I noticed a 1" black pipe gas union was doped in my basement. The 1/2" union on my furnace is doped. However, the 1/2" union on my water heater is not.

I always assume pipe dope on a union, esp gas, was a no-no.

Is this something I should be concerned about?

only be concerned if it is leaking..

It's the way I ALWAYS do it. Nothing to worry about. IT makes them seal better.

ground joint bronze on bronze makes them seal better

a/k/a 'old style' Dart

before the age of junk


unions do NOT require pipe dope as they are a MECHANICAL seal (a little neva-seez on the mechanical threads and bearing surface does not hurt - NONE on the mating surfaces, but make sure they are clean and 'nick' free)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The
mating surfaces could have imperfections so dope on them helps them seal better also.

I lightly dope the male face.

i grease the unions behind where the big nut contacts one end. reduces drag as the nut is tightened.
DOD 1963 recomendation..

Quote

The mating surfaces could have imperfections so dope on them helps them seal better also.

If imperfect or 'nicked' the union should NOT be used at all, ESPECIALLY on flammable gas.

? Can we not see 20/20 ?

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

quote; imperfect or 'nicked' the union

NOT "imperfect or nicked", just the machining process.

purchase better ASTM compliant unions

for gas

either

steel

or

ground joint malleable

forget

the inexpensive junk

IF YOU NEED DOPE TO SEAL -> by definition = junk

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638