If your looking to reuse these containers it might be better to go with some cooking equipment. I’ve used a “can cooker” while camping with some friends. They cost more, but I imagine they would last much longer, though it is only a 4 gallon, it already has a vent.
https://www.amazon.com/gp/aw/d/B0036QZ7I0/ref=mp_s_a_1_5?ie=UTF8&qid=1521923071&sr=8-5&pi=AC_SX236_SY340_QL65&dpPl=1&dpID=41V0DtiObVL&ref=plSrch
