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CAI / Arnel Chemical Plant Explosion

Overview

During the early morning hours of November 22, 2006, a powerful explosion and fire destroyed the CAI/Arnel ink and paint manufacturing facility in Danvers, Massachusetts. The incident damaged scores of nearby homes and businesses, some beyond repair, and a number of residents were hospitalized. There were no injuries in the plant, which was unoccupied at the time.

Incident Snapshot

Field Value
Facility / Company CAI, Inc. and Arnel Company, Inc.
Location Danvers, MA
Incident Date 11/22/2006
Investigation Status The CSB's final report was approved by a vote of the Board at a public meeting in Danvers, Massachusetts, on May 13, 2008.
Accident Type Community Impact Investigation
Final Report Release Date 05/13/2008

What Happened

  • On Tuesday afternoon, November 21, 2006, CAI employees began mixing a 2000-gallon ink vehicle batch in mix tank 3.
  • The CAI production manager opened the steam valve at about 3:00 pm to begin heating the mixture.
  • Shortly before 6:00 pm, the last CAI employee in the building turned off the dust collector fans, wall-mounted exhaust fans, and fresh air supply fan, then locked the building and left for the night.
  • During the early morning hours of November 22, 2006, a powerful explosion destroyed the CAI/Arnel ink and paint manufacturing facility in Danvers.
  • At 2:46 am on Wednesday, November 22, the fire department alarm signal began sounding.
  • A few seconds after the alarm began sounding, fire department personnel heard and felt an explosion.
  • The Danvers fire department launched a search-and-rescue operation and later extinguished the fire after it burned for more than 17 hours.

Facility and Process Context

  • CAI/Arnel ink and paint manufacturing facility in Danvers, Massachusetts.
  • CAI manufactured solvent-based inks and stored alcohols, heptane, other solvents, pigments, resin, and nitrocellulose in its Danvers facility.
  • Arnel manufactured solvent and water-based stains, lacquers, coatings, and paints, as well as polyurethane coatings and adhesives.
  • The facility was jointly operated by CAI, Inc. and Arnel Company, Inc.
  • The production area included mix tanks used for ink manufacturing.
  • The building ventilation system consisted of a fresh air distribution system and production area exhaust fans to remove flammable vapor from around the unsealed ink and paint mixers.
  • The facility stored flammable liquids in underground storage tanks and other storage tanks.
  • The facility was unoccupied at the time of the explosion.

Consequences

  • Fatalities: 0
  • Injuries: At least 10 residents required hospital treatment for cuts and bruises; minor injuries were reported from the community.
  • Environmental release: Thousands of gallons of solvent, paint and ink products, the building’s heating oil, and more than 50,000 pounds of nitrocellulose burned for many hours.
  • Facility damage: The explosion and fire destroyed the facility; the CAI/Arnel building was leveled. Nearby homes and businesses were heavily damaged, some beyond repair.
  • Operational impact: Twenty-four homes and six businesses were damaged beyond repair; dozens of boats at a nearby marina were heavily damaged; numerous residents could not return for many months.

Key Findings

Immediate Causes

  • The steam valve on the mix tank heater was inadvertently left open overnight.
  • High-temperature steam continued flowing through the heating jacket and heated the mixture to its boiling temperature.
  • The mix tanks were not equipped with automatic controls to prevent overheating the mixture when the process was unattended.
  • The flammable vapor accumulated within the building and was ignited by an unknown ignition source, causing the explosion.

Contributing Factors

  • The building ventilation system was turned off at night.
  • The vapor cloud accumulated and was confined inside the closed building.
  • The mix tank was not vented to a safe location outside of the building.
  • The mix tank had no alarms or indicators to alert the operator that the steam valve was open.
  • CAI did not prepare or use written procedures or checklists for daily activities involving the hazardous material.
  • The fire doors on the east and west walls of area E were open the night of the explosion.
  • The facility had congestion from process equipment, raw material storage racks and containers, and interior walls within the confined volume.
  • The fire department had not inspected the facility in more than four years.
  • The 2002 inspection did not identify several fire code compliance deficiencies involving flammable liquids storage.
  • The 2002 inspection did not identify that required permits had either expired or were never issued.

