Abstract: A double-walled fiberglass reinforced resin underground storage tank including a generally cylindrical inner wall having a plurality of circumferential support ribs bonded thereto, at least one spacer filament mounted on the outer surface of the inner wall of the tank over a substantial portion of the length of the tank, and an outer wall substantially conforming to the contour of the inner wall and the support ribs but not adhered to the inner wall or the support ribs. The outer wall cures into relatively tight conformance with the inner wall and support ribs resulting in a reduced annular space between the walls. Small voids are created immediately adjacent to the spacer filaments, providing fluid passageways which enhance the otherwise slow migration of fluid in the annular space.

Abstract: An underground storage tank comprises a cylindrical inner wall, a cylindrical outer wall of plastic resin and reinforcement fibers, and a layer of spacer filaments wound around the inner wall, the spacer filaments separating the inner and outer walls, and the spacer filaments being at least partially surrounded by voids to enable liquids to flow along the filaments.

Abstract: An underground storage tank having secondary containment comprising a self-supporting, semi-rigid thin wall located on the inside of the tank. The thin inner wall completely lines the inside of the tank and is structurally independent of the tank.

Abstract: An underground storage tank has an inner wall and an outer wall defining a generally annular space for receiving a leak detecting fluid, and a plurality of ribs bonded to the inner and outer walls and projecting radially outwardly from the inner wall, each rib comprising sidewalls and a top wall, the outer wall being attached to the top wall of each rib but substantially unattached to the sidewalls of each rib, and the outer wall substantially conforming to the contour of the inner wall and the ribs.

Abstract: A composite wall for storage of organic liquid is disclosed. The wall has an outer layer and the outer layer is a resin that is reinforced with chopped glass strands. The wall has an inner layer that is positioned adjacent the outer layer. The inner layer is in contact with the organic liquid. The inner layer comprises a resin containing an inorganic filler and the inner layer provides an inner surface that is resistant to organic liquids to reduce the effect of the organic liquids on the wall.

Abstract: The assembly includes a pultruded glass fiber reinforced resin strap each end of which is secured between a pair of plates. At each end the plates and the strap are apertured to receive a retaining rod.

Abstract: An upper tank half provided with a manway and a lower tank half provided with a sump are each formed of thermosetting resin reinforced with chopped glass fiber strands and then secured together with several plys of resin-impregnated glass mat applied around the circumference at the joint inside and outside of the tank. Each tank half is flared adjacent the joint to provide half of a tank strengthening rib for the completed tank, which has a diameter larger than its height. Two semicircular perforated olive retaining plates are removably mounted in the upper tank half adjacent the lower end of the manway. Aboveground and underground embodiments of the tank are provided.