Summary of Globe Valves
Globe valves are designed to start, stop and regulate process flow in the pipeline by moving the disc against the flow stream. The globe valve gets its name from the globular shape of the valve body. Globe valves tend to be used in wastewater plants, power plants, and process plants. The part of the globe valve that controls the flow is the disc, which is attached to the valve stem. Turning the valve stem in until the disc is seated into the valve seat closes the valve preventing the fluid from flowing through the valve. The edge of the disc and the seat form a tight seal when the valve is closed. When the valve is open, the fluid flows through the space between the edge of the disc and the seat. Since the fluid flow is equal on all sides of the center of support when the valve is open, there is no unbalanced pressure on the disc that would cause uneven wear. The rate at which fluid flows through the valve is regulated by the position of the disc in relation to the valve seat. There are 2 types of discs used, depending on the job:
plug-type discs have a long, tapered configuration with a wide bearing surface, providing maximum resistance to the erosive action of the fluid stream; the composition disc has a flat face that is pressed against the seat opening like a cap, making it unsuitable for high differential pressure throttling.