Pipe Fitting

john4703 · 16 Dec 2019

I plumbed in my kitchen about 15 months ago. I used mainly Speedfit pipe and everything was fine until this morning. The main feed to the storage tank in the loft has a brass stopcock in it and the feed pipe to that stopcock became disconnected.
This flooded my kitchen and bedroom and the flat below me.
The joint had the correct Speedfit insert and was not under any strain.
Does anyone have any idea why a joint should suddenly fail after this time. I doubt it was frost as it is next to the hot water cylinder which is insulated but I'd think gives enough heat to prevent freezing.

Burnerman · 16 Dec 2019

Maybe the stopcock nut just wasn’t tight enough......its best to use a copper olive rather than a brass one as they bite into the plastic with less effort than the brass olive.
Presumably the olive slipped off the Speedfit?
John

john4703 · 16 Dec 2019

Burnerman said:
Maybe the stopcock nut just wasn’t tight enough......its best to use a copper olive rather than a brass one as they bite into the plastic with less effort than the brass olive.
Presumably the olive slipped off the Speedfit?
John

Thanks John,
That is exactly what happened. The Speedfit pipe looked perfect. I used a copper olive when I redid the joint so hopefully it will last. I'm just surprised that it lasted so long if there was a fault.

Burnerman · 16 Dec 2019

A huge chunk of bad luck there.....

The olive needs to be compressed sufficiently to actually dig in to the plastic pipe, and once that has happened there’s hardly any chance of it coming off again. Famous last words!
Be lucky
John

foxhole · 16 Dec 2019

Did you mark the pipe before inserting ? Common newbie fault is to not fully insert pipe before tightening . A mark on the pipe will help you see if it’s moved before tightening .

john4703 · 17 Dec 2019

foxhole said:
Did you mark the pipe before inserting ? Common newbie fault is to not fully insert pipe before tightening . A mark on the pipe will help you see if it’s moved before tightening .

I can't remember, it is a really awkward place to reach. This time I fitted the olive using a spare fitting and made sure it was secure before doing the joint in the difficult to reach place so it is well inside the fitting.

Burnerman · 17 Dec 2019

https://www.screwfix.com/p/jg-speedfit-plastic-push-fit-pipe-inserts-15mm-10-pack/64318
I use a similar insert to these when connecting to Conex compression fittings or whatever.......sometimes the Superfit range have a longer nose which can prevent full insertion to radiator fittings and suchlike. Naturally they are perfect for their own range of couplings!
The purpose of the insert, naturally enough, is to prevent the wall of the plastic pipe collapsing - I really prefer the stainless inserts if I can get them, so long as they are a perfect fit.....
on occasion they can swell the pipe preventing the olive from sliding on.
John

John D v2.0 · 21 Dec 2019

Yes has to be a copper olive, even so, for mains water i prefer to compression into a length of copper and then speedfit from then next joint. Speedfit is spot on when you stick to its own fittings but I've never trusted compression joints as much.
I do put compression directly on the 10mm pipe for radiators as it's a sealed system so limited water.

john4703 · 21 Dec 2019

John D v2.0 said:
Yes has to be a copper olive, even so, for mains water i prefer to compression into a length of copper and then speedfit from then next joint. Speedfit is spot on when you stick to its own fittings but I've never trusted compression joints as much.
I do put compression directly on the 10mm pipe for radiators as it's a sealed system so limited water.

I can see that would work well but my puzzle is why this joint lasted for well over a year then failed. It does not make sense that it last so long before failure.

Burnerman · 21 Dec 2019

I doubt if you’ll ever discover why, John.....utility works in the area maybe?
Of course, every time a valve closes, a shock wave will be created in the system which could eventually
work yours loose. Are there any pipes that clunk in the property when a tap is closed?
Guessing!
John

john4703 · 21 Dec 2019

Burnerman said:
I doubt if you’ll ever discover why, John.....utility works in the area maybe?
Of course, every time a valve closes, a shock wave will be created in the system which could eventually
work yours loose. Are there any pipes that clunk in the property when a tap is closed?
Guessing!
John

Yes one tap does, maybe I'll fit a damper on it, as far as I know a short vertical air filled pipe will reduce the clunking or knocking. I've fitted them to ball valves but not to taps. I'll need to look and see where there is space.

Burnerman · 21 Dec 2019

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199v#_=p
Maybe this device could help?
John

john4703 · 21 Dec 2019

Thanks Burnerman, I'll look at fitting one of them. Anything to reduce the risk is worthwhile.

Burnerman · 21 Dec 2019

I have fitted a similar thing before, and it did cure a clunk on a pipe somewhere in the underfloor of the building.
I was a bit apprehensive as to what would happen should the diaphragm fail, but it looks to have a schrader air valve on the top which should easily hold back the water if that occurs.
Always a bloomin' nightmare to see what you've suffered!
John

John D v2.0 · 22 Dec 2019

if you have a water meter it has a check valve ie non return valve for obvious reasons
With the current weather the incoming supply will be very cold, if you run in water and then it warms up, just by being at room temperature and maybe near other pipework it can expand a little. Water doesn't compress so if your pipework isn't flexible there would be a tiny pressure increase. It won't be enough to void any warranties, but it could be the straw that breaks the camel's back.
With an extra year's worth of thermal cycling and the water hammer Burnerman mentions above it could have got to that point.

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Pipe Fitting

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