Try M-Metals they list 5"od x 10gauge C106 £8.75 an inch +VAT + Carriage

David

That's M-Machine in David's post who I use a lot

My bit will be a bit big for you at 6.25 dia x 22" long but at least your post gives me a rough idea of what to expect pricewise when I move it on. Be interested in knowing where you get your pipe.

Rik

Hi Stephen, did you have any luck? I'm in a similar boat trying to buy copper pipe. I was warned to "bring my chequebook" as copper isn't cheap but the bewildering lengths people sell it in makes it hard to compare. I'm looking at some 108mm (~4.25" ) copper pipe on ebay, it's £120 for 900mm (~35" ) making it around 3.50 an inch. This is about the cheapest I can find for a reasonably wide pipe but I'm hesistant to buy 35 inches when I only really need 9. Maybe I will have to just stomach it and try and find a use for the rest. Perhaps attempts 2 and 3…!

Edited By Matt T on 26/09/2023 10:22:51

Good catch, I did check and it's 1.5mm wall thickness. Would it okay to simply reduce the working pressure of the boiler? As it's my first boiler build the object is primarily to get some experience with silver soldering, hammer forming etc. I note that mamod boilders have a safety valve that goes off at around 20psi so perhaps building and testing to this (20/40) would allow me to use a thinner and hence cheaper pipe?

High Matt T, you would be better off visiting a scrap metal merchant and buying some big bore copper tube say 1& 1/2 to 1 &3/4 " pipe to make Tubal Cain's Polly for practice. You can buy that for £10 a kilo.

If you want to make something as big as 4 &1/2" that will be a lot of money in silver solder and it would be a shame to waste that on something that can only run at 20 PSI.

Although the mamods run at a low pressure they struggle with the skin off a rice pudding so as Noel says what do you want to use the boiler for, little point in making a low pressure one if it won't run a wobbler than has been built a bit on the tight side. Or you overheat and melt the tube while trying to learn how to solder.

The thicker walled tube of known parentage will not be a big percentage of the overall cost by the time you have added in silver solder, the other tubes and platework and your time. Even less if you only have to make the one boiler not two.