bolt and nut marterial for valve

[farhad2474]

I will appreciate some body answer my question .i have stainless steel valve with body AISI 316SS.they use A193 B7 and A194 2H for bolt and nut in this valve .i think they are wrong. they should to use A193 B8M and A194 8M. Am I righ
best regard
farhad

 

[gr2vessels]

farhad,
The short answer: it depends. If the environment is corrosive and salty, rainy sea shore location, you could see your carbon steel bolting corroded prematurely. If not, then B7 is fine. You could ask the B7 bolting to be PTFE coated. It is however, nothing wrong using B8M (S/S 316) bolting, except a bit expensive. I would use B8M bolts for the peace of mind.
cheers,gr2vessels