GB808984A - Pipe joints - Google Patents

Abstract

808,984. Pipe couplings. STEWARTS & LLOYDS Ltd. Jan. 14, 1957 [Feb. 21, 1956], No. 5304/56. Class 99(1). A spigot of a coupling piece b is pushed into and enlarges an end a, of a pipe of thermoplastic material of a kind which can be expanded by an internally applied force and a sleeve d of hard polythene or similar material which may be expanded and has an inherent tendency to contract embraces the pipe end tightly. Sharp circumferential ridges c on the spigots embed in the inner surfaces of the pipes. The coupling b may be made of a corrosion resisting metal or of thermoplastic or thermosetting material or of synthetic rubber of the styrene-butadiene type. The sleeve d is slipped over the pipe end prior to the insertion of the spigot and may have either a smooth bore or ridged bore, the ridges of the latter corresponding to the ridges on the socket. The sleeve thickness should not be less than 0À08 inch and if made of polythene the molecular weight of the material should be not less than 95,000. After insertion of the spigot, the pipe ends should be expanded by at least 0À05 inch, and the sleeves which are clear of the enlarged ends, being further along the pipes, are forced over the enlargements so as to compress the pipe ends on to the spigots. The material of the sleeves should be such to provide at least a minimum free shrinkage of 10 per cent. after expansion. To accelerate the shrinkage of the sleeves on the expanded pipe ends, heat may be applied at a temperature of 100‹C. as e.g. by immersion in boiling water.