Manhole is a safety emergency ventilation device installed on the top of the storage tank. It is usually used together with fire extinguisher and mechanical breather valve. It can not only avoid accidents caused by sudden overpressure or vacuum in the tank and damage the tank, but also play a role of safety and fire resistance. It is a safety device to protect the storage tank, especially suitable for the dome roof atmospheric pressure tank with materials sealed with nitrogen. The utility model has the advantages of constant pressure discharge, constant pressure suction, flexible opening and closing, safe fire resistance, compact structure, good sealing performance, safety and reliability, etc.
Horizontal hanging cover with stiffening flat welding flange manhole is a kind of hole with cover, through which people can enter and exit the drain, boiler, water pipe, weak current well including telecommunication and cable TV, internal channel for large bridge maintenance, etc.
Manholes are divided into emergency relief manholes, explosion-proof and fire retardant breathing manholes, tank top manholes, tank wall manholes and cored manholes, etc
