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BP Amoco Thermal Decomposition Incident

Overview

On March 13, 2001, three workers were killed at the BP Amoco Polymers plant in Augusta, Georgia, when a pressurized process vessel containing hot plastic was opened and the cover blew off. The release expelled hot plastic, broke nearby tubing, and hot fluid from the tubing ignited, resulting in a fire. The final report identified reactive hazards, inadequate process safety information, inadequate hazard analyses, and failures in opening process equipment and management of change as key issues.

Incident Snapshot

Field Value
Facility / Company BP Amoco Polymers, Inc.
Location Augusta, GA
Incident Date 03/13/2001
Investigation Status The final report on this investigation was approved on May 20, 2002.
Accident Type Oil and Refining - Reactive Incident
Final Report Release Date 05/20/2002

What Happened

  • On March 10, 2001, the unit was shut down for repair of an equipment failure in the extruder.
  • On March 11, 2001, the polymer catch tank was prepared for opening, the cover was removed, the frame inside was extracted, and the tank was cleaned of accumulated polymer.
  • On March 12, 2001, operators commenced prestartup checks at 6:45 am.
  • Raw material feed was introduced to the reaction section at 1:29 pm on March 12.
  • At 2:17 pm on March 12, operators attempted to start the extruder and discovered that the screws would not turn.
  • At 2:35 pm on March 12, supervision made a decision to abort the startup.
  • At 2:41 pm on March 12, flushing solvent was injected to begin cleaning the piping and equipment of accumulated polymer.
  • At approximately 3:45 pm on March 12, an engineer noticed vapor leaking from the top of the bolted cover on the polymer catch tank.
  • At approximately 3:55 pm on March 12, process flow was diverted from the polymer catch tank to the adjacent reactor knockout pot.
  • At 6:53 pm on March 12, the solvent flush was completed and water was circulated through the unit.
  • At 11:21 pm on March 12, the water flush was discontinued, completing the shutdown.
  • At 2:15 am on March 13, a maintenance technician arrived to empty the polymer catch tank and the reactor knockout pot.
  • At 2:25 am on March 13, the maintenance technician began removing the 44 bolts from the polymer catch tank cover with the assistance of two operators.
  • At 2:36 am on March 13, after 22 bolts had been removed, the remaining bolts suddenly broke and the cover blew off the polymer catch tank.
  • At 2:42 am on March 13, a vapor cloud formed from hot oil escaping from broken tubing and ignited.
  • The fire was extinguished at about 8:15 am on March 13.
  • The BP Amoco facility shut down all manufacturing units after the incident to review safety programs and conduct additional training.
  • The Amodel unit did not restart until July 27, following the implementation of major design changes.

Facility and Process Context

  • The BP Amoco facility is located on a 100-acre site in Augusta, Georgia, and produces various specialty plastics.
  • The facility employed approximately 250 full-time personnel.
  • Amodel is a high-performance nylon thermoplastic used for automotive, electronic, consumer, and medical device applications.
  • The Augusta site was the first and only commercial manufacturing facility for Amodel.
  • The process operates continuously after the initial batch-wise preparation of the ingredients in water.
  • The polymer catch tank was used during startup, shutdown, and process upsets.
  • The catch tank also played a role if there were problems with the extruder.
  • The catch tank has a sister vessel called the reactor knockout pot.
  • The reactor knockout pot serves as a destination should the pressure or safety release device in the outlet of the reactor burst.
  • The process was described as a new process and the first and only commercial implementation of a new process.

Consequences

  • Fatalities: 3 killed
  • Injuries: The maintenance technician and both operators suffered severe impact trauma.
  • Environmental release: Hot plastic was expelled and scattered widely, traveling as far as 70 feet. Hot oil escaped and formed a vapor cloud that ignited.
  • Facility damage: The 1,750-pound cover blew off the polymer catch tank; the tank was propelled backward; attached piping bent; a section of hot oil supply tubing broke; a girder was damaged; the vent system and vessel nozzles were plugged with polymer.
  • Operational impact: The unit was shut down; the fire burned for several hours; all manufacturing units at the Augusta site were shut down after the incident; the Amodel unit did not restart until July 27 following major design changes.

