Just after 3:00 pm on Saturday, October 11, 2008, a tank located in a storage building at the INDSPEC Chemical Corporation (INDSPEC) resorcinol facility in Petrolia, Pennsylvania, overflowed during an oleum transfer. Oleum, a mixture of sulfