Choosing the correct pipe/valve size

[mattaius25]

Before I start, I would like to say that I'm a bit of a novice with this!!

I need to extend some pipework for a wash hand basin. I believe the existing pipes are 15mm, so I bought more of that, plus various compression fittings to allow me to do the job.

Even though the new pipe and all fittings are 15mm, when I tighten the compression joint, the pipe slips out. The nut and olive aren't dead tight on the pipe.

Should I use PTFE tape to make everything tight, or is there something else I should be doing?

Thanks

 

[buck51]

What are you tightening the fitting with, and where did you buy them from ?

 

[mattaius25]

With a spanner. Got the fixings from B&Q?

 

[mogget]

With a spanner. Got the fixings from B&Q?

B+Q fittings... how can I put it, umm, aren't the best.

You will need two spanners, one to hold the fitting and one to tighten the nut.

Quite often you'll need jointing compound as well. PTFE round the threads will do no good at all, and will make the job more difficult.

 

[mattaius25]

Where would be the best place to get the fittings from do you think?

 

[seco services]

can't see how you say the fitting slips off .
where ever you brought the fittings bq or plumbcentre.

you sure the old pipe is not 1/2" instead of 15mm ?

 

[mattaius25]

oooh, could be!

I originally bought 12mm fittings which were too small, so the only other option I could see was 15mm which was too big. I couldn't see any other sizes in B & Q, I didn't realise there were 1/2 inch sizes too.

That would seem to make sense though.

When you put the nut and olive on the pipe, I'm guessing they should fit quite tightly, even before you start with the spanners? Excuse my naivety, I'm new to this!

 

[seco services]

if you slide the olive on 15mm pipe it will be snug fit.
but on 1/2" pipe it will be slightly loose.
but there is no reason why you can't fit 15mm olives on 1/2" pipe they just need abit more nipping up.

 

[mattaius25]

Thanks a lot. What is 'nipping up' though?

 

[seco services]

tightening.

 

[mogget]

Where would be the best place to get the fittings from do you think?

Use the b+q ones since you already have them.

Nipping up means to tighten the nut slightly but not too much.

Edit - sorry Seco, simultaneous posts

 

[mattaius25]

Cheers everyone, much obliged.

 

[Agile]

There is virtually no difference between 15 mm and 1/2" and the fittings should work without being noticeably different.

Be aware that there is a 14mm pipe size used in France and so there is a miniscule chance that someone has used 14 mm somehow but thats most unlikely.

You could measure the outside diameter with a caliper I suppose.

Even the B&Q fittings should work fine.

Tony

 

[seco services]

Edit - sorry Seco, simultaneous posts

not a problem

 

[TicklyT]

Some find copper olives easier to nip up, as they are a bit softer.


The OP never mentioned the type of pipe, only the size. So far the assumption is it's copper, not plastic.