Key Findings

Immediate Causes

  • The workers were unaware that the vessel was pressurized.
  • The partially unbolted cover blew off the vessel, expelling hot plastic.
  • The force of the release caused some nearby tubing to break.
  • Hot fluid from the tubing ignited, resulting in a fire.
  • A sudden and explosive release of energy broke the remaining bolts and propelled the cover off the polymer catch tank.
  • A mass of hot molten polymer was ejected from the polymer catch tank.
  • The polymer catch tank became pressurized because evolving vapor from chemical reactions had no pathway to escape after the vent lines solidified and plugged.
  • The source of the pressure in the vessel was caused by an unintended chemical reaction.

Contributing Factors

  • More than the normal amount of hot plastic entered the polymer catch tank during the aborted startup.
  • Reactions and decomposition of the material produced gases, which caused the plastic to foam and expand.
  • The expanded plastic forced its way into connecting pipes, where it solidified and plugged the inlet to the vent line.
  • Once this occurred, the gases could not escape and the vessel became pressurized.
  • The design of the polymer catch tank did not afford a practical and reliable method for workers to check for hazards before opening the vessel.
  • Drains were often plugged with solidified plastic, making it impossible to verify the absence of pressure or hazardous chemicals in accordance with Occupational Safety and Health Administration lockout/tagout regulations and standard company safety procedures for opening process equipment.
  • Process safety information inadequately described the design basis and operating principles for the polymer catch tank.
  • There was no discussion of the means by which overfilling could occur and its consequences.
  • The possibility of overfilling was increased when the original startup procedures were revised; the diversion of output from the reactor to the polymer catch tank was extended from 30 to 50 minutes.
  • This modification of procedures was not subjected to a management of change (MOC) review.
  • Process hazard analyses were inadequate.
  • Credible scenarios for overfilling or pressurizing the polymer catch tank were not recognized.
  • The consequences of the extruder failing to start or shutting down during routine operation were not considered.
  • Reactivity and decomposition hazards were treated inadequately or not at all.
  • Operators had no direct measure of the extent to which the polymer catch tank had been filled.
  • The design for the level detector on the vessel was inadequate.
  • The failure of the extruder to run forced the startup to be aborted.
  • Although the prestartup checklist called for verification of the operability of the extruder, that procedural check was omitted on this occasion.
  • The extruder was not pre-run on this particular startup.
  • The extruder screws would not turn during startup.
  • Polymer continued to accumulate in the polymer catch tank while the extruder malfunction remained unresolved.
  • More than twice the normal amount of polymer had been directed to the tank.
  • The amount of heat and energy inside the vessel was likely larger than it had ever been in the past.
  • The vent nozzle and vent system were completely plugged with polymer.
  • The relief line on the catch tank and knockout pot were not shielded from process fluid with a rupture disk.
  • The level instrument on the catch tank was unreliable and prone to false indications.
  • There was no reliable alternate method identified to indicate the level in the catch tank.
  • The double-block and bleed line on both the inlet and vent lines of the vessel were fouled by solidified plastic and would not close.
  • The ram-type valves on the drain line of each vessel were prone to polymer pluggage.
  • There was no standard practice among the workforce for ensuring the vessel was depressured prior to opening.
  • A written guideline existed, but it could not be followed due to the design issues.
  • The policy at the Augusta site did not advise the workforce when to suspend activities if problems occurred and safe equipment opening procedures could not be met.
  • The HAZOP method contained no protocol for examining startup and shutdown issues during operations involving the extruder.
  • The HAZOPs did not document any discussion of reactivity issues associated with the catch tank.
  • The process change request procedure was not necessarily applied to modifications to practices and procedures.
  • The time that the startup material was sent to the catch tank was increased from 30 to 50 minutes.
  • This increased the volume of the polymer accumulated during the startup threefold.
  • The follow-up HAZOP recommended in 1990 was never conducted.
  • Previous occurrences of overfilling and plastic entrainment in the connected piping indicated that the vessel was too small.
  • The level-indicating device was unreliable.
  • The Augusta site system for investigating previous incidents and near-miss incidents did not adequately identify causes and hazards.
  • Management did not have a system to detect trends and patterns among the incidents.
  • The extruder was supposed to be pre-run for approximately one to two minutes to verify its operability, but it was not pre-run.
  • The local pressure gauge was installed to alert personnel of the potential for pressure in the vessel, but it could become plugged and useless.
  • The relief system was considered an adequate safeguard against high pressure, but the normal vent and relief lines both became plugged.
  • The double-block and bleed line on both the inlet and vent lines of the vessel would not close.
  • The drain valves could not be used for their intended purposes.
  • The pressure gauge could not be used for its intended purpose.
  • The isolation valves could not be used for their intended purposes.
  • No immediate action was taken in response to the leak at the reactor knockout pot.
  • No corrective action had been made regarding the personnel hazard associated with removing material from the vessels.
  • No such review took place when safety requirements could not be met.
  • No system was provided to ensure the relief line was clear during operation.
  • No specific guide word to guide the team to reactive chemicals was documented in the HAZOP.

