GB709252A - Improvements in manufacture of pipe - Google Patents

Abstract

709,252. Pipes of fibrous material. GANAHL, C. DE. June 18, 1952 [Aug. 4, 1951], No. 15402/52. Class 99 (2). In a pipe consisting essentially of glass reinforcing fibres bonded together by and substantially embedded in a substantially impervious body of plastic material, a portion of the fibres is disposed helically in at least two layers 4, 8, the pitches of the helices being equal in magnitude and opposite in direction and a portion of the fibres is disposed in wholly random orientations in a substantially felted mat 1, e.g. two helically wound tapes 2, 3 preferably having overlapping adjacent edges. The angle a which the helically-wound fibres make with the axis of the pipe may be such that 3 sin<SP>2</SP>a+2/m sina=1 where m is the ratio of the total cross-sectional area of the, helically disposed fibres to the total crosssectional area of longitudinally-disposed fibres 9 which may be incorporated in the wall of the pipe. There may be disposed over the fibres 9 a further helically wound layer of fibres 10 which are fewer in number and more widely spaced than the fibres in the layers 4, 8. There may be additional felted mat layers 5, 11 as shown. The plastic material may be thermosetting or thermoplastic in character, and comprise a composition of styrene and an alkyd resin. or vinyl halide resins and copolymers with vinyl esters, nylon, methacrylate resins, polyethylene, phenol-, urea-, and melamine-formaldehyde condensation polymers, cellulose esters and various blends of these materials; also, a natural wax, resin or gum may be employed. The pipe may be made on a machine, such as that described in Specification 687,552, wherein packages of glass fibre rovings are carried on a number of horizontal tables revolving about upwardly advancing mandrels onto which the plasticcoated fibres are wound. Specification 709,251 also is referred to.