Abstract: A ported slide gate valve having a gate for regulating the flow of a fluid through the valve, a seat located in the valve interior, and a means for causing the gate to move in such a manner that the gate fractures any scale built up in the lower portion of the valve interior, prior to the gate's movement to a valve closed position. The scale is fractured in a direction away from the seat and deposited in the fluid. More particularly, the means for causing the gate to move includes a primary piston and a secondary piston, where the primary piston is coupled to the gate. In the valve closed position, the secondary piston holds the primary piston in the desired position. A movement of the secondary piston causes the gate to move to fracture the scale in the lower portion of the valve interior.

Abstract: In general, the invention relates to a ported slide gate valve having a gate for regulating the flow of a fluid through the valve, a seat located in the valve interior, and a means for causing the gate to move in such a manner that the gate fractures any scale built up in the lower portion of the valve interior, prior to the gate's movement to a valve closed position. The scale is fractured in a direction away from the seat and deposited in the fluid. More particularly, the means for causing the gate to move includes a primary piston and a secondary piston, where the primary piston is coupled to the gate. In the valve closed position, the secondary piston holds the primary piston in the desired position. A movement of the secondary piston causes the gate to move to fracture the scale in the lower portion of the valve interior.

Abstract: A gate valve seal for a gate valve including a body having an inlet aperture and an outlet aperture, and a gate closure reciprocally disposed within the body between a closed valve position where the gate closure blocks the apertures and an open valve position where the gate closure does not block the apertures. The seal includes a first resilient seat for placement in the inlet aperture of the gate valve body and a second resilient seat for placement in the outlet aperture of the gate valve body. The seats sealingly engage one another and the gate closure when the closure cycles between the valve positions. Each of the seats includes an inner diametrical surface which generates sealing pressure that increases as internal pipeline pressure increases.