Black plastic mains water pipe - questions

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Stirlingshire
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Our underground water supply pipe is 3/4" black plastic and it crosses a stream on its way to the house, via a small bridge where it is fixed to a suporting steel I beam. It froze up in the recent cold weather. One reason for this is that it has frozen in the past and burst, and has been repaired with a short section of blue pipe, joined to the black at each end by very large plastic compression joints, which are difficult to insulate. I'm thinking of installing trace heating and improved insulation but I'd like to get rid of these big joints if I can. There are two other joints in the exposed pipe - a brass compression joint just after the pipe emerges from the ground on the supply side, and a smaller plastic compression joint just before it goes back underground on the other side. I suppose it isn't possible to get the original black plastic pipe any more to replace the central section, thus eliminating the repair ?

Also, I used a supply of steam from a wallpaper stripper, fed into the black pipe, to melt the ice where it went underground. This took about three hours, although I withdrew it at regular intervals and flushed it with cold water from a hose. Would this cause any damage to the black pipe ?

Final question - when I rejoined the pipe using the large plastic compression joints and turned the water back on, they started leaking slightly. I'll need to go back and try again with them at the weekend - could it just be dirt on the threads ? We tried tightening them with a wrench which reduced the leak to a dribble.

Cheers

John
 
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I dont think there is any alternative to the big joints but my suggestion is to put a longer length of blue so that the joints can be burried.

Unlikely you can get the black anywhere now. Its been obsolete for about 30 years now. I might still have a length of th smaller bore but thats no use to you in Scotland.

Tony
 
Thanks Tony,

I was afraid that might be the case. Unfortunately it would mean digging up tarmac on one side of the bridge but I suppose we could do it if we had to.

John
 
Surely you get something wrapped around the joins? I have used foiled bubble wrap in my weird pipes in the past to good effect....
 
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the black is (usually( an imperial measurement and not quite the same. However you can still buy olives to fit at a proper plumbers merchant. Also connectors though a blue-pipe one might fit if you use the correct olives.

Look carefully at the old pipe as it may have identification printed or engraved on the side. Measure it as accurately as you can.

Black polythene pipe is still made, but it is now in metric sizes. I believe it is supposed to be used overground and blue underground, might be something to do with resistance to sunlight.

You can buy waterproof pipe lagging in plastic foam, I think Armaflex do one. It is more expensive than ordinary Climaflex. I would recommend the Regulation thickness, which is the size of your arm. Try to get it in 3-metre lengths or a col to minimise joins, which are a weak spot. For best results slide it down a pipe from the end rather than slitting it (if you are repairing joints this will be easier). You might find an extra-large size fits over the joins.

I agree with extending the repair so your connectors are buried, preferably in an accessible pit.
 
Running water through a pipe outdoor,overground, over a stream in SCOTLAND??

Good luck to you!
 
[Look at "similar topics" at the bottom of this page for your answers.
 
Actually the black mdpe is readily available from the larger merchants try BSS or Pipeline.


You will have the ID markings on the pipe blue writing for class D or green writing for class C. :LOL:

For what it's worth black is suitable for above ground use, blue isn't. ;)
 
Thanks to everyone for the input. Could I use a push-fit fitting to join the black and blue pipes together ? They look easier to insulate than the ones I have at the moment and would keep us going until we can dig out and replace the whole section.

John
 
You can buy pushfit fittings for MDPE pipe.

I would just lag the pipe, and wrap something around the fittings.
 
I saw my roll of black tube yesterday, its about 1" outside diameter and about 1/2" inside but thats before I read the above so did not look for any writing on the pipe.

Now I have to look for a stream to install it across!

Tony
 
Running water through a pipe outdoor,overground, over a stream in SCOTLAND??

Good luck to you!

Well, technically speaking it's a burn, as we are in Scotland. It didn't freeze last year, and it was b****y cold then as well !!
 

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