| 摘要 |
Plastics coated metal tube produced by folding a strip of metal into a tubular form, seaming the tube and immediately extruding layers of plastics material onto the inner and outer surfaces of the metal tube, and cooling the plastics layers by passing the tube through a water bath (19), contains air injected under pressure to assist adhering the extruded plastics coating onto the inner surface of the metal tube and to test the integrity of the tube. The invention provides apparatus comprising jaws (10),(11) which clamp the tube within the water bath in order to seal the tube while the inner coating is still plastic so that when the tube is cut into lengths at the seals the internal pressure is retained until the tube is eventually used. |
