Abstract: To improve the strength, resistance to leaks, and formation of tears and fissures in the inner wall of a double-wall tank, the inner wall is formed, as described in the inventor's earlier U.S. Pat. No. 4,739,895 (U.S. Pat. No. Re. 33,421) by a plurality of foil or sheet elements which are overlapped at the edges, and covered by a plastic, preferably epoxy layer. The sheet elements are preferably aluminum foils of from 0.15 to 0.3 mm, preferably 0.2 mm thickness. The plastic layer is reinforced by a multi-ply, preferably two-ply, glass fiber fabric, which is so woven that the layers or plies of the fabric are interwoven or interlocked. The fabric is embedded in the plastic coating, before it is cured, for example by rolling it into the plastic coating. To assure good fitting of the inner wall against the outer wall, a vacuum is applied in the space formed by the projections or puckers of the sheet elements and the outer wall before the plastic coating has cured, and maintained until it is cured.

Abstract: To form a substance supported inner wall of a doublewall bottom and portion of the side wall of a tank, the inner wall is formed by a ridged, ribbed, puckered or embossed aluminum foil of, for example, 0.15 mm to 0.3 mm, preferably about 0.2 mm thickness, with protrusions or projections extending towards the outer or bottom wall. Since such foils are not available in sizes sufficient to lay out an entire tank in one unit, a plurality of foil units are placed adjacent each other, preferably with edge zones overlapped, and the overlap is bridged and connected by a fiber reinforced ribbon or tape, preferably glass fiber, the thus formed bottom wall being coated with an epoxy resin in which the glass fiber reinforced ribbon or tape is embedded.

Abstract: To form a substance supported inner wall of a double-wall bottom and portion of the side wall of a tank, the inner wall is formed by a ridged, ribbed, puckered or embossed aluminum foil of, for example, 0.15 mm to 0.3 mm, preferably about 0.2 mm thickness, with protrusions or projections extending towards the outer or bottom wall. Since such foils are not available in sizes sufficient to lay out an entire tank in one unit, a plurality of foil units are placed adjacent each other, preferably with edge zones overlapped, and the overlap is bridged and connected by a fiber reinforced ribbon or tape, preferably glass fiber, the thus formed bottom wall being coated with an epoxy resin in which the glass fiber reinforced ribbon or tape is embedded.