If a boiler steam outlet exceeds a specified size, what type of valve must be used according to the ASME power piping code?

According to the ASME Power Piping Code, when a boiler steam outlet exceeds a specified size, the utilization of a 2-inch Outside Stem and Yoke (OSY) valve is mandated. This type of valve is specifically designed for steam and provides a reliable means of controlling the flow while ensuring that the system can safely handle the pressure and temperature associated with boiler operations. The OSY design features an exposed stem that provides visual confirmation of the valve's position and enhances accessibility for actuation, which is critical in emergency situations or for regular maintenance.

The selection of a 2-inch OSY valve aligns with safety and performance standards that are vital in high-pressure steam applications. It can effectively manage the volume of steam while minimizing potential hazards associated with pressure surges. This requirement exists to ensure that the valve can handle the demands placed on it due to the size of the steam outlet, maintaining the integrity and efficiency of the system.

It is important to note that smaller valves, such as 1-inch or 1.5-inch options, may not be suitable for larger steam outlets due to their inability to manage the flow rate adequately and their reduced structural integrity under high-pressure conditions. A 3-inch valve may also exceed the necessary size for certain applications