Washing machine plumbing - advice needed.

[flameport]

If I cut there, unscrew the nut on the left, how does the remaining piece of copper pipe that disappears inside the T through the nut come away with the nut, is it loose or somehow attached to the T?

This is how the fittings work:


Compression fitting isolating valve 15mm screwdriver turn [Public domain], by Mike1024 (Mike1024), from Wikimedia Commons

The nut and the olive (copper ring) both fit over the copper pipe. The pipe fits inside the valve / tee or whatever else.
When tightened, olive is compressed between the nut and the fitting, causing it to deform and grip the pipe, and at the same time seal against the tapered part of the fitting.

When the nut is undone, the pipe can be removed from the fitting, the olive will remain compressed onto the pipe.

The pipe is not threaded and does not fix to the fitting in any way - the only thing holding it in is the pressure of the nut against the olive.
If this type of fitting is not tightened enough, it will leak. If overtightened, the olive will be damaged and it will leak.

So this 'olive', is it underneath the nut that's screwed onto the T? Or under neath the silver part on the right hand side?

Both. If you undo both nuts, you will have a very short piece of copper pipe with two nuts on it, and an olive on each end which prevents you from removing the nuts.
Cutting the pipe in half will allow the nuts to be removed and used again. The olives on the pipe are then useless.

 

[mogget]

There'll be an olive under the nut on the valve, and another one under the nut on the tee.

2 options:

Unscrew nut from tee, add blanking nut.

Unscrew nut from valve, replace with a 15mm stop end with some jointing compund (water hawk or similar) smeared roumd the olive.

A dead leg of that length won't cause any problems, general rule is if the dead leg is more than 5-6 times thed pipe diameter it should be taken out.

Mogget




Edit, crossed posts

 

[Madrab]

wot they said

 

[Sleebagz]

Ok so I went away and learned how compression fittings work etc - so simple really!

I've decided to just add the 15mm blanking disc into the nut and screw back onto the T, I presume the tapered end of the blanking disc with the recess in it faces into the T? With the flat end resting against the inside of the nut?

Is it worth sticking some Ptfe tape round the disc?

Many thanks again for the replies

 

[mogget]

The tapered end will go toward the fitting. I wouldn't use ptfe, being flat you'll have a job getlting it in the right place. Potable water jointing compound such as water hawk would be better, but it might seal ok without.

 

[Sleebagz]

And by 'fitting' you mean the T?

 

[mogget]

Sorry for not being clearer, I do indeed mean the tee.

 

[Madrab]

Yup, just rub the inside face on the T with a bit of scotchbrite, or green scouring pad to clean it up 1st