Re: Pipe dope on union mating surfaces?
Posted by dick on April 20, 19100 at 10:08:08:
In response to Re: Pipe dope on union mating surfaces?
Got carried away explaining how they work and forgot to answer your question. on pipe unions. on the threads, always apply a lubricant and (on iron) anti galling agent. This can be a pipe dope , teflon tape, grease or some combination. On the sealing surfaces, most of the time nothing is absolutely necesary, but, It is good practice to apply some grease or DOPE THAT DOESN'T CONTAIN BIG CHUNKS. The grease or dope will help slow down corrossion at the sealing point. and will help the seal a little if you don't get enough torque into it.

: I (a civilian) got a lecture from an experienced plumber the other day that the proper procedure for using copper unions was to apply pipe dope to the WHOLE fiting - threads, friction surface (where nut turns) AND on the mating surfaces.

: Being a civilian, I had never used pipe dope on a union, and in particular, felt that the the nature of soft metal would have the union seal better with no dope on the mating surfaces.

: So, what is good practice with unions? Is there an definitive reference on this in some plumbing standards manual?

: Just curious.

: David

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