Is any old copper pipe the 'same'.

I fear in sourcing some copper 1/4" pipe / tube locally I have possibly been supplied that which refrigeration engineers use. Is this likely to be a problem for my 71/4" model steam loco "plumbing".

I have also heard people refer to hard / cold extrusion copper tube what is this ?

Paul McGee

Copper can be annealed to a softer form which which work hardens. Extruding copper will clearly work harden it. If it is a problem, anneal it.

Copper pipe for refrigerators is 99.9% pure with a dash of Phosphorous. By specification it is de-oxidised, Nitrogen free and fully degreased (provided it's still properly packaged). You could say it's posh copper!

When supplied in a roll it's Soft, but straight pipe could be either Hard or Half-hard. The pipe is either work hardened or softened by heating to get the desired property. In use the soft form is easier to bend but weaker - about ⅓rd as strong as fully hard.

One concern may be the thickness of the pipe wall - I believe refrigerator tube is only good for about half the pressure taken by brake pipe. But as brake pipe is rated about 3000psi, perhaps not a problem on a small engine. (Warning - I'm not a boiler expert!). Did the seller provide a specification?

Dave

As it is outside the boiler you should be fine.

Brake pipe is 10% Nickel

If you mean tubing for vehicle hydraulic brakes, some is 100% carbon steel (plus protective plated finish)

Ian P

But the OP refers to copper

You can get three grades of brake pipe: cunifer, copper and steel. Halfords sell brake pipe to the 99.9% + phosphorous recipe in Dave's post.

Neil

q

Thanks all particularly info about working pressure limits. As pointed out i'm well within the capacity of its capability. I'm in Brisbane Qld and unlike the uk sourcing any specialist materials here is not as easy as in the UK where you have large demand for anything. We have two suppliers of nonferrous metals and they have limited ranges and want to sell commercial quantities. Then we have our model suppliers who have the range we want but are not always in stock. Trick is to have several jobs on the go whilst waiting but its frustrating at times.

For really small tube i buy the little handy packs that some model shops stock . Have a look at emma’s spare room machine shop on youtube , if you send her a message maybe she can point you in the right direction as she makes her own boilers and is based in the Brisbane area . For larger stuff like what you want for a boiler sometimes making friends with a local plumber or gasfitter can be an advantage , they usually collect offcuts to send to the scrapyerd for some pocket money.

What M.E suppliers have you tried ?

Try a local Airconditioning / refridgeration company. The will probably give a couple of feet of off-cut if you ask nicely.

Getting imperial size may be an issue but you neve know.

Robert G8RPI.