When I was moving my washer and dryer to a new location I was
surprised to find *no* joint compound or teflon tape in two places
where I would have expected it. 1. The connection between the flexible
gas line at either end - the dryer and the gas pipe. 2. At either end
of the washer flexible supply hoses.
Should there be dope on any of those threads? I have not been able to
find a definitive answer.
Many thanks in advance,
"Joint compound" isn't the material you are talking about... You are
about "pipe thread dope"..
Dope is used ONLY where the threads are the point of sealing. It
fills in the
voids and makes the thread to thread joint airtight...
Gas lines are pressure fitted by smooth mating surfaces .
No thread dope is used because the threads
are not the place where the seal occurs.
Washer water hoses are gasket fitted. A rubber washer does the
with a pressure fit... No thread dope is ever used...
Using thread dope in either of these applications will probably
the ability to seal, because they are a foreign substance which coats
surfaces that should NOT be coated with anything...
Are you sure?...
I happened to be watching one of those Saturday morning shows that are
heavily sponsored by home depot and they carefully applied dope to all
threaded surfaces on a gas line appliance connection including the nut
on the supply line. So that must be the right way...
Andy's description of the different sealing mechanisms is 100%
Pipe dope / teflon tape are needed only when the thread to thread
contact are the actual sealing mechanism..
Connections where rubber washers, flares or compression ferrules do
the sealing, means no dope or tape.
But I've seen a lot of plumbers use dope on flares & compression
ferrules......because using dope makes the initial fit up less likely
So despite the fact that dope should not be used....it often is.
Nope. The gas line is a flare fitting and the water hoses have washers.
NOW , having said that, a little antisieze or pipe dope may prevent those
threads from sticking and rusting together. But for a seal, it's not
I can't address the gas lines, but why tape the feed lines? They are
just garden hose fittings, including the rubber washer. I've never seen
one leak if undamaged. The hose bursts, or the packing on the wall valve
starts dribbling, but the screw-on, never.
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