Modifications were done to vessels, causing them to be connected in series. Unbeknown to the personnel, iron sulfite built up in the connecting lines. On a shut-down, after two workdays three artisans got out of one of the vessels and left down the stairway. The iron sulfite spontaneously ignited, and blew a heavy lid from an adjacent vessel, connected in the system. At that stage there was nobody present in any of the vessels. The lid came down, crashing between two of the aforementioned artisans, on the stairway. The lid collided elastically with the grating, jumping back and cutting one man in two. He died on the scene.
South African Accident Investigators are known to be tough. The one that came to investigate this specific accident was known to be even tougher. To make a long story short. The MFDs (Mechanical Flow Diagrams) were never updated to reflect the changes. When the production supervisor was questioned he could not even give a proper flow description to the inspector. He was subsequently tried and executed.
Just kidding! The way in which the investigator pulled those guys to pieces was, however, not a joke and court cases are still going on about that.
Lessons learned: Manage the Changes You Make
Make sure that procedures and documentation are in place BEFORE you hand the unit back to Production/Operations. If you do not have the MFDs ready at the time of re-commissioning then make sure that EVERY legal copy of the MFDs on the unit is marked up with the modifications. By implication: Control the amount of copies of the MFDs on the plant. That way you save yourself one heck of a headache.
‘Till next time – stay out of jail. Do it right!
by Marius Grobler