A new way for pipes to leak...

Currently running a bunch of 22mm copper pipes through an awkward location. Difficult to get the torch to the joints, and very difficult to get to an earlier joint after more are done. So I'm air pressure testing as I go.

All well and good, everything passing first time. And then I and see the pressure gauge gently falling and can hear a very faint hiss.

Damn - have to slice up some pipework and do it again.

Except the hiss is coming from the plastic push fit stop end I'm using during pressure testing.

The copper pipe I'm using has a BS number very lightly stamped on it in regular spots - seems that one of those spots is just enough to allow a leak past plastic push fit.

Reply to
dom
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mmm presumably this will apply to Hep plastic pipe "scraped" (down its' length) where it would seal in pushfit fittings..?

looks like I'd better use some compression fittings to get past those bits.... are there any better ideas?

JimK

Reply to
JimK

Don't know. I've never had plastic fittings leak, even when reusing old fittings onto existing pipes. Obviously a large enough longitudinal score will leak, but IME the combination of seals against the pipe and the insert seem to be sufficient even at 3 bar.

Reply to
dom

Pressure testing aside, have you considered plastic pipe runs in this situation?

I'd never used plastic pipe before, but I'm well converted now for difficult runs. Single run, flexible, up and over and round about all manner of obstructions. No mid-span joints to leak. No trying to blowtorch fittings in confined spaces and burning the place down!

Reply to
Ron Lowe

I think this is most likely because its not full of water.

You need hydraulic pressure to seal it.

Reply to
The Natural Philosopher

agreed! just put plenty masking tape over the end sections so that (hopefully) you don;t scratch it....

JimK

Reply to
JimK

Monsieur Pascal says bollocks.

Reply to
Andy Dingley

Hmm, We have high-pressure o-ring seals here at work which sometimes fail under low pressure, but seal properly once the pressure increases. I think some types of seal need to be 'activated' by pressure from a certain side.

I can certainly imagine fluid viscosity being a factor in seal efficiency.

Reply to
Ron Lowe

Before you consider plastic check that small furry gnawing chaps cannot get access. I speak from experience.

R.

Reply to
TheOldFellow

what happened then?

JimK

Reply to
JimK

Yes - all the runs through studwork are plastic - but these bits are behind a Rayburn (with a slim possibility of an "overheating event"), and connect up to pumps/valves etc where the stiffness and support of copper pipe is welcome.

Reply to
dom

Certainly, but the static pressure in a domestic waterpipe is going to end up the same (mains pressure or header tank pressure), whether it's full or part-full. Neither of these are "high pressure", compared to that for industrial hydraulics.

Reply to
Andy Dingley

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Ron Lowe saying something like:

Why not ask Morton Thiokol?

Reply to
Grimly Curmudgeon

Are you sure it's not a damaged O-ring in the end-cap? I also pressure test new plumbing using JG end-caps and a pressure guage with a JG-type connection. After a while, with repeated refitting, I have to change the O-rings. They eventually get damaged by a sharp pipe-end if you aren't cutting all your own ends with a ring pipe cutter.

Reply to
Andrew Gabriel

Yes, that's possible. But I was able to move the end cap onto a fresh piece of pipe away from the markings and have it seal. It's also possible that it was a coincidence between something under the seal and noticing the leak - that happened to coincide with the end cap being over the pipe markings.

Incidentally, I've got some monument pipe test plugs (they push into the end, then screw up tight to expand the seal) - but mine will blow out of the end of a pipe around 2.5-3 bar.

Reply to
dom

Plumbed to my UFH through the loft with polypipe, with insulation. The mice started to eat the insulation, and carried on into the pipe. Just a pin hole - the mouse was probably more surprised than I was. I got a drip into a bedroom and sorted it before any damage.

It's a very rural location, and I can't find where they get in.

I now just wage perpetual war. I hate those meeces to pieces!

R.

Reply to
TheOldFellow

Why? That was elasticity of a solid reducing at low temperatures.

Reply to
Andy Dingley

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Andy Dingley saying something like:

It was a general suggestion. I presume they know quite a lot about seals now.

Reply to
Grimly Curmudgeon

use soft copper and it bends a treat

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Reply to
peter richards

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "peter richards" saying something like:

What the f*ck are you replying to?

The badge of the clueless.

Reply to
Grimly Curmudgeon

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