How could it have? Now..I do not have one on my pot because it always want to leak, but that is besides the point. If you put pressure in a pot, the valve will not go off until you exceed the value set on the valve. So if I load it with 40 Lbs and the valve is set for 50 Lbs, the valve will not go off. Now, the pot is loaded to 40, the hose is removed from the pot and it is simply sitting there all on it's own. The pressure in the pot is not going to increase to 50 and set of the safety valve, it can't do that on it's own. Even if the pot was in the window with the sun shining on it, it couldn't increase 10 Lbs of pressure over 3-4 minutes. So the answer is that the relief valve would not have done a thing to prevent it.
My believe is that some pots are not 100% round. It got dinged around somewhere or something at sometime happend to it. Now if it isn't perfectly round, then air pressure is going to make it even more out of round. Eventually with the flexing of the pot being used, it will reach a breaking point. I think it's pretty simple in theory and why should it have to be complex? I believe that if the pot had 6 tie downs instead of 4, it would be a drastic improvement. I don't think you will see any pot companies rushing to go do that, because what we are doing with a pot is not what it was meant to do. I do not believe a pot will just pop like this on it's first go, even if it's a bit out of round. But, after a dozen flexes, that's like bending a wire back and forth several times. The only cure I could foresee would be to constantly measure your pot with some calipers prior to each use. If you kept measuring it each time, one side is going to be growing a hair at a time and the other side will be shrinking a hair at a time, not necessarily noticable to the eye. Each time it would grow a hair more on one side. As the pot warps, it is doing the same thing to the lid. I am believeing that Curtis' adjustments to the lid are a good idea. It will extend the life of the lid. I don't believe what he has done had any impact on the life of that pot, other than the over-presurizing part..but ya'll know what I mean. I think the over-pressurizing part simply made the pot fail faster and more dangerously, but otherwise, that pot was destined to fail prematurely.
Best idea I gained from this post was making a box to put the pot into. That's a good solution. Just stack up some cinder blocks and put the pot inside just like a fireplace. They do the same thing when working on big trucks. They always put my tire inside a thick metal cage before they inflate it. They always put my brake chambers in a solid thick metal box and cut the retaining clamp with a torch. Otherwise, the spring in those brakes can go right through a cinderblock wall! So why should working with a pressure pot be any different?
ah...crossed posts with Neil! Pretty much what he says, I agree!