Flexible steam tubing suggestions?

[Kimball McGinley]

I am finally getting around to installing the steam lines on my "Marie Estelle" 7-1/2" gauge 2-1/2" scale Don Young 0-4-0 Porter. These go from the front tubesheet drypipe down to each cylinder. There does not seem to be room to put a 1/8 pipe to flare fitting alongside the saddle and the exhaust tubes so that I can run a 1/4" copper supply tube.

Can anyone suggest a source for a suitable flexible metal (SS) line that would do the trick?

All suggestions welcome, I already looked at McMaster-Carr and only found some 1/4 lines.

Thanks, Kimball

[Bill Shields]

flex tubing in that size is very tough to find...like you (or maybe because of my age...longer)...been looking off and on for a LONG TIME in my industrial career where we dealt with nasty fluids and pressures) and never really found something suitable at a reasonable cost (or at ANY COST).

I have succumbed to making fittings to fit (not flare) that are compact enough to get in there...the 'shoulder' type of fittings can be made very small, and even with only .030 of surface to bear on, are quite strong...after all, 200 PSI on such a small ID really amounts to very little axial load.

BvBrocklin created a standard line of these fittings which I have been copying and using for decades and they just don't fail.

[Kimball McGinley]

Thanks Bill! Is there any way I could get a copy of some B V B drawings?

[Bill Shields]

will have to dig them up and scan them...have them around here somewhere..

keep reminding me...

know that some of them are on his pump drawings.

what size tube are you going to use?

[Kimball McGinley]

Bill: You have given me an idea to make a suitable fitting from 1/2" hex stock with a soldered transition to a copper tube, so I believe I now have a solution.

Thanks for all your valuable other posts too!

[Bill Shields]

that is basically where I was headed...it's a variation on the old British steam fitting. BvB just scaled them up.

Stay away from compression 'olives' here....the copper under them will compress and they will eventually leak.

[Fred_V]

I have a CAD drawing for unions from 1/8" to 3/8" copper tube. Send me a PM if you would like a copy.

[Kimball McGinley]

Fred V - PM sent, thanks.

[10 Wheeler Rob]

1/4" copper tunings sounds to small for supply lines to cylinders. The Allen Ten Wheeler I build called for 5/16".

You do not need to make the nuts. For 5/16" tubing I buy 1/4" compression fitting nuts (7/16 hex) drill them out to accept a butt ferrul I make. I machine the mating fitting from 3/8" hex stock, or what ever size is needed for the mating part if its an NPT fitting. I silver solder the tube into the ferrul.

I make most of my fittings using the drilled out compression nuts: 1/8" nuts for 3/16 tube, 3/16 nuts for 1/4 tube, 1/4 nuts for 5/16 tube, 5/16 nuts for 3/8 tube.

Rob

[Kimball McGinley]

Rob: Great suggestions, thanks. I was going from (faulty) memory when I wrote 1/4"; Don Young did specify 5/16", and that is what I am using. The difference is significant, 25/16 or 156%!!!

[Builder01]

1/4" from 5/16" is 1/16". Where did 25/16 come from?

[Kimball McGinley]

Sorry; I was not clear. 25/16 is the ratio of the area between the two, not a dimension. The area of a circle is Pii * R squared. So in comparing the area of a 5/16" line to a 1/4" (4/16") line, I just squared 5 and 4, which is 25 vs. 16.