Considerations on wet hydrogen sulfide corrosion in pipelines of methanol washing units
Thread Content
I would like to ask everyone: how is it determined in a methanol washing unit whether a pipeline is subject to corrosion in a wet hydrogen sulfide environment? Should NACE or HG20581 be used as a reference? How should pipelines in media containing methanol rich in H2S (with trace amounts of water) at low temperatures be considered?
It is mainly hydrogen corrosion; the material can be selected based on the hydrogen partial pressure. Wet hydrogen sulfide is quite problematic, but alloy steel P11 and stainless steel 321 can both be used. If carbon steel is acceptable, then it’s necessary to consider increasing the corrosion allowance. Both the yield strength and tensile strength of the material are required. Good post, don’t let it get buried!
This post was last edited by dragon__x on 2012-4-26 22:40. Does the previous comment refer to the partial pressure of hydrogen sulfide? If the temperature of the pipeline is below 0°C, with only trace amounts of water present and a high partial pressure of hydrogen sulfide, exceeding 0.00035 MPa, does this constitute wet hydrogen sulfide corrosion? A methanol solution containing H2S at very low temperature (with trace amounts of water)? Personally, I think both of these cases fall under wet hydrogen sulfide corrosion; I’m not sure if that’s correct
With the hydrogen partial pressure, it’s possible to find the appropriate material using Nelson plots........
The Nelson curve refers to hydrogen damage; it occurs only at temperatures above 200°C, and it is not the same as wet hydrogen sulfide. . . .
This post was last edited by 19751107w on 2012-4-27 at 10:17. Oops, I didn’t notice the temperature you mentioned... If the design pressure of the pipeline isn’t high, I think carbon steel seamless pipes will suffice; post-weld heat treatment is necessary! A corrosion allowance of 3.2 for the pipeline is sufficient! When the material is determined using the hydrogen partial pressure, the Nelson curve is indeed used as a reference. Hydrogen sulfide corrosion is actually mainly hydrogen corrosion~
Theoretically, dry hydrogen sulfide is non-corrosive, but is an environment with trace amounts of water considered a wet hydrogen sulfide environment?