Organizational and Systemic Factors

  • Amoco, the developer of the Amodel process, did not adequately review the conceptual process design to identify chemical reaction hazards.
  • Neither Amoco’s R&D department nor the process design department had a systematic procedure specifically for identifying and controlling hazards from unintended or uncontrolled chemical reactions.
  • The Augusta facility did not have an adequate review process for correcting design deficiencies.
  • Operations management did not ensure that deficiencies were corrected in a timely manner.
  • The Augusta site system for investigating incidents and near-miss incidents did not adequately identify causes or related hazards.
  • Incidents and near misses tended to be treated as isolated events.
  • Management did not have a review system to detect trends and patterns among incidents.
  • No effective measures were developed to prevent recurrence of overfilling and vent line plugging.
  • No effective countermeasures were developed for fires at the extruder.
  • Design documentation did not adequately describe the Amodel process.
  • Operations management did not update the documentation to reflect changes in procedures and practices.
  • Equipment opening procedures did not specify what actions to take when safety precautions could not be met.
  • Revisions to operating procedures were not subjected to management of change reviews to evaluate safety effects.
  • The Amoco development team did not conduct research into the hazards of normal or unanticipated reactions.
  • They were unaware that a reactive hazard existed that could result in an incident such as this.
  • The significance of product degradation testing was never realized with respect to process safety.
  • The principles of operation for the polymer catch tank were not documented in the process safety information.
  • The design information did not explain that the catch tank was acting as a separator.
  • The documentation explained the vessel's role during the flush process, but not particularly during startup, shutdown, or process upsets.
  • Operations management did not update the documentation to reflect changes to procedures and practices.
  • The Augusta facility did not have an adequate review process for correcting design deficiencies.
  • Workers were unable to follow established company policies for lockout/tagout and equipment opening because the plug drains on the polymer catch tank prevented them from verifying the absence of pressure in the tank.
  • The Augusta site system for investigating previous incidents and near-miss incidents did not adequately identify causes and hazards.
  • Effective countermeasures were not developed.
  • Revisions to operating procedures were not subject to management of change reviews to evaluate safety effects.
  • The plant seems to have been orphaned from the parent corporation due to substantial organizational change.

Failed Safeguards or Barrier Breakdowns

  • The level detector was often damaged during cleanout of hardened polymer and was not in the vessel when it was closed on March 11.
  • The pressure gauge on the vent line would likely have been unreliable because plastic had entered the vent line and solidified.
  • The drain valves were ineffective because solidified plastic seized the internal mechanisms.
  • The nozzles leading to the ram-type valves were obstructed by solid polymer.
  • The double block valves were ineffective.
  • The pressure relief valve on the polymer catch tank was fouled with polymer and required repeated repair.
  • The pressure relief valve on the reactor knockout pot was reconditioned twice in the same period.
  • The emergency pressure relief system on the reactor knockout pot was not sufficient to prevent pressurization when the common vent piping became obstructed.
  • The try step on the equipment isolation list was not completed on the day of the incident.
  • No positive verification occurred that the polymer catch tank was depressurized before opening.
  • The extruder was supposed to be pre-run for approximately one to two minutes to verify its operability, but it was not pre-run.
  • The local pressure gauge was installed to alert personnel of the potential for pressure in the vessel, but it could become plugged and useless.
  • The relief system was considered an adequate safeguard against high pressure, but the normal vent and relief lines both became plugged.
  • The double-block and bleed line on both the inlet and vent lines of the vessel would not close.
  • The drain valves could not be used for their intended purposes.
  • The pressure gauge could not be used for its intended purpose.
  • The isolation valves could not be used for their intended purposes.
  • No system was provided to ensure the relief line was clear during operation.

