Have always been told that steel shipping containers must not be buried without internal support. I agree with that. However here is what I would like to discuss. Suppose the seacan was used as a form for concrete, with proper temporary internal bracing which could be removed after the concrete had set and cured to first strength say minimum of 48 hrs. The seacan would be placed inside the excavation with enough room around the exterior walls to construct a plywood form. The walls would have appropriate size footings and rebar. The roof would have I-beam of say 4 inch section and wire panel placed on top and tack welded. The I-beam extending to sit on top of the concrete walls. Then 6 inch of concrete poured for the roof. Giving 2 inch of concrete over the wire and I-beam. After the concrete had reach strength the internal framing and walers would be removed. It would have to be sealed after full cure then buried. What am I missing?