Boiler design and construction on a Burrell 4 1/2"

Hi all. Hopefully there are some people with experience of Burrell 4 1/2" boilers.

Just starting my build of my Burrell with the drawings from Plastow. The boiler drawings show a 9" OD copper tube with a 3/16 wall thickness

First question, does anyone know if its possible to purchase this tube and if so where from?

2nd question related to the boiler construction

I don't seem to be able to purchase the tube. So it looks like I will have to roll 5mm (4.76mm is 3/16) copper plate to form a tube then double butt joint the seam.

The question is, what loss in strength should I be working with for a double butt joint KN Harris book suggests 95%

Can anyone help me with this. I have my calculations for the pressure V material thickness supplied by Harriss book if anyone wants to check them for me.

Thanks

Mark

Mark,

Personally I wouldn't build a boiler for a 4 1/2" scale engine from copper whatever the drawings say, I would get a steel one built. I reckon you could buy a steel one fully certified for less than the cost of the copper to make a copper one! Disadvantage with copper in that scale is the boiler is the backbone of the engine and strength wise steel will be a much better bet. You are going to need some serious heat to solder up a copper boiler that size.

But don't let me put you off! It's just my personal opinion.

Paul.

I'd agree with Paul; a copper boiler is a bad idea, for the reasons given.

What pressure are you planning to run at? The equations in K N Harris's book make some assumptions about safety factors and I'm not sure if they take into account the loss of strength with temperature. Whichever way you look at it this is going to be a big boiler, so you need your figures to be checked by a club inspector, or more likely a professional insurance company.

While I am making as much of my 4" Burrells as I can, I know my limitations and bought professionally made steel boilers.

Andrew

Mark, plus one for a steel boiler, there are folk out there that are making these to a proven design, and these will take the rough and tumble of the rally field.

Chris Gunn

Hi guys, thanks for the replies. All interesting thoughts and now under consideration. So, with that advise, who are building good boilers?

Thanks

Mark

Mark,

Tony Baldwin (AJB) did mine for the half size, nice job, fair price. Rub is there is a an18m to 2 year waiting list from order to delivery but you will find the same with most of the reputable boiler makers I think.

Paul.