boiler tube removed to get to pipes back of firebox

[Ron HancockParticipant @ronhancock63652]

i have cut the barrel of as i need to silver solder tubes.

I have fitted new tuber except the four super heater tubes.

Still wondering if i should cut out the back of fire box make new flanged plate and weld the pipes into firebox plate before welding a new plate into fire box.

Welcome views on it as very unsure at moment i was just going to weld the pipes with silver solder

Ron

[Ron HancockParticipant @ronhancock63652]

[JasonBModerator @jasonb]

Ron, how do you weld with silver solder? or are you thinking of using the tig to melt the solder

[KWILParticipant @kwil]

You cannot!

[AndyAParticipant @andya]

I'm slightly curious to know what your boiler inspector has said about this slightly unorthodox method of repair?

[KWILParticipant @kwil]

Wise words, perhaps "bin it, all is lost! ?

[JasonBModerator @jasonb]

Posted by Ron Hancock on 10/03/2015 16:46:18:

Still wondering if i should cut out the back of fire box make new flanged plate and weld the pipes into firebox plate before welding a new plate into fire box.

Ron why would you feel the need to flange a tubeplate if you intend to weld it into place?

To my mind the flange provides a suitable surface area for the solder when using silver solder as the jointing material. If welding then the weld will not reach along the flange so there is little point in having one, the joint should just have a properly designed weld prep be it a simple chamfer or a "J" type for fuller penitration

Same would apply to your comment about a strip behind the joint where you intend to weld the barrel back on in your other thread, it will have little effect as the weld won't reach that far in particularly if you are not purging air from inside by filling withh gas.

Again as I said in the other thread talk with your inspector as to the type of weld or other joins he is happy to accept before going any further

Edited By JasonB on 11/03/2015 14:47:08

[PTParticipant @pt]

The flanged plates can and should be flanged, sharp corners on a pressure vessel is poor joint design. The plates should be flanged to the same width as the wrappers and a seam weld with 'v' prep. This is how bullied designed the merchant navy welded boilers. Note the pic above, a nice radius with the weld meeting the wrapper. The other disadvantage on sharp corners, the stays will have to go further out to make up for the weak spot of losing this radius.

Ron I am sorry but this boiler should go no further, I dont know where this design of jointing has come from but it has no place in miniature boilers. Scrap it, read up on silver soldering and try again. Paul.

[JasonBModerator @jasonb]

Paul I was Imagining that Ron was joing to flange teh plate like you would a silver soldered boiler and have the flange go inside the wrapper and then just weld the edge. This is different to what you show where I agree the bend will add to the strength and the stay spacing can be taken from where the plate becomes flat rather than teh extream edge.

Maybe I'm more used to looking a model traction engine steel boilers where corners are right angles and not flanged

J

[KWILParticipant @kwil]

With the botched tubes buttered with silver solder and not properly "soldered", the state of the remaining copper parts it would be sensible to take the moment, learn the lessons and start again, perhaps supervised step by step by the Boiler Inspector, who will have to be satisfied anyway.

That way Ron, you should be guided away from further mistakes, costly as they become and, learn the right ways, not preaching but you do need that individual help, even if you can indeed already weld.

Edited By KWIL on 11/03/2015 18:37:19

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