Is there an older 30mm copper pipe size?

[nhpb]

I run an older guest house which I've been refurbishing. The incoming water main is copper, and goes to a stop cock and up around the building.

Did there ever used to be a 30mm copper pipe size? the incoming copper pipe the circumference is 95mm which makes the pipe a 30mm pipe (outer diameter)? If it helps i'm told the work on the building conversion knocking it around was done in 1978.

Just an overview, the cold water supply Ts off around the building in the same 30mm? pipe, goes up to the loft as a 22mm, bypasses an old header tank and to 40 or 42mm copper pipe down to the hot water system. this 40/42mm copper has had a pinhole leak previously and was very expensive to repair and i was advised the same could happen elsewhere in this pipe

I had wanted to replace the old stop cock with a lever ball valve and T off and run a new feed to the newer 5 year old hot water system. The room where the water comes in is being refurbed so its the ideal time to run a new pipe, but the size has thrown me.

 

[Mottie]

I didn't think copper pipe would corrode on the inside with just water going through it?

 

[nhpb]

I didn't think copper pipe would corrode on the inside with just water going through it?

it had pinhole leaks in the pipe - there seems to be a lot of links online about it and reasons for it https://sila.com/blog/pinhole-leaks-copper-pipes-repair-or-replace/ if it helps anyone!

Irrespective of this, I water to tidy the pipework and do a direct feed from the incoming main to the unvented cylinder for other reason too (clear the loft of the pipework / tank and can't be great for pressure / flow with the feed going up and round the building through Ts, and going up / down pipe sizes)

So... any ideas on changing the valve / pipe size? the existing stopcock looks soldered (it can be isolated outside) its an all or nothing once this is taken off!

 

[oldbuffer]

1. The old imperial pipe sizes (nominal bore sizes) were 1/2", 3/4", 1" 1 1/4" and 1 1/2" and up.
2. Outside diameters were 15.14, 21.49, 28.24, 34.59, 40.94 mm respectively. There were thicker walled pipes used where threading of the pipe was required, which would give greater outside diameters.
3. Standard common UK copper pipe sizes (outside diameter) are (and have been since metrification) 15, 22, 28, 35, 42 mm
4. So a pipe with an outside diameter of 30.24 mm doesn't fit either the old imperial or the "new" metric system.
5. How are you measuring the circumference?
6. Are you sure the pipe is actually copper?

 

[oldbutnotdead]

If you're getting pinholing problems you'd be best off replacing the metal incomer with MDPE from the water meter- yes it means digging a trench but might as well do it now rather than try and do it when the place is up and running

 

[nhpb]

5. How are you measuring the circumference?

>>

Ok thanks that did make me think, i was using a 3mm string and just did it again with a strip of paper. new measurement is 90mm circumference! wouldn't have though using a thicker string would have made a 5mm difference!

so that makes it a 28mm copper feed. Thanks for this, i can order some bits now

 

[nhpb]

If you're getting pinholing problems you'd be best off replacing the metal incomer with MDPE from the water meter- yes it means digging a trench but might as well do it now rather than try and do it when the place is up and running

Thanks, that is a good point. The external water meter / stop cock is on the front which is going to to dug up and reslabbed / new blocking to perfect time to do this