Can 304 be used as the casing for filtration equipment when natural gas contains 5% hydrogen sulfide?
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Is 5% hydrogen sulfide in natural gas highly corrosive to 304? The temperature is at room temperature. I checked NACE MR0175; 304 stainless steel meets the requirements, but is it safe? How fast is the corrosion rate generally? Thank you all for your guidance! ! !
H2S corrosion is a type of stress corrosion that causes brittle fracture without any prior signs; the corrosion rate is not a suitable parameter in this case. Additionally, normal temperatures facilitate the presence of liquid water, thus creating the conditions for such corrosion to occur. There is disagreement regarding whether 304 is safe against H2S. A senior engineer in equipment development who was involved in the formulation of HG/T 20580–20585-2011 knows me, and he believes that 304 is suitable for use in environments with sulfur ； However, two years ago, experts from the expert panel responsible for the certification review of pressure pipelines believed that 304 steel was less resistant to H2S-induced stress corrosion compared to normalized 20 steel... I personally agree with the latter view, as I have heard of instances where 304 steel suffered damage due to H2S stress corrosion on more than one occasion; in all such cases, it was attributed to quality issues with the material itself... It can be said that there is indeed a risk involved, but the key lies in controlling it.
If stainless steel is to be used, which type would be more suitable? Or, as you suggested, normalizing the 20 steel and then applying surface galvanizing, or using a coating – which option is more suitable?
Agree with @Yimi’s opinion. In many cases, the usability of the material itself is not an issue; the problem arises when the purchased material does not meet the required quality standards, leading to frequent accidents or problems. In such situations, it is better to consider that such material is unusable and to reject that option outright.
First, one needs to look at the degree of dehydration, that is, the dew point temperature. Let’s talk about the material selection after checking if there’s water.
Since it is used as material for filter housings, the gas already undergoes primary filtration before passing through the filter; the filtered gas can be used in vehicles and similar applications, so there should still be some water molecules in the gas after primary filtration