The simple answer is don't get anywhere near it with flame treatment. You may only have a leaky gasket
. I have seen thousands of these tanks
and the only leaks
I ever saw were gaskets or someone accidentally put a hole in the tank. Those tanks
have no seams to weld and they are not flame treated. Cross linked PE tanks are rotomolded, not welded together. That way they are seamless. What do you mean, "the tank wall" the pickup tube should come out of the top of the tank. If it's on a side wall the tank is on its side.