What safety precaution should be taken before anyone enters a boiler drum or shell?

Blanking off the blow-off valves before entering a boiler drum or shell is crucial for ensuring safety. This precaution prevents any accidental drainage or release of water, steam, or pressure that could occur while someone is inside the drum or shell. It is essential to eliminate the risk of high-pressure steam or heated water escaping, which could lead to severe injuries or even fatal accidents.

In addition to blanking off the blow-off valves, it is a best practice to follow established lockout/tagout procedures to ensure that all energy sources are isolated. This helps to further safeguard personnel from unexpected releases of energy while they are working in potentially hazardous environments like boiler drums and shells.

While opening all valves, inspecting the boiler exterior, and cooling the boiler are also important safety measures, they do not specifically address the immediate dangers present when entering a confined space such as a boiler drum. Each of these precautions serves a purpose, but guaranteeing that blow-off valves are properly blanked off is a direct action that minimizes risk to the individual entering the space.