Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1988-09-26
1991-01-01
Dawson, Robert A.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
1563042, 1563046, 1563096, 138120, 138155, B65H 6908
Patent
active
049815415
ABSTRACT:
Pipes, typically of medium density polyethylene for use in underground distribution systems for natural gas are joined by fusion using a very short period (25 seconds) for heating the pipe ends and a very short period (3 seconds) between separation of ends from the heater body and engagement of the ends. Those periods are such that the beads formed by upset of the softened end material of the pipes are relatively small, e.g. beads have a cross-sectional area of 10mm.sup.2 for pipe for 250 mm outside diameter and wall thickness 15 mm. Typically such a bead extends only some 2.5 mm away from the adjacent pipe wall surface. Tensile, bending and impact tests show joint strength equivalent to the parent wall strength. In accelerated lifetime tests at high pressure and temperature the joints are at least equal to conventionally made joints.
REFERENCES:
patent: 3929541 (1975-12-01), Spears et al.
patent: 4288266 (1981-09-01), Konrad et al.
patent: 4640732 (1987-02-01), Stafford
patent: 4923659 (1990-05-01), Kunz
"Specification of Butt Welding for Pipes and Fitting of Polythene with a Density of at Least 930 KG/M.sup.3 " (Jan., 1985) VEG-GASINSTITUT, The Netherlands.
"Welding of Thermoplastics, PE-HD, Pipes and Pipeline Components for Gas and Water Mains" (Data Sheet DVS 2207, Part 1, May 1984) DVS German Welding Society.
ASTM Designation D-2513-88b, "Standard Specification for Thermoplastic Gas Pressure Pipe, Tubing, and Fittings".
ASTM designation D-2657-79, "Standard Practice for Heat-Joining Polyolefin Pipe and Fittings".
British Gas Corporation
Dawson Robert A.
Yoder Michele K.
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