Unions and Pipe Dope/Teflon Tape

[Smith Mcmahon]

A couple quick questions. 1) what are the proper areas to apply pipe dope on a union? The threads? The machined face? 2) My builder (not a licensed plumber)uses teflon tape followed by pipe dope on any metal thread. Is this overkill? He says it helps it install easier. 3) My water heater fittings first go to a galv nipple, then to copper. Is this going to cause any kind of dissimilar metals problem?Thanks, for any help.Kris

[Kris D. ThompsonParticipant]

2) Generally using both is overkill but once in a while can save a lot of labor so many experienced quality oriented plumbers do so (and so maybe not a bad idea). 3) YES, a steel (glass lined tank) with galvanized nipples connecting to copper flexes and then copper pipe IS a di-electric situation. Is it a problem? Really depends on your water, etc. Using di-electric unions or a copper flex (which most of the time has fittings that will break the electrical current) is STILL not enough to not have any di-electrical problems in many conditions. Some waters are worst than others. I ALWAYS recommend using quality stainless steel flexes between the galvanized nipples and the copper pipe.

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