copper pipe for model engines

I'd be grateful if someone could advise me as follows: I have to replace some 1/4" copper pipe to the pressure gauge on a model traction engine running at 80 psi Is all small diameter copper pipe of the same specification? Or are there differences between that used for steam at pressure and that used for car brake systems? I'm unsure what to order until I know what I should be seeking

thanks

Rod Gentry

Rod

I tend to get this sort of thing from THESE folk - just tell them what you want it for.

Norman

Rod,

The copper pipe used for car breaking systems is suitable for use on systems like ours.....

the wall thickness is such that it will withstand pressures greater than 1000psi....

you could Google the pressure rating of copper pipe for the given wall thickness....

Check out the link below.....

http://www.swagelok.co.uk/downloads/WebCatalogs/EN/MS-01-107.pdf

Edited By John Rudd on 23/12/2013 20:25:19

I'm not sure about the UK but copper brake lines are absolutely not allowed on cars and trucks in Canada and USA. Any car or truck fitted with copper brake or fuel lines will not pass a vehicle safety inspection. The reason is that copper tubing is unsafe for hydraulic applications - it will work harden and develop cracks and leaks after repeated pressurization at hydraulic pressures (700 psi and up) and this effect worsens with normal shocks and vibrations in a car chassis.

Only plated mild steel tubing or stainless steel brake tubing with an SAE rating for automotive use is allowed for hydraulic brake service on passenger vehicles and trucks in Canada and USA, with double flared ends and heavy wall compression fittings. In heavy equipment worldwide, all rigid metal tubing used for hydraulic systems is steel or stainless steel hydraulic tubing. Stainless mesh reinforced rubber tube may be used for flexible hydraulic lines. Copper is not allowed for tubing in heavy equipment hydraulic systems at all.

For steam or water up to about 300 PSI, copper tubing is fine, but do use a heavy gauge tube for high pressure. When I worked in industry with copper piping in hot water heating systems we were taught never to exceed 400 psi working pressure in any copper pipe or tube as a general rule, as most copper pipe was rated for no more than 400 psi working pressure in North America. Actual burst pressure was far higher than 400 psi, but the material was de-rated to 400 psi WP at room temperature to ensure adequate safety factor.

I'd ask your boiler inspector though before buying or fitting any piping, especially any that deviates in size from the published design for your engine's boiler.

Just my $0.02. JD

Edited By Jeff Dayman on 24/12/2013 00:03:36

Edited By Jeff Dayman on 24/12/2013 00:04:41

Hi Rodney,

Do not use any plumbing grade of copper. It may contain lead so affecting flow characteristics of your silver solder.

Do not use any copper that may contain dissolved oxygen that could cause cracking of the copper during the silver soldering operation (hydrogen embrittlement)

Use C103 or C106 grade copper with total confidence.

For more info go to **LINK**

regards

keith

PS

and a Merry Christmas and Happy New Year to all

Jeff,

Thanks for that very informative post.

Prompted by your comments, I dug a little further, and found this useful reference.

MichaelG.

Edited By Michael Gilligan on 24/12/2013 09:17:11

Still on copper tube but slightly different aspect.......I bought a Gauge 1 loco boiler kit the plans for which specify "thin walled" copper tubes for the 5/16" firetubes in a 2" boiler shell. The tubes that I have got with the kit are 1/32" wall thickness. Is this thin walled enough or should I be looking at 1/64" or nearest?

Mick

May sound a bit stupid, but make sure your tube is copper. Brake tube can be 'Bundy tube' which is copper plated steel tube - you don't want that for sure !

BobH

Michael;s reference is interesting. Here in the UK it is usual for self-fit brake [pipes to be fabricated from what we call 'cunifer' rather than pure copper. I'm not aware of any problems with using these, and have fitted them to a good eight or ten vehicles and never had a query from the MOT testers. Also, I've never had one fail or corrode but I've seen lots of ferrous brake pipes in a bad way.

Cunifer does seem to be legal for US use: **LINK**

"High performance manufacturers such as Aston Martin, Porsche, Volvo and Audi, have chosen to install copper-nickel alloy over all other materials including stainless steel brake lines."

Neil

I used thick walled copper pipe with silver soldered nipples to connect the oxygen cylinder to the regulator in my glider, and that runs at up to 2000psi. It hasn't failed yet.

Regards,

Andrew