What condition must be met before a main boiler is considered operating safely?

For a main boiler to be considered operating safely, it is essential that all safety valves are functional. Safety valves are critical components designed to prevent excessive pressure buildup within the boiler. If the pressure exceeds the safe operational limit, the safety valves will open to release steam and reduce pressure, preventing potential catastrophic failures such as explosions.

Without functional safety valves, the boiler operates under increased risk, as there is no mechanism in place to safely release pressure should it become too high. Thus, ensuring that all safety valves are operational is a fundamental requirement for safe boiler operation.

While stable fuel flow, the absence of smoke emissions, and firing at rated capacity are also important considerations for boiler operation, they do not directly ensure the safety of the overall system in the same way that functional safety valves do.