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Formosa Plastics Vinyl Chloride Explosion

Overview

On April 23, 2004, five workers were fatally injured and three others were seriously injured when an explosion and fire occurred in a polyvinyl chloride (PVC) production unit at Formosa Plastics in Illiopolis, Illinois. The event followed a release of highly flammable vinyl chloride monomer (VCM), which ignited, caused major facility damage, and led to a community evacuation.

Incident Snapshot

Field Value
Facility / Company Formosa Plastics Corporation, USA (FPC USA) / Formosa-IL
Location Illiopolis, IL
Incident Date 04/23/2004
Investigation Status The CSB's final report on this investigation was issued at a news conference in Springfield, Illinois, on March 6, 2007.
Accident Type Chemical Manufacturing - Fire and Explosion
Final Report Release Date 03/06/2007

What Happened

  • On April 23, 2004, an explosion and fire at the Formosa Plastics Corporation, Illiopolis, Illinois, polyvinyl chloride (PVC) manufacturing facility killed five and severely injured three workers.
  • The explosion and fire destroyed most of the reactor facility and adjacent warehouse and ignited PVC resins stored in the warehouse.
  • Smoke from the smoldering fire drifted over the local community, and as a precaution, local authorities ordered an evacuation of the community for two days.
  • The CSB determined that this incident occurred when an operator drained a full, heated, and pressurized PVC reactor.
  • The CSB believes that the operator cleaning a nearby reactor likely opened the bottom valve on an operating reactor, releasing its highly flammable contents.
  • Opening the bottom valve on the operating reactor required bypassing a pressure interlock.
  • Two operators working with the shift supervisor attempted to manage the release, did not evacuate, and subsequently died.
  • A few minutes after 10:30 p.m., workers throughout the plant heard a very loud rumbling and some smelled VCM.
  • The shift supervisor stated that two areas had levels above the instrument’s measurable limit, suggesting a large release.
  • The shift supervisor saw material spraying from the bottom of D310 and a foaming mixture on the floor about 1.5 feet deep.
  • The shift supervisor instructed operators to open vent valves on reactor D310 to relieve pressure and slow the release.
  • A series of explosions occurred.
  • The explosions knocked over two 3,000 gallon VCM recovery tanks; lifted multi-ton dryers off their supports; and destroyed the laboratory, safety, and engineering offices.
  • The ensuing fire spread to the PVC warehouse west of the reactor building, burned for hours, and sent a plume of acrid smoke into the community.
  • Four operators were killed by the explosions: two working near the top of the reactor and two working on the lower level.
  • A fifth operator died in the hospital two weeks later.
  • The shift supervisor and two workers were hospitalized, and four workers were treated at the scene.
  • Emergency responders evacuated approximately 150 residents living within one mile of the plant and the Illinois State Police closed the major roadways in the area.

Facility and Process Context

  • Formosa-IL, a wholly owned subsidiary of Formosa Plastics Corporation, USA (FPC USA), bought the Illiopolis facility from Borden Chemical and operated it for approximately two years before the incident.
  • The Formosa-IL PVC plant included a commodity PVC resin process (PVC1) and a specialty PVC resin process (called “Paste”).
  • These two processes used 24 reactors to produce up to 400 million pounds of PVC resins per year.
  • The reactor building housed the two PVC production areas – PVC1 and Paste.
  • At the time of the incident, Formosa-IL employed 139 workers (106 hourly and 33 salaried).
  • Six operators per shift worked in the PVC1 area where the incident occurred.
  • The poly operator worked exclusively on the upper level of the building where the reactor controls and indicators were located, while the blaster operator worked on all levels.
  • At Formosa-IL, the PVC1 reactors were arranged in groups of four, with a control panel for every two reactors.
  • Reactor bottom and drain valve control panels were on the lower level.
  • Operators working on the lower level had no means to communicate with operators on the upper level who had ready access to reactor status information.
  • The Formosa-IL deluge system was activated by high-temperature sensors, VCM vapor monitors set at one-half the lower flammability limit for VCM, loss of instrument air pressure, or manual pull stations located throughout the facility.
  • The facility had six different procedures relating to VCM release emergencies.
  • The facility had not conducted a drill of a large release scenario in more than 10 years.
  • As of the issue date of the report, the facility remained closed, and no actions had been taken to rebuild.

