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:
Sep. 17, 1991
Filed:
Apr. 12, 1990
Brian E McGuire, Shaw, GB;
British Gas plc, London, GB;
Abstract
A liner 30 of polyethylene housing an SDR of 33 or less is pulled through a die 36 and through the pipe 10 and allowed to revert to the internal diameter of the pipe. The force of pulling is half the yield strength of the liner or less. The die has an entry; a throat and an exit, the entry decreasing in diameter towards the throat and the exit increasing in diameter away from the throat. The liner has a maximum diameter before the die, a minimum diameter in the die and intermediate diameter after the die. The liner bending inwards before first contacting the die at the entry, then continuously bending through its minimum diameter as it passes the throat and then undergoing die swell resulting in said intermediate diameter. The throat is defined by the merger in a continuous curve of a radius joining the entry and a radius joining the exit.