In a feedwater system, what valve is located close to the shell of the boiler for easy maintenance?

In a feedwater system, the stop valve is located close to the shell of the boiler to facilitate easy access for maintenance. This positioning is crucial because the stop valve controls the flow of feedwater into the boiler. If maintenance or repairs are needed, having the stop valve readily accessible allows operators to quickly shut off the water supply, ensuring safety and minimizing downtime.

In contrast, other types of valves serve different functions. The relief valve is primarily designed to relieve excess pressure within the boiler, ensuring safe operation and preventing potential over-pressurization. The isolation valve, while similar to a stop valve, is typically used to isolate sections of the system when maintenance or repairs are needed, but it may not be situated as conveniently for immediate boiler access. The feed valve regulates the water flow into the system but does not have the same maintenance accessibility focus as the stop valve. Therefore, the stop valve's position and function make it ideal for easy maintenance operations in a feedwater system.