New plumbing leak

Texas Reefer · Jun 11, 2017

I'm water testing my new frag tank and the only leak is coming from the union of the bulkhead to PVC. Should I use plumber's tape on the threads?

Rufus’ goofs · Jun 11, 2017

That's all I've ever used on threads. If you're really worried about it you could get a slip bulkhead and slip x threaded street 90, but even in plumbing, we just tape the threads. The pipe dope is just for lubrication, the tape makes the seal.

jsker · Jun 11, 2017

I have used this in the past and it work well. link

Texas Reefer · Jun 11, 2017

Ergodyne said:
That's all I've ever used on threads. If you're really worried about it you could get a slip bulkhead and slip x threaded street 90, but even in plumbing, we just tape the threads. The pipe dope is just for lubrication, the tape makes the seal.

Thanks! I've got some on hand.

Rufus’ goofs · Jun 11, 2017

Just my 2 cents, on plastic I like to do at least 10 or 12 wraps with the T tape. Metal you can get away with half that.

Also don't crank the plastic to tight. Hand tight is usually pretty good. You can even stop a little shy as long as it's stiff and the tape has made a good seal in between the fittings.

Sleepydoc · Jun 11, 2017

You should use a non hardening thread sealant on threaded fittings like this or this. Thread sealants do a better job of filling voids than teflon tape. Put it on the male threads.

To echo what Ergodyne said, hand tight + ¼ turn is what I've always used. Especially with ABS bulkheads, over tightening will cause the female fitting to crack. Teflon tape can lead to over tightening as it does a better job of lubricating the threads than sealing them.

Rufus’ goofs · Jun 11, 2017

Sleepydoc said:
You should use a non hardening thread sealant on threaded fittings like this or this. Thread sealants do a better job of filling voids than teflon tape. Put it on the male threads.

To echo what Ergodyne said, hand tight + ¼ turn is what I've always used. Especially with ABS bulkheads, over tightening will cause the female fitting to crack. Teflon tape can lead to over tightening as it does a better job of lubricating the threads than sealing them.

Personally I wouldn't use either of those on an aquarium. They're non toxic, and safe. But I wouldn't use it. Also, I disagree about the teflon tape being a better lubricant than sealer. Go get a garden hose. Test it with T tape, just dope, as well as T tape and dope. The dope will not hold a seal for very long. They're are higher qualities sealants, but they're just timebombs for leaks. Further more the teflon tape provides more resistance against the threads than the dope but it becomes noticeable when working with metal. I think it would be more than adequate as well as more reliable to use to teflon tape.
Teflon tape is not a lubricant. Telling tape IS the seal for threaded fittings.

mfinn · Jun 11, 2017

Ever since I cracked ( broke loose in the middle of the night) a threaded fitting, I've used thread paste.
There are a couple designed for pvc threads.

Ubergroover · Jun 11, 2017

just my .02...been a tradesman for 30 years. used every kind of teflon/plumbers tape and pipe dope. pipe dope needs a curing time some quicker than others. teflon tape will split PVC if you over tighten. for me, tape. tighten it until it snugs then another 1/2 turn. 5-8 wraps in the same direction as the opposite fitting.never had a leak. Pipe dope works great dont get me wrong. personally dont like on platics...

Sleepydoc · Jun 11, 2017

A threaded hose connection is completely different from NPT threaded connections (well, except for the fact that it's threaded.) Lasco and multiple other sources I've read recommend non-hardening thread sealant for PVC connections. (non-hardening sealant does not need to cure.) The second link below has a nice explanation.

http://www.lascofittings.com/threads
https://www.linkedin.com/pulse/what-thread-sealant-use-pvc-fittings-larry-workman

Edit: I should also clarify that you need to use a sealant specified for use with PVC; not all sealants are the same.

Ubergroover · Jun 11, 2017

Sleepydoc said:
A threaded hose connection is completely different from NPT threaded connections (well, except for the fact that it's threaded.) Lasco and multiple other sources I've read recommend non-hardening thread sealant for PVC connections. (non-hardening sealant does not need to cure.) The second link below has a nice explanation.

http://www.lascofittings.com/threads
https://www.linkedin.com/pulse/what-thread-sealant-use-pvc-fittings-larry-workman

the better pipe dopes are non-hardening. absolutely true.