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Technic Inc. Ventilation System Explosion

Overview

On February 7, 2003, at approximately 9:30 am, an explosion ignited a fire inside a vent collection system (VCS) at Technic Inc., a plating chemicals manufacturing and research facility in Cranston, Rhode Island. The CSB determined that a hammer blow likely initiated an explosive reaction of chemicals inside the duct. One employee was critically injured, eighteen other employees were transported for medical evaluation, the surrounding community was evacuated, and facility operations were interrupted for several weeks.

Incident Snapshot

Field Value
Facility / Company Technic Inc.
Location Cranston, RI
Incident Date 02/07/2003
Investigation Status The Board voted 5-0 to approve the final report on August 20, 2004.
Accident Type Chemical Manufacturing - Fire and Explosion Investigation
Final Report Release Date 08/20/2004

What Happened

  • On Friday, February 7, 2003, at approximately 9:30 am, an explosion ignited a fire inside a vent collection system (VCS) at Technic Inc.
  • According to witness testimony, the incident likely began when an employee—suspecting the plastic ventilation duct to be clogged—tapped on it with a small hammer.
  • An instant later—at approximately 9:30 am—the duct exploded, knocking him to the floor.
  • Subsequent to the explosion, a fire involving accumulated combustible materials broke out inside the main vent header duct.
  • The fire propagated through the main header duct to the branch ducts on mezzanine 1 and eventually consumed a plastic acid hood.
  • The administrative assistant called the CFD at approximately 9:34 am.
  • Employees evacuated to the guard station for a headcount.
  • Within 10 minutes of notification, CFD arrived on scene to find that the building’s sprinkler system was operating, and the fire was confined to the new addition.
  • The sprinkler system was turned off after some discussion among the firefighters, Technic management, and the Rhode Island Department of Environmental Management (RI–DEM) inspector because of concern that cyanide salt and acid might mix to form hydrogen cyanide, a toxic gas.
  • After testing the air for organic vapors, the CFD hazmat team entered the building and extinguished the smoldering fires inside the ventilation duct near the scrubber using portable extinguishers.
  • Eighteen Technic employees who may have been exposed to cyanide or other potentially toxic chemicals were decontaminated and transported to Rhode Island Hospital for medical evaluation.
  • The CFD incident commander directed the Cranston police to evacuate several businesses and residents downwind of the Technic plant.
  • One dozen residents were bused to the Cranston Recreation Center, 2 miles away, in accordance with evacuation plans previously developed by the Region 8 Local Emergency Planning Committee (LEPC).

Facility and Process Context

  • Technic is a privately owned plating chemical and equipment manufacturing company founded in the 1940s.
  • The Cranston facility employs 150 people, including several chemists.
  • The facility is located in a mixed residential/industrial neighborhood alongside Rhode Island Route 10.
  • The facility includes two buildings, one of which houses the corporate offices and main research laboratories (1 Spectacle Street); the other houses the plating chemical manufacturing processes and related laboratories (88 Spectacle Street).
  • The manufacturing building was expanded in 1990 to accommodate new production operations.
  • The vent collection system was installed in conjunction with a 1990 plant expansion.
  • The system consisted of interconnected polyvinyl chloride duct segments, gradually decreasing in diameter, suspended approximately 20 feet above the floor.
  • The purpose of the collection system was to transport vapors, gases, and mists emitted from various processes to a scrubber, in compliance with EPA air emission standards.
  • With the addition of vent ducts from over 20 process vessels from 1992 to 2003, the demand on the vent collection system increased significantly from the time of the plant expansion in 1990.
  • These additions were designed and installed without engineering analysis.
  • The minor source construction permit for the vent collection system included only the processes on mezzanine 2, the Kestner unit, the kettle room, the weigh room, and the metals reclaim areas.
  • Technic had made a number of significant changes to the ventilation system since its installation in 1992.
  • These modifications were not anticipated by the original design and construction permit and diminished the system’s performance capacity.
  • The vent collection system was designed to transport vapors, gases and mists from various processes to a scrubber, to be treated in accordance with EPA air emission standards.
  • Between 1992 and 2003, vent ducts from over twenty process vessels were added.
  • In addition, the vent collection system was used to collect dusts, which the initial design did not anticipate.
  • Maintenance personnel made modifications in-house without consulting a ventilation design engineer or similar expert and without applying best practice guidelines.

