Abstract: A valve comprising a valve housing (10), having a valve seat (18) therein, a valve member (16) moveable via a valve spindle (15) between positions spaced from and seated on the valve seat. The valve member is required to lap a plurality of times on the valve seat to compensate for any variation of tolerance between the valve member and the valve seat resulting from build up of medium or erosion. The valve spindle extends outwardly from the valve housing and a pair of pillars (28) extend from the valve housing to a bridge member (30) whilst the collar (36) in threadable engagement with the valve spindle extends to and surrounds the pillars to be axially moveable relative thereto. Belleville washers (41) are provided between the underside of the collar and washers (47) forming abutments carried by the pillars. The Belleville washers compensate for relative movement between the valve spindle and the valve housing during lapping action of the valve member on the valve seat.