Seal opening or seal closure is a safety management measure, a safety indication, common in the safety valve line valve requires a seal, and the safety valve front and rear valves require a seal open.
The seal close(car seal close) indicates that the sealed valve is closed.
A car seal open indicates that the sealed valve is open.
Valves with lead seals (just like instrument calibration lead seals) are generally not allowed to change their state. Once they change, the seals will be destroyed, relevant records need to be recorded, and the seals will be renewed.
Sealed off valves should be on a bypass pipe. Whether the role can be understood is that, under normal circumstances, “restricted orifice plate” is not used. The boiler feed pump supplies water to the steam drum with normal flow, so the valve is normally under Is closed (sealed off); abnormal state is open, so that the water that should enter the drum at normal flow passes through the flow restriction and is decremented.