Advances in electronics and materials of construction have increased the attractiveness of V-Port control valves for tight shut-off and control applications. In combination with new, smaller digital smart positioners, the actuator, valve and positioner package also represents a space-saving and lower-cost alternative to traditional globe-style control valves for similar process-control uses.
Some of the other operational benefits of using V-ball valves are extended service life and high turndown capability. In addition, the rotary motion of the V-ball cleans the seat with every cycle, helping to maintain a tight seal. Globe valves typically use resilient seats mated to stainless-steel plugs to achieve a Class-4 shutoff rating. These softer resilient seats have a tendency to wear and tear over time and thus require frequent maintenance.
In addition, packing deteriorates, due to the rising and falling linear action of globe valves, which reduces sealing capacity. The resulting exposure can accelerate corrosion. The rotary-action design of the V-ball shaft mitigates these problems. As a result, rotary V-port ball valves are now replacing globe style control valves in more and more applications.
On one modulating-control ball-valve series, a solid-steel stainless ball is used for throttling, instead of a seat insert. This results in higher flow capacities and controllable rates, excellent repeatability and high-pressure drop capability with straight-through flow. The self-compensating live-loaded stem packing, high-temperature ball seats and matched ball and stem create an economical solution and lower operating cost option.
For maintenance engineers, maintenance of the V-port control valve is as easy as changing a standard seat. Control valves are commonly available with flanged ends in 150, 300 and 600, 3-piece threaded, socket-weld or butt-weld configurations.