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Public Meeting November 22, 2006 Explosion at CAI/Arnel in Danvers, Massachusetts May 9, 2007 PowerPoint Presentation
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Public Meeting November 22, 2006 Explosion at CAI/Arnel in Danvers, Massachusetts May 9, 2007. Investigation Team. John Vorderbrueggen, PE Johnnie Banks, CFEI Angela Blair, PE Robert Hall, PE Katherine Leskin Jeffrey Wanko, PE, CSP. Meeting Agenda. Incident Summary

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Public Meeting November 22, 2006 Explosion at CAI/Arnel in Danvers, Massachusetts May 9, 2007

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Public MeetingNovember 22, 2006 Explosion at CAI/Arnel inDanvers, MassachusettsMay 9, 2007

investigation team
Investigation Team
  • John Vorderbrueggen, PE
  • Johnnie Banks, CFEI
  • Angela Blair, PE
  • Robert Hall, PE
  • Katherine Leskin
  • Jeffrey Wanko, PE, CSP
meeting agenda
Meeting Agenda
  • Incident Summary
  • Investigation Activities
  • Companies Involved
  • Preliminary Findings
  • Board Questions
  • Public Comment


Google Earth

emergency response
Emergency Response
  • Danvers fire and police departments
  • Salem, Peabody, Beverly, and other fire and police departments
  • Massachusetts Environmental Police
  • U.S. EPA
  • U.S. Coast Guard
emergency response8
Emergency Response
  • U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives
  • Massachusetts Department of Environmental Protection
  • Massachusetts State Fire Marshal
  • Massachusetts State Police
community impact
Community Impact
  • Ten treated at hospital for lacerations and bruises
  • Multiple homes and two adjacent businesses damaged beyond repair
  • Structural damage to homes and businesses as far as 1/4 mile
  • Window breakage as far as one mile
  • Dozens of boats at marina damaged
community impact14
Community Impact
  • About 300 residents were evacuated
  • 77 families originally displaced
  • 50 families still unable to return home
  • 16 homes razed, more expected
  • Two nearby businesses destroyed
  • Five nearby businesses heavily damaged
investigation activities
Investigation Activities
  • Interviews and discussions
    • CAI and Arnel employees
    • CAI electrical contractor
    • Contractor working at Abbey Fence
    • Maritimes and Northeast Pipeline
    • KeySpan (natural gas utility)
investigation activities18
Investigation Activities
  • Local residents
  • Local businesses
  • Town of Danvers
    • Town Manager
    • Police and Fire departments
    • Department of Code Administration
    • Public Health department
investigation activities19
Investigation Activities
  • Documentation
    • CAI and Arnel
    • Duke Energy and KeySpan
    • Town of Danvers
    • Raw materials suppliers
    • EPA remediation records
    • State regulations
investigation activities20
Investigation Activities
  • Photographs
    • Community
    • CAI/Arnel Facility
    • Township fire and police photos
    • Aerial photos
investigation activities21
Investigation Activities
  • Evidence Collection/Review
    • Facility equipment
    • Raw material chemical samples
    • Liquid/solid material samples
    • Fragments from the CAI/Arnel building found in the community
  • Explosion dynamics modeling
  • Chemical testing
companies involved
Companies Involved
  • Building constructed in early 1900’s
  • 1985 - Danvers Chemical divided
    • CAI, Inc.
    • Arnel Company, Inc.
cai inc
CAI, Inc.
  • Private company operated since 1985
  • Headquartered in Georgetown, MA
  • 25 employees
  • Manufacture water and solvent based printing inks
cai inc24
CAI, Inc.
  • Georgetown facility
    • Administration, marketing, sales
    • Water based ink manufacturing
    • Product warehousing and shipping
  • Danvers facility
    • Solvent-based ink manufacturing
    • Daily production shipped to Georgetown
arnel company inc
Arnel Company, Inc.
  • Operated in Danvers facility since 1985
  • Nine employees
  • Products
    • Solvent-based stains, lacquers, coatings, and paints
    • Polyurethane coatings and adhesives
    • Water based urethane coatings

Covered outside storage

1100 sq. ft.

1200 sq. ft.

5100 sq. ft.


Offices, labs, restrooms

4000 sq. ft.

cai hazardous materials handling
CAI Hazardous Materials Handling
  • Flammable solvents
    • Three underground storage tanks
    • Four 3000-gallon production mix tanks
    • Eight 500-gallon containers (totes)
    • Several ink product mixers
    • Many 55-gallon drums and small containers
cai hazardous materials handling28
CAI Hazardous Materials Handling
  • Flammable solid (nitrocellulose)

~150 fiber drums stored in truck-trailer

  • Fuel oil tanks

Relocated from courtyard into the building one week before explosion

Photo: ICI Nobel Enterprises



5100 sq ft

arnel hazardous materials handling
Arnel Hazardous Materials Handling
  • Flammable solvents
    • Underground storage tanks
    • 1000-gallon product mixer
    • Two 300-gallon totes
    • Several paint product mixers
    • Many 55-gallon drums and small containers
arnel hazardous materials handling32
Arnel Hazardous Materials Handling
  • Flammable solid (nitrocellulose)

