Is A Trunnion Ball Valve A Two-way Valve?

Trunnion-mounted ball valves can go both ways. Their bidirectional sealing function is mainly achieved by spring seat, floating seat or DBB/DIB seat configurations, ensuring zero leakage regardless of direction. Here's a closer look:
Trunnion-mounted ball valves use axial ball valves to install spheres safely and to maintain stability under high pressure and large diameter conditions. Spring seats or floating seats are designed to ensure a tight seal regardless of direction of flow. For example, the API standard defines DBB (double seat isolation and Vent) and DIB (double seat isolation and vent) seat configurations, both of which support bidirectional sealing:
DBB Configuration: When the valve is closed, the cavity between the two seats provides a sealing device to prevent pressure from coming from both ends, achieving a bidirectional blocking.
DIB configuration: When closed, each seat is sealed independently under pressure from one direction, and the cavity between the seats provides double isolation while supporting bidirectional sealing.
In addition, the two-way sealing ability of trunnion-mounted ball valves makes them ideal for multiport valves and low voltage applications. In multiport valves, a bidirectional sealing prevents cross-contamination, and in low-pressure applications, even if fluid pressure is insufficient to move the sphere, the sphere and spring seat mounted on the shaft neck ensure reliable sealing.