Welding a copper boiler?

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Brian W

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I have just acquired a Stuart 504 boiler. The original builder welded a copper tube into the top of the boiler for a compressed air inlet. The copper weld was done off center and is quite sloppy with weld splatter around it. I would like to reverse this and restore the boiler to it's original condition. From another thread I see that welding copper requires pre and post welding treatment to prevent warping and cracking. What is that treatment? Looks like I can't just take this to my neighborhood TIG welder to seal up the hole. I hope to be able to get the tank back to where I could sand & polish the tank and the weld would be both invisible and usable for making steam.
 

ddmckee54

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Weld splatter?? What did they use to weld that fitting on? It sounds like this boiler may just have been the victim of somebody with a brand new welder and a "How hard can this be?" attitude. (Been guilty of that one myself in my younger and stupider days.) You got any pictures of this fitting/weld?

Not many places TIG weld copper, silver soldering - or silver brazing if you prefer, being the more common practice. Assuming that you can find a local welding shop with experience in welding copper, they should also be able to handle the pre/post welding treatments. They'd probably also be able to tell you if the top of that boiler can even be saved.

Don
 

Brian W

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Thanks Don,

I will explore local welders. I live near Everett Washington, home of Boeing so there are a lot of skilled people around here.
 
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Hello Brian. Did you get anywhere with the copper welding information? I am also looking to getting a boiler replaced and would like to have it welded construction.

Bri
 

Brian W

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I spoke with a welder that said he could do it but I have not had a chance to visit him yet. I will post an update when I have taken care of it.
 
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It looks like they use de oxidised filler rods, helium ( which holds the heat better?) and lots of power. My friend welded me a test piece and it seemed ok. I have yet to have a pressure vessel made to test.
Our club boiler inspector is a very cautious chap and likes the silver soldered method best so I would have to convince him before I start to manufacture.
Even though the main construction can be welded, they still put the fittings on with silver solder! Which is a bit strange.

Professionaly I work with stainless steel, however boilers over here would not be allowed in this material.

Bri
 

Brian W

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Another possibility is to drill out the welded in tube with a large enough hole to silver solder in a threaded bushing. Then I would have another steam port for a whistle. The reason I do not like this option is that it would be an off center hole which would not look very good. It would also not be into the superheated steam tube so the steam coming from it would be wet steam.
 

mrputz1

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Silver solder is the best .Sure Tig will work . But silver solder is strong enough . What pressure are you thinking of running ? Also does your state have boiler laws that legally should be followed ?Copper requires a lot of heat to silver solder . Two people are really needed one holding a heating torch and the other one soldering , The whole boiler probably will need to be heated at the point of soldering . The whole thing probably can't be entirely heated to soldering temperature without melting other soldered joints. Clean clean clean the surface .
 

pkastagehand

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My understanding (and I don't remember the reason) is that welding straight copper is a no-no for steam boilers/pressure vessels. A guy in Finland has done a copper alloy boiler with TIG (GTAW) successfully. If memory serves it was nickel copper.
 

jacobball2000

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Look at Keith Appleton video's on YouTube. You'll see allot on steam boilers. How their made, their working pressure and what kind there are. ex sample one is heated by rubbing alcohol. Silver soldering and repairing them. He even show one that been riveted but I don't think he did it. There's an episode where he goes to the shop where the copper is fabricated in to a boiler.
 
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Hi, Maxitrack use mostly TIG welded boilers for their Kit engines. Some or our club members have them. They are very nicely made.

I will have a look at Keith's page as I am a subscriber.

Bri
 

Brian W

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I had this tig welded yesterday. It is not as pretty as I had hoped but the metal buildup is plenty strong. I will hydro test it before steaming.

I had hopped to get it to a point where I could grind/sand it flush and polish it it to the point where it would disappear. Unfortunately the heat caused the copper to dish in a bit so that won't work. Now I am thinking about filling the depressed area with brazing or silver solder , get that flush and smooth and then getting it copper plated. Am I crazy?
 
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I don't think I would do that. Being that you are not the welder on this you really are not a hundred percent informed on the weld depth. You could grind out the strength of the weld and not realize it. If it is that unsightly what about a boiler jacket?

Kenny
 

Brian W

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That is my revised thinking also. I am thinking of hardwood cladding or a second copper skin over the top half of the boiler.

To all that replied thank you for your remarks.
 

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