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. 13, 1994
Filed:
Nov. 01, 1991
Applicant:
Inventors:
Assignee:
British Gas PLC, London, GB;
Primary Examiner:
Int. Cl.
CPC ...
F16L / ;
U.S. Cl.
CPC ...
138 98 ; 138 97 ; 4051501 ; 264269 ; 156287 ;
Abstract
A method is provided for replacing a length of a branch gas main 1 joined to a spine main 2 with a length of replacement main 7 having an outer diameter smaller than the inner diameter of the branch main. In the method access is gained to the bore of the branch main and one end of the replacement main 7 is fed along the branch main 1 via the access point and towards the spine main 2 until the branch main 1 has been replaced. During and after the feeding step gas is prevented from entering any clearance 20 between the mains 1 and 7 by means of a head 9 attached to the leading end of the main 7. After the feeding step a sealant 25 is injected into the branch main 1 to form a seal within the clearance 20.