Does a pvc union need to have teflon tape?

[FloridaFishMan]

Hi,
Just putting some plumbing together and want to know if I should put some teflon tape on the pvc union?
Chris

 

[TippyToeX]

I always have. It's a good safeguard.

 

[billybob2092]

As someone who works as a pipefitter, you are better off using pipe dope(plumbers paste) that contains TFE on PVC.

 

[jeffbrig]

Never, there's a gasket on the inside where the flat surfaces meet, the coarse threads are not meant to hold water.

I'm assuming that you have slip unions. Obviously, if they're threaded, you will be using teflon tape where they connect to other PVC fittings.

 

[billybob2092]

One thing I forgot to add, don't put anything on the thread where the 2 halves of the union connect. Only put it where the pieces connect to the pipe.

 

[FloridaFishMan]

So leave the union itself un-taped? I always use teflon tape on the screw in type pvc connectors but was unsure of the threads that connect each side of the union.

 

[cioutlaw]

Another pipfitter here...Like Billy Bob said teflon paste on the seat or leave it dry if there is a rubber gasket & teflon paste on the threads will lubricate & allow you to tighten more with less effort & also allows dis-assembly easier in the future. The threads have absolutly no sealing ability.

 

[cioutlaw]

<a href=showthread.php?s=&postid=6523587#post6523587 target=_blank>Originally posted</a> by FloridaFishMan
So leave the union itself un-taped? I always use teflon tape on the screw in type pvc connectors but was unsure of the threads that connect each side of the union.

The pipe fitting threads are tapered & that is your seal, with a union it is a straight or machine thread & does not have any sealing value.

 

[FloridaFishMan]

cioutlaw, what would the teflon past be called at homedeopt? thanks for the help.
Chris

 

[SSragtop]

pipe thread sealant

 

[cioutlaw]

you want a teflon based pipedope paste that is non hardening. you are wanting a lubricant not so much of a pipe thread sealant. dont get carried away with it...it doesnt take much & although it is safe for pottable water it might not be good to have an excess in your tank.

It really is not needed but is something I do when putting unions together. Most PVC unions have a gasket or an O-ring & that normally works fine but a lil teflon paste is better.