Garden Railway Forum

On Brian Wilson's Eric (and few other designs I looked at) steam pipe is quoted as 1/8" dia tube, but nobody ever mentions the wall thickness...
I can get 1/8" copper tubing in following SWG - 27, 26, 24, 22, 20 (or for metric guys from 0.4mm to 0.8mm wall thickness).

Which size of copper tube do you guys use for steam pipe fitting to cylinder

bambuko wrote: ↑Fri Apr 24, 2020 7:54 pm Which size do you guys use for steam pipe fitting to cylinder.

The annealed 1/8” copper tubing I use is listed by the supplier as 24g. I'm not sure it's available in other sizes here in Oz, the ME suppliers only list that size. Annealed copper tubing comes in a coil, but there's no point in buying straight copper tube, you have to anneal it and bend it anyway and it costs a lot more per foot.

The stainless steel tubing I use for the 'superheater' is heavier wall than the copper, 22g I think. The only easily available source locally is the K&S rack.......

Regards,
Graeme

Thank you Graeme,
25 swg is smack in the middle of what's available from my supplier and it leaves 2mm dia delivery hole in middle.
Sounds just about right - good to have confirmation
As for stainless, I am still long way off before I need it, but I have filed the info.
BTW - what is K&S rack ?

bambuko wrote: ↑Sat Apr 25, 2020 12:29 pm BTW - what is K&S rack ?

https://www.ksmetals.com/

The local radio control hobby shop keeps a useful stock of the K&S range.

Graeme

bambuko wrote: ↑Fri Apr 24, 2020 7:54 pm On Brian Wilson's Eric (and few other designs I looked at) steam pipe is quoted as 1/8" dia, but nobody ever mentions the wall thickness...
I can get 1/8" copper pipe in following SWG - 27, 26, 24, 22, 20 (or for metric guys from 0.4mm to 0.8mm wall thickness).

Which size do you guys use for steam pipe fitting to cylinder

That sort of stuff missing from text and drawings gets me feeling rather

Because of the lack of such dimensions I was able to probe and check MAM's Lady Ann kit for such confirmations. I would have it my drawings, I will look it up later. This is why I take the time and effort to do full 3D and 2D drawings and go back and edit them and have them updated so such stuff can be referred to and tested, proven and quoted later.
However I am yet to steam test my little beast to prove any thing.
Note, be careful using "Pipe" dimensions as this refers to the bore/internal diameter, which in this case is what you are seeking.
"Tubing" refers to the outside diameter and the internal diameter could be anything, so one needs to know the wall thickness.

K&S for me too. 3/32" tube slides into a 1/8" tube

Hydrostatic Dazza wrote: ↑Sat Apr 25, 2020 11:23 pm
...I will look it up later...

thank you

Hydrostatic Dazza wrote: ↑Sat Apr 25, 2020 11:23 pm...This is why I take the time and effort to do full 3D and 2D drawings and go back and edit them and have them updated...

that's professional way of doing things

Hydrostatic Dazza wrote: ↑Sat Apr 25, 2020 11:23 pm...Note, be careful using "Pipe" dimensions as this refers to the bore/internal diameter, which in this case is what you are seeking.
"Tubing" refers to the outside diameter and the internal diameter could be anything, so one needs to know the wall thickness.

Yes, that was confusing choice of word on my behalf - sorry.
Steam is delivered by "pipe", but model engineers specify and use "tubing" to create piping
I have edited thread title and my original post to be more precise

dewintondave wrote: ↑Sun Apr 26, 2020 12:13 am ...3/32" tube slides into a 1/8" tube

That would imply 0.4mm (27 SWG) wall thickness for the 1/8" tube ...
Rather thin? but clearly it works OK for you
Maybe it is also the function of the steam pressure?
Steam pressure in 16mm locos tends to be lower than what it is for example in G1 locos?

bambuko wrote: ↑Sun Apr 26, 2020 8:17 am That would imply 0.4mm (27 SWG) wall thickness for the 1/8" tube ...
Rather thin? but clearly it works OK for you
Maybe it is also the function of the steam pressure?
Steam pressure in 16mm locos tends to be lower than what it is for example in G1 locos?

Don't overthink things.......

If you do the calculation, 1/8” x 1/64” annealed copper tube at room temperature can take over 1500 psi. It will be lower at higher temperatures, but still well above anything encountered in model engineering.

My hydraulic test rig has 1/8” copper tubing and I've taken that up to 300 psi when testing gas tanks. No problems with the tubing, but making fittings that won't leak at that pressure is another matter.

You can increase the pressure rating of the copper tubing by increasing the wall thickness, with the trade-off that pressure drop will increase, but the performance difference between the 1/64” and 24 SWG wall thickness tubing is negligible in our applications.

I use 1/8” x 24 SWG tube most of the time, but will use the K&S 1/8” x 1/64” tubing if I run out, as I can get it much faster.

Regards,
Graeme

GTB wrote: ↑Sun Apr 26, 2020 11:07 am ...Don't overthink things...

Yes, you are right, should have calculated things, before making flippant comments.
As you say wall thickness in our application is limited by practicality of using it rather than max pressure.

bambuko wrote: ↑Sun Apr 26, 2020 8:17 am That would imply 0.4mm (27 SWG) wall thickness for the 1/8" tube ...
Rather thin? but clearly it works OK for you
Maybe it is also the function of the steam pressure?
Steam pressure in 16mm locos tends to be lower than what it is for example in G1 locos?

I run my locos at 40 PSI when I can.
It's a function of area.
The nipples on the Quarry Hunslet's 3/32" blower pipe and 1/16" pressure gauge tube are Loctited on rather than the usual silver brazing as the force from the 40 PSI is so low on these tiny tubes at that diameter