Abstract: A method for securing a branch assembly to a “live” pipeline. An upper part of the assembly incorporating the branch is positioned on the pipeline over a containment ring located on the pipeline and within which is an annular seal surrounding an area from which the branch is to extend. A lower part of the assembly is positioned on the pipeline beneath the upper part and the two parts are secured together so that the seal is compressed and an annular space is left between the two parts and the external surface of the pipeline. Grout is injected into the annular space and cures to bond the two parts forming the branch assembly in position on the pipeline. The use of grout avoids having to use welding techniques on a “live” pipeline. A coupon can be cut out of the pipeline, via the access through the branch.

Abstract: An outlet opening (14) to a branch line 40 in a pipeline 10 is sealed without interrupting the flow of gas in the pipeline 10 by cutting an access opening 60 in the wall 62 of the pipeline 10 opposite the branch line 40. A seal 100 is inserted through the access opening 60 using a sub-assembly 70, which consists of a flange 74 having a screw-threaded through aperture, an externally screw-threaded tube 82 received in the aperture and a rod 80 carrying a handle 72 at one end and the seal 100 at the other. The seal 100 has a sealing face 102 which is part-cylindrical in shape and is held in the correct orientation by the handle 72 while the tube 82 is screwed home. When work on the branch line 40 has been completed a temporary seal 160 is installed in the joint-flange 16 which is welded to the pipeline 10 allowing removal of the isolation valve 64 which is replaced by a blanking flange fitted to the joint-flange 16.