I have a small modification that I want to do to the end of a gasline. It looks like it will be very easy but I have a couple of questions.
1) Do you dope both mating surfaces?2) When installing a T or a valve,do you fully tighten the fitting, then back it off a few degrees to its final position
Thanks in advance, As a carpenter, I make a great plumber NOT.
Thanks for giving the city you live in. I'll sleep better knowing you're not going to blow up the house next to mine.
Great info for amateur gas installers:
No, Dope male threads only.
NOOOOOO. Never back off a fitting or What have you, fully tighten to its final positon!
Also, make sure you leak test!
Dean
Couple of observations on homeowner jobs using cheap materials from Home Depot etc.
Beware of poorly formed threads, burrs, oil. Remove oil with solvent and a toothbrush if necessary. Forget "hand tight" plus 3 turns as cheap fittings may not freely turn at all. Don't hesitate to toss out (or return) a part that looks questionable.
A conservative practice is to use an acid brush to carefully dope the inside threads (rectorseal #5), working it in evenly everywhere. Then a couple wraps of yellow gas tape on the male threads. Then tighten to a couple turns past where the resistance to turning with a wrench starts to pick up. If it doesn't feel tight enough when you stop with the fitting in the right position go around again. Don't back off, if you do then take it apart, clean up and start over again.
Beware of over-threaded pipe ends and poorly cast street fittings that bottom out before the threads draw up tight.
Use a reasonable size wrench like a 14" for 1/2" and 3/4", and a 24" for 1" pipe, to make it harder to under or over-do it.
Don't re-use fittings esp. unions (outdoors only!) and gas connectors.
Pressure test, or at the very least use leak test liquid, and use that anyway on the parts of the system that can't be pressure tested like appliance connections.
This advice may sound silly and wasteful to a pro who has a well-honed "feel" for everything, but following it makes it hard to screw up.
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