Actually it does both. A tapered pipe thread is by definition a "dry seal" joint - but in practice it is imperfect. The tape "flows" to fill imperfections in the joint as well as functioning as a low-friction "lubricant" to allow the two parts of the joint to turn together without galling. If ALL it did was provide the low friction, common EP Grease would do the job - and it does NOT.
That sounds reasonable to me.
That's not what I wrote. The tape mechanically forces the threads to seal. Grease would simply flow out of the joint.
Grease would never all flow out, there would be at least a thin film remaining. And if the sole function of pipe dope or Teflon tape was lubrication, then grease would work. It sounds logical that the threads are not perfect, will have imperfections and pipe dope or tape in addition to lubing helps fills those voids.
It forces the thread to seal by filling tiny gabs - ie - it is a SEALANT.
If you proper use tape, it's all you'll need.. Most people, I say most because of whom I've witnessed using it, usually just wrap and screw on the end... But by taking your fingers and smashing it into the threads like your screwing in a imaginary end cap in the same direction you wrapped the tape, you tend to force them down into the threads and that gives a way better seal. I always tend to wrap at least 3 times around the pipe, depending, it is also possible to wrap too much as it will get pushed backwards but if you do a good smash, it's less likely and harder for that to happen.. Always clean your connections too... Reason why certain products don't work is because even the oil in your fingers can keep it from sticking or sealing... Many times I used items like JBWeld when I was younger and due to impatience, I'd skip cleaning and 99% of the time, the bond would fail because of oils or other contaminants on the items to join or it wasn't abrasive enough to grab onto something. Glues like that are best when you scratch the surfaces lightly with a low grit. it wasn't until I worked for a large sign company that used to make the huge signs of a business, one of them had a piece of angle iron simply epoxied to another thin piece of metal.. Using acetone cleaner and scuffing, you could pick up the whole sign (several hundred pounds) right up with a skylift and it wouldn't give... When you see things like the flex tape boat on water not leaking, that's guaranteed a professional cleaning and scuffing job than it is the tape to make that happen... I know I type too much.. so I keep typing and say both is ok if you properly prep, I use tape cause it's less messy and inexpensive comparatively...
I only do this for myself at home, but for gas pipe tapered threads, I have used only Pro-dope for years and years, with no evidence of any leaking. Used it on 1/2", 3/4" and 1" pipe. Applied to male threads only, per code. And made connections as tight as I could. And believe me, I take the dangers of natural gas very seriously, so I've checked and re-checked for leaks for weeks after installation.
Recently discovered a tiny leak in they threads on a utility side gas supply pipe fitting that even the gas company didn't detect. It generated a small "bag" of tiny bubbles after a soapy-water spray. Took a couple of DAYS to notice it - could not even smell gas, the leak was so small, but the utility did of course fix it. I am not sure what sealant was used on it - the fitting hadn't been touched for over 10 years, and might have been leaking for that long - but it was not Pro-dope; that I could tell.
I only do this for myself at home, but for gas pipe tapered threads, I have used only Pro-dope for years and years, with no evidence of any leaking. Used it on 1/2", 3/4" and 1" pipe. Applied to male threads only, per code. And made connections as tight as I could. And believe me, I take the dangers of natural gas very seriously, so I've checked and re-checked for leaks for weeks after installation.
Recently discovered a tiny leak in the threads on a utility side gas supply pipe fitting that even the gas company didn't detect. It generated a small "bag" of tiny bubbles after a soapy-water spray. Took a couple of DAYS to notice it - could not even smell gas, the leak was so small, but the utility did of course fix it. I am not sure what sealant was used on it - the fitting hadn't been touched for over 10 years, and might have been leaking for that long - but it was not Pro-dope, and it was certainly not teflon; that I could tell.
FYI this is a bit ott-topic, but for water pipe tapered threads, I have also typically used only Pro-dope,. But recently I had a PVC water pipe tapered fitting not stop leaking until I used a combination of teflon tape and Pro-dope. Go figure.
FYI this is a bit off-topic, but for water pipe tapered threads, I have also typically used only Pro-dope,. But recently I had a PVC water pipe tapered fitting not stop leaking until I used a combination of teflon tape and Pro-dope. Go figure.
FYI this is a bit off-topic, but for water pipe tapered threads, I have also typically used only Pro-dope. But recently I had a PVC water pipe tapered fitting not stop leaking until I used a combination of teflon tape and Pro-dope. Go figure.
There is a tape made for gas lines. It is yellow in color. I've used it at home and we've used it at work for some 4" gas lines with higher pressure and never had a problem.
We also used Pro Dope in another section. That worked also.
Either one done right works. No short cuts and you will be good.
It's good that we have choices in these things, and are allowed to have our favorites. As usual, be safe!
Chinese PVC. Maybe you shoulf have just used PVC cement - - -
Yup pasting up a threaded PVC fitting should do it.
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