The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 01, 1991
Filed:
Sep. 26, 1988
Trevor G Stafford, Tyne & Wear, GB;
British Gas Corporation, London, GB;
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.