Four-way switch valves
- Size range(s)
- NPS 3 - 18 (DN 80 - 450)
- Pressure rating
- ASME Classes 150 - 900
- Standard connections
Features and benefits
- The sturdy one-piece ball and stem provides optimal strength, and is well suited to applications where fouling due to coke fines are a concern. The one-piece design avoids the problems generally associated with the more conventional two-piece ball and stem, which is highly susceptible to solids buildup in the ball-stem joint and a resulting increase in operating torques.Avoids hysteresis and misalignment.
- A Lantern ring with steam block and extra deep stuffing box minimizes the risk of leakage occurring through the packing chamber. Live-loading is available on request.
- Strong bellows offer a unique seat loading design that maintains the floating seats in constant contact with the ball and ensures a positive seal.
- Velan’s unique scraper type seats design scrapes coke buildup from the surface of the ball during each cycle. Seats are hard-faced to ensure a long, trouble-free service life.
- Steam purges to bellows and body area ensure the valve cavities are kept free of coke buildup.
- The stem coupling is designed to perform three main functions:
- Protect against “overtorquing” of the stem.
- Protect the actuator components.
- Protect against an unintentional switch into bypass (typically applies to four-way switch).
The electric, hydraulic or pneumatic actuator is selected in function of coker service. A large torque safety factor ensures the valve will cycle under the most stringent conditions. When selecting actuators, special attention is paid to the coker deck environment.