combustion chamber testing

Good morning All.

I am building a locomotive boiler ( LBSC / Josslin Uranus ) and have tested the silver soldering of the cross tubes in the combustion chamber to 200 psi all good. Now the combustion chamber has been soldered to the tube nest I am trying to test the combustion chamber to front plate and the tube nest joint, inside out so to speak; as once its soldered in to the boiler you cant get at it at all.

I cant seem to get a good enough seal on the tubes at the smokebox end to get pressure up sufficiently high and don't want to tighten up the test rig any more in case a tube buckles.

I seem to recall an article in EIM regarding a similar test and how he sealed the tube ends, can anyone point me in the direction of that article or have any ideas how a better seal might be achieved ? I had considered making ali or wooden plugs and fitting with silicone, but I am concerned about them swelling the ends of the tubes and the difficulties of getting them all the same length.

Over to the knowledgeable ones from this old dunce !

Forgot to load photos DOH !!

Look under album Test rig.

I used a very similar rig to yours to do the same thing and I sealed both ends with a sheet of rubber from an old inner tube. That worked well. It's soft enough that it seals the tube ends even if they aren't all exactly the same length. I have copies of all EIMs and seem to recall the article you mention, will try and find it.

John

Unless all the tube ends are in ye same plane, which is unlikely I think you will struggle. How about turned plugs with O rings? Or even rubber corks in the firebox end

Duncan and John, thanks .

I am also using old inner tube, but I tend to leave the tube lengths slightly different to help feeding them in the SB tubeplate later on. I have cut them to the same length but not successful. Unfortunately you cant reach the inner ends of the tubes because of the cross tubes in the combustion chamber. I've been through all my back eim copies without success, so I presume it must be in one I loaned out and didn't get back. sods law !! Just cant remember what he actually used, so if you can find it I would be most grateful.

Cheers Brian.