Stop end compression sizes

[Lupa Monkey]

I've just bought a stop end compression cap to fit on the hot water pipe of the bath which we have removed.

I went out to get a 20mm one but I was told that 22mm was the standard size and they didn't do 20mm pipe.

Came back and it's too loose

The cold water one fits nice and tight btw.

What do I do now? I can't turn the water back on if I can't cap this soddin pipe off

 

[ChrisR]

If it's OLD and copper it'll be 3/4 inch internal, which is about 1mm less than 22mm o/d.
You can
1) get a 3/4" olive, which is the proper way
2) do it up really tight and hope it seals - it probably will
3) use extra sealant, like silicone or many turns of ptfe tape, to help option 2.

 

[Lupa Monkey]

Thanks for the quick response. Yes it's old and copper! I'll have to cycle back to the diy shop for the olive

Or do you think I can get away with lots of ptfe tape?

 

[Softus]

If they don't have a 3/4" olive...

1. Tighten up the fitting, but extra tight to compress down the olive.
This is best done with a copper olive.

2. Remove the fitting (leaving the olive exactly where it was).
3. Wrap PTFE tape around the olive on one side only (the wet side).
4. Replace fitting and tighten up normal amount.

 

[Lupa Monkey]

Seems that they don't have the olive at the diy shop

Sorry Softus, being a bit dim here do you mean tighten up the fitting while on the pipe?

And by the wet side do you mean the top part of the olive?

 

[Softus]

Seems that they don't have the olive at the diy shop

Without wishing to sound smug, I didn't think they would, but I didn't catch you in time. Sorry.

Sorry Softus, being a bit dim here do you mean tighten up the fitting while on the pipe?

Yes - push the fitting fully home, onto the pipe, and tighten it up dry. Your aim is to lightly crimp the olive onto the pipe, so it won't move when you undo the fitting, which you'll be doing in order to apply the tape.

The point of doing this dry is so that the effort you put into doing up the fitting isn't being absorbed by squishing the tape, and so that you only apply the tape once.

And by the wet side do you mean the top part of the olive?

Well, I suppose it's the top part if your pipe emerges from the floor, by what I mean is the side of the olive that's nearest the water, i.e. nearest the open end of the pipe. Think about what you're trying do here - apply the tape to the place where, if there was a gap between the olive and the pipe, the water would get through.

Does that help?

 

[Lupa Monkey]

Yes thanks Softus.

And don't worry, I didn't actually go to the diy shop I phoned them

 

[Softus]

Diagram, just in case:

 

[Lupa Monkey]

Thanks for going to the trouble of doing the diagram

You been fantastic assistance, as always!