HELP!! PVC Pipe (Threaded)

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Gambusia
MFK Member
Apr 22, 2012
15
3
18
Los Angeles
I'm using a few threaded PVC parts for my filtration.

Does any one know if you have to use PVC cement on threaded PVC pipe? I've
heard yes and no. Some state that the cement melts the threads and causes
failure so some type of PVC sealent should be used instead. Is that true? I've
also heard not to use pipe tape as that is for metal pipes not PVC.

Any Thoughts?
 
i've used teflon tape for around 3 years now and i still do for some applications, like for bulkheads and valves. heck i even get an occasional cement joint leak.
 
No, don't cement a threaded fitting - cement is really only intended for slip fittings. As you noted, cement will melt the threads. Also, the cement will start to set up as you are tightening the fitting and you are probably going to end up either not being able to screw in the fitting completely or breaking and weakening the newly-formed bond as you apply more pressure to screw it in.

Silicone is also not a great idea. The problem is that silicone doesn't have the ability to self-repair if the seal gets disrupted. It will work fine as long as you allow it to set up and then never disturb the fitting, but if you do end up twisting or bumping it you can end up shearing the silicone resulting in leaks.

Teflon tape works, but I've had the best luck with some sort of teflon/PTFE paste. It's a little messier to apply but more foolproof than teflon tape. Just spread a nice even layer on all the threads and don't over-tighten your fittings.
 
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