A large volume natural gas storage tank comprises a plurality of rigid tubular walls each having opposing ends and an intermediate segment with a closed tubular cross-section, the plurality of rigid tubular walls arranged in a closely spaced relationship and interconnected at their ends, with each end of a given of the plurality of rigid tubular walls connected with respective ends of two others of the plurality of rigid tubular walls to define a corner of the storage tank, such that the interiors of the plurality of rigid tubular walls define an interior fluid storage chamber.