Di-electric nipples

[MasterPlumbersKeymaster]

There are di-electric nipples sold that are basically galvanized nipples with a plastic insert. How does this stop dielectric action because you are still making a metal to metal connection of 2 metal that do not get along with each other?

[DUNBARParticipant]

Even as a plumber, I am stumped on this question.

Any time I run into using a tank with these already installed, I still use female dielectric unions to separate the metals.

It is still a connection directly into the water heater and there is dissimilar metals like copper to galvanized which can trigger galvanic action.

[nicktheplumberParticipant]

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In reply to message posted by flockheart:
There are di-electric nipples sold that are basically galvanized nipples with a plastic insert. How does this stop dielectric action because you are still making a metal to metal connection of 2 metal that do not get along with each other?

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There are two effective ways to join ferrous and cupric metals together to minimize electrolysis. One method is to use a fitting with a non-conductor (plastic non-metal) buffer material between the cupric and ferrous pipe. These are the “dielectric” unions. The second method is to use a low-zinc content brass nipple, which should be at least 6″ in length. You could also use a plastic fitting (such as PVC) to connect the Fe-Cu pipes, which might be good from the electrolysis point of view, but might not be mechanically strong.

[SelgasParticipant]

Nick

Well answered I take my hat off to you.

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Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

[AquamanParticipant]

Metals have a level of reduction from strongest to weekest or fast to slow. You are trying to separate the two opposites with two that are closest, to slow down the reaction. We have found in the pump business that simply wraping the union with good electrical tape considerably reduces the reation time.

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