Sealing threaded connections - what's the secret?

[Flot]

Ok, just redid my pump and filter connections, and everything went great, except that 2 of my 3 threaded fittings have a slow drip.

What's the secret here? I gave each 2-3 wraps of teflon tape, hand tightened, and then tightened some more. The ones on the filter appeared to be almost all the way in to the stop, but one is dripping and one isn't.

And maybe a better question is, there was no way for me to tell beforehand...how do the pros deal with this afterwards?

 

[pwrstrk]

I use PVC thread sealant on all my threaded connections. You can get at any hardware store.

 

[duraleigh]

If the pipes are 1.5 inch or larger, thread sealant seems to do a bit beter job. Clean off ALL the teflon if you decide to redo them

 

[AdelaidePooler]

A plumber friend of mine says you can never use too much PTFE (Teflon) tape, 2-3 wraps is just the beginning!

 

[Patrick_B]

A plumber friend of mine says you can never use too much PTFE (Teflon) tape, 2-3 wraps is just the beginning!

You can on plastic pipe, especially smaller stuff.

I agree with Dave above, use thread sealer like Rector-Seal. It can be messy, but it works incredibly well.

 

[pwrstrk]

A plumber friend of mine says you can never use too much PTFE (Teflon) tape, 2-3 wraps is just the beginning!

Gotta be real careful with a lot of wraps of Teflon tape. I've seen cracked fittings because of that.

 

[Flot]

Right, so, no option but to cut the nearest straight section of pipe and try, try again - correct? (unfortunately I already did that once, still a leaker and I don't think I have enough space for another coupler!)

 

[Divin Dave]

not enough wraps. 4-5 wraps and use the Pink colored teflon tape. Make sure you wrap it the right direction too.

 

[danjaymor]

Do not use teflon tape on PVC threaded fittings.....the fittings manufacturers don't want you doing that. It will work in a pinch, but absolutely no more than 3 wraps.

Preferably use a thread sealant paste, which is manufacturer recommended.

PVC threads are a molded taper, as opposed to steel pipe with machined threads which take away some of the pipe material. If you add solid material like tape it the male fitting can act like a splitting maul when tightened.

Also use the "oil filter" rule on PVC threaded fittings.....hand tighten, and then no more than 1/2 a turn or so.

I've only used a wrench on PVC fittings for disassembly, never for assembly and utilizing thread sealant.

Search "thread sealant" at the Home Depot site, or just get it from your local hardware store.

The fittings manufactures also say not to use teflon paste, which has chunks of teflon in it, although it will work pretty well.......

Again, never use tape unless it's all you've got handy for an emergency repair, and if you do use it "less is more"....

 

[duraleigh]

A plumber friend of mine says you can never use too much PTFE

Your plumber friend must've been hit on the head by a pipe wrench falling off the truck! Too much tape and the pipe either cracks or doesn't thread and/or seat properly.

This discussion has been on the forum before and I am surprised at the wide variety of suggestions. 2-3 turns should be perfectly adequate BUT, having done it about every way you can (including some incorrect), I would not use it on pipes larger than 1 inch.

Thread sealant will make a better joint on the large pipes. You can actually "feel" it seating better with thread sealant, I think.

 

[Patrick_B]

I agree, you can absolutely put too much tape and crack a fitting. Done it more than once and I'll say again....Rector Seal is a champ.

 

[Flot]

Ok, I get the message on the rectorseal, I'll check it out. I actually may have a can of their "t plus 2" stuff around here somewhere, that looks very familiar.

On the Teflon tape - for the record - 2-3 wraps of it was specifically what was recommended by the Hayward Filter manual. As a couple people noted, I didn't want to go overboard for fear of cracking. I think I'll leave it be until I replace the pump, it's a slow drip but frustrating.

 

[linen]

When you replace the pump, be sure and do unions on both sides so that you can deal with these issues easier in the future.

 

[AdelaidePooler]

Your plumber friend must've been hit on the head by a pipe wrench falling off the truck! Too much tape and the pipe either cracks or doesn't thread and/or seat properly.

Interesting, I didn't know that. I have used fair amounts of PTFE (like 5 wraps) on PVC joints before and had no issues.
He was working with my central heating at the time, and those pipes aren't PVC so in retrospect that was probably a general comment of his, and most likely exagerrating, he was wont to do that, on occasion.
I say was as he was actually killed by complications after a blow to the head... although not by a pipe wrench!

He also ran the local plumbers merchants and so had a vested interest in selling PTFE tape (and more PVC fittings when they cracked, probably!)

 

[danjaymor]

Just to clarify....on metal to metal threaded connections liberal use of teflon tape is just fine......just avoid use on plastic threads!

I still prefer sealant paste even on metal to metal....the gunk flows to the voids in threads better.....

 

[DBfan187]

I use the tape and a bead of silicone.

 

[Patrick_B]

I use the tape and a bead of silicone.

Silicone on the threads?

 

[DBfan187]

yup, right over the teflon. works every time!