collapsed compression joints

[.]

[.]

it is.

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IMEE it's 2 pairs of grips. no spanners.

[.]

oh, really :-)

[Guy King]

The message from "." contains these words:

Seems clear enough to me. The clamping by the nut should tighten the olive onto the pipe sufficiently to indent the pipe all the way round - that's how they work.

[Tim Downie]

I think it is. If you tighten it up as far as it will go, if you need to take the joint apart at any future date you'll have a hard time getting it watertight again as there's nothing left to compress.

Tim

[.]

/deform/ the pipe (sic) ?

overtightening the joint deforms the /tube/, that's what causes leaks.

a /light/ touch of jollop, good control on the static part of the joint and knowing when the joint is nipped up all takes experience and it's for that reason that them who are not dealing with compression joints day in, day out should take the time to learn how to solder a joint.

YMMWV, of course.

[Chris Bacon]

If the olive does not indent, how has the joint any mechanical strength at all? ISTR that a compression joint in 15mm is safe to 45 bar, but ICBW. They shouldn't be over-tightened, else wrinkles are a problem, that's why they leak AFAIK.

[Ed Sirett]

Either the pipe was not inserted past the olive (it may have been but then pulled out before tightening), in this case the tightening tends to roll the olive over the end of the pipe and tends to expel the pipe.

The fitting was in noway adequately tightened. If the pipe/fitting are in good alignment and everything is clean then the back nut will "finger spin" up to the "bite point". After that I would say you are looking at adding 2-4 'flats' (1/3 to 2/3 of a turn to tighten most fittings).

HTH

[zymurgy]

Probably. You came to the right place for conflicting advice ;-)

Definitely possible. You can overtighten it enough to damage the pipe (and hence the joint) if you go at it like some gorilla. There's a distinct difference between loose, tight (watertight) and overtight.

I think experience has shown you what 'loose' feels like.

I wouldn't choose pushfit over compression, especially in hot water situations, no matter what 25 year guarantee the pushfit manufacturers give .....

All plumbing with whatever fitting of choice takes practice. It's easy to undertighten a compression if you've not had much experience of them, as much as it's easy to make a bad solder joint.

Practice. Then take it apart (compression) or heat up a practice solder joint and separate to check how well the joint has 'wetted'. Then you'll know how much solder is enough ..

Cheers

Paul.

[.]

I would if I couldn't trust my comression skills :-)

[fred]

In article , Ed Sirett writes

The voice of reason from one who does this for a living, respect.

[Guy King]

The message from "." contains these words:

That's right - deform the pipe. The olive will be pressed into the pipe, deforming it in a ring all the way round.

What's wrong with that?

[.]

1/ it's copper /tube/

2/ if the olive deforms the tube the joint is over tightened and will weep

[Dave Plowman (News)]

No it's not.

I'm one of those who does use PTFE round the olive. And non of mine leak - and certainly don't pull apart. The only way a compression fitting can pull apart is when it's not properly tightened.

[Dave Plowman (News)]

Not so - once the olive is compressed on the pipe it remains compressed. The tapers on the olive and body are then the seal - and if in good condition will seal again ok even if moved round. However, an old fitting may well have some corrosion on the seats due to electrolytic action and if so will be difficult to seal.

[Dave Plowman (News)]

If it doesn't 'deform' the pipe slightly it isn't correctly made. It's impossible to pull off an olive from a properly made joint, and this wouldn't be so if it was merely friction.

[TheOldFellow]

... and that's the one time I put some PTFE tape on the olive. To form a new seat.

R.

[kevin foote]

Dan,

Temp change, pressure change??? one of those things.

Why are you using PTFE tape, Ive never found a need to use it, i allways use new pipes and fittings, there cheap enough esp if you go to a plumbers merchant.

Kev

[G.W. Walker]

Yup, all the joints that I'd convinced myself were leaking cos I'd over-tightened them turned out to be not tight enough. Just an extra 1/8 turn was all that was needed for most of them.

G.