I just installed an English bar in my basement and was hooking up a water line this evening. Before connecting two CPVC water pipes, I wrapped the threads with 2-3 wraps of Teflon tape, making sure I wrapped it in the right direction. After that, I tightened the connection quite well. After connecting, the pipe dripped–just a tad.
I started from scratch, using new tape. The pipe still drips, but just barely.
Should I be using the pink, heavy-duty Teflon tape instead of the white? Should I be using Teflon tape at all? Someone told me that no Teflon tape is needed if connecting two plastic plumbing parts.
I’m not sure about the rules about plastic pipe but I’ve asked the pros about the merits of teflon tape versus pipe dope and they say they use both because they hate going back. So for me, it’s two or three turns of the teflon tap and then some good pipe dope.
Plastic pipe uses two types of connections. One is just a slip fit on which you put primer followed by platic cement. The other is a standard pipe thread fitting that takes a joint sealer of some kind to prevent leaks. Teflon tabe is one of the sealers and some, but not all, joint compounds are for use on plastic pipe.
I’ve had good luck with teflon tape on plastic pipe, but it’s tricky to work with. Not tight enough and you have a leak, too tight and you crack the female fitting (and have a leak). If possible, I’d use glued fittings, or transition to copper with a male PVC adapter and a female copper fitting, though this is less than ideal.
I have used pipe dope and PTFE tape on pvc and metal fittings with varying degrees of success. IME, a good pipe dope with sintered PTFE works better than the tape, but it can be very messy. The tape is more convenient, requires no clean up and won’t leave goopy messe in the bottom of your tool bag. Before you run out and buy a tube or can of PTFE pipe joint compound, try using more tape. Clean all the old tape off of the threads and wrap it 5 or 6 times at least.
The first time I saw PTFE tape was in the Navy in the late 70’s. Only then it was called anti-sieze tape and was used to prevent galling of threaded parts. We never used it for joint sealing at all. Maybe that explains why it doesn’t seem to work as well as the pipe dope.
Teflon’s actually not recommended for CPVC. Also, I’m not sure what you’re actually connecting, but many plumbing codes prohibit female-threaded PVC or CPVC fittings at anything over 1 PSI as the fittings have been found to crack as the water pressure presses outward on the fitting. The added bulk of teflon in the joint will only hasten that process.
The recommendation is to use metal female-threaded fittings, and to be sure that any sealant or dope used is compatible with CPVC.
Wait, I thought PVC/CPVC fittings–female or otherwise–are nearly universal. They are where I live and I think the trend, nationally, is toward plastic, not away.
>> Can anyone tell me if “pipe dope” is reversible?
Reversible, as in you can unscrew the connection? Sure. Might not be the easiest thing to clean off, though.
As for plastic being a trend, I don’t know that one. Some municipalities around here are just figuring out that a house won’t explode if PVC or ABS is used for the sewers. Copper is generally required for water, steel/cast iron for sewer. There are even some spots that require copper for sewers. I understand that’s mainly a move by unions to preserve themselves as not too many do-it-yourselfers can sweat 4" copper.
[hijack]
Have you ever checked out the rigid pro-press system? Fittings cost 2 to 4 times as much as sweat fittings but the pressing of the fitting is performed quickly, and can be done with wet pipes.
I assume you are refering to PVC drain and waste lines. These should be cemented with PVC cleaner & glue/cement.
The new high pressure plastic water supply tubing still uses metal connectors/fittings where the use of teflon tape simplifies joint make up. Neve use the gray pvc plastic for supply lines. It will eventually rupture with disasterous consequences.
No, I’m working on my fresh water lines. In doing so, I’m installing two items: a lever water cutoff switch (brass) and a dual backflow device (brass)–connecting both to THREADED CPVC (FlowGuard gold) connectors using 2-3 wraps of white Teflon tape. No glue. That said, I did use the appropriate cement when connecting two segments of CPVC but, again, not when connecting brass female ends to male CPVC parts. (I want the joints to be reversible, as these units need new seals, every few years.)
BTW, I read on a plumbing website that the pink Teflon tape is thicker, “thus ensuring no leaks.”
Lowe’s and Home Depot has a huge inventory of PVC and CPVC connectors. Very little with metal fittings.
A millwright once told me teflon tape was first developed as a “thread lubricant” for use on auto assembly lines to prevent galling when threading hydraulic fittings together. His opinion of ptfe as a thread sealant was no less than a colorful diatribe ending with Rectorseal #5, or equal, as the only thing a “real” pipefitter/plumber would use.
In years since I’ve used PTFE when nothing else was available and the results have been mixed. On properly manufactured fittings where thread engagement (that which really seals tapered pipe thread) was proper, no problems. With cheap imports all bets are off. Never been disappointed with #5. Get some!
