Sorry to see you experienced problems, but yours is a perfect example of why every tank should be pressure tested before being put into service. The test can be as simple as using a plastic bag for a gasket between the cap and the tank and then putting air pressure thru the petcock while spraying a soap and water solution on the tank as you look for bubbles . Obviously you want to pay particular attention to the welds or places where the metal may have been streched thin during the forming process. You want to use a regulator so you can accurately controll the air pressure. A few pounds pressure is plenty, and will reveal any leaks. In fact, if you venture beyond 10 psi you run the very real possibility of deforming or distorting your tank. Not good!!
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An alternative to the soap test on the outside of the tank is a hydro test. A hydro test is performed by in a similar fashion but you fill the tank with water before applying air pressure, and then look for for signs of seeping thru the tank. Once again, keep your pressure in the single digits when testing gas tanks. Back in my days of building refineries and chemical plants we always hydro tested critical piping systems but we tested under much higher pressure. Good Luck to you in the future.
Regards,
Geo.
