if the furnace trips 4-5 hrs of the switch over of the coke drum then you can restart the heater but not later than 1-1.5 hrs, you need to ensure that the rest of the cycle the COT is maintained 1-2 deg C above the normal operating temperature. this will take care of the deheading problem and the VCM content in the coke. if the heater could not be started within in the above time it is better bypass the block
