How to seal a female coupler?

PenguinWithHair · 25 Apr 2018

Apologies for what's probably a very basic question, but I've just bought a female straight coupler, which has a normal compression fitting on one side, and the other side screws onto a thread.

The normal part is fine, compresses an olive. But the 'female' side doesn't have an olive, it just screws onto a half inch thread. What makes the water tight seal here? There's no olive or rubber washer, just two threads.

Many thanks.

terryplumb · 25 Apr 2018

PTFE thread sealing tape.

Dan Robinson · 25 Apr 2018

Liquid PTFE of Loctite 55

FiremanT · 25 Apr 2018

PenguinWithHair said:
Apologies for what's probably a very basic question, but I've just bought a female straight coupler, which has a normal compression fitting on one side, and the other side screws onto a thread.

The normal part is fine, compresses an olive. But the 'female' side doesn't have an olive, it just screws onto a half inch thread. What makes the water tight seal here? There's no olive or rubber washer, just two threads.

Many thanks.

What are you doing with it? Nothing complicated I hope

Dan Robinson · 25 Apr 2018

FiremanT said:
What are you doing with it? Nothing complicated I hope

dilalio · 25 Apr 2018

It’s not a female coupler... it’s a lesbian!

bigdrew · 26 Apr 2018

Fiber or rubber washer in the base if it's a straight thread, if male is tapered ptfe/paste.

ReganAndCarter · 26 Apr 2018

Wind PTFE tape on CLOCKWISE like in this video. Only thing I would do different is use a few more turns than he does in vid. If you turn the tape on anticlockwise, it will wind out of the joint as you do it up.

PenguinWithHair · 26 Apr 2018

Thanks for all the replies folks. What I'm using for reference (pictured above in first post) is a readily avaliable 'female coupler' part from screwfix, nothing special. It just threw me a bit when there was no rubber washer or olive to 'make the seal'. Is it worth me seating a rubber washer in there like bigdrew says as well as PTFE thread? Or will that reduce the amount of thread engagement too much?

It's a straight coupler, so not lesbian! (wheeeeey)

The part is for fitting a replacement electric shower, I've got a threaded elbow sticking out the wall which my old shower fitted nicely onto but not my new one. I'm using this coupler for a mini extension of that elbow and it's a perfect fit.

I should have checked this before really, but can anyone confirm that I will be ok mixing my pipes? All the house uses copper, except for some reason my electric shower which is plastic piping which splices into a copper cold mains feed. Am I ok to use this coupler with that mix of materials? The water into my shower will be going copper plastic and then copper again. Something I didn't think of to ask.

Cheers everyone.

Jackrae · 26 Apr 2018

What you use depends on what it's being screwed onto. If it's a parallel length of screwed brass, such as shower manufacturers supply then you should use a back nut and a fibre washer, with the seal being formed between the machined outer face and the back nut (with the fibre washer trapped between). You should not screw tapered male fittings into parallel female ones : it might work but it's a botch.

FiremanT · 26 Apr 2018

Jackrae said:
You should not screw tapered male fittings into parallel female ones : it might work but it's a botch.

No its not.

Jackrae · 26 Apr 2018

As you wish, but the majority of the load is taken by a single thread. The difference between the world of engineering and plumbing

Hot&Cold · 26 Apr 2018

PenguinWithHair can you post a photo of the male fitting you intend to conn to

dilalio · 26 Apr 2018

You’ve gotta do what you’ve gotta do!
Fitting in OP’s pic looks like a female iron... iron = poof, female iron = lesbian.

FiremanT · 26 Apr 2018

Jackrae said:
What you use depends on what it's being screwed onto. If it's a parallel length of screwed brass, such as shower manufacturers supply then you should use a back nut and a fibre washer, with the seal being formed between the machined outer face and the back nut (with the fibre washer trapped between). You should not screw tapered male fittings into parallel female ones : it might work but it's a botch.

FiremanT said:
No its not.

Jackrae said:
As you wish, but the majority of the load is taken by a single thread. The difference between the world of engineering and plumbing

If one uses parallel to parallel, one would need a washer / gasket, would one not?.
For example, we use to use a lot of "long screws", which obviously have to be parralel. One had to use a lock nut and hemp to create a seal.

If fitting a continental oven, they are typically supplied with a P/P connector set.
And a washer.

We generally do not use washers, apart from the above examples.

I take it, Jackrae, you are an "engineer", not a plumber.

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How to seal a female coupler?

PenguinWithHair

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