A ball valve is a valve with a spherical disc, the part of the valve which controls the flow through it. The sphere has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked.
Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse. They are therefore an excellent choice for shutoff applications. There are two type of ball valves based on the ball type, floating ball valves and trunnion mounted ball valves. Depending on the bore size of the ball itself, ball valves are designated as full port ball valves and reduced port ball valves. A full port or more commonly known full bore ball valve has an over-sized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. Flow is unrestricted but the valve is larger and more expensive so this is only used where free flow is required, for example in pipelines which require pigging.
In reduced port or more commonly known reduced bore ball valves, flow through the valve is one pipe size smaller than the valve's outlet size resulting in flow area being smaller than pipe. As the flow discharge remains constant and is equal to area of flow (A) times velocity (V), A1V1 = A2V2 the velocity increases with reduced area of flow.
FBV ball valves designs include two piece split body, three piece split and welded ball valves.
Reliable Stem Seal
The blow out proof design for the stem assures that even if the pressure in the body cavity has risen accidentally and the packing flange breaks, the stem cannot be blown out by the medium. The stem features a backseat, assembled from within the body. The sealing force against the backseat gets higher as the medium pressure becomes higher. Therefore, a reliable stem seal can be assured under variable medium pressures. The stem cannot be removed during service.
V type packing material has been employed to effectively transform the pushing force of the gland flange and the medium pressure into a sealing force against the stem.
Based on customer requirements, a live loaded gland flange can be ordered for low emissions valves using a set of Belleville springs installed on each gland stud to provide a continuous compressive force on the gland, which guarantees permanent load retention for the stem packing to avoid fugitive emissions.
Blowout Proof Stem
Blow-out proof structure is designed to avoid stem blow-out due to accidental medium pressure rise. The stem is positioned by screwed up-end cap.
To prevent unauthorized operation, the fully opened or closed position of the valve can be locked, especially useful when the valves are mounted outdoors or when valves may be opened or closed by unauthorized persons. A lockable hole on the pad is a standard feature.