14 drums in truck-trailer


CAI equipment

1200 sq ft


1100 sq ft

fuel sources considered
Fuel Sources Considered
  • Nitrocellulose
  • Fuel oil
  • Natural gas
    • High-pressure pipeline
    • Low-pressure city gas system
  • Flammable liquids
  • Industrial grade
    • Flammable solid
    • Fiber drums stored in trailers, not in the building
    • Drums burned in place
fuel oil
Fuel Oil
  • Located in isolated, closed section of building
  • Tanks intact after explosion
  • No mechanism to form flammable vapor cloud
natural gas
Natural Gas
  • Lighter-than-air gas
  • Rises when released
  • Odorized for public safety
  • CAI/Arnel did not have gas service
  • Two sources in Danversport
    • Maritimes and Northeast Pipeline
    • KeySpan city gas system
maritimes and northeast pipeline
Maritimes and Northeast Pipeline
  • 215 feet south of CAI/Arnel
  • 1440 psi Maximum Allowable Operating Pressure (MAOP)
  • 30-inch diameter
  • 0.618 inch wall thickness
  • Welded carbon steel construction
  • Four years old
  • Odorized
maritimes and northeast pipeline41
Maritimes and Northeast Pipeline
  • High-pressure leak would escape very close to the buried pipe
maritimes and northeast pipeline42
Maritimes and Northeast Pipeline
  • No “conduit” to travel underground to building 215 feet away
  • No post-explosion natural gas fire or leak
keyspan gas system
KeySpan Gas System
  • Not connected to CAI/Arnel
  • Not connected to nearby Abbey Fence or Danversport Bottle Gas
  • 150-200 feet away, on Water and Bates streets
  • Very low pressure (0.36 psi)
  • Odorized
keyspan gas system44
KeySpan Gas System
  • 90+ years old
  • Cast iron pipe
  • “Bell and spigot” joints
keyspan gas system46
KeySpan Gas System
  • Explosion caused many leaks
  • Leaks after the incident were too small
  • No natural gas fires during or after the incident
csb blast modeling
CSB Blast Modeling
  • Neighborhood damage surveyed and quantified
  • Overpressures estimated
  • Compare to available explosion energy to natural gas

2.3 psi

365 ft

1.2 psi

581 ft

csb blast modeling50
CSB Blast Modeling
  • Fuel accumulation in production area (volume ~ 110,000 cubic feet)
  • Estimate explosion energy in the explosive range
  • Compare explosion energy estimates to observed community damage
csb blast modeling51
CSB Blast Modeling
  • Maximum blast energy from natural gas is not sufficient to cause observed damage
flammable solvents
Flammable Solvents
  • Scenarios
    • Large leak from solvent-filled storage container
    • Solvent-filled process tank overheating
large leak from storage container
Large Leak From Storage Container
  • Tote or drum leak spreads along production area floor
  • Vapor cloud accumulates above liquid pool
  • Unknown ignition source explosively ignites the vapor cloud
process tank overheating
Process Tank Overheating
  • Steam continues to heat liquid mixture in process tank
  • Highly volatile flammable solvent vaporizes
  • Vapor accumulates on building floor
  • Unknown ignition source explosively ignites the vapor cloud
november 21 st solvent processing
November 21stSolvent Processing
  • Arnel
    • 1000-gallon mixer was empty
    • Small batch quantities in other equipment
    • No process heating
    • No overnight processing
november 21st solvent processing
November 21st Solvent Processing
  • CAI
    • 2000-gallon batch mixed in unsealed tank
    • Batch heated to dissolve resin in heptane and alcohols
    • Tank mixer operated overnight
process tank overheating60
Process Tank Overheating
  • Three ways to overheat the tank
    • Steam valves left open
    • Steam valves not fully closed
    • Steam valves leak
fire and explosion prevention
Fire and Explosion Prevention
  • OSHA 29 CFR 1910.106

Flammable and Combustible Liquids

  • Massachusetts Board of Fire Prevention Regulations

Flammable and Combustible Liquids, Flammable Solids (527 CMR 14)

  • National Fire Protection Association

NFPA 30 Flammable and Combustible Liquids Code

the osha standard
The OSHA Standard
  • Building ventilation requirements
    • Acceptable minimum ventilation rate: One cubic foot / minute / square foot
    • Local ventilation must limit flammable atmospheres to within five feet of open process equipment
preliminary findings
Preliminary Findings
  • Manufacturing area ventilation most likely inadequate
  • Local ventilation only used when adding dry material
  • Building ventilation was turned off at night (including night of the incident)
    • Minimize noise
    • Minimize building heat loss
fire and explosion prevention practices
Fire and Explosion Prevention Practices
  • Flammable liquids handling
    • Automated temperature controls on process equipment
    • High-temperature shutdown/alarm
    • Sealed process equipment
  • None in place at the facility
massachusetts fire regulations
Massachusetts Fire Regulations
  • Flammable liquids storage inside building
    • Must be vented to building exterior
    • Approved self-closing valve required
    • Gravity draining prohibited
    • Fire-resistant pipe materials required
    • Permit and license required
  • None in place at facility
  • Available energy from the optimum quantity of natural gas inside the building could not generate explosion overpressures sufficient to cause the damage observed in the community
  • No evidence of natural gas leak that could provide enough gas to destroy the CAI/Arnel building
  • The industrial-grade nitrocellulose did not explode – it burned inside the storage trailers
  • Boiler fuel oil did not cause the explosion
  • Flammable vapor from highly volatile heptane and alcohol solvents was the only material capable of fueling the explosion that caused widespread community damage
continuing investigative activities
Continuing Investigative Activities
  • Sufficiency of flammable liquids fire prevention standards
    • Automated controls, alarms
    • Unsealed containers
continuing investigative activities70
Continuing Investigative Activities
  • Urban planning and land use near hazardous chemical manufacturing facilities
  • Guidance provided in the Massachusetts fire regulations to the local fire departments
    • Hazardous materials permits, licenses, and inspections

U.S. Chemical Safety Board

2175 K St. NW Suite 400

Washington, DC 20037