Abstract: Various pipe wall constructions comprising thermosetting resin, randomly disposed chopped glass fibers, sand, circumferentially extending continuous glass filaments, and axially extending glass fibers in various percentages in structural wall portions thereof, and having various protective inner liner and outer wall portions.

Abstract: End caps of the tank are generally spherical adjacent the axis of the tank and frusto-conical adjacent the circumference of the tank to eliminate voids normally occurring in the backfill under fully hemispherical end caps.

Abstract: A sandwich wall for pipes, tanks, and the like fluid confining uses, wherein concentric inner and outer glass fiber reinforced plastic skins or shells are separated from one another by essentially radial ribs integrated into the shells to form a monolithic construction. The ribs are of limited axial extent and are separated from one another by rib forms of substantially greater axial extent, the rib forms functioning essentially as spacers without otherwise materially contributing to the strength or rigidity of the structure. The ribs are composed of essentially the same resinous material as the shells plus a filler, which typically can be chopped glass fiber strands, sand, or other particulate material, glass fiber mat or woven fabric, glass flakes, or mixtures of such materials. The ribs may be either helical and continuous throughout the axial extent of the wall or annular and independent of one another. Various methods of making such sandwich wall structures are also disclosed.

Abstract: Large volume tubular structures, particularly such structures made of reinforced plastic, are slit longitudinally and convolutely coiled to effectively reduce their volume for shipping, handling, or storing. For further volume reducing advantage a plurality of such tubular structures are coiled together in a shippable package. The slit tubes are subsequently reunited or joined together with other tubes for a variety of end uses.

Abstract: A preformed manhole suitable for use underground is made of reinforced plastic. The manhole comprises a dome section integrally joined at one end of a tubular body by an endless band of reinforced plastic. The dome is arcuately shaped to provide resistance to buckling, and in one specific embodiment is generally hemispherical. The dome includes a manway and a load bearing shoulder for supporting the manhole cover and frame. An upwardly extending rib or collar is provided around the manway to provide additional stiffness and stability.The method for making the preformed manhole is also disclosed. The tubular body is made by applying resin, glass fiber reinforcement, and particulate filler on an endlessly advancing mandrel. The dome is made by applying resin and glass fibers on the surface of a rotating mold. The dome and body are joined by laying-up resin and glass over their mated ends.

Abstract: A preformed manhole suitable for use underground is made of reinforced plastic. The manhole comprises a dome section integrally joined at one end of a tubular body by an endless band of reinforced plastic. The dome is arcuately shaped to provide resistance to buckling, and in one specific embodiment is generally hemispherical. The dome includes a manway and a load bearing shoulder for supporting the manhole cover and frame. An upwardly extending rib or collar is provided around the manway to provide additional stiffness and stability.The method for making the preformed manhole is also disclosed. The tubular body is made by applying resin, glass fiber reinforcement, and particulate filler on an endlessly advancing mandrel. The dome is made by applying resin and glass fibers on the surface of a rotating mold. The dome and body are joined by laying-up resin and glass over their mated ends.