Isolation valve assembly

摘要

An isolation valve assembly for use in a pipeline comprises a valve housing (1) body having inlet (12) and outlet (13) openings. In the housing there is disposed a pair of independently operable rotary valve balls (3) each having a port (25) therethrough The valve balls (3) are each rotatable between an open position in which the respective port is in communication with the adjacent opening and a closed position in which the valve ball closes the adjacent opening. A valve seat (9, 14) supports each valve ball in the housing and a valve seat retention member (10) is disposed in each of the openings (5). The retention member (10) defines a flow passage (11) therethrough for communication with the adjacent valve ball port and has a first end proximal to one of the valve balls. The first end supports said valve seat and a second end has means for engagement to the pipeline. The arrangement allow a relatively large bore valve assembly to have a length conforming to International Standard ANSI B16.10 or equivalent so as to enable a single ball valve assembly to be replaced with a double valve assembly without any modification to the pipework.