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Universal Form Clamp Co. Explosion and Fire

Overview

Mixing and heating a flammable liquid in an open top tank at Universal Form Clamp, Inc. in Bellwood, Illinois. The incident involved a vapor cloud ignition during heating and mixing operations, resulting in an explosion and fire. The final report identified key issues including flammable liquid process design, engineering controls, plan review and code enforcement, and emergency preparedness.

Incident Snapshot

Field Value
Facility / Company Universal Form Clamp, Inc.
Location Bellwood, IL
Incident Date 06/14/2006
Investigation Status The CSB's final report was issued at a news conference in Chicago on April 10, 2007.
Accident Type Flammable Vapor Investigation Status: The CSB's final report was issued at a news conference in Chicago on April 10, 2007. One fatality and five injuries resulted from an explosion and fire in a mixing room at the Universal Form Clamp facility. Workers were heating and mixing flammable solvents in an open top tank. During the heating process, there was a sudden evolution of flammable vapors that ignited, resulting in the explosion and fire.
Final Report Release Date 04/10/2007

What Happened

  • On the morning of June 14, 2006, an operator was mixing and heating a flammable mixture of heptane and mineral spirits in a 2,200-gallon open top tank equipped with steam coils.
  • As the operator was adding an ingredient to the batch, he observed a "dense fog" accumulating on the floor below the tank.
  • He immediately notified a senior operator who helped him shut down the operation.
  • They both exited the building and advised workers in adjoining areas to leave.
  • As the vapor cloud spread throughout the mixing area and surrounding workspaces, other employees exited the building.
  • Within about 10 minutes after the operator first observed the vapor cloud, most employees who were working in the area had evacuated.
  • A contracted delivery driver passed some of these employees as he walked into the building and into the spreading vapor cloud.
  • The cloud ignited within seconds of him entering.
  • The pressure created by the ignition blew the doors open to an adjacent area, injuring a temporary employee.
  • The Bellwood Fire Department battled a fire confined to a bagged resin storage area for about three and one-half hours.
  • The fire and pressure from the initial ignition produced moderate damage to the structure and interrupted operations for nearly one month.
  • UFC suspended the flammable liquid mixing operation indefinitely.

Facility and Process Context

  • The incident occurred at the Universal Form Clamp (UFC) facility in Bellwood, Illinois, a suburb of Chicago.
  • UFC manufactures and distributes approximately 3,000 products for the concrete industry.
  • The company has 450 employees at its eleven North American locations.
  • UFC added the chemical mixing area during 2002 and 2003 to produce concrete chemicals, including Super Clean and Tilt.
  • According to company officials, Bellwood was the only UFC facility that mixed and heated flammable liquids.
  • The mixing room was designed to meet the requirements of 1910.307, but the adjacent area where the vapor cloud migrated and likely ignited, was not.
  • The UFC facility was subject to the requirements of the OSHA Process Safety Management standard, 29 CFR 1910.119 at the time of the incident.

Consequences

  • Fatalities: One contractor was killed.
  • Injuries: Two employees were injured, one seriously. The temporary employee suffered second-degree burns and was hospitalized for three days. A third employee suffered a minor injury to his arm when he tripped and fell while evacuating. The status page states one worker died and five others were injured.
  • Environmental Release: Not reported.
  • Facility Damage: The fire and pressure from the initial ignition produced moderate damage to the structure; the status page describes an explosion and fire.
  • Operational Impact: The incident interrupted operations for nearly one month. UFC suspended the flammable liquid mixing operation indefinitely. The facility suffered a significant business interruption.

Key Findings

Immediate Causes

  • ignition of a vapor cloud generated by mixing and heating a flammable liquid in an open top tank without adequate safety controls
  • The temperature controller malfunctioned, allowing the steam valve to remain open and heat the mixture to its boiling point.
  • The boiling mixture produced a heavy, flammable vapor.
  • The vapor cloud spread into adjacent areas where it was ignited by one of several possible ignition sources.
  • there was a sudden evolution of flammable vapors that ignited