Consequences

  • Fatalities: None reported.
  • Injuries: One employee was critically injured. Eighteen other employees were transported to Rhode Island Hospital for medical evaluation. The injured employee suffered permanent eye damage and chemical burns to his face and upper body. He also suffered lacerations to his face, respiratory tract irritation, and a broken finger. He remained in the hospital for 14 days and was discharged with diminished sight in both eyes.
  • Environmental Release: None reported.
  • Facility Damage: The vent collection system was severely damaged. The effects of the explosion and fire were largely confined to the vent collection system, with minor damage to connected equipment (acid hood, vent hood, scrubber). The 4-inch-dia vertical duct connected to tank 8 fractured and shattered. The 10-inch-dia overhead horizontal branch duct connecting tanks 5, 6, and 7 had a large crack at main header connection and sharp fractures where vertical ducts were attached. The main header duct separated and collapsed. The plastic acid hood and its contents were totally destroyed by fire. Fifty feet of duct melted and collapsed.
  • Operational Impact: Plant operations were interrupted for several weeks. The surrounding community was evacuated.

Key Findings

Immediate Causes

  • The CSB determined that the hammer blow likely initiated an explosive reaction of chemicals inside the duct.
  • The explosion and fire were caused by a violent chemical reaction inside the vent collection system, which was likely initiated when the employee tapped on a duct with a small hammer.
  • The incident was likely caused by a chemical reaction inside the vent collection system which started when an employee tapped with a small hammer on a duct that sounded blocked.

Contributing Factors

  • Neither Technic nor CFD adequately planned for this type of emergency.
  • Technic did not have process and equipment integrity procedures or training to inspect or maintain the vent collection system.
  • Technic did not identify and evaluate the hazards created by changes to facility processes and equipment (i.e., management of change).
  • Technic did not conduct a process safety review to identify and evaluate the hazards associated with installing a vent collection system to handle the exhaust from multiple processes.
  • The vent collection system had no inspection ports or cleanout doors.
  • It had not been cleaned since 1996.
  • The system was not designed with enough velocity to transport dusts generated in the weigh room to the scrubber; it was designed only for gases, vapors, and mists.
  • The baghouse created a drag on the system; by removing it, they expected the capture velocity to improve enough to reduce employee exposure to within acceptable limits.
  • The vent collection system also collected dusts, although not accounted for in its design.
  • The system did not provide capacity for processes that were added at a later date.
  • The 10-inch branch duct connected to the acid hood on mezzanine 1 did not have sprinklers.
  • Technic did not evaluate the potential hazards of exhausts from multiple processes interacting in the VCS during its design.
  • Technic did not evaluate the potential impact of a number of significant changes made to the VCS over several years.
  • Those changes diminished transport velocity and allowed substances from a variety of different processes to accumulate inside the system.
  • The manual did not specifically recommend consideration of potential incompatibilities between materials that could interact in a ventilation system.
  • NFPA 91 specifically prohibited incompatible materials from being mixed in exhaust ducts (see Section 4.2.2), but it did not reference appropriate methods for evaluating chemical compatibility, such as ASTM International’s Standard Guide for the Preparation of a Binary Chemical Compatibility Chart (E2012).
  • The absence of a formal program for inspection and preventive maintenance of the vent collection system.
  • Deficiencies in the facility’s emergency action plan.
  • Delays and miscommunication during the emergency response to the incident.

Organizational and Systemic Factors

  • Technic did not conduct a process safety review as a part of the engineering process to identify and evaluate the hazards associated with installing a vent collection system to handle the exhausts from multiple processes.
  • Technic did not identify and evaluate the hazards created by changes to facility processes and equipment (i.e., management of change).
  • Technic did not have process and equipment integrity procedures or training to inspect or maintain the vent collection system.
  • Neither Technic nor the Cranston Fire Department (CFD) adequately planned for this type of emergency.
  • Technic maintenance personnel modified the vent collection system without applying good engineering practices.
  • Technic did not take advantage of the expertise and engineering review services of its loss prevention insurer.
  • There was no system in place that required the review.
  • Technic had no established inspection, cleaning, or maintenance program for the vent collection system.
  • The emergency plan Technic provided to CFD did not include key facility information, and CFD was not familiar with the facility or its managers.
  • Neither Technic nor CFD had ever conducted a chemical release exercise.
  • The CSB identified failures within Technic’s safety management system as the underlying cause of the incident.
  • There were no formal procedures for conducting a process safety review.
  • There was no formal system for evaluating changes to a process (i.e., a Management of Change procedure).
  • Maintenance personnel made these modifications in-house without consulting a ventilation design engineer or similar expert and without applying best practice guidelines.