Consequences

  • Fatalities: 5 dead.
  • Injuries: 3 severely injured workers; the shift supervisor and two workers were hospitalized, and four workers were treated at the scene.
  • Environmental release: Approximately 15,000 pounds of VCM was released, along with water, PVC, and other reaction ingredients. Smoke from the smoldering fire drifted over the local community. Some off-site soil sampling revealed dioxin levels slightly above suggested background level of 1.0 part per trillion, but none were at or above the action level of 1.0 part per billion.
  • Facility damage: The explosion and fire destroyed most of the reactor facility and adjacent warehouse, destroyed much of the plant, blew off the reactor building roof, tore asbestos-containing paneling and insulation from framing and piping, spread it across the plant site, and heavily damaged offices used by day shift employees.
  • Operational impact: The facility is shut down and has not been rebuilt; as of the issue date of the report, the facility remained closed, and no actions had been taken to rebuild.

Key Findings

Immediate Causes

  • The CSB determined that this incident occurred when an operator drained a full, heated, and pressurized PVC reactor.
  • The CSB believes that the operator cleaning a nearby reactor likely opened the bottom valve on an operating reactor, releasing its highly flammable contents.
  • The interlock for the reactor D310 bottom valve had been bypassed and the drain valve opened, which released the reactor contents into the reactor building.

Contributing Factors

  • The safeguards to prevent bypassing the interlock were insufficient for the high risk associated with this activity.
  • Formosa-IL facility emergency procedures for evacuation were ambiguous.
  • Formosa-IL employees were unprepared for a major VCM release.
  • Operators on the lower level had no means (indication or communication) to determine the operating status of a reactor from the lower level.
  • Even though the operators were not authorized to use the reactor bottom valve interlock bypass, they had uncontrolled access, and the bypass could be used without detection.
  • The Formosa-IL plant had no written procedure to ensure that safeguards were sufficient to control the risk of a given hazard.
  • Formosa-IL had vague and conflicting procedures for responding to a large VCM release.
  • NFPA 15 (NFPA, 2001) provides no clear engineering design basis, including limitations, for water spray deluge systems intended to prevent or mitigate fires and explosions.

Organizational and Systemic Factors

  • Borden Chemical did not adequately address the potential for human error.
  • Borden Chemical did not implement 1992 process hazard analysis (PHA) recommendations to change the reactor bottom valve interlock bypass to reduce potential misuse.
  • In a 1999 PHA, Borden identified severe consequences for opening the reactor bottom valve on an operating reactor, but accepted the interlock, controlled by procedures and training, as a suitable safeguard.
  • Formosa-IL did not adequately address the potential for human error.
  • After a 2003 incident at FPC USA’s Baton Rouge facility, Formosa-IL did not recognize that a similar incident could occur at the Illiopolis facility or take action to prevent it.
  • Formosa-IL relied on a written procedure to control a hazard with potentially catastrophic consequences.
  • When it bought Formosa-IL, FPC USA implemented a new organizational structure and reduced staffing.
  • Formosa-IL did not analyze the safety impact of this change.
  • FPC USA corporate safety personnel and Formosa-IL managers should have recognized the similarities in these incidents, specifically the possibility that an operator might mistakenly open the wrong reactor bottom valve, and made the installation of a more effective interlock an urgent priority.
  • The FPC USA incident investigation program did not effectively evaluate incidents and communicate findings that could have prevented this incident.
  • FPC USA did not have written guidelines for matching safeguards with risk.
  • FPC USA did not have comprehensive written standards managing interlocks at its PVC facilities.
  • FPC USA did not recognize and address common elements among several serious incidents at its PVC facilities.

Failed Safeguards or Barrier Breakdowns

  • The reactor bottom valve had a safety interlock that prevented opening it with the control switch if reactor pressure exceeded 10 psi.
  • Borden added a manual interlock bypass.
  • The emergency transfer procedure required a supervisor to authorize, but not necessarily witness, bypassing the interlock.
  • The 1992 PHA recommendations to require that no plant interlock be defeated without direct hands-on approval and witnessing of operating supervision were never implemented.
  • The recommendation to replace the emergency air hose system with one that required a supervisor’s key to override it was never implemented.
  • The 1999 PHA accepted the existing bottom valve safety interlock, procedures, and training as suitable safeguards.
  • The reactor cleaning procedure was not addressed in either PHA.
  • The Formosa-IL bypasses all lacked physical controls needed to make them secure.
  • Failure to provide indication of the bypass condition meant that the condition could be undetected.
  • The PVC1 deluge system did not activate during the April 2004 fatal incident.
  • The CSB was unable to determine a cause for the malfunction.
  • The facility had no written requirements or procedures for conducting drills or exercises.
  • The facility had not conducted a drill of a large release scenario in more than 10 years.
  • The VCM alarm system required personnel to either put on a protective respirator or evacuate when activated, but the workers did not do so.
  • The shift supervisor and operators who tried to control the release were not trained to the appropriate HAZWOPER emergency response requirements.

