Abstract: A throttling gasket insert (34) for attaching a knife gate valve (10) into a pipe string is constructed of a single piece of resilient gasket material having a washer-shaped flange portion (36), to be clamped between a facing surface (52) of a knifegate-valve face plate (26) and a pipe flange (60), and a tubular portion (42), extending through a knife-gate valve flow passage (22) to a knife-gate blade (12) thereof, having a V-shaped passage therethrough.

Abstract: A method of constructing a gate valve includes the step of placing a slidable valve gate (46) in a valve cavity (16) between aligned holes (21) of a valve body (10) in a position for closing a fluid passage through the body. Removable mold fixtures (22, 24 and 26) are attached at each opening into the valve body for covering it and thereby preventing liquid material from flowing out of the hole. The valve body (10) and its attachments are heated and a molten resinous material is inserted into the valve cavity so as to surround the aligned holes (21) and to fill spaces between the body (10) and the valve gate (46). The valve body and the resinous material are then allowed to cool so that the resinous material hardens to form a valve liner in which the valve gate moves for opening and closing the fluid passage (80). The mold fixtures are shaped to form flange rings (76, 78) outside the valve-body openings and to form a cavity (84) for packing material (86). A fluoropolymer is used as the resinous material.