What type of boiler is this? If this is a fire tube boiler, ususally they are rolled in. Is this boiler used for comercial or industrial applications? Do you have a R Stamp? I guess there is a lot more information we need to know before we can help you.

Mike

Hello waps75, If you don't have an "R" stamp authorization I advise you NOT to perform any type of welding on this boiler! As Mike had said the tubes in your boiler are expanded into the tube sheet by using a tube expander. Some high pressure scotch marine style boilers, the tubes are expanded then seal welded to the rear tube sheet on the hot pass. I own a boiler repair shop and have had to go in to repair a boiler or pressure vessels that someone did a weld repair and didn't have an "R" stamp and was caught by a boiler inspector. An "R" stamp code repair requires that every thing is documented on a traveler such as weld procedures, material documentation, welders continuity log, and equipment calibration record. Some repairs require NDT and pre/post weld heating as per the original code of construction usually ASME. All repairs are documented on an R-! form and should be registered with the national board and the state boiler divison. I just wanted to save you some grief before you struck an arc. If you need to find a "R" stamp holder in your state, look at the national board of boiler and pressure vessel inspectors web site.
Good luck
Ray