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Formosa Plastics Propylene Explosion

Overview

This case study describes a fire and series of explosions in the Olefins II unit at the Formosa Plastics Corporation, USA, Point Comfort, Texas, on October 6, 2005. A forklift towing a trailer snagged and pulled a small drain valve out of a strainer in a liquid propylene system, releasing pressurized propylene that formed a vapor cloud and ignited. Sixteen employees were injured, one seriously. A shelter-in-place order was issued for the Point Comfort community, the local elementary school was evacuated, and the fire burned for 5 days.

Incident Snapshot

Field Value
Facility / Company Formosa Plastics Corporation, USA
Location Point Comfort, TX
Incident Date 10/06/2005
Investigation Status The CSB issued a case study report about this incident at a news conference in Houston on July 20, 2006.
Accident Type Chemical Manufacturing - Fire and Explosion
Final Report Release Date 07/20/2006

What Happened

  • A worker driving a fork truck towing a trailer under a pipe rack backed into an opening between two columns to turn around.
  • When the worker drove forward, the trailer caught on a valve protruding from a strainer in a propylene piping system.
  • The trailer pulled the valve and associated pipe out of the strainer, leaving a 1.9-inch diameter opening.
  • Pressurized liquid propylene (216 psig) rapidly escaped through the opening and partially vaporized creating both a pool of propylene liquid and a rapidly expanding vapor cloud.
  • The fork truck driver and other contractors saw the release and evacuated.
  • An operator also heard and saw the escaping propylene and immediately notified the control room.
  • Control room operators saw the vapor cloud on a closed circuit television and began to shut down the unit.
  • Outside operators tried unsuccessfully to reach and close manual valves that could stop the release.
  • Outside operators turned on fixed fire monitors.
  • Control room operators shut off pumps from the motor control center and closed control valves to slow the leak.
  • The vapor cloud ignited.
  • Outside operators left the unit.
  • Control room operators declared a site-wide emergency.
  • Control room operators smelled propylene vapors and evacuated.
  • A large pool fire burned under the pipe rack and the side of an elevated structure that supported a number of vessels, heat exchangers, and relief valves.
  • The Formosa ERT arrived and took command of the incident response.
  • About 30 minutes into the event, the side of the elevated structure collapsed, crimping emergency vent lines to the flare header.
  • Crimped pipes and steel, softened from fire exposure, led to multiple ruptures of piping and equipment and the loss of integrity of the flare header.
  • The Formosa ERT isolated fuel sources where possible, and allowed small fires to burn the uncontained hydrocarbons.
  • The fire was extinguished about five days after the start of the incident.

Facility and Process Context

  • The incident occurred in the Olefins II unit at the Formosa Plastics Corporation, USA, Point Comfort, TX, complex.
  • The Point Comfort complex, the largest Formosa facility in the United States, began operations in 1983.
  • The complex employs 1400 full-time workers and 400 contractors and covers 1,800 acres.
  • The fire and explosions occurred in the Olefins II unit, one of 17 units at the complex.
  • The Point Comfort Olefins II unit uses furnaces to convert either naphtha, or natural gas derived feedstock, into a hydrocarbon mixture.
  • Distillation columns then separate the hydrocarbon mixture.
  • Relief valves protect the distillation columns, heat exchangers, and other large vessels in the unit from overpressure.
  • Formosa’s Point Comfort complex has a large trained and equipped Emergency Response Team (ERT) that includes 120 members and two fire trucks.
  • On the day of the incident, two of the off-shift crews were on site for training; as a result, 90 trained emergency responders were immediately available.
  • Firefighters from the surrounding communities also supplemented the Formosa ERT by providing and staffing a fire fighter health monitoring station.
  • The Formosa emergency response strategy was to prevent the fire from spreading to other units and to isolate fuel sources where possible.
  • Within minutes of the initial explosion, local officials ordered a shelter-in-place for the Point Comfort community and closed Highway 35 that runs adjacent to the Formosa complex and through Point Comfort.
  • Students and staff at the Point Comfort Elementary School evacuated to Port Lavaca, about five miles away.
  • The Red Cross assisted employees and contractors at the Port Lavaca Community Center.

Consequences

  • Fatalities: None reported.
  • Injuries: Sixteen employees were injured, one seriously. The explosion knocked down several and burned two (one seriously) operators exiting the unit. Fourteen workers sustained minor injuries including scrapes and smoke inhalation.
  • Environmental Release: Escaping propylene rapidly vaporized, forming a large flammable vapor cloud. A large pool fire burned under the pipe rack and the side of an elevated structure. The fire burned for 5 days and about seven million gallons of water were used to cool vessels and contain the fire.
  • Facility Damage: The extensive damage shut down Olefins II unit for 5 months. Part of a structure supporting the relief valves and emergency piping to the flare header collapsed. Crimped pipes and steel, softened from fire exposure, led to multiple ruptures of piping and equipment and the loss of integrity of the flare header.
  • Operational Impact: Operators immediately began to shut the plant down and attempt to isolate the leak. Formosa initiated a site-wide evacuation. The fire was extinguished about five days after the start of the incident.

