For which purpose should gate valves not be used unless specifically authorized?

Gate valves are designed primarily to operate in fully open or fully closed positions, making them ideal for shutting off flow. They are not built for throttling, which involves regulating the flow of fluid to a desired level. When a gate valve is partially open, it can create issues such as vibration, erosion, and cavitation, which can lead to damage over time. Therefore, their use in throttling applications can negatively impact performance and reliability.

In contrast, other valve types, like globe or ball valves, are specifically designed to control flow rates effectively and are more suitable for throttling purposes. Using a gate valve for this function could lead to operational inefficiencies and potential safety hazards, which is why authorization or specific guidelines are necessary before proceeding with throttling applications involving gate valves.