From reading this forum I only use pipe dope when connecting metal FIP to MIP joints.

But when I remove old valves I noticed residues on other types of joints. I noticed some plumbers put dope on the threaded connection of compression angle valves. I also noticed dope on water heater hose connections and washing machine hose connections where there is already a washer there to provide the seal. Are these situations proper use of pipe dope? They shouldn't be necessary right? So by using it does it make a better sealed joint or no?



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I can remember a few times that I've had a slight drip on a compression ferrule on copper tubing, the application of a bit of pipe dope stopped it.
It's more of a lubricant than sealer when used on compression connections.

i automatically apply plumbers grease to compression fittings..

quote; So by using it does it make a better sealed joint or no?

It does do anything to HELP seal the joint, but it probably deteriorates any rubber seals, and gaskets, it is applied to.

I take them out of the bag, slide them on to the tubing, and tighten them up.

I apply dope to the ferrule and the top of the threads for lubrication, not water tightness.

not necessary

a dab of plumber's grease on the threads maybe if old fitting for lube only

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