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.