Organizational and Systemic Factors

  • CAI management did not conduct a process hazards analysis or similar systematic review to ensure that the flammable liquids processes were safely designed and operated.
  • CAI did not install or use automated process controls, alarms, or safeguards when heating flammable liquids in process equipment inside a closed building.
  • CAI did not maintain adequate building ventilation during all flammable liquids process operations.
  • CAI management did not use written procedures or checklists to ensure that flammable liquids manufacturing processes were operated safely.
  • CAI management did not recognize the increased risk of fire or explosion due to flammable vapor accumulation in the unventilated and unoccupied building.
  • The Massachusetts fire code did not require companies that handle flammable and combustible liquids to apply NFPA 30 or organic coatings manufacturers to apply NFPA 35.
  • The Massachusetts fire code did not specify a frequency for local fire department inspection of indoor flammable liquids storage areas.
  • Local authorities were unaware of the increase in quantities of flammable materials stored in the facility.
  • The town of Danvers did not have bylaws addressing the licensing process.
  • The town of Danvers did not have an active LEPC at the time of the incident.

Failed Safeguards or Barrier Breakdowns

  • automatic process controls
  • alarms
  • written procedures
  • checklists
  • building ventilation system
  • fire department-issued permits
  • local fire department inspection
  • foam fire suppression sprinkler system
  • automatic shutdown system
  • over-temperature alarm
  • venting to the outdoors
  • separate license and permit for each class of flammable material

