6 replies to this topic

[J_Leo]

Hi There,

 

 

With my former employer, it was the metallurgist who guided the material selection for equipment and piping. With my current employer, basically the process engineers have to decide what to use for all equipment.

 

I am working on a gas plant project, with H2S 600ppmv, CO2 6mol% in the feed (1350psig). The amine system and NGL are by the licensers.

 

 

My understanding is the main corrosion within our scope would be H2S cracking. In the stabilizer feed separator (5 ft x 12ft) and overhead drum (1.5ft x 8ft), H2S in the gas reaches 1000-2000ppm with pressure around 130psig.

 

 

From NACE chart, the sour gas falls in the sulfide stress cracking region. Can I use KCS with 304SS lining inside the drums? For the small drum, is it better just to specify 304ss instead of lining?

 

 

Anybody can give me some info on material selection? Maybe base on the life span of the equipment and the corrosion speed per year. I have no any document on hand to use except a copy of NACE MRO175 which is difficult to understand.

 

 

Thank you.

 

Regards,

 

Leo

Edited by J_Leo, 24 April 2015 - 11:44 AM.

[Bobby Strain]

My suggestion to you is that your company enlist a metallurgist to make material recommendations.

 

Bobby

[srfish]

In the book " A Working Guide to Process Equipment", Lieberman has a short discussion on this problem. Perry's Chemical Engineering Handbook has a chapter on corrosion.

 

In my opinion 304 SS  is OK but 316 SS is much better.

[J_Leo]

Thank you, SRfish.

I have the perry's, I am going to take a look.

[kiansafaie]

Dear Leo
If you have trace of Cl2 in your feed, SS304 (nace) could not be resist to pitting and you should select SS316 (nace) instead of it. In general use of cladding with ss304 or 316 for top side of this separators with base material of carbon steel is common.
Thanks

[gegio1960]

leo,

in a competitive bid, the winning offer would be cs + ss304 clad + nace for both vessels... if client's specific requests don't overcome that.

more than a book, you should consult the standards of oil majors like saudi aramco, xom, shell, chevron, bp....

good luck!

[J_Leo]

Thank you all for your kind inputs!

 

Best regards,

Leo