The Coker unit has a valve to send drum outlet to the blowdown system when the cooling step is working. It is a routine operation.
- This operation was done at 4 pm.
- At 7 pm the shift supervisor and operators changed shift.
- The authorization was done, but the inspection was not.
- At 8 pm maintenance operators opened the flanges over the drum to clean the lines from drum to fractionator to remove coke added in the line wall.
- At 9 pm the fire ocurred because the valve to the blown down system was NOT closed and the pressure sent the liquid to the drum top.
Oil went out because the flanges were OPEN too. Nobody was hurt but the unit was out for 7 days becasue of damage in the drill system.
Lessons Learned: Never touch a flange without a previous check list of the system.
by Horacio Marchueta