Curiosity got the better of me, so I went out and drilled out the worst of the leak points with a 3/16" drill bit. It looks like I was incorrect in my assumption, I was thinking that these were dimples stamped into flat plate, in actuality it was a flat plate that had slots cut into it and these are reinforcing slats or stays that are welded from one wall to the other to keep the walls from spreading apart. Thanks dougtrr2 on TBN and Peakbagger on Hearth for pointing that out. If my HF micrometer is accurate, the metal has not eroded, it is still 1/4" thick. The leak is a crack at the point where the stay is welded into the wall plate. A couple of pictures: Also found a couple more leaking stays on the sides, one on each side. Right side: Left side: So I guess the question is, do I weld these up with the stick (and if so which rod), or with a MIG... dougtrr2 on TBN had the same issue with one and and said that the guy he had work on it had better luck with a stick than with a MIG and I may end up chasing my tail with leaks on this. I am thinking that if I can get it to weld up that I may want to hit all the stays in the firebox as a precautionary measure, but that could also mess with the HAZ and make more cracks occur. Decisions, decisions , decisions... Aaron Z
I would use 6010 for the root weld and 7018 for fill. This is what I was taught to use for boiler repair and it worked well. Practice on some scrap steel in the same position as the boiler walls.
Pulled out the DHW (Domestic Hot Water) coil to look at the inside of the vessel last night, this is looking across above the top of the firebox, the two cylinders on the far side are thermowells: Looking down the sidewall of the firebox from the DHW opening: Looking over and toward the back/chimney from the DHW opening The DHW coil: All in all, it looks pretty clean inside, I think the leaks are just from the welds cracking. Aaron Z
View attachment 374283 If you look at the stay, you can see the groove all the way around it. I do not know if the weld was insufficient from the manufacturer, or if the weld has been eaten away by corrosion. Either way, you need to weld it so that the weld goes all the way through. If you can access it, I would cut each one of those stays all the way out and replace them. It is hard to get a good feel for the situation from pictures though. Maybe you can just burn real deep with the 6010 and go around each one just like they are.
Looking at this picture and discussing the boiler with the "old timers" at work: We are thinking that the root cause of the cracks is stress risers coming off of the corners of the square holes punched in the walls that the stays go through. My plan is to clean up all the points where the risers are welded in, drill all 4 corners with a 3/16" drill bit and weld around each one. If it works, great. If not, it will either get migrated to the scrapyard, or make a trip to MI (if corncob still wants it at that point) Related to heat cycling, these are all in the bottom half of the firebox where it would change temperature more when the boiler cycles on and off as the "flame" goes down to get to the exhaust. Aaron Z
