Not sure how good the weld would be but from a safety stand point filling with water does work. I haul scrap as part of my towing business and will take anything they can fit into a junk car. Well I got about a dozen propane tanks one time and I removed all the valves since that is what the scrap yard used to require to scrap them. Well now they want them cut in half, so I filled them with water and cut them in half with a torch.

PC7 is supposed to be aircraft grade stuff,weather it is or not I am unsure.

I learned all I need to know about life by killing smart people and eating their brains.
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