Abstract: A method of tying over an individual customer service connection from a live outer gas main to an inner gas main inserted within the liver outer gas main comprises defining a generally annular region within the space between the inner and outer mains. The region is upstream from the customer service connection between the customer service connection and the source of gas for the outer main. The sidewall of the outer main is opened intermediate the ends of the region, and an amount of a high-density liquid foaming composition sufficient to fill the region is introduced into the opening. The foaming composition is permitted to foam and harden to a plug in the region. Before the foaming composition is permitted to foam and harden, a first end of a first conduit is inserted into the opening, and pushed into the space so that the first end lies upstream from the region.

Abstract: A pipe slitter comprises a base for fixing the slitter to a pipe to be slit thereby. The base includes a pair of end plates for mounting transversely of the pipe and a carriage guide for coupling the end plates to each other. The carriage guide extends longitudinally of the pipe. The carriage guide movably supports a first carriage. A second carriage movably supports a slitter blade. The second carriage is movably supported on the first carriage for movement of the slitter blade longitudinally and transversely of the pipe.