Recommendations

  1. 2001-03-I-GA-R1 — Recipient: Solvay Advanced Polymers, L.L.C. — Status: Not specified — Summary: Examine the manufacturing businesses acquired from BP Amoco Performance Polymers and ensure that a systematic safety review procedure is developed and implemented for identifying and controlling hazards from unintended chemical reactions. Additionally, ensure that reactive hazards are identified and evaluated: During product R&D, during conceptual design of a new process, and during detailed design of a new process. Before changes are made to existing equipment or process chemistry. Communicate the results of this review to the workforce.
  2. 2001-03-I-GA-R2 — Recipient: Solvay Advanced Polymers, L.L.C. — Status: Not specified — Summary: Ensure that a program is in place at facilities acquired from BP Amoco Performance Polymers to systematically review the hazards associated with new and modified processes and equipment as operating experience accrues. Ensure that facilities correct all identified design, operation, and maintenance deficiencies. Verify that operating experience does not invalidate the design basis for equipment.
  3. 2001-03-I-GA-R3 — Recipient: Solvay Advanced Polymers, L.L.C. — Status: Not specified — Summary: Revise the Material Safety Data Sheet (MSDS) for Amodel to warn of the hazards of accumulating large masses of molten polymer. Communicate the MSDS changes to current and past customers (who may retain inventories of this product).
  4. 2001-03-I-GA-R4 — Recipient: Solvay Advanced Polymers, L.L.C., Augusta Facility — Status: Not specified — Summary: Implement a program to conduct periodic management reviews of incidents and near-miss incidents. Look for trends and patterns among incidents. Address root causes and implement and track corrective measures.
  5. 2001-03-I-GA-R5 — Recipient: Solvay Advanced Polymers, L.L.C., Augusta Facility — Status: Not specified — Summary: Revise process safety information to include: Information regarding the decomposition reactions of Amodel. Design intent, basis, capacity, and limitations of equipment. Hazards and consequences of deviations from design intent and operating limits.
  6. 2001-03-I-GA-R6 — Recipient: Solvay Advanced Polymers, L.L.C., Augusta Facility — Status: Not specified — Summary: Revalidate hazard analyses for the Amodel process to address: Credible deviations from process intent and their consequences. Hazards associated with startup and shutdown operations. Prevention of accumulations of potentially hazardous masses of polymer.
  7. 2001-03-I-GA-R7 — Recipient: Solvay Advanced Polymers, L.L.C., Augusta Facility — Status: Not specified — Summary: Revise your lockout/tagout program to ensure that equipment is rendered safe prior to opening for maintenance. At a minimum, ensure that equipment opening procedures contain a stop work provision that requires higher levels of management review and approval when safe opening conditions, such as equipment depressurization, cannot be verified.
  8. 2001-03-I-GA-R8 — Recipient: Solvay Advanced Polymers, L.L.C., Augusta Facility — Status: Not specified — Summary: Ensure that your management of change policy applies to operational and procedural modifications.
  9. 2001-03-I-GA-R9 — Recipient: BP Chemicals Group — Status: Not specified — Summary: Communicate the findings of this report to your chemical and plastics manufacturing facilities in North America.
  10. 2001-03-I-GA-R10 — Recipient: American Chemistry Council — Status: Not specified — Summary:
  11. 2001-03-I-GA-R11 — Recipient: Society of Plastics Engineers — Status: Not specified — Summary:

Key Engineering Lessons

  • Reactive hazards and unintended or uncontrolled chemical reactions must be identified and controlled during product R&D, conceptual design, detailed design, and before changes to existing equipment or process chemistry.
  • Process safety information must clearly describe design intent, basis, capacity, limitations, and the hazards and consequences of deviations, including decomposition reactions and startup/shutdown conditions.
  • Hazard analyses must explicitly consider credible overfilling, pressurization, startup, shutdown, and process upset scenarios, including the consequences of extruder failure or shutdown.
  • Equipment opening procedures must require positive verification that vessels are depressurized before opening, and must include a stop-work path when safe opening conditions cannot be verified.
  • Management of change must cover operational and procedural modifications, not only hardware changes.
  • Designs that rely on drains, gauges, or relief paths that can be fouled by process material may not provide a reliable means to verify safe conditions before opening.
  • Incident and near-miss reviews must look for trends and patterns so recurring overfilling, vent plugging, and related hazards are not treated as isolated events.

Source Notes

  • Priority 1 final report was used to resolve conflicts and establish authoritative facts.
  • Priority 4 transcript was used only to supplement event sequence, facility context, and descriptive details where consistent with the final report.
  • All facts included are explicitly stated in the provided source extracts; no external information was added.

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