Had my first go at a big boiler on a nat. gas rig here in Colorado. The internal burner tubes were coming apart at the factory welds. I knew I was only going to buy some time before a truck showed up with a new boiler unit. After several attempts with both Low Hy and 5p, my efforts were in vein. I preheat before each weld around the outside of the tubes, but I found that once I was succesfull stopping one tube from leaking, the one next to it would spring a leak. The only thing I think I could have done any different or "better" would have been to use an ln-25 for the whole welding process. Unfortunatly some affable fella decided to take mine out of the back of my pick-up last month, so I didn't have one on this job.
As a last ditch effort, I made some templates and cut some patterns out of 3/16" plate to actually try and isolate 24 of these leaking tubes at one time. Needless to say, I got halfway home at 1am and they called me back out to try again. Long story short, I told them they were sol, because there just wasn't anything I could do, beyond what I had, that would take us forward with the repair. I suggested they turn the pressure down way low, and nurse it along until the new unit showed up the next day. That's what they did, and they had enough steam to keep everything from freezing solid.
I suppose I'm asking for some sort of validation that I did everything I could to save the remaining volume of the boiler. Believe me, I would have liked to be the hero of the day by making that thing purr, but I'm convinced I did everything I could for them. Please share your thoughts on this subject - Sourdough