304 SS will, generally, not have sufficient corrosion resistance for oilfield environments

thread338-120479

The principal parameter will be the chloride content of the water. If you get formation water, it may be too high for 316L (refer Bruce Craig chart in referenced thread). Having solved that issue, then it is time to consider the external environment. The indicated temperature is way above the usually quoted Cl- SCC threshold for 316L, therefore, there is a risk of cracking. Some companies will hold that an organic external paint system is good enough to provide protection, others will propose that thermal spray aluminium is the only coating that can be used. That issue will be another discussion thread.

Good luck.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[Viewsonic]

SJones,

Yes I was referring to ASME 31.3 piping. And the information I've gathered so far is leaning towards the coated carbon steel being less attractive. The coating manufacturer the client suggested has a spool length capability of 10' and simply looking at construction of the piping would be fairly expensive with just welding. Once the pipe is welded, coated, and then painted, I'm sure it will be more expensive than going with SS.

The people I've been talking to have been suggesting that I'll likely be fine with 316 SS over 316L or the 304 series. I just wanted to see if there were any obvious problems with suggesting 316. I'm not sure of the chloride content in the water, but I'm inclined to not suggest a low carbon SS primarily because of the reduced allowables per 31.3 and the cracking issues.


Thanks for the input.

 

[SJones]

The "cracking issues" will also apply to UNS S31600 material. And, don't forget that chlorides are in the external environment too.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[stanweld]

Today, you can purchase dual certified 316/316L and use the design allowables of 316 at your design conditions. Like Steve; however, I have major reservations using 316 in chloride containing environments.