I need to attach two male threaded attachments to each other and both are stationary (neither one can rotate). I bought a coupler with threads, but discovered that when one side tightened, the other loosened! I went to the Hardware store and was directed to a left/right coupler, but this one is a gray metal and the things I am attaching are 1/2" copper pipe and brass from a shower control section.
Is it acceptable to use these metals together and get a good water tight seal?