Which valve is not appropriate as a boiler steam outlet valve on a high pressure boiler?

The selection of a boiler steam outlet valve is crucial for ensuring safety and efficiency in high-pressure boiler systems. A ball valve, while suitable for many applications due to its rapid open and close capabilities and minimal flow resistance when fully open, is generally not recommended as a steam outlet valve in high-pressure steam systems.

One key reason is that ball valves can become more susceptible to wear and tear from the high pressures and temperatures experienced in steam applications. The sealing mechanism of a ball valve may not be designed to withstand the fluctuation of pressure and the thermal cycling associated with steam systems, which can lead to potential leakage over time. In contrast, other valve types, such as gate, check, and globe valves, provide better sealing and throttling capabilities which are important for controlling steam flow, making them more appropriate for such high-pressure applications.

Additionally, the operational characteristics of a ball valve do not lend themselves well to routine throttling situations often encountered in steam systems. This can lead to issues in managing the system effectively. Thus, while ball valves are useful in various contexts, for high-pressure boiler steam outlet applications, other valve types are typically preferred.