gas facility design with high H2S and CO2 content

[aka2]

I have to design a gas facility dealing with 22000 ppm H2S, 5.5% CO2 and water content. I reviewed NACE MR0175 part 1, 2 and 3 but I wonder wich pipe spec should I use, pipe material, pipe fittings and if I can use carbon steel threaded fittings 1/2" diameter.

 

[aka2]

Sorry, I forgot to say it would operate at 400 psig

 

[Unotec]

I'd give stainless steel serious consideration or even PVC. Carbon steel does not get along with H2S very well. However, your concentration is not too high. It will all come down to economics, I guess. You could also consider scavenging it.

 

[JLSeagull]

I have worked lots of very sour gas at lots higher pressure with carbon steel. However the NACE requirements recently changed. I regard 22,000 ppm H2S as very highly sour but still not like acid gas from an amine tower. You might consider welded connections for piping in this service. Even with welded piping connections I would expect plenty of NPS 1/2 threaded instrument connections.

 

[aka2]

ok, so I can use carbon steel. But I am not sure if carbon steel will resist this corrosive fluid. If you can help me please

 

[gr2vessels]

aka2,
There is no material imune to the corrosive environment. There is one consideration, which material vesus cost will resist longer. You can learn this easily and quickly looking up the NACE MR0175. Moreover, you should take the advices on this forum as indicative only, use them as guidance, not engineering decisions made by others for you. Remember, if anything goes wrong, you cannot blame a forum for your mistake. After reading the mentioned standard, you will be able to make your own decisions, based on engineering judgement and the depth of your pocket. However, we can help you to clarify issues in the standard you have read it.
best regards,
gr2vessels

 

[SJones]

http://www.google.com/custom?domain...000000;GFNT:0000FF;GIMP:0000FF;FORID:1;&hl=en

Steve Jones
Materials & Corrosion Engineer

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

 

[Unotec]

My company treats and dispose the produced water from wells like yours. For sour service we use carbon steel sched 80 (sched 40 for sweet service). We would like to use stainless steel but economics do not allow for it. We are prepared to replace piping when the time comes. However, the tanks, filter pots and such have chemical resistant coatings.

 

[aka2]

ok, thanks.
Any of you knows a "piping class" or "piping specification" for a gas facility with this characteristics

 

[SJones]

You have to select the material first!

Steve Jones
Materials & Corrosion Engineer

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

 

[mjpetrag]

For hydrogen, hydrogen sulfide and hydrocarbons with 400 psig, we use 600#RF 3/4" - 2" schedule 80 1-1/4 CR-1/2 MO alonized, seamless pipe in accordance with ASTM A335 GR P11

-Mike

 

[aka2]

Ok, We decided to use ASTM A-106 Gr B piping, sch 160 for 1/2 to 1", sch 80 for 1 1/2 to 6" and sch 60 for 8 to 16" pipes.
ASTM A-105 for flanges,
ASTM A-234 Gr. WPB for conections like tees, bends, etc.
I would apreciate your comments

 

[SJones]

What service life do you predict for this selection?

Steve Jones
Materials & Corrosion Engineer

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

 

[aka2]

Well, usually the design is for 10 to 20 years, but I dont know how many years will this system resist. If somebody can help me to answer this question I will apreciate it

 

[SJones]

http://www.google.com/custom?domain...000000;GFNT:0000FF;GIMP:0000FF;FORID:1;&hl=en

Steve Jones
Materials & Corrosion Engineer

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

 

[pipexp]

Please correct me if I am wrong. At ppm and total pressure i.e. for 22000ppm H2S and 400psi total, partial pressure works out to be 8.8 psi. Considering NACE MR 01 75 this seems to be very high corrosive condition. For analysis of the issue Ph of the fluid is also very important. But with the situation mentioned above i.e. 5.5% CO2. I would suggest UNS 32205 materail. With injection of corrosion inhibitor CS - NACE is also can be an alternative with respect to H2S.