Question for you plumbers

[NanciL]

I am installing a water filter on the incoming cold water supply to our washing machine.
The connection on the filter is plastic threaded female and I will be using a male threaded plastic (PVC) on PVC piping.

I have always been told that you don't use Teflon tape when you are going plastic threads to plastic threads.

Is that correct ? Or should I use it ?

The instructions with the filter say "never use pipe sealant or pipe dope"

just looking for the above question answered not suggestions on using PEX, etc

Jack L

[time2roll]

Tape but go easy. 2 laps is max.

[RJsfishin]

And I'd bet there ain't a bit of truth in that statement either !

Hank MI wrote:
Teflon tape is not a sealant like pipe dope/sealer. It just allows the threads of the pieces to slide together easier, as mentioned without galling. End result the 2 surfaces seal together better with less force required. Use it, sparingly.

[RJsfishin]

Where did this come from ?? No one ever even mentioned garden hose connections. You've done a lot of pvc connections alright !!

DutchmenSport wrote:
I've never used tape on PVC thread to thread connections. The female end has a rubber washer (like a garden hose) that seals the connection. If you have the rubber washer there's no need at all to use tape. (And I've done a LOT of PVC plumbing in my lifetime!)

Edit:
Manufacturer of your washing machine probably recommends no tape or putty so there is no risk of either coming loose and clogging small holes inside your washer, or that filter screen where the hoses hook up to the machine.

[Hank_MI]

Teflon tape is not a sealant like pipe dope/sealer. It just allows the threads of the pieces to slide together easier, as mentioned without galling. End result the 2 surfaces seal together better with less force required. Use it, sparingly.

[DutchmenSport]

I've never used tape on PVC thread to thread connections. The female end has a rubber washer (like a garden hose) that seals the connection. If you have the rubber washer there's no need at all to use tape. (And I've done a LOT of PVC plumbing in my lifetime!)

Edit:
Manufacturer of your washing machine probably recommends no tape or putty so there is no risk of either coming loose and clogging small holes inside your washer, or that filter screen where the hoses hook up to the machine.

[cbshoestring]

ernie1 wrote:
I'm confused. So the manufacturers say not to use pipe dope and some of you are saying not to ever use teflon tape on plastic pipe. WELL, what is a body to use then? Nothing? Just for the record, I use teflon tape some times and pipe dope sometimes and sometimes both. If there is a good reason not to do this please explain and then I'll follow your advice.

I was installing a shower valve awhile back and tried both teflon tape, then tried pipe dope, then tried both and I continued to get a leak. Called the manufacturer, Hansgrohe, a German company, and sought their advice. They said in Germany, because of the way the threads were cut, as in pipe threads with lateral lines cut perpendicular to them, they use hemp!! I said whaaatt? I dumped their fittings and used standard American made fittings instead. Problem solved.

Manufacture do not recommend using pipe dope or tape on plastic fittings because their engineers say the fitting seals itself.

Reality is...they tend to leak more often than not. So a quick wrap (not the 1st thread) with a bit of teflon seems to do the trick. When you hear about people saying it cracks the fitting, what normally happened was someone made several wraps (making the male to big to fit the female, thus cracking the female---no dirty thoughts intended) or the fitting was over tightened. IT'S PLASTIC

[ernie1]

I'm confused. So the manufacturers say not to use pipe dope and some of you are saying not to ever use teflon tape on plastic pipe. WELL, what is a body to use then? Nothing? Just for the record, I use teflon tape some times and pipe dope sometimes and sometimes both. If there is a good reason not to do this please explain and then I'll follow your advice.

I was installing a shower valve awhile back and tried both teflon tape, then tried pipe dope, then tried both and I continued to get a leak. Called the manufacturer, Hansgrohe, a German company, and sought their advice. They said in Germany, because of the way the threads were cut, as in pipe threads with lateral lines cut perpendicular to them, they use hemp!! I said whaaatt? I dumped their fittings and used standard American made fittings instead. Problem solved.

[nomad297]

cbshoestring wrote:
TAPE

Just do not over do it. Couple wraps, screw em' together. Get carried away with the wrapping---crack.

RLS7201 is correct in saying that manufactures say DO NOT use tape. However, BRUCE the plumber has probably learned the hard way that not doing so frequently results in a leak.

Where Not To Use Teflon Tape:
•Any Gas Connections or threaded connections with a built in rubber seal.
•Flared Fittings

They tend to have a buit in SEAL.

Threaded gas pipe use cement.

Permanent PVC/ABS connections---Glue

Correct me if I am wrong--Bruce.

The only times I use tape are for plastic threads and for Chinese shower heads that don't have a NPT tapered female thread.

Bruce

[cbshoestring]

TAPE

Just do not over do it. Couple wraps, screw em' together. Get carried away with the wrapping---crack.

RLS7201 is correct in saying that manufactures say DO NOT use tape. However, BRUCE the plumber has probably learned the hard way that not doing so frequently results in a leak.

Where Not To Use Teflon Tape:
•Any Gas Connections or threaded connections with a built in rubber seal.
•Flared Fittings

They tend to have a buit in SEAL.

Threaded gas pipe use cement.

Permanent PVC/ABS connections---Glue

Correct me if I am wrong--Bruce.

[RJsfishin]

I hate thread to thread plastic, it always leaks usless tape or pipe sealer is used. Either one works.
But I glue plastic whenever possible.

[RJsfishin]

I hate thread to thread plastic, it always leaks usless tape or pipe sealer is used. Either one works.
But I glue plastic whenever possible.

[ScottG]

Another vote for the tape. No reason not to and it will keep the threads from galling.

[nomad297]

I am a plumber. Use Teflon tape for plastic to plastic threaded connections. Do not use any type of compound.

Bruce

[RLS7201]

You are absolutely correct! NEVER use Teflon tape on plastic/nylon NPT fittings. The tape will cause the fittings to distort when screwed together. I know there are those using Teflon tape where they shouldn't with success but that don't make it right. Even the RV manufactures use Teflon tape on pipe threads but it's not good practice. If you poll the plastic/nylon pipe manufactures, they'll support my comments.

Richard