Recommendations

  1. 2007-03-I-MA-R1 — Recipient: General Court of the Commonwealth of Massachusetts — Status: Open — Summary: Revise the General Laws of Massachusetts addressing flammable materials licensing and registration: As part of the annual registration renewal, require new and existing product manufacturing registrants to submit written certification to local governments stating that the facility complies with, at a minimum, all state and local fire codes and hazardous chemical regulations. Require all companies holding a license and current registration to apply for an amended license and re-register the facility before increasing any flammable material quantity above the licensed amount or adding a different regulated chemical. Include a requirement in the approval process to solicit input from affected landowners, similar to the requirement for obtaining the original license and registration.
  2. 2007-03-I-MA-R2 — Recipient: General Court of the Commonwealth of Massachusetts — Status: Closed – Acceptable Alternate Action — Summary: Amend the General Laws of Massachusetts to require the Office of the State Fire Marshal to audit local governments for compliance with the flammable materials licensing regulation and audit fire departments for compliance with permit issuance and inspection of manufacturing facilities licensed to store and handle flammable liquids and solids. The audits should be conducted at least once every five years.
  3. 2007-03-I-MA-R3 — Recipient: Commonwealth of Massachusetts Office of Public Safety, Department of Fire Services — Status: Closed – Acceptable Action — Summary: Incorporate the Flammable and Combustible Liquids Code (NFPA 30) and Standard for the Manufacture of Organic Coatings (NFPA 35) into the Massachusetts Board of Fire Prevention Regulations.
  4. 2007-03-I-MA-R4 — Recipient: Department of Fire Services (formerly the Massachusetts State Fire Marshal) — Status: Closed-Acceptable Action — Summary: Revise 527 CMR 14 to specify the maximum interval (such as annually) for local fire departments to conduct inspections of manufacturing facilities holding one or more licenses and permits to store and handle flammable materials.
  5. 2007-03-I-MA-R5 — Recipient: Department of Fire Services (formerly the Massachusetts State Fire Marshal) — Status: Closed-Acceptable Action — Summary: Develop mandatory written inspection criteria to be used by the local fire departments when performing manufacturing facility inspections. Develop inspection training material and provide training to the local fire departments.
  6. 2007-03-I-MA-R6 — Recipient: Department of Fire Services (formerly the Massachusetts State Fire Marshal) — Status: Closed-Acceptable Action — Summary: Revise the license and registration forms (FP-2 and FP-5) to require listing each hazardous material type and quantity. Identify the requirement that a separate license and permit are required for each of the eight classes of flammable material when the facility possesses more than the listed threshold quantity specified in 527 CMR 14.03 (2).
  7. 2007-3-I-MA-R2 — Recipient: Commonwealth of Massachusetts — Status: Closed – Acceptable Alternate Action — Summary: Amend the General Laws of Massachusetts to require the Office of the State Fire Marshal to audit local governments for compliance with the flammable materials licensing regulation and audit fire departments for compliance with permit issuance and inspection of manufacturing facilities licensed to store and handle flammable liquids and solids. The audits should be conducted at least once every five years.
  8. 2007-3-I-MA-R7 — Recipient: Town of Danvers — Status: Closed – No Longer Applicable — Summary: The Board voted to change the status of Recommendation No. 2007-3-I-MA-R7 to: “Closed – No Longer Applicable.”
  9. 2007-03-I-MA-R8 — Recipient: CAI, Inc. — Status: Open — Summary: Develop a written safety program to manage hazardous process operations. The program should: Prohibit heating flammable or combustible liquids above their flashpoints in tanks inside buildings unless the tanks are sealed and vented to the building exterior. Require safety controls to prevent overheating of flammable or combustible liquids. Apply the process safety management program elements as contained in the American Institute of Chemical Engineers (AIChE) Center for Chemical Process Safety (CCPS) Guidelines for Implementing Process Safety Management Systems to all processes that use flammable, toxic, or reactive chemicals. Comply with the following, as applicable: OSHA Flammable and Combustible Liquids standard (29 CFR 1910.106), OSHA Process Safety Management standard (29 CFR 1910.119), National Fire Protection Association Flammable and Combustible Liquids Code (NFPA 30), and National Fire Protection Association Standard for the Manufacture of Organic Coatings (NFPA 35).
  10. 2007-03-I-MA-R9 — Recipient: National Fire Protection Association — Status: Closed-Acceptable Action — Summary: Revise Flammable and Combustible Liquids Code (NFPA 30): Prohibit heating flammable and combustible liquids above their flashpoints in tanks inside buildings, unless the tanks are sealed and vented to the building exterior. Require heated tanks and vessels containing flammable and combustible liquids to have equipment to prevent overheating, such as devices to stop the heating process if the temperature exceeds the safe operating limits; devices to stop the heating process if the flammable vapor control equipment malfunctions (e.g., building ventilation system or heated tank vent); and a heating medium that is unable to heat the tank above safe operating temperatures.
  11. 2007-03-I-MA-R10 — Recipient: National Fire Protection Association — Status: Closed-Acceptable Action — Summary: Revise The Standard for the Manufacture of Organic Coatings (NFPA 35): Define equipment specifically discussed in the standard, such as kettles and thin-down tanks. Define the terms "open," "closed," and "sealed and vented." Prohibit heating flammable and combustible liquids above their flashpoints in tanks inside buildings unless the tanks are sealed and vented to the building exterior. Require heated tanks and vessels containing flammable and combustible liquids to have equipment to prevent overheating, such as devices to stop the heating process if the temperature exceeds the safe operating limits; devices to stop the heating process if the flammable vapor control equipment malfunctions (e.g., building ventilation system or heated tank vent); and a heating medium that is unable to heat the tank above safe operating temperatures.
  12. 2007-03-I-MA-R11 — Recipient: International Code Council (ICC) — Status: Closed – Unacceptable Action/No Response Received — Summary: Revise the International Fire Code: Chapter 20 specifically include “printing inks” in the definition of “organic coating.” Define equipment specifically discussed in the standard, such as open and closed kettles. Require heated tanks and vessels containing flammable and combustible liquids to have equipment to prevent overheating, such as devices to stop the heating process if the temperature exceeds the safe operating limits, devices to stop the heating process if the flammable vapor control equipment malfunctions (e.g., building ventilation system or heated tank vent), and a heating medium that is unable to heat the tank above safe operating temperatures. Chapters 20, 27, and 34: define “open,” “closed,” and “sealed and vented” process tanks; define “non-listed” process tanks; prohibit heating flammable and combustible liquids above their flashpoints in tanks inside buildings unless the tanks are sealed and vented to the building exterior.

Key Engineering Lessons

  • Do not rely on manual valve position alone to control heating of flammable liquids; provide automatic controls to prevent overheating when a process is unattended.
  • If flammable vapors can be generated, the process equipment should be vented to a safe location outside the building rather than allowed to accumulate indoors.
  • Building ventilation should not be turned off in a way that permits flammable vapor accumulation during flammable liquids processing.
  • Written procedures and checklists are needed for hazardous process operations to reduce the chance of human error such as leaving a steam valve open.
  • Inspection and licensing systems need to track the specific classes and quantities of flammable materials stored so that changes in inventory trigger re-licensing and inspection.

Source Notes

  • Priority 1 final report information was used where available and overrides lower-priority extracts in conflicts.
  • Recommendation status and regulatory follow-up details were consolidated from multiple recommendation status change summaries.
  • Some source documents used slightly different wording for the same event sequence; the consolidated dataset preserves the official terminology from the highest-priority source where possible.
  • The final report title and incident metadata identify the event as a community impact investigation in Danvers, MA on 11/22/2006.

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