MDPE olives

[polygonum]

A couple of years or so ago our water mains were replaced and the company used blue MDPE connected to a brass stopcock. This has been leaking for a while - getting to a steady drip-drip-drip the other day.

Have tightened it up as much as I feel comfortable, about 190 degrees extra turn of the nut. Rather sadly, it is still weeping.

With other pipework, I'd happily undo it, trim a bit off if needed, replace the olive and do it up again. Having never touched MDPE before, I am in the area of assumptions. Like, I assume there is an olive in there (how could it grip otherwise - I don't know)! I assume the olive is a special size. Can I buy the appropriate olive without replacing the stopcock? Can't see one (other than standard 10/15/22/28 mm ones) on Screwfix or Toolstation.

[Tim Watts]

Yes, there's an olive. There's also supposed to be a pipe insert for the olive to bite against.

If not, perhaps this is why the joint is not responding to being tightened?

[Andrew Gabriel]

There are olive and O-ring couplings for MDPE, although the brass ones I've used have been olive ones. I wonder if they used a pipe insert?

A picture posted somewhere might help.

[polygonum]

Honestly, looks almost identical to the catalogue pictures of a brass stopcock with MDPE going into it!

Have ordered a couple of olives, thanks ebay.

[Andrew Gabriel]

You need a matching pipe insert too. They come in metal or plastic; I used metal ones because they obstruct the pipe less (which was probably insignificant in the scale of things).

[harryagain]

There are several different sorts of connection. Some have an O ring so tightening makes no difference. These are the newer ones. The O ring can be damaged if the pipe has been cut off raggedly (when the pipe is inserted into the fitting), you're supposed to use a special tool to cut the pipe, not a hacksaw. (You can use a hacksaw. but then you must carefully trim the end of the pipe square and form a "lead in" with a Stanley knife)

Others have an olive, In both cases there should be a pipe insert (metal or plastic). Only the very old black plastic pipe needed no insert, the walls very thick.

All you can do is dismantle it and see. Depending on the pipe size, you might be able to use a standard compression fitting (but bigger than the nominal pipe size). This is what was done years ago. An insert will be needed (a bit of copper pipe will be needed) to stop the pipe deforming as the fitting is tightened up.

[polygonum]

It does not have an O-ring - it looks like a classic compression fitting.

I have made many pipe joints in various forms of plastic and copper. I know how to cut pipe.

I was trying to fully understand *before* disassembling. I want to do it once, and right.

I find it difficult to believe that using a wrong fitting or wrong olive could ever be worth doing.

Why do I need a piece of copper pipe? I appreciate inserts - what is this pipe?

[harryagain]

There you are shit-fer-brans.

O rings mentioned here.

[Tim+]

I don't think you do, you only need the pipe insert. It's just a "Harryism". ;-)

Tim

[polygonum]

That is what I had assumed. It made no sense so obviously attributable to Harry. :-)

[harryagain]

It is what was used in place of the plastic inserts in days of yore.. They are better because they obsruct the flow less than the plastic ones. And cheaper. And they use up the odd little bits of pipe.

[Tim+]

Who's got shit for brains? Go back and read what you wrote.

It was the purpose of your bit of copper pipe that was being questioned. We're not questioning the need for the correct insert.

Tim

[charles]

but the point abut proper inserts is they have a flange to stop them wandering down the pipe.

[polygonum]

You are assuming that I have odd little bits of pipe of the required outer diameter to fit my MDPE. Do you know what inner diameter *my* MDPE is? Or, indeed, whether you can get odd little bits of pipe that would snuggly fit, say, 15.4 or 20.4 mm inner diameter MDPE?

[Tim+]

Oh, I see, a bodge (and bad English). Try rewriting the sentence with an "or" and ditching the unnecessary brackets.

Tim

[harryagain]

They were a tight fit. Not going anywhere especially after being nipped by the compression of the olive.