We're in the middle of a turnaround at our plant and a question came up about bull plug metallurgy on low point and high point 3/4" stainless steel gate valves. Our contractor installed threaded stainless bull plugs in stainless gate valves for the hydrotest.... these plug were round head and our standard is to use hex head... in the process of replacing these with hex head plugs, the threads were found to be galled.

We are thinking of going with carbon steel hex head bull plugs regardless of the material of the low point/high point gate valve to reduce the risk of galling threads. Does anyone have experience with this or have any thoughts on this?