35CrMoA and 30CrMoA are the materials used for matching bolts and nuts; are they stainless steel?
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Since my flange is made of stainless steel, the site requires that the bolts and nuts also be made of stainless steel 304. Will the 35CrMoA/30CrMoA material I have chosen meet this requirement? The temperature and pressure of the pipe are not high; it’s just that the medium flowing through it is corrosive. Thank you!
35CrMoA and 30CrMoA are low-alloy high-strength steels, not stainless steels. In the case where the flange is made of stainless steel, the bolts and nuts do not necessarily have to be made of stainless steel as well. When the pressure is relatively low and the environmental corrosion is severe, stainless steel should be used for bolts and nuts ； If the environmental corrosion is not severe, carbon steel can also be used for bolts and nuts. When the pressure is relatively high, carbon steel bolts and nuts still need to be used.
Since the site requires that the material of bolts and nuts be stainless steel 304, why was 35CrMoA/30CrMoA chosen? If the flange is made of stainless steel, it is best to use stainless steel bolts and nuts as well. Or at least use double stainless steel gaskets.
I don’t know if the bolts/nuts are made of stainless steel How to enter it in the material list? Could it be written down?
It is sufficient to specify that the material of the nuts and bolts is 304.
If stainless steel flanges are used with low-alloy steel bolts, care must be taken to prevent pitting corrosion of the bolts.
If standard parts are used, bolts and nuts can be A2-70 (or A2-50), and washers can be A140.
If it’s from the Ministry of Chemicals, 304 material can be specified; for American standards, use ASTM A193 B8 for bolts and ASTM A194 8 for nuts. It’s still 304 material, but its properties are determined according to the ASTM A193/A194 standards. A2-70 can also be used for small bolts and small hex heads; however, it cannot be used for bolts used in pipeline flange connections