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Yenkin-Majestic Resin Plant Vapor Cloud Explosion and Fire

Overview

On April 8, 2021, a vessel leak, vapor cloud explosion, and fire occurred at the Yenkin-Majestic resin plant in Columbus, Ohio. The CSB determined that flammable solvent vapor was released through the seal of a closed reactor manway that was not designed, constructed, or pressure tested to a design pressure appropriate for the process. The incident fatally injured one employee and injured eight others. It also caused major facility damage and offsite impacts.

Incident Snapshot

Field Value
Facility / Company Yenkin-Majestic Paint Corporation / OPC Polymers
Location Columbus, OH
Incident Date 04/08/2021
Investigation Status The CSB's final report was released on November 30, 2023.
Accident Type Explosion and Fire
Final Report Release Date 11/30/2023

What Happened

  • At approximately 12:02 a.m., a mixture of flammable naphtha solvent vapors and resin liquid became pressurized and then released through the seal of a closed manway of an operating kettle.
  • The naphtha vapor spread throughout the enclosed building and formed a flammable vapor cloud both inside and outside the building.
  • Approximately two minutes later, at 12:04 a.m., the flammable vapor cloud found an ignition source, and an explosion erupted.
  • The explosion ignited additional flammable material, resulting in a large fire that was extinguished after approximately 11 hours.
  • Employee A departed the kettle room at 10:19 p.m. to review sample results at the laboratory.
  • At 10:22 p.m. the Kettle 3 agitator unexpectedly shut down.
  • Employee A returned at 10:25 p.m. and did not realize that the agitator had shut down.
  • At 10:33 p.m., with the batch temperature at approximately 455 °F, Employee A pushed the control system’s “Batch Done” button to begin cooling the kettle’s contents.
  • At approximately 11:06 p.m., Employee A began adding solvent (VM&P) into the kettle through the spray heads at the top of the kettle.
  • About 300 gallons of solvent flowed into the kettle at a steady rate over about 26 minutes, from approximately 11:06 p.m. to 11:32 p.m.
  • Around midnight, the kettle temperature was recorded as 424 °F.
  • At 12:02 a.m., Employee A turned the agitator back on.
  • When the agitator began mixing the kettle’s stagnant layers at 12:02 a.m., the liquid solvent began to vaporize, increasing the pressure inside the kettle from approximately 0 to 4 psig in 15 seconds.
  • Two seconds later, when the kettle’s pressure reached approximately 9 psig, Kettle 3’s closed manway could no longer contain the pressure and began to release a mixture of hot resin liquid and flammable solvent vapor through the sealing surface around its lid into the kettle room.
  • The pressure inside the kettle continued to climb until it peaked at 18 psig.
  • At 12:04 a.m., the released flammable vapors found an ignition source and exploded.

Facility and Process Context

  • Yenkin-Majestic Paint Corporation (Yenkin-Majestic) is a coatings and resin manufacturer based in Columbus, Ohio.
  • The incident occurred at the OPC Polymers resin plant within the Yenkin-Majestic facility.
  • A portion of Yenkin-Majestic’s resin plant was subject to the OSHA Process Safety Management of Highly Hazardous Chemicals (PSM) standard due to its usage of flammable liquids present in quantities of 10,000 pounds or more.
  • The part of the process that experienced the incident was PSM-covered.
  • The resin plant was a multi-story enclosed building that housed six kettles and other process equipment.
  • The kettles spanned two stories of the resin plant; the kettles rested on the furnaces on the first (ground) floor, and the equipment on and near the top of the kettles to control the process was accessible on the second floor.
  • The laboratory, where operators analyzed samples during the batch runs, was on the third floor.

Consequences

  • One employee was fatally injured from thermal injuries and inhalation of products of combustion and was found partially covered by rubble inside the second floor of the resin plant.
  • Eight other employees were transported to area hospitals for injuries suffered during the explosion and building collapse, including third-degree burns and limb fractures, with one employee requiring a leg amputation after he was crushed under collapsed debris. Four of the injured employees were burned by the fire, two of whom received third-degree burns.
  • Firefighting water runoff entered the nearby Alum Creek through a storm drain. The Ohio EPA reported that it observed offsite impacts from this incident, including firefighting water runoff, through at least April 11, 2021.
  • The incident damaged buildings on the Yenkin-Majestic site and caused a fire in a commercial property adjacent to the site. Yenkin-Majestic estimated its total property damage from the accident at over $90 million and demolished the severely damaged resin plant after the incident.
  • The large fire was extinguished after approximately 11 hours. More than 100 firefighters responded to the scene, including hazmat teams. The resin plant was severely damaged and demolished over a 19-month period after the incident.

