CO2 or Crevice Corrosion

[Joss10]

Background:RTJ CS gasket, see pic attached, was found badly corroded upstream CS valve, grooves on CS flanges were not affected, this is the only part in CS rest is DSS.
Gas composition : 6% CO2 and 1% H2O, WP 140 Barg.

RTJ corroded : complete internal perimeter in contact with the fluid heavy corroded, some portion of the RTJ against the groove also fairly corroded.

Is it to be considered as CO2 corrosion, Crevice Corrosion or corrosion combination of both.

Thanks in advance for any input.

 

[harith07]

Hi Eva, what about Carbonic Acid attack? Possible at such a pressure and elements ratio? Not sure about the temp though.

 

[Joss10]

It is very possible since CO2+H2O=H2CO3

 

[rustbuster]

Pikotech has a solution to your problem.

http://www.gptindustries.com/product/vcs

Good luck

 

[SJones]

Strictly, it is classified as "flange face corrosion," at least it is if one follows the Energy Institute Guidance for corrosion management. However, the same document states that it is a form of crevice corosion. Overlaying the CS groove and changing the gasket material could be an option.

Steve Jones
Materials & Corrosion Engineer

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

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