I am getting ready to remove our failed RV absorption refrigerator and cap the LP line. The local mom and pop plumbing supply store where I found the plug said not to use teflon tape on the threads. My jack-of-all trades neighbor who is helping me, said to use teflon tape. The Internet says to use Yellow Teflon Tape which is made for gas lines.
What is the correct and safest thing to do?
Thanks
Bob
If all you are doing is capping or plugging the LP line, then that's a flare fitting and no pipe dope is required. Pipe dope or the various flavors of teflon tape are for sealing the remaining spiral grooves in pipe fittings. You wold think that since the pipe fittings are tapered the space between the crest of one thread and the valley of the other would be filled up, but it doesn't work that way because steel is more elastic than rubber.
White teflon tape: Water
Yellow teflon tape: hydrocarbons
Red teflon tape: large pipe fittings.
https://www.lowes.com/pd/RectorSeal-No-5-Pipe-Thread-Sealant-Sealant/1087353
Flare fitting = no tape or sealer
Teflon tape is for pipe threads used anywhere else just makes a mess.
I try not to use teflon tape as when removing a fitting, little pieces get into the pipe and may find their way into regulators, etc. Teflon tape is the #1 cause of aircraft vacuum instrument failure with smoking in the cockpit #2.
I like the can with the teflon paste in it best.
Pierce
Having had a propane/natural gas license and running numerous gas pipe, everyone is correct. Nothing on Flared fittings and I like and use teflon paste. White teflon tape is for pipe an Yellow is for gas. Much easier to use the paste in my opinion. Just make sure you don't have any leaks when done. Check and recheck!
I agree about the paste. Replaced my LPG regulator 3 weeks ago and used paste on the pipe fittings. Checked with Camco LPG leak finder.
I switched to this stuff a year or two ago. Use it on any pipe threads, I haven't used tape for a long time,
Amazon.com: Rectorseal 31631 1/4 Pint Brush Top Tru-Blu Pipe Thread Sealant... (https://amazon.com/gp/product/B0012YO0Z4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1)
As a pipeline technician I've used literally miles of Teflon tape. I prefer the thinner tape. There are correct and incorrect ways to apply teflon tape. You want to wind the tape in the same direction as the threads. IOW the same direction as if you were screwing on a fitting. That forces the teflon down into each thread groove. And you need to make sure there is no tape over the opening of the fitting or pipe.
I know some of yall like the paste and it does work good. But once it dries if you have to tighten the fitting again to stop a leak it will probably just make the leak worse.
And here is a picture of a gas pipe we removed from my son's house, his BBQ wasn't getting as hot as he'd like. Yep, that's a dried glob of paste partially blocking the pipe.
The paste is supposed to go on the male threads and not down in the female side. Who did this work? If the paste is on the male threads, there will be zero down inside.
Pierce
I have found teflon tape fails quite often especially in pipe 1 inch and over. I never had
a failure with pipe dope. I mostly use both but if I only use one it's pipe dope.
I always been a fan of the thread sticks, been using them for over 40 years with no issues. Water, Air, Gas, etc. Just make sure you keep the sealer away from the last couple of threads inside to keep it out of the pipe.
Ace Natural Pipe Thread Stick 1 oz - Ace Hardware (https://www.acehardware.com/departments/plumbing/solvents-and-cements/plumbers-putty-and-sealers/40968)
I use Gasoila on all threaded connections. Was recommended by my son that works in the propane industry. As for flare fittings. Most flare fittings in the US today are made in China. The quality varies widely. When I installed gas shutoff valves in each seperate gas line in my coach I found that some new fittings leaked. I applied a small dab of Gasoila on the male portion of the flared fitting to resolve the leaks. Gasoila does not dry and stays flexible.
I use Gasoila on all liquid fittings. The stuff is amazing. Also sticks to clothes and cannot be removed. Very difficult to get it off your skin also. Don't ask me how I know that.
Roland
But you can use a sealing washer made for flare fittings. Should be tossed after use because they work harden when tightened up. The copper ones can be annealed. Just thought i would throw this is to the mix.
SFG-3 by TRAMEC SLOAN - 3/16" 45° Flare Gasket (https://www.finditparts.com/products/2041016/tramec-sloan-sfg-3?srcid=CHL01SCL010-Npla-Dmdt-Gusa-Svbr-Mmuu-K2041016-L164&gclid=CjwKCAiAh_GNBhAHEiwAjOh3ZD0PO9zJdX8C8q2nJ7WCGhfks7QhoQvfmArVidKaWXL3xlOiNa3aURoCLSoQAvD_BwE)
Used those on liquid Oxygen, Nitrogen and Hydrogen at Rocketdyne on the rocket engines. They were called Voi Shan's at that time
BS (before Scott ) my father worked on rocket sleds in Hurricane Utah. Closed down in 1962. Had lots of stories of supersonic monkeys and Beagle dogs. Often the steel brake scoop would shear off and launch the sled off the end of the mesa. Wish I was electronically as smart as him. Full size remote controlled helicopters, but not wireless. Big difference between jet engines then and rockets. Cool stuff for sure.
Hurricane Supersonic Research Site - Wikipedia (https://en.wikipedia.org/wiki/Hurricane_Supersonic_Research_Site)
Scott