Failed Safeguards or Barrier Breakdowns

  • The vent collection system had no inspection ports or cleanout doors.
  • It had not been cleaned since 1996.
  • The emergency plan did not describe the exact quantities and locations of cyanides and acids, or the provisions taken by Technic to safeguard them.
  • The emergency plan did not outline important roles and responsibilities.
  • Technic did not have a fire brigade, or the requisite equipment or training to carry out its functions.
  • Technic personnel were trained only in the use of portable fire extinguishers to put out incident stage fires.
  • The procedures for the use of SCBA in firefighting situations were not followed.
  • The system was not designed with enough velocity to transport dusts generated in the weigh room to the scrubber; it was designed only for gases, vapors, and mists.
  • The baghouse created a drag on the system; by removing it, they expected the capture velocity to improve enough to reduce employee exposure to within acceptable limits.
  • The vent collection system also collected dusts, although not accounted for in its design.
  • The system did not provide capacity for processes that were added at a later date.
  • The 10-inch branch duct connected to the acid hood on mezzanine 1 did not have sprinklers.
  • formal process safety review procedures
  • process hazard analysis
  • reactive chemical hazard evaluation
  • design evaluation consistent with applicable codes and standards
  • management-of-change program
  • reviews for any proposed changes to the vent collection system and its connected processes
  • NFPA 91 did not reference appropriate methods for evaluating chemical compatibility, such as ASTM International’s Standard Guide for the Preparation of a Binary Chemical Compatibility Chart (E2012).

Recommendations

  1. 2003-08-I-RI-R1 | Recipient: Technic Inc. | Status: Closed- Unacceptable Action | As a part of the engineering process, implement formal process safety review procedures for projects involving chemical processes—including the vent collection system. Incorporate a process hazard analysis, reactive chemical hazard evaluation, and design evaluation consistent with applicable codes and standards.
  2. 2003-08-I-RI-R2 | Recipient: Technic Inc. | Status: Closed- Unacceptable Action | Implement a management-of-change program and ensure that reviews are conducted for any proposed changes to the vent collection system and its connected processes.
  3. 2003-08-I-RI-R3 | Recipient: Technic Inc. | Status: Closed-Acceptable Action | Implement a preventive maintenance program for the vent collection system that includes regular inspection, training and troubleshooting.
  4. 2003-08-I-RI-R4 | Recipient: Technic Inc. | Status: Closed-Acceptable Action | Work with the Cranston Fire Department to improve the facility's emergency response plan, including emergency response procedures and interface with the surrounding community. Submit the plan to the fire department for review.
  5. 2003-08-I-RI-R5 | Recipient: National Fire Protection Association (NFPA) | Status: Closed – Acceptable Action | Revise the appendix of NFPA 91, Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids, emphasizing the need to evaluate potential incompatibilities when dusts, fumes, or vapors are intermixed in vent collection systems to ensure that they do not result in fire or explosion hazards, or destructive corrosion. Reference appropriate methods for such evaluations, such as the ASTM E 2012-00 standard.
  6. 2003-08-I-RI-R6 | Recipient: American Industrial Hygiene Association (AIHA) | Status: | Revise the appendix of ANSI Z9.2, American National Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, emphasizing the need to evaluate potential incompatibilities when dusts, fumes, or vapors are intermixed in local exhaust ventilation systems with common headers to ensure that they do not result in fire or explosion hazards, or destructive corrosion. Reference appropriate methods for such evaluations, such as the ASTM E 2012-00 standard.
  7. 2003-08-I-RI-R7 | Recipient: American Conference of Governmental Industrial Hygienists (ACGIH) | Status: Closed- Acceptable Action | Update the preliminary steps in the chapter on exhaust system design in the next revision of the Industrial Ventilation Manual, emphasizing the need to evaluate potential incompatibilities between dusts, fumes or vapors that are likely to be intermixed in main header ducts of a ventilation system to ensure that they do not result in fire or explosion hazards, or destructive corrosion. Reference appropriate methods for such evaluation, such as the ASTM E 2012-00 standard.

Key Engineering Lessons

  • Vent collection systems handling exhaust from multiple processes require formal process safety review, including process hazard analysis, reactive chemical hazard evaluation, and design evaluation consistent with applicable codes and standards.
  • Management of change is necessary when vent collection systems and connected processes are modified over time, because added ducts and process changes can diminish transport velocity and allow accumulation of reactive materials.
  • Ventilation systems should be evaluated for potential incompatibilities when dusts, fumes, or vapors are intermixed in common headers or exhaust ducts.
  • Preventive maintenance programs for vent collection systems should include regular inspection, training, and troubleshooting.
  • Emergency response planning should include key facility information, defined roles and responsibilities, and coordination with the local fire department and surrounding community.

Source Notes

  • Priority 1 final report facts were used to resolve conflicts where later recommendation-status documents differed in detail or completeness.
  • Priority 3 recommendation-status documents were used to supplement recommendation statuses and later implementation details.
  • Official terminology from the source documents was preserved where possible, including 'vent collection system (VCS)', 'management-of-change', and 'Closed- Acceptable Action'.

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