Abstract: Method and apparatus for constructing a plurality of large diameter storage tanks of strip material. A continuous strip is fed to a support assembly at a single building site which supports the strip for production of a large diameter storage tank structure. The storage tank structure includes a plurality of helical convolutions extending upwardly, with the edge portions of adjacent convolutions secured together. The storage tank structure is severed along a horizontal plane above the support assembly. The portion of the severed tank structure above the severing plane is transported from the building site to a use site remote therefrom through use of a lifting collar removably positioned below the top of the transported tank structure. The above steps are continued to complete the production of one or more additional storage tanks.