Abstract: The wall of a pipe is prepared for a subsequent cutting operation by a double-edged shear plate, by cutting axially spaced circumferential notches in such wall with a flexible strand cutter capable of operating in the limited confines of a housing designed in the rectangular pattern of the shear plate. The flexible strand cutter advantageously employs roller cutters on a power transmission type chain which is tensioned against and moved circumferentially over the wall of the pipeline.

Abstract: Apparatus for altering flow in an existing pipeline, including a shear and first actuator means for cutting transversely through the pipe wall and independent second actuator means for moving a surface associated with the shear into engagement with a sealing surface surrounding the pipe. The shear operates through a rotary valve element, mounted directly in a body of a housing surrounding the pipe. Channels encircling the shear sealing surfaces and rotary valve element distribute sealant between the respective mating surfaces to assure a fluidtight assembly. Fluid circulates through a chamber carried on the housing to isolate the first shear actuator means from the pipeline fluid. In a variant of the invention, a flapper plate valve replaces the rotary valve element where the pipe size is relatively large.

Abstract: A safety cock for positively maintaining a coupled connection between a fluid delivery conduit and a chamber during fluid delivery to the chamber and for permitting the conduit to be uncoupled when fluid delivery is disestablished. The safety cock comprises a block having a valved passageway therethrough. A handle projects from the valve and prevents uncoupling of the fluid delivery conduit when the valve opens the passageway by blocking the conduit removal path, but permits uncoupling when the valve closes the passageway.

Abstract: A split coupling for repairing, hot tapping, or joining pipelines, and particularly underwater pipelines, is disclosed. The coupling comprises a pair of members each having semicylindrical inner surfaces and a pair of faces adapted to oppose the faces of the other member. A first gasket continuously extends circumferentially on each semicylindrical surface and along the faces, with the face extending portion of each first gasket being adapted to mate with the face extending portion of the other first gasket. A second gasket is spaced from each first gasket. Each second gasket continuously extends circumferentially on each semicylindrical surface and along the faces with the face extending portion of each second gasket being adapted to mate with the face extending portion of the other second gasket. Ports are drilled through the coupling and into a zone defined by the first and second gaskets.