A vent stack collects and discharges gas from atmospheric or pressurized process components to the atmosphere to safe locations for final release during normal operations and abnormal conditions. In vent stacks, the gas exiting the system is dispersed in the atmosphere. Flare systems generally have a pilot or ignition device that ignites the gas exiting the system because the discharge may be either continuous or intermittent. Stacks have sites of numerous explosions and blockage.In the following paper you will see some incidents related to the vent stacks and the required checking in order to prevent these incidents.