Contributing Factors

  • The temperature-sensing bulb and thermometer well housing (thermowell) did not conform to the manufacturer’s specifications.
  • The thermowell, designed to be filled with thermal conductive fluid, was dry, and parts designed to hold the bulb in place were missing.
  • The bulb was not fully inserted into the well.
  • There was a restrictive bend in the liquid-filled capillary tube connecting the sensing bulb to the temperature controller.
  • UFC did not filter oil or remove moisture from the "plant air" flowing through the temperature controller.
  • The mixing tank was not equipped with a temperature display or high temperature alarm, and there was no backup shutoff device.
  • The local exhaust system was incapable of controlling vapors released from the tank because both exhaust fan drive belts were broken before the incident and it was not designed to capture and remove a high volume of vapors from an open top tank.
  • The area ventilation system was incapable of removing tank vapors because there were no floor level exhaust registers (floor sweeps) and the exhaust registers were located at ceiling level and a significant distance from the top of the tank.
  • The process was not designed and constructed in accordance with fire safety codes and OSHA regulations.
  • Mechanical design plans that should have illustrated ventilation and other safety systems were not stamped or reviewed by a registered design professional before being submitted to the Village of Bellwood.
  • The Village Fire Department required UFC to install a fire suppression system, but did not require UFC to comply with other critical safety requirements outlined in BOCA (1990) and NFPA 30.
  • workers were heating and mixing flammable solvents in an open top tank in the mixing room

Organizational and Systemic Factors

  • UFC hired a professional chemist with concrete chemical production experience to manage the design, construction, and operation of the chemical mixing area.
  • Shortly after his arrival he hired two engineers through a temporary service to work on the construction planning.
  • They reported directly to him, and it was their responsibility to draft the plans for the building permit application.
  • Facility managers did not follow regulatory requirements or good engineering practices.
  • At the time of the incident, UFC had not implemented a program to comply with the Process Safety Management standard.
  • UFC had no emergency action plan, employees had not received emergency action training and had not conducted an evacuation drill, and the facility was not equipped with an employee alarm system.
  • UFC had not trained its employees on actions to take in response to a hazardous substance release.
  • UFC had not conducted required employee training for portable fire extinguishers.
  • the Flammable and Combustible Liquids standard covers technical issues pertaining to facility design, but does not contain a requirement for these facilities to have Emergency Action Plans
  • OSHA stated that its web-based guidance material assists employers in determining when drills may be beneficial

Failed Safeguards or Barrier Breakdowns

  • local exhaust ventilation
  • high temperature alarm
  • backup steam shutoff
  • floor level ventilation
  • temperature display
  • backup shutoff device
  • employee alarm system
  • emergency action plan
  • emergency action training
  • evacuation drill
  • Process Hazard Analysis (PHA)
  • Mechanical Integrity
  • Emergency Planning and Response
  • portable fire extinguisher training

Recommendations

  1. 2007-08-I-IL-R1 | Recipient: Occupational Safety and Health Administration | Status: Not specified | Amend 1910.106 Flammable and Combustible Liquids to require facilities that handle flammable and combustible liquids to implement the requirements of 1910.38 Emergency Action Plans.
  2. 2007-08-I-IL-R2 | Recipient: Occupational Safety and Health Administration | Status: Not specified | Amend 1910.38 Emergency Action Plans to require employers to conduct practice evacuation drills at least annually, but more frequently if necessary to ensure employees are prepared for emergencies.
  3. CSB Recommendation No. 2006-8-I-IL-R1 | Recipient: Occupational Safety & Health Administration (OSHA) | Status: Closed – Reconsidered/Superseded | Amend 1910.106 Flammable and Combustible Liquids to require facilities that handle flammable and combustible liquids to implement the requirements of 1910.38 Emergency Action Plans.
  4. CSB Recommendation No. 2006-8-I-IL-R2 | Recipient: Occupational Safety & Health Administration (OSHA) | Status: Closed – Reconsidered/Superseded | Amend 1910.38 Emergency Action Plans to require employers to conduct practice evacuation drills at least annually, but more frequently if necessary to ensure employees are prepared for emergencies.

Key Engineering Lessons

  • Open top tanks used for heating flammable liquids require effective temperature control with reliable sensing, alarm, and backup shutoff features.
  • Temperature-sensing components must conform to manufacturer specifications and be properly installed to ensure the controller functions as intended.
  • Local exhaust and area ventilation must be designed to capture and remove vapors from the actual release location, including low-level vapor migration from open tanks.
  • Engineering design plans for flammable liquid processes should be reviewed and stamped by a registered design professional before submission for permitting.
  • Safety systems for flammable liquid operations must address both the process area and adjacent spaces where vapor clouds can migrate and ignite.

Source Notes

  • Priority 1 final report used as the primary authority for incident facts, causes, safeguards, and recommendations.
  • Priority 4 status page used only to supplement recommendation status and to note the later CSB status change.
  • Where the sources differed on casualty counts, the final report's casualty description was retained as higher priority.

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