A valve of special usefulness in handling solids-containing or solids-producing fluids comprises a floating valve seat comprised of inner and outer rings, the outer ring being fixed within the valve body and the inner ring being urged directly from the outer ring by one or more springs against a gate element controlling the flow of fluids through the valve. The springs are housed within chambers provided by aligned cavities in the inner and outer rings while similarly aligned notches house a bellows or accordian shaped flexible metal seal. The flexible metal seal is in contact with the fluid but prevents entry of fluid between the rings to the spring; thus, the action of the inner and outer rings is not impeded by solids depositing from the fluid.
A gate lifter for shifting a gate from a valve seat in a gate valve. The gate lifter is provided on the downstream, or low pressure side of a valve, and is a tubular structure that surrounds and is slidable relative to a tubular valve seat. Hydraulic or other pressurized fluid is adapted to be introduced between an end of the lifter and a flange carried by the valve seat to cause the parts to move in opposite directions, as a result of which the lifter operates by shifting the gate member away from the valve seat to avoid damage to the valve seat as the gate member is moved there across. The gate lifter includes a face that is adapted to engage with a corresponding face of the gate member, the gate lifter face preferably including a low friction coating, such as teflon, gearings or gearing type material.
Corrosion resistance of valves or fittings exposed to corrosive attack by the environment in which they are normally used can be improved by covering those portions of the valve or fitting of thinner cross-section by a thin metal sleeve fabricated from an alloy resistant to corrosive attack by the environment.
