With a tin soldered sleeve job, you would have to take the entire barrel set apart (unsolder) ribs and barrels from the back end to completely remove all solder. Then it would be possible to have the joints welded. If any of the solder remains and gets into the weld puddle you would have a very contaminated weld. It is sleeved,enjoy it that way. The only advantage to a welded job is the joint generally doesn't show.

Dennis Potter