What kind of bolts are good for use in oil production wells?
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At a depth of about one kilometer underground, the pipe material is 25Mn2. Initially, ordinary bolts of grade 10.9 were used for the flange connections, but later it was decided to switch to 17-4PH (0Cr17Ni4Cu4Nb), which is a precipitation-hardening stainless steel. But I heard that mixing different steel grades can accelerate corrosion, and now I don’t know what to do.
Then what about using 17-7ph?
There are problems when ordinary carbon steel comes into contact with stainless steel, especially in water-containing environments with high temperatures underground, where carbon steel will corrode. Can the bolt be replaced with an alloy steel whose composition is similar to that of 17-4 precipitation-hardening stainless steel?