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John Clarke · Joined: 19 Feb 2003 Posts: 1

I have a gas hot water heater with what I think are galvanized stubs sticking out the top. I had someone come out and replace the flex lines a few months ago. The flex lines are copper with copper nuts and a plastic or rubber inteface sleeve inside I assume to prevent galvanic action. They did not use teflon tape OR pipe dope! The joints have both been leaking and the water combined with the heat from the chimney has begun to corrode the outside of the galvanized pipes. I want to seal the joints properly and have tried teflon tape with no success. I have read about pipe dope and some places on the net have said not to use it here for some reason. I have also read that there are certain types to use when plastics are involved. I want to stop this leak and I think pipe dope is the answer. Could someone please help with some detail? Thanks.

ChrisR · Posted: Thu Feb 20, 2003 7:26 am Post subject:

I'm guessing from your words that you're in the USA? In UK, and surely there too we use a type of silicone a lot, like Fernox LS-X. Dow Corning make one too. These stick well, are neutral cure, and DO come off when you need to get them off! Alternative - LaCo make a goo/dope called Slic-Tite or someting spelled slightly differently, which is good for just about everything. Avoid the oil-based "Boss-White" variety of compunds, which can attack plastics and rubbers.

Having said that my first try would have been teflon/ptfe tape - sometimes you have to use a lot!

Just Bill · Posted: Fri Feb 21, 2003 11:28 am Post subject:

Teflon tape or Teflon paste lubricate the threads for a tighter connection, and fill voids. This should work if the nuts have not been cross threaded. There should be no problem with galvanic action. Are the plastic washers in place in the flex couplings???