Abstract: The valve assembly of the present invention is intended for use, within a section of pipe, to control the flow of a fluid within the pipe. The invention discloses an arrangement in which two sections of concentric pipe are slidable with respect to each other between a first position which allows fluid to flow along the pipe and a second position in which fluid flow is stopped. The outer section of pipe has a sealing plug supported in an annular position within its bore which either abuts the end of the inner section of pipe to close the valve or is separated from it to open the valve.