"API 6D, March 31, 1994. Synonym for disk." . "Qualified" . "VALVE CLOSURE MEMBER" . "VALVE CLOSURE MEMBER" . "RDS428894" . "An 'artefact' that is the part of a valve which is positioned in the flow stream to permit, obstruct, divert or regulate flow." . "u82237" . "2005.12.21" . .