Key Findings

Immediate Causes

  • The release of flammable solvent vapor through the seal of a closed reactor manway that was not designed, constructed, or pressure tested to a design pressure appropriate for the process.
  • The reactor became pressurized by the rapid vaporization of solvent when the reactor’s agitator was turned on.

Contributing Factors

  • Yenkin-Majestic’s failure to adhere to basic pressure vessel integrity quality assurance practices.
  • The absence of clear industry guidance specifically for the design, construction, and alteration of pressure vessels in highly hazardous chemicals service not exceeding 15 psig.
  • The absence of engineering controls to prevent the incident sequence.
  • The failure of Yenkin-Majestic’s administrative controls (overreliance on operator actions).
  • Yenkin-Majestic’s inadequate emergency preparedness.

Organizational and Systemic Factors

  • Yenkin-Majestic did not adequately ensure the mechanical integrity of a new 20-inch manway that was installed on Kettle 3 approximately three months before the incident.
  • Yenkin-Majestic performed a leak check up to 4 psig and allowed Kettle 3 to continue operating for approximately three months until the incident.
  • Yenkin-Majestic had taken the position that Kettle 3 was exempted from pressure vessel regulation based on its process safety information documenting that it would not exceed 15 psig.
  • Yenkin-Majestic had not installed or configured interlocks to prevent solvent addition to the kettle when the agitator was off during normal batch operations.
  • Yenkin-Majestic relied upon computer panel status indicators, that were not equipped with alarms, to communicate the agitator status to the operator.
  • Yenkin-Majestic did not specifically train its employees to recognize and respond to the presence of a flammable solvent vapor cloud and its associated hazards.
  • Yenkin-Majestic allowed resin plant operators to wear cotton short-sleeved shirts while working in proximity to flammable materials unless they were performing specific tasks.
  • Yenkin-Majestic did not have adequate written mechanical integrity procedures for quality assurance of alterations to process vessels in highly hazardous chemicals service or for preparing and maintaining records of inspections, alterations, maintenance or repairs.
  • Yenkin-Majestic took the position that Kettle 3 was exempt from the ASME pressure vessel codes because Kettle 3 was documented as not exceeding 15 psig.
  • Yenkin-Majestic did not require its resin plant employees to wear flame-resistant (FR) clothing, but should have done so based on regulatory requirements, industry guidance, and its own internal assessments and incident history.

Failed Safeguards or Barrier Breakdowns

  • The new manway did not withstand more than 9 psig of pressure during a process upset and leaked hot resin and flammable solvent vapor into the facility.
  • The high-pressure alarm and trip activated after Kettle 3’s pressure began to rise, and the rupture disk did not burst.
  • The flammable gas detectors triggered automatic furnace shutdowns; however, they were not configured to sound an audible alarm.
  • The fire alarm system had not been activated to warn workers to evacuate prior to the explosion.
  • No one used the resin plant’s intercom communication system to call for an evacuation or otherwise warn workers of the imminent danger.
  • The new manway was only leak-checked up to 4 psig.
  • The manway did not appear to leak during the 4-psig leak check on January 4, 2021, but it did not withstand pressures exceeding 9 psig during the April 8, 2021, incident.
  • The agitator status indicators were not equipped with alarms.
  • There was no process alarm to warn the operator if the agitator shut down in the middle of a batch.
  • The flammable gas detectors inside the furnace room began sensing elevated flammable gas concentrations and triggered automated shutdowns of the operating furnaces, but they were not set up with audible and visual alarms to alert the workers to a flammable atmosphere.
  • The agitator was not interlocked with solvent addition.
  • The computer system allowed solvent addition while agitator was off.

