RETROFIT UNDERGROUND TANK AND ITS MANUFACTURING PROCESS

摘要

The present invention is directed to a retrofit underground storage tank (30 ) and method for making the same. A portion of an underground primary tank (32 ) is uncovered and an access opening (42) is formed therein. A plurality of trifolds (50, 120, 122 and 124) comprising three folded up and banded togeth er panels (52, 54, 56) which are jointed together by hinges are inserted into t he primary tank. A monorail or conveyor (90) is inserted into and suspended fro m above the primary tank (32). Trolleys (102, 104) on the monorail (90) assist in transporting the trifolds (50, 120, 122 and 124) within the primary tank (32) and then the monorail (90) is removed. Trifolds (50, 120, 122 and 124) are unbanded and unfolded and are arranged circumferentially about the tank. Jack stands are used to hold panels of the trifolds in place. Circumferentia l and longitudinal joints are formed between abutting edges on the panels usin g fiberglass reinforced plastic mats, woven rovings and resins layups thus creating an inner cylindrical wall (230) within primary tank (32). Further panels are joined together to form a pair of end caps (260, 300) which are jointed to inner cylindrical wall (330) thus creating an inner tank (312).