Method of fabrication of collapsible storage tank
In one embodiment, a collapsible, flexible storage tank is provided that is capable of holding a liquid material. The tank includes a sheet of flexible, moisture impervious side wall material; at least one opening for receiving a fitting to fill and drain the tank; joining seams wherein edges of the sheet are joined, the seams extending about the tank in a spiral orientation; and closing seams wherein the side ends of the pillow tank are sealed. In another aspect, a collapsible, flexible storage tank is capable of holding a liquid. The tank includes a sheet of flexible side wall material; at least one opening for receiving a fitting to fill and drain the tank; and butt seams wherein edges of the flexible sheet are joined together in the same plane in a butt joint configuration using an overlapping piece of flexible, moisture impervious sealed material over the top thereof.
1. A method of fabricating a collapsible, flexible storage tank capable of holding a liquid material, including the steps of:
providing an elongated sheet of flexible, moisture impervious side wall material;
winding the sheet of material in a spiral orientation to form a side wall of the storage tank;
providing first and second lengths of flexible, moisture impervious material constructed of the same material as the side wall material;
butting together and joining edges of the sheet of side wall material to form a butt joint along a spiral seam about the tank;
placing the first length of the flexible, moisture impervious material over an exterior side of the butt joint;
placing the second length of the flexible, moisture impervious material over an interior side of the butt joint
sealing the lengths of material to surfaces of the sheet of the side wall along the butt joint;
cutting ends of the sheet of side wall material to form straight side ends; and
making closing seams wherein side ends of the flexible storage tank are sealed.
2. The method of fabricating a collapsible, flexible storage tank as set forth in claim 1 , wherein only two or less spiral seams encounter a closing seam.
3. The method of fabricating a collapsible, flexible storage tank as set forth in claim 1 , further including the step of placing a filler material between edges of the butt joint.
4. The method of fabricating a collapsible, flexible storage tank as set forth in claim 1 , wherein the sheet of flexible, moisture impervious side wall material is a polymer with internal reinforcing synthetic fibers.
5. The method of fabricating a collapsible, flexible storage tank as set forth in claim 4 wherein the construction is such that any liquid that leaks into the internal reinforcing synthetic fibers of the side wall material has no leak path out of the tank.
6. The method of fabricating a collapsible, flexible storage tank as set forth in claim 3 , wherein the filler material forms a cap and extends over the joining edges along and in contact with an outer surface of the sheet of side wall material.
7. The method of fabricating a collapsible, flexible storage tank as set forth in claim 6 , wherein the cap is located on and extends over the joining edges on the interior side of the sheet of side wall material.