Recommendations

  1. 04-10-I-IL-R1 — Recipient: Formosa USA — Status: Not specified — Review the design and operation of FPC USA manufacturing facilities and implement policies and procedures to ensure that site-wide policies are implemented to address necessary steps and approval levels required to bypass safety interlocks and other critical safety systems; chemical processes are designed to minimize the likelihood and consequences of human error that could result in a catastrophic release; safety impacts of staffing changes are evaluated; risks identified during hazard analyses and near-miss and incident investigations are characterized, prioritized, and that corrective actions are taken promptly; high-risk hazards are evaluated using layers of protection analysis (LOPA) techniques and that appropriate safeguards are installed to reduce the likelihood of a catastrophic release of material; all credible consequences are considered in near-miss investigations; emergency procedures clearly characterize emergency scenarios, address responsibilities and duties of responders, describe evacuation procedures, and ensure adequate training; periodic drills are conducted; and the siting of offices for administrative and support personnel is evaluated to ensure the safety of personnel should an explosion or catastrophic release occur.
  2. 04-10-I-IL-R2 — Recipient: Formosa USA — Status: Not specified — Conduct periodic audits of each FPC USA PVC manufacturing facility for implementation of the items in Recommendation R1. Develop written findings and recommendations. Track and promptly implement corrective actions arising from the audit. Share audit findings with the workforce at the facilities and the FPC USA Board of Directors.
  3. 04-10-I-IL-R3 — Recipient: Formosa USA — Status: Not specified — Design and implement a program requiring audits of newly acquired facilities that address the issues highlighted in this report. Document, track, and promptly address recommended actions arising from the audits.
  4. 04-10-I-IL-R4 — Recipient: Formosa USA — Status: Not specified — Communicate the contents of this report to all employees of FPC USA PVC facilities.
  5. 04-10-I-IL-R5 — Recipient: National Fire Protection Association — Status: Not specified — Revise NFPA 15, Standard for Water Spray Fixed Systems for Fire Protection, to provide additional design guidance for deluge systems designed to prevent or mitigate fires and explosions. Include information concerning the limitations of using deluge systems for this purpose.
  6. 04-10-I-IL-R6 — Recipient: Vinyl Institute — Status: Not specified — Issue a safety alert to your membership highlighting the need to identify design features that may render processes vulnerable to human error and to implement sufficient layers of protection to minimize the likelihood human error causing catastrophic releases of hazardous material. Include lessons from PVC industry industrial accidents (including those described in this report and others highlighted in The Encyclopedia of PVC and elsewhere) that involved human error.
  7. 04-10-I-IL-R7 — Recipient: Environmental Protection Agency — Status: Not specified — Ensure that the EPA’s Enforcement Alert concerning PVC facilities includes the causes and lessons learned from this investigation. Emphasize the importance of analyzing human factors and the need to implement adequate safeguards to minimize the likelihood and consequences of human error that could result in catastrophic incidents.
  8. 04-10-I-IL-R8 — Recipient: AIChE Center for Chemical Process Safety — Status: Not specified — Develop guidelines for auditing chemical process safety at newly acquired facilities. Emphasize the identification of major hazards, a review of the acquired facility’s previous incident history and hazard analyses, the adequacy of management safety systems, and harmonization of the acquired facility’s standards and practices with those of the acquiring company.

Key Engineering Lessons

  • Safety interlocks and bypasses for high-risk operations require physical controls and clear indication so bypass conditions cannot be used without detection.
  • Written procedures and training alone were not sufficient safeguards for preventing catastrophic release from an operating reactor.
  • Hazard analyses must address reactor cleaning and other credible human-error scenarios, including mistaken opening of the wrong reactor bottom valve.
  • Emergency response systems and procedures must clearly define evacuation responsibilities and be supported by periodic drills for large-release scenarios.
  • Deluge systems may not provide a reliable standalone mitigation basis for preventing or mitigating fires and explosions, and their limitations should be recognized in design guidance.
  • Safety impacts of staffing and organizational changes should be evaluated when they affect process supervision, communication, and emergency response.

Source Notes

  • All fields were consolidated from the provided structured extract for the Final Investigation Report, which has the highest priority among the supplied documents.
  • Direct causes were kept separate from contributing factors and organizational/systemic factors per the report's findings.
  • No external facts were added; terminology was preserved from the source text where possible.

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