This article mainly stipulates the safe operation requirements of safety valves and pressure relief discharge systems. The safety valve shut-off valve refers to the shut-off valve installed before and after the safety valve to facilitate the verification or replacement of the safety valve. The pressure relief discharge system refers to the system that can quickly discharge the pressure of the storage tank, usually refers to the flare system or the special discharge system. If the safety valve shut-off valve is closed or the pressure relief system is added with a blind plate, the pressure of the storage tank cannot be released in an overpressure or emergency situation. The storage tank may explode or catch fire due to overpressure.

Typical accident case: On July 16, 2015, a liquefied balloon tank fire and explosion accident occurred in Shandong Shida Science and Technology Petrochemical Co., Ltd., causing 2 firefighters minor injuries and 7 fire trucks destroyed. Some spherical tanks and surrounding facilities and structures are different degree of damage. The direct cause of the accident was that during the tank inversion operation, after the water in the No. 6 tank was completely cut out, the liquefied petroleum gas leaked and diffused from the water cut pipe, and burned in the ignition source, causing the liquefied hydrocarbon tank area to catch fire; the safety valve of the spherical tank was closed and A blind plate was added to the pressure relief system, causing an explosion and expanding the consequences of the accident.