I recently had to redo the piping coming out of my water heater and there
were several joints in the iron pipe that I couldn't get to stop leaking
when using the teflon tape. I got some of the dope with teflon in in and
that finally stopped the leaks. If you look at what happens to the tape
when you tighten the joint you can see that it gets cut to shreads.
Lubricate, maybe. Seal, no.

wrote in message
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On Sun, 19 Aug 2012 22:40:35 -0400, Wayne.B
wrote:

Any marine plumbing experts here?

I'm in the middle of a small plumbing job involving the salt water
cooling loop for the air conditioning units. I'm planning to use PTFE
(teflon) tape on the pipe threads. Are there any issues with that as
opposed to using joint compound goop that anyone knows of?

If you use pipe dope, be sure it is OK for plastic (assuming this is
PVC). I have some teflon laced pipe dope that works great on plastic.

In both cases, this is really a lubricant more than a sealant. It is
the thread to thread connection that does the sealing. The dope/tape
is just there to prevent galling.