Key Findings

Immediate Causes

  • a trailer being towed by a forklift snagged and pulled a small drain valve out of a strainer in a liquid propylene system
  • Escaping propylene rapidly vaporized, forming a large flammable vapor cloud
  • At about 3:07 PM, the vapor ignited, creating an explosion

Contributing Factors

  • The propylene piping involved in this incident protruded into an open space, yet had no impact protection.
  • Passive fire protection (fireproofing) was installed on only three of four support column rows and the columns that supported the pressure relief valves and emergency vent piping had no fireproofing.
  • Operators were unable to reach the manual valves capable of stopping the flow from the distillation column.
  • The operators were also unable to reach the local control station to turn off the pumps supplying propylene.
  • Neither of the two operators burned in this incident was wearing FRC.
  • The PSSR team verified that traffic protection around emergency equipment had been installed, but did not look at specific process equipment.
  • During the facility siting analysis, the hazard analysis team discussed what might occur if a vehicle impacted process piping, but because the frequency of occurrence was judged very low, the team considered existing administrative safeguards adequate and did not recommend additional traffic protection.
  • The written hazard analysis did not consider a catastrophic loss of containment within the unit, and did not consider if local isolation valves would be accessible or if remotely operated isolation devices would be necessary.

Organizational and Systemic Factors

  • Formosa has administrative safeguards for vehicle operation in the unit, including a plant-wide speed limit, a vehicle permitting process, and a crane use procedure. However, these safeguards do not specifically address where vehicles may operate within the unit.
  • Formosa contracted M. W. Kellogg to design the Olefins II unit in 1996.
  • The Olefins II unit is an identical copy of the Olefins I unit, which Formosa contracted Kellogg for in late 1988.
  • Olefins I unit is a nearly identical copy of an ethylene plant that Kellogg sold to another company in the mid 1980s.
  • American Petroleum Institute (API) Publication 2218 recommends that steel supporting important piping such as relief and flare lines be fireproofed, but the designs sold to Formosa were never updated to incorporate this guidance.
  • Kellogg, the designer of Formosa’s Olefins II unit, specified remotely actuated valves for raw material supply and final product lines, but only local manual valves pump controls for equipment within the unit that contained large hydrocarbon inventories.
  • Formosa decided to require FRC for specific high-risk assignments, but decided not to require FRC for operators in the Olefins II unit except for those involved in emergency response.
  • While Formosa conducted a preliminary hazard analysis, a process hazard analysis, a siting analysis, and a PSSR prior to operating the Olefins II unit, these reviews did not fully address protection of specific process equipment from vehicle impact or the use of remotely actuated valves to control a catastrophic release.

Failed Safeguards or Barrier Breakdowns

  • no impact protection
  • Passive fire protection (fireproofing) was installed on only three of four support column rows and the columns that supported the pressure relief valves and emergency vent piping had no fireproofing.
  • operators were unable to reach the manual valves capable of stopping the flow from the distillation column
  • the operators were also unable to reach the local control station to turn off the pumps supplying propylene
  • Neither of the two operators burned in this incident was wearing FRC.
  • The PSSR team verified that traffic protection around emergency equipment had been installed, but did not look at specific process equipment.
  • the written hazard analysis did not consider a catastrophic loss of containment within the unit, and did not consider if local isolation valves would be accessible or if remotely operated isolation devices would be necessary.

Recommendations

  1. 2006-01-I-TX-R1 | Recipient: Formosa Plastics USA | Status: Not specified | Revise policies and procedures for process hazard analysis and pre-startup safety review to more fully evaluate vehicle impact hazards, passive fire protection, and catastrophic releases.
  2. 2006-01-I-TX-R2 | Recipient: Formosa Plastics USA | Status: Not specified | Require flame resistant clothing for workers in units at the Point Comfort complex where there is a risk of flash fires.
  3. 2006-01-I-TX-R3 | Recipient: Kellogg, Brown, and Root | Status: Not specified | Communicate the findings and recommendations of this report to all companies that contracted with either M. W. Kellogg or Kellogg, Brown, and Root (KBR) for plant designs similar to the Formosa Olefins II unit.
  4. 2006-01-I-TX-R4 | Recipient: Kellogg, Brown, and Root | Status: Not specified | Communicate the findings and recommendations of this report to your petrochemical process plant design engineers. Emphasize the importance of using current consensus safety standards when designing and constructing petrochemical process plants, including the earlier designs reused for new facilities.
  5. 2006-01-I-TX-R5 | Recipient: Kellogg, Brown, and Root | Status: Not specified | Revise KBR petrochemical process plant design procedures to ensure they address the use of current safety standards for new designs and earlier designs reused for new facilities.
  6. 2006-01-I-TX-R6 | Recipient: Center for Chemical Process Safety (CCPS) | Status: Not specified | Incorporate guidance for vehicular traffic protection and remote equipment isolation into the next revision of the Center for Chemical Process Safety’s Guidelines for Hazard Evaluation Procedures.

Key Engineering Lessons

  • Vehicle impact hazards to process piping and equipment must be evaluated in hazard reviews and siting analyses, including the need for impact protection where vehicles can operate near exposed piping.
  • Passive fire protection for steel supporting important piping such as relief and flare lines is a critical design consideration and should reflect current consensus safety standards.
  • Emergency isolation and shutdown provisions should be designed so that operators can reach and use them during a release, or be remotely actuated where necessary to control a catastrophic loss of containment.
  • Pre-startup safety review should verify protection of specific process equipment, not only general traffic protection around emergency equipment.
  • Flame resistant clothing requirements should match the flash fire risk for operators working in process units.

Source Notes

  • All facts were taken from the source extract labeled FINAL REPORT: Case Study with source_priority 1.
  • Where the source used official terminology such as Olefins II, PSSR, FRC, ERT, and API Publication 2218, that terminology was preserved.
  • No external information was added; empty strings were retained where the source did not specify a value.

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