H2S pipeline material
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Medium: H2S 0.23%, CS2: 0.35%, COS: 90 ppm, O2: 19.67%, N2: 74%, H2O: 5.74%； Temperature: 35°C, pressure: -3 kPa. Now we need to select a pressurization fan. I would like to ask the experts: what material should be used for the fan’s impeller? Can the pipeline behind the fan be made of carbon steel? Thank you
Carbon steel cannot be used; carbon steel and low-alloy steel are most susceptible to sulfur cracking in the temperature range of 20–40 degrees. The susceptibility of austenitic stainless steels increases as the temperature rises
But isn’t it a problem either if the hydrogen sulfide content is very low?
Due to the water content in your composition, H2S will cause relatively severe stress corrosion under these conditions. Carbon steel materials need to be treated with acidic gases before they can be used; this is just my personal opinion for reference only!
So the impeller material of the fan also needs to be stainless steel?
Obviously, with the presence of chloride ions and a typical acidic environment, nickel-based materials could be an option for pipes; you might consider 825 or 625.
H2S decomposes into hydrogen ions and hydrogen sulfide ions; the hydrogen sulfide ions then decompose further into hydrogen ions and sulfur ions. This approach is acceptable when the concentration of hydrogen sulfide is low, but with a temperature of 35 degrees, it’s too sensitive, and therefore pipes made of this material cannot be used at such temperatures.
Fiberglass can be used; under these medium conditions, fiberglass works perfectly fine
Fiberglass, PTFE, PTFE-lined pipes, and composite pipes can be used
It is recommended to use steel-reinforced plastic composite pipes, which can last up to 50 years and are resistant to corrosion by chloride ions and hydrogen sulfide. Moreover, the overall cost is low.
After the fan increases the pressure, it is around 14 kPa – can carbon steel be used at this pressure?