Trunnion mounted ball valves are specialized quarter-turn valves designed to control the flow of media in a pipeline. Unlike the traditional "free floating" ball valves, trunnion mounted ball valves feature a ball that is connected to the stem on one end and a shaft, known as the trunnion, on the other. This design change ensures that the ball is held firmly in place, providing several advantages over floating ball valves.
For high pressure applications, trunnion mounted ball valves are the preferred choice. In floating ball valves, the ball has some freedom of movement, allowing it to float slightly downstream against the seat ring and create a seal on one side only. This can increase the torque on the stem, making it harder to operate the valve. In contrast, trunnion mounted ball valves, with their fixed ball design, maintain a proper seal on both sides without adding torque to the stem. This results in better sealing and easier operation, especially in high pressure environments.
Another significant advantage of trunnion mounted ball valves is their spring-loaded seats. In floating ball valves, high pressure is required to force the ball against the seats to create a seal, making them less effective in low pressure systems. Trunnion mounted ball valves, however, are effective in both low and high pressure situations. The spring-loaded seats ensure a reliable seal even in low or no-pressure conditions, while still functioning efficiently in high pressure applications.
Trunnion mounted ball valves are designed according to industry standards such as API 608 and API 6D. These standards provide guidelines for basic design, dimensions, and testing, ensuring that the valves meet rigorous performance and safety requirements. API 6D also specifies the standard weights of trunnion ball valves based on different bore sizes and body dimensions, ensuring consistency and reliability across various applications.
In summary, trunnion mounted ball valves offer superior performance and reliability in both high and low pressure applications, thanks to their fixed ball design and spring-loaded seats. Adhering to industry standards, these valves provide an effective solution for controlling media flow in pipelines.
