Strange pipe size - approx 17mm?

[A.Lee]

I was fitting a new kitchen today, went to turn off the water, then fit an isolating valve on the pipes when I noticed that the pipe looked unusally large for 15mm or half inch pipe. I mentioned this to the homeowner, who said, yes,last time they changed the sink, the plumber took hours to file the pipe down to get a fitting on. I measured it, and it was roughly 2mm wider than the 15mm copper pipe I had with me. Strange. I didnt bother cutting it where I wanted, and did the cutting on the 'new' pipe under the sink.

Having never seen this pipe before, what is it?

1930's house, possibly original piping, going by the amount of paint on it. Definitely larger than 15mm/ 1/2", but a lot smaller than 22/ 3/4". Copper throughout, not iron.

Ta Alan

[The Medway Handyman]

Wierd. Iron pipe is approx 17mm OD, but never heard of copper that size. If it was the old 1/2" that should fit 15mm fittings.

[John Rumm]

more like 18mm+ I would have thought for iron - since that is the diameter of a 1/2" BSP thread

I wonder what the inside diameter was (and could one have shoved some

15mm up it and soldered that)?

[Kevin Poole]

There were a number of houses in Derby in the 1930s built by Browning Brothers of Humberstone which used threaded copper pipe. It's 30-odd years since I had to work on it, so I can't remember the exact size, but I discovered that just one local plumber's merchant had stocks of adapters. They closed years ago.

IIRC, the thread was much finer than BSP - probably BSB.

[John Rumm]

BES do some "transition fittings" that are special compression type fittings designed for mating odd pipe sizes with more common stuff. (Listed along with the Leadlok type fittings).

[A.Lee]

Funny you should say that, this is in Leicester, so possibly the same builder, or source of this strange sized pipe. It is visibly bigger than 15mm pipe, so how the previous bloke got a compression fitting to fit it, I dont know. Alan.

[Kevin Poole]

I remembered you'd mentioned Leicester. No idea where Humberstone is, only Humberstone Rd signalbox.

Get a zoomed-in birds-eye view of DE23 8RR, with

to see the type of houses. Is the Leicester one with the odd pipe a similar design? The Browning Brothers houses in Derby are very recognisable.

[TheScullster]

"A.Lee" wrote

It's possible this was made to match the dimensions, or at least the OD, of steel piping. Looking at tables, 3/8" nominal bore steel pipe has an OD of 17.1mm

Phil