During regular inspections, which components of a valve require the closest examination?

The correct choice focuses on the disc and set of a valve, which are critical components that directly affect the valve's function and efficiency. The disc operates as the primary mechanism responsible for controlling the flow of the fluid; it moves within the valve body to either open or close the path for fluid flow. Regular inspections of the disc ensure that it is in good condition, free from wear or damage, which is crucial for maintaining proper sealing and preventing leaks.

The set includes the parts that support the disc's operation, such as the seat and any associated seals. The integrity of the seat is vital for achieving a tight closure when the valve is not in use. If the disc or set has any defects, it can lead to significant performance issues, such as leaks or flow restrictions, ultimately impacting the operational safety and efficiency of the entire system.

In contrast, other components mentioned, while important, do not have the same level of immediate impact on the flow control as the disc and set do. The body and bonnet are structural components and the actuator and handle relate more to the operation mechanism than to the fluid control itself. Regular attention to the disc and set helps ensure that the valve will perform effectively under the stresses of operation, making it a priority during inspections.