Patent ID: 8752576

Claim:
An apparatus for mechanically reducing an internal pressure of a column in a refinery or petrochemical process, comprising: an emergency shutdown valve for blocking supply of a heat source to the column positioned between a heat source and the column; and a safety relay valve for mechanically operating the emergency shutdown valve using the internal pressure of the column connected with a emergency shutdown valve and the column through a pipe, wherein the safety relay valve comprises a hollow valve body having at a lateral wall thereof ventilation ports through which compressed air in the column for operating the emergency shutdown valve flows, a plunger for opening or closing the ventilation ports with the compressed air while moving in the hollow valve body, a spring section having a predetermined pressure value being lower than that of the safety relay valve provided in the apparatus and connected to one end of the hollow valve body so as to apply pressure to the plunger, and a pressure transfer section connected to the other end of the hollow valve body so as to transfer the internal pressure of the column to the plunger.