Abstract: A layered tubing for use in a motor vehicle has a thick tubular inner layer formed of one or more sublayers of a synthetic resin having a predetermined hardness and a predetermined thickness and designed for use in a temperature range down to -40.degree. C., and a thin tubular outer crack-absorbing layer bonded externally to and surrounding the inner layer. The outer crack-absorbing layer is formed of a synthetic resin resistant to attach by lacquer solvent over the temperature range of the inner layer and having a hardness equal to at most 0.8 of the hardness of the inner layer and a thickness equal to at most 0.5 of the thickness of the inner layer. When lacquer is intentionally or accidentally applied to such tubing and the tubing subsequently is flexed at extremely low temperatures, the lacquer will crack but the soft outer layer will not transmit the sudden change in shape and energy to the inner layer, causing a crack therein.

Abstract: A layered tubing for use in a motor vehicle has a thick tubular outer layer formed of a Nylon 11 or Nylon 12, a thin tubular inner solvent-blocking layer inside the outer layer and formed of a copolymer of ethylene and vinylalcohol, and a tubular intermediate layer between and bonded to the inner and outer layers and formed of polyethylene or polypropylene. The outer layer has a thickness of between 0.2 mm and 0.7 mm and the intermediate layer comprises by weight 30% to 45% polyethylene. The inner layer has a thickness of between 0.1 mm and 0.2 mm and the intermediate layer has a thickness of between 0.05 mm and 0.2 mm.

Abstract: A layered tubing for use in a motor vehicle has five layers, namely a thick tubular outer layer formed of a Nylon 11 or Nylon 12, a thick tubular intermediate layer of Nylon 6, a thin tubular intermediate bonding layer between and bonded to the thick outer and intermediate layers and formed of polyethylene or polypropylene, a thin tubular intermediate solvent-blocking layer inside the thick layers and formed of a copolymer of ethylene and vinylalcohol, and an inner layer of Nylon 6 inside the blocking layer. The thick outer and intermediate layers each have a thickness of between 0.2 mm and 0.7 mm. The thin intermediate blocking layer comprises by weight 30% to 45% polyethylene and the intermediate blocking layer has a thickness of between 0.1 mm and 0.2 mm. The inner layer has a thickness of at most 0.1 to 0.5 mm and the bonding layer has active side chains of maleic acid anhydride and a thickness of between 0.05 mm and 0.2 mm.

Abstract: A fixed-length fuel line, for automotive vehicles to be powered by an alcohol-containing fuel such as gasohol, has a relatively thick polyamide wall which is internally lined by a polyvinyl alcohol based alcohol-barrier layer protected against the fuel by a water-barrier layer, e.g. of polyamide, the line being constructed so that swelling of the water-barrier layer does not change the length of the line because any swelling stress is taken up by the thicker polyamide wall.

Abstract: Monofilament threads which are wound around a thermoplastic synethetic resin core tube to form one or more reinforcement coils are generated as they are wrapped around the core tube by liquid crystalline polymer material emerging from respective spinning nozzles which rotate around the core tube while a difference in speed is maintained between the speed at which the reinforcing plastic emerges from the nozzle and the monofilament thread is wound on the core tube to maintain a stretch in the monofilaments.