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CSB Investigation Report No. 2004-10-I-IL 2004 Safety Safety Environmental Environmental
Formosa Plastics Illiopolis PVC Reactor Wrong-Valve Release and Explosion
Formosa Plastics Corporation, Illiopolis, Illinois
Related equipment → Reactor (reactor)
5Fatalities
3Injuries
ExplosionMechanism code HIO
⌗Failure Mode · ISO 14224 Mapping
Damage mechanism (recorded in KB)
ExplosionHIO
ISO functional code (as recorded · corrected)
ISO 14224:2016 functional failure code
STD · Structural failure
Original code HIO corrected to ISO STD — Structural failure.
Original recorded code semantics mismatch · corrected to STD
1What Happened

Operator opened bottom valve of an operating PVC polymerization reactor by mistake (interlock bypassed); large vinyl chloride release ignited and exploded

2Root Cause

Operator went to the wrong reactor platform, opened the bottom valve of an operating reactor using an interlock bypass; vinyl chloride monomer released and ignited — 5 killed, 3 seriously injured, plant destroyed

3Reliability Lessons (from investigation root cause)
  • The 'Root Cause' above is the core lesson of this accident; not split further.
4Associated Failure Mechanisms (Keywords)
polymerization reactor vinyl chloride human error interlock bypass explosion PVC
About the Failure-Mode Code (click to expand)

The originally recorded code HIO is an ISO 14224 functional code but its semantics do not match the actual failure (see the Mapping block above); it has been corrected to STD based on the accident narrative. ISO 14224 functional codes describe what the equipment failed to do; the damage mechanism (how it failed) is a different dimension.

5Evidence Source (transparent)
Authority：U.S. Chemical Safety and Hazard Investigation Board (CSB)
Official Report：www.csb.gov ↗
Data Verification：verified_url_csb_case_page_curl200
↗Related Failure Modes · Traceability
Fatigue Fracture fatigue_fractureBending bendingKeyway Wear keyway_wearCorrosion/Erosion corrosion_erosionBlade Crack blade_crackBlade Detachment blade_detachmentGlass-lining Damage glass_lining_damageGear Wear/Pitting gear_wear_pittingBearing Failure bearing_failureOil Seal Leak oil_seal_leakInternal Corrosion Thinning internal_corrosion_thinningStress Corrosion Cracking (SCC) sccWeld Crack weld_crackGlass-lining Failure glass_lining_failureCorrosion corrosionAnchor Bolt Loosening anchor_bolt_looseningFace Wear face_wearO-ring Aging o_ring_agingSpring Failure spring_failureSecondary Seal Leak secondary_seal_leakDry-running Burn dry_running_burnFlush Loss flush_lossFilter Clogging filter_cloggingGasket Aging gasket_agingFlange Face Corrosion flange_face_corrosionJacket Corrosion jacket_corrosionJacket Fouling jacket_foulingHalf-pipe Weld Leak half_pipe_weld_leakCoil Perforation coil_perforationVibration Fatigue vibration_fatigueSupport Loosening support_looseningSet Point Drift set_point_driftValve Seat Leakage seat_leakagePremature Fatigue Rupture premature_ruptureBackside Corrosion backside_corrosionRelief Line Blockage vent_line_blockageQuench System Failure quench_system_failureSensor Drift sensor_driftThermowell Corrosion thermowell_corrosionDiaphragm Failure diaphragm_failureImpulse Line Blockage impulse_line_blockageImpulse Line Blockage impulse_line_blockage_2Coating→False Reading coating_false_readingElectrode Fouling electrode_foulingCalibration Drift calibration_drift
Report No. 2004-10-I-IL · Data from CSB public investigation conclusions, compiled by Reliability AI, for reliability demonstration purposes only. This case is derived from public incident investigation reports for learning purposes only. AIM does not endorse or guarantee its accuracy.