Investigating Investigation Methodologies

Handout 2 For IRIA2003 Presentation

Examples of questions raised by MES

• Why didn't solvent clean out ash in extruder?
• Timing of fire/solvent shutoff/fire out?
• Was hot oil involved with PCT pressure rise?
• Why did workers have to position themselves in harms way to remove the head?
• Why did Maintenance Tech remove bolts in sequence he did, and would another sequence have changed the outcome?
• Need to confirm that hot oil continued flowing to heat inlet line to PCT after shutdown
• before and after head blew off - did that contribute to heading of contents?
• Why didn't HAZOP recommendation successfully control hazard? (Methodological problem)
• Why wasn't unsuccessful recommendation remedied when experience showed it was unsuccessful? (system problem)
• Why did Operators position selves with Maintenance Technician at head of PCT (if they did)
• What exactly created internal pressure -what were roles of hot oil, overfilling, and decomposition of stored material in PCT
• What ignited fire in extruder? Why did it spread
• Who told whom what and why about pre-run?
• What was data and rationale for this decision? Who made it?
• Find out what procedure is to learn from incidents ≠system breakdown or people problem?
• Find out why air could get into the extruder, providing oxygen for fire??
• What was the impact trauma that killed 2 workers - tank cover or plastic from inside tank?