A valve apparatus (10) comprises a housing (12) defining a flow path (14), a valve seat (42) located within the housing (12) around a periphery of the flow path (14), a carriage member (16) located within the housing (12), a cutting arrangement (28) mounted on the carriage member (16), and a valve member (32) mounted on the carriage member (16) via a connection assembly (34) which permits relative movement between the valve member (32) and the carriage member (16). The carriage member (16) is moveable from a first position towards a second position to drive the cutting arrangement (28) across the flow path (14) and to move the valve member (32) into a position in which relative movement between the valve member (32) and the carriage member (16) permits the valve member (32) to sealingly engage and disengage the valve seat (42) to control flow along the flow path (14).