Milt said:I have held a stinger in my hand only once, and I laid down only about an inch of bead at that time. I am no welder.
In a former life, I was a technical writer and one of my more epic tomes, (still in use today), was about how to make an initial weld that will not crack when stressed, and how to make a repair to one which has cracked under repeated stress. There are a couple of things that strike me when I look at the pictures, one being the difference in the oxidation of the welds and the surrounding metal, the locations of the cracks, and the repetitious nature of the problem. When I see things like that, I think that there are issues with the original design in that the metal in the stove must flex rather than be allowed to expand and contract, that the original welding included a lot of slag and gas bubbles meaning that the welder has a skill level similar to my own, that the welds were made to cold metal with a substandard machine and that the welding rod itself might have been incompatible with the intended purpose.
All of these things support numbers 1, 3, and 4 in the preceding post.
Thank you Milt, those are interesting observations! The original welder for my firebox was probably a robot, since the PE manufacturing process is automated. Therefore, if the settings were out, weld would be out. Unfortunately, the robot does not have senses to be able to judge the heat penetration, etc., unlike a human welder.