Abstract: A fiber reinforced plastic pipe tee is wound around a mandrel according to this method and apparatus. Fiber rovings are delivered to the mandrel by way of a delivery ring translated in an X-Y plane. The mandrel can be rotated around an A axis parallel to the X direction or a B axis parallel to the Y direction. By switching between either rotation around the A axis or around the B axis, a three axis numerical control system can be employed. Means are provided for alternately rotating the mandrel around the A and B axes. Means are provided for independently translating the delivery ring in the X and Y directions as the mandrel rotates. The delivery ring comprises a curved bar around which a band of resin impregnated rovings makes a turn enroute to the mandrel for maintaining a reasonably constant width of the band of rovings.

Abstract: A fiber reinforced plastic pipe tee is wound around a mandrel according to this method and apparatus. Fiber rovings are delivered to the mandrel by way of a delivery ring translated in an X-Y plane. The mandrel can be rotated around an A axis parallel to the X direction or a B axis parallel to the Y direction. By switching between either rotation around the A axis or around the B axis, a three axis numerical control system can be employed. Means are provided for alternately rotating the mandrel around the A and B axes. Means are provided for independently translating the delivery ring in the X and Y directions as the mandrel rotates. The delivery ring comprises a curved bar around which a band of resin impregnated rovings makes a turn enroute to the mandrel for maintaining a reasonably constant width of the band of rovings.

Abstract: Plastic pipe is continually produced from a curable resin on a plurality of horizontal mandrels which are repeatedly simultaneously moved between plastic pipe production stations. There is at least one station for applying resin to a mandrel, at least one station for curing resin on the surface of a mandrel, and at least one pipe removal station for removing pipe from a mandrel. The pipe stations are substantially radially equidistant from a central horizontal axis and are circumferentially spaced apart by substantially equal increments around the horizontal axis. Each mandrel is progressively rotated between the stations.The temperature of each mandrel is controlled by passing a fluid through the mandrel. Heating fluid passes through mandrels in resin cure stations and cooling fluid passes through mandrels in resin application and pipe removal stations. A control system minimizes mixing of the cooling and heating temperature control fluids when the mandrel is rotated between stations.

Abstract: Plastic pipe reinforced with rovings is produced by wetting the rovings with liquid resin and winding the wetted rovings onto a rotating mandrel from a carriage that moves to and fro along the length of the mandrel. The rovings are drawn onto the mandrel over a concavely arched surface mounted on the carriage. As the carriage reverses its direction at each end of the mandrel, the tilt of the concavely arched surface with respect to the carriage also reverses so the rovings always pass over the same section of the concavely arched surface. Apparatus for practicing this process is described.

Abstract: A moving, fibrous web is impregnated with a liquid by placing the liquid on the surface of the web, spreading the liquid over the web surface, pressuring a portion of the liquid into the web to partially saturate the web with the liquid and leave residual liquid on the web, and metering the residual liquid into a layer of substantially uniform thickness. This layer is then forced into the web to saturate it with liquid. This method is particularly effective for producing plastic pipe incorporating at least one layer of fibrous material saturated with liquid resin .Apparatus for practicing this method comprises a first surface transverse to the surface of the web, and a second surface converging with the web in the direction of travel of the web. The first surface performs the spreading step and the second surface performs the pressuring and metering steps.

Abstract: Reinforced plastic pipe is made at high rates using a wiper to remove resin from the surface of the rovings after they are applied to a rotating mandrel. The wiper leaves an optimum surface layer of resin on the rovings. For small diameter pipe, production rates are further increased by rotating the mandrel above its first critical speed.

Abstract: Plastic pipe is removed from a mandrel by forming two circumferential grooves of different depth in the pipe wall, attaching a holding means to the pipe where the holding means has projections which fit into the grooves, and then applying an axial force to the holder. This method prevents damage to the mandrel and the pipe.

Abstract: An energy-absorbing protective coating is bonded to the exterior of a plastic pipe. Preferably, the coating is a layer of low-cost, crushable, multicellular, inorganic particles, such as natural volcanic lightweight aggregate, expanded shale, expanded clay, pumice, slag, or furnace cinder, embedded in a thin film of plastic resin. The particles crush by breaking upon impact, which absorbs the energy of the impact and protects the pipe from damage.