Old plastic water pipe caps?

[JOEPRO]

I am clearing out what used to be an outside toilet, masonry built attached to my house. The old cistern feed pipe coming out of the concrete floor and from God knows where is still live so I need to cap it off.

It is a black plastic pipe, very much like modern MDPE. But the outside diameter is measuring 17.63mm approx.

What size of cap fitting do I need to order for this does anyone know please? Maybe it's a known old imperial size. Common fittings are 20mm and up which is no good for this pipe.

 

[8ob]

One of these, dont forget the insert, they say its not needed but I use them Stop end

Bob

 

[JOEPRO]

From more research I see this which must be what it is as my house was originally built in the 1970s



I may have to buy one of these purpose made adapters to get it sealed for sure in one go then a copper end cap after that.

 

[julianf]

Id fit a valve. As you never know, you may want some water there in the future, and a valve is way easier to join to than an stop cap.


Hmm... Dead legs on potable water...

 

[JOEPRO]

Id fit a valve. As you never know, you may want some water there in the future, and a valve is way easier to join to than an stop cap.

Not for me no. I'll be filling it over with concrete once capped and fitting it out with metal shelves for storage. The whole lot will be demolished and removed in a few years anyway for a new garage extension.

I bought this which is pricey but the only fitting that seems sure to fit this old back pipe with 17.6mm external diameter.

Pardon our interruption...

 

[julianf]

The philmac range fit, pretty much, anything, it seems.

Usually for lead pipes etc but I don't see why they can't be used elsewhere.

 

[JOEPRO]

The philmac range fit, pretty much, anything, it seems.

Usually for lead pipes etc but I don't see why they can't be used elsewhere.

But they are 20mm fittings?

This is a 17.6mm pipe.

 

[Cobbler]

Back in the early 70’s there were 2 sizes of 1/2 poly pipe, bit rusty on this as I’ve had no dealings for 50 years, but from what I recall it was high & lower pressure. The larger one was the same as either 22 or 3/4 copper (3/4 I think) & with inserts compression fittings went on, the other was thinner wall, so the OD was smaller. For this you fitted a special compression ring in the fitting plus an insert. The ID were both the same. Whether the adapter rings are still available I don’t know, a trip to the plumbers merchant is required.

 

[cocker]

There will be a Philmac fitting in that size , you'll just need to find a proper plumbers merchants !
The type with a surley old git behind the counter will be best .

 

[julianf]

But they are 20mm fittings?

This is a 17.6mm pipe.

Philmac are sold with a x-y size range, not an exact number.

Be careful that you look at the variable side though - somtimes you might get a, say, 26-30mm (or whatever) on one side, and a 20mm (fixed) on the other.

 

[julianf]

I thought i edited my initial post to mutter about dead legs on potable supplies, but, clearly, the edit did not take...

 

[dave h 2]

You measure pipe by the bore NOT by the OD
Tube is measured outside, pipe is measured inside even though they look like the same thing. That's why the sizes seem weird.

 

[dave h 2]

I thought i edited my initial post to mutter about dead legs on potable supplies, but, clearly, the edit did not take...

You did have a point.
100 M dead leg to a disused for years social club at work and we ended up with legioneer's when they tested our showers.

 

[julianf]

You measure pipe by the bore NOT by the OD
Tube is measured outside, pipe is measured inside even though they look like the same thing. That's why the sizes seem weird.

15mm copper pipe is 15mm OD.

As are a whole load of other modern pipes.

(I don't mean they're all 15mm OD, just that they're sold by their OD!)

 

[julianf]

To illustrate (note I did not put either pipe or tube in the search) -

 

[JOEPRO]

You measure pipe by the bore NOT by the OD
Tube is measured outside, pipe is measured inside even though they look like the same thing. That's why the sizes seem weird.

Yes.

In this case I have determined my pipe size to be as per the snip I posted back in this thread. Below again:



3/8 bore
17 - 18mm OD

Which is what the fitting I purchased is suitable for and includes a reinforcement insert.

 

[JOEPRO]

I thought i edited my initial post to mutter about dead legs on potable supplies, but, clearly, the edit did not take...

It's been like this already for 20 years with just the cistern left on the wall and 100% unused.

I don't know where the pipe comes from is the problem. But as I said in a couple of years time I'll be able to trace and remove this whole pipe leg as I'll have a digger in demolishing the WC and Utility room etc.

 

[Gareth J]

You could just fold it over and zip tie...if its getting knocked down next year anyway

 

[Turbo]

Cut off a sample of the pipe and bring it to an old school plumbers merchants or agri supplies.
Its probably class c alkathene but it could be the stuff they use in ROI thats a slightly different size.

 

[Farside]

I don't know where the pipe comes from is the problem.

'Bout 20 years ago I was doing a repair in an ex LA house and ran into a weird plastic pipe that matched nothing I had with me.
I ended up going to the Council depot to get a fitting, and was told about how that entire estate was plumbed with that stuff because of the copper shortage due to fighting in Zambia, iirc.