CTA Report, Draft 1, ISP Review - US Chemical Safety and Hazard ...

the possibility of an explosion or fire damaging other portions of the plant. To control dust accumulation,
this version of the standard recommended that:
• Horizontal surfaces be minimized by having their tops sharply inclined, or by “boxing” in
steel I-beams or similar structural shapes.
• Buildings be equipped with explosion venting.
Combustible dust-handling operations at the Corbin facility were not detached. Two-hour-rated masonry
block firewalls—not physical barriers designed to withstand fire and explosion hazards—partially
segregated these operations from surrounding storage and maintenance areas. In addition, the facility did
not minimize horizontal surfaces, I-beams and open web roof trusses were not boxed, and no explosion
venting was provided.
CTA did not follow the more recent editions of NFPA 654 when modifications were made to the blend
rooms (1992) or when firewalls were removed separating the production area from the finished goods
area (2002). At the time of the incident, the building contained numerous elevated, hard-to-clean
horizontal flat surfaces—such as tops of process pipes, sprinkler pipes, electrical conduits, and cable
trays. These surfaces allowed the accumulation of substantial combustible dust, which provided fuel for
the fire and explosions. Minimization of flat surfaces likely would have prevented accumulation of
combustible dust and eliminated it as a source of fuel for the fire and explosions.
Lack of effective firewalls at CTA allowed the fire to spread beyond line 405. Proper placement of
firewalls around the production area could have prevented the spread of the fire to the raw material
storage and maintenance areas. Some existing firewalls were knocked down in the explosions. Use of
blast-resistant physical barriers designed to withstand deflagration and use of deflagration venting to a
safe outside location could have minimized the spread of explosive forces (Appendix D.2.3).
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