GB840602A - A chemically inert tube and a process for its manufacture - Google Patents

Abstract

840,602. Reinforced non-metallic tubes. RESISTOFLEX CORPORATION. Jan. 6, 1958 [Jan. 11, 1957], No. 521/58. Class 99(2). A pipe has a wall including an outer layer of thermosetting resin, an inner layer of polytetrafluoroethylene resin of which a lining portion has been produced by extrusion, and an intermediate layer of fabric all bonded together to form a unitary structure, preferably with either or both of the resin layers reinforced with additional layers of fabric. As shown, a layer of unfused paste-extruded polytetrafluoroethylene (P.T.F.E.) free of volatile constitutents is wrapped helically upon a mandrel 10 the turns of the tape having an overlap 12, and a layer 14 of fused P.T.F.E. tape is wrapped over and in the same direction as the layer 12 but with the overlapping edges 16 of the tape located intermediate the areas of overlap 12. Wrappings 18, 20 of fabric tape, preferably glass fibre impregnated with fused or sintered P.T.F.E., are added, the tape forming the wrapping 20 being impregnated only in the innermost surface thereof; the wrappings are laid on in opposite directions and the edges of the respective tapes overlap or abut each other. Finally, a wrapping 24 of uncoated glass fabric tape is applied over and in the same direction as the wrapping 20, and the assembly is heated to a temperature in excess of the gel point of the P.T.F.E. and preferably to 700‹F. The pressureapplying wrapping 24 is removed to provide a sub-assembly. Subsequently, a number of wrappings of fabric tape saturated on both surfaces with an uncured thermosetting resin, e.g. an epoxy resin, are placed upon the subassembly, these wrappings being wound in opposite directions and with the turns thereof overlapping, and these wrappings are followed by temporary wrappings of fused P.T.F.E. tape and glass fabric tape ; the resin is cured by heat or a catalyst. Reference has been directed by the Comptroller to Specification 783,240.