Copper pipe selection

[GaryMParticipant @garym]

for steam fittings

[GaryMParticipant @garym]

Hi,

Simple question that I cannot find the answer to anywhere.

A while ago I bought some copper pipe for connecting to the S50 that I'm making (on hold at the moment).

The pipe I bought is 5/32" OD 0.014" wall thickness (28 SWG ?) from Reeves as here

**LINK**

Later I thought I might use 1/8" pipe instead so at last years Midlands show I bought some 1/8" OD from Blackgates. However this pipe has a much thicker wall (~1/32&quot and is coiled whereas the Reeves pipe is dead straight.

Which is the correct sort to use and does it matter?

Note this is for connecting pipe not a potential boiler.

Thanks for any replies.

Gary

[AnthonyParticipant @anthony]

I built the S50 last winter, and used car brake pipe for the inlet and exhaust, easily obtained and threads really good.

[GaryMParticipant @garym]

Hi Anthony,

Thanks for the reply, but I don't want to thread it. I want to silver solder a union to it.

Gary

[GaryMParticipant @garym]

Your S50 looks very nice by the way. I particularly like the main bearing caps and the cylinder cleading and banding.

Gary

[Neil WyattModerator @neilwyatt]

The cunifer pipe ought to silver solder easily (at least I hope so – I have several feet retained as future steam pipe!)

Neil

[AndyPParticipant @andyp13730]

Gary

Using the formula and data here I calculated a safe working pressure of 738 psi for the thin wall 5/32 tube and no doubt the 1/8 would be higher so your choice.

Incidentally if you want dead straight copper pipe in the smaller sizes like this then at the expense of the end couple of inches just clamp one end in the vice and grip t'other end with favourite grips and pull – at some point you will feel a 'give' and there you go – straight tube.

Andy

[Neil WyattModerator @neilwyatt]

Alternatively, for about 12" or so of tube, put it on a clean flat surface (e.g. a bit of worktop) and place something heavy, clean and flat on top. Rioll back and forth and the pipe will become very straight very quickly.

Neil

[julian atkinsParticipant @julianatkins58923]

if you pop into your local model shop you can get KS copper pipe 1/8"dia in thin wall section.

incidentally 3/16" dia thinwall stuff seems to be unobtainable these days unless someone knows of a source? ive very little of this size left.

cheers,

julian

[John BaguleyParticipant @johnbaguley78655]

Julian, the last lot of thin wall tubing I purchased was from Doug Hewson a couple of years back and he had 3/16".

Maidstone Engineering list 3/16" x 26swg as well.

I tend to use thin wall all the time as you can go down a size and still have the same bore as the thicker stuff.

John

[GaryMParticipant @garym]

Thanks for the replies.

AndyP: I think I should be OK with 20psi then I might try your idea for straightening at some point, just out of curiosity.

Julian: Yes, I think the 5/32" was KS pipe, so I know you can get it.

John: "I tend to use thin wall all the time as you can go down a size and still have the same bore as the thicker stuff" Hadn't thought of that.

I just thought one sort might be easier to bend than the other and there seemed to be no guidance on any suppliers web sites. For that matter the whole subject of piping, unions, valves etc. never seems to get a mention in books or on web sites. Loads of build logs on engines and boilers but nothing on connecting them. Article Neil?

Off to Harrogate now.

Gary

[Neil WyattModerator @neilwyatt]

I have a very old ME article on 'standard unions' for steam pipes. I used it to make unions for my 10V, but on later models I used flanged joints as closer to scale.

If I can find it again, I'll put it up on this website.

If anyone wants to write up this subject afresh, it's probably an ME article rather than MEW.

Neil

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