Recommendations

  1. 2021-04-I-OH-R1 | Recipient: Yenkin-Majestic | Status: Open – Unacceptable Response/No Response Received | Update mechanical integrity procedures for all process vessels in highly hazardous chemicals service, including pressure vessels not exceeding 15 psig, to adopt alteration guidance in API 510 Pressure Vessel Inspection Code or Part 3 of the National Board Inspection Code.
  2. 2021-04-I-OH-R2 | Recipient: Yenkin-Majestic | Status: Open – Unacceptable Response/No Response Received | Assess and document applicable design, construction, and alteration standards for all pressure vessels in highly hazardous chemicals service in new resin plant designs, including pressure vessels not exceeding 15 psig. At a minimum, adopt PIP VESLP001 Low-Pressure, Welded Vessel Specification as design and construction guidance for pressure vessels not exceeding 15 psig. Implement a program to assess the pressure vessels against updated applicable recognized and generally accepted good engineering practices, such as those published by API, ASME, PIP, and other organizations, at least once every five years, and address the gaps identified. Develop and implement written procedures to document and maintain records of (i) all inspections of, (ii) all alterations to, and (iii) all maintenance and repairs on all pressure vessels in highly hazardous chemicals service.
  3. 2021-04-I-OH-R3 | Recipient: Yenkin-Majestic | Status: Open – Unacceptable Response/No Response Received | Demonstrate the use of prevention through design using the hierarchy of controls in future resin plant designs. Specifically, prioritize inherently safer design and engineering controls to prevent process safety events.
  4. 2021-04-I-OH-R4 | Recipient: Yenkin-Majestic | Status: Open – Unacceptable Response/No Response Received | Identify and document all equipment that could release flammable materials and install LEL detectors in accordance with sources and guidance such as Guidelines for Engineering Design for Process Safety by the Center for Chemical Process Safety and Explosion Hazards in the Process Industries by Rolf K. Eckhoff. Ensure that detection of hazardous conditions automatically triggers both visual and audible alarms to alert plant personnel of the hazard. Develop and implement employee training on actions to take, such as prompt evacuation, when such alarms are activated.
  5. 2021-04-I-OH-R5 | Recipient: Yenkin-Majestic | Status: Open – Unacceptable Response/No Response Received | Develop and implement requirements for personnel to wear flame-resistant uniforms in all operating areas that process flammable chemicals. Update employee training material to include the requirement for and purpose of PPE use.
  6. 2021-04-I-OH-R6 | Recipient: American Petroleum Institute (API) | Status: Open – Awaiting Response or Evaluation/Approval of Response | Develop specific design, construction, and alteration guidance for low-pressure process vessels in flammable and other highly hazardous chemicals service not exceeding an internal pressure of 15 psig in API 510 Pressure Vessel Inspection Code, API RP 572 Inspection Practices for Pressure Vessels, and/or other appropriate products. At a minimum, include guidance for: (i) determining and documenting the low-pressure vessel’s design pressure (such as through a data sheet and a nameplate affixed to the vessel); (ii) determining when or if all or parts of the ASME Boiler and Pressure Vessel Code should be applied; (iii) acceptable alternative engineering methods, if applicable; and, (iv) alteration requirements, such as design assessments, inspections, and pressure testing.
  7. 2021-04-I-OH-R7 | Recipient: American Society of Mechanical Engineers (ASME) | Status: Open – Awaiting Response or Evaluation/Approval of Response | Assist API in developing design, construction, and alteration guidance for low-pressure vessels in flammable and other highly hazardous chemicals service not exceeding an internal pressure of 15 psig. If any new design and construction guidance is specifically developed for pressure vessels in flammable and other highly hazardous chemicals service not exceeding an internal pressure of 15 psig, reference the design and construction guidance in the Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code (BPVC).

Key Engineering Lessons

  • A closed manway on a low-pressure process vessel must be designed, constructed, and pressure tested for the actual process pressure conditions, not only for documented normal operating pressure.
  • Mechanical integrity procedures for process vessels in highly hazardous chemicals service need explicit alteration guidance, inspection records, and pressure-testing expectations.
  • Prevention through design should be used so that a single human action, such as turning on an agitator, cannot set off an irreversible chain of events leading to a catastrophic explosion.
  • Interlocks or other engineering controls should prevent solvent addition when the agitator is off during batch operations.
  • Detection of flammable vapor releases should automatically trigger both audible and visual alarms so personnel can evacuate promptly.
  • Emergency preparedness must address flammable vapor cloud hazards, including prompt evacuation and worker response to alarms.
  • Flame-resistant clothing is a necessary protective measure in operating areas that process flammable chemicals.

Source Notes

  • Priority 1 final report used as primary authority for causes, sequence, consequences, and recommendations.
  • Priority 3 recommendation status summaries used to confirm recommendation statuses for R1-R7.
  • Supporting documents at Priority 4 contained no incident-specific causal or consequence information and were not used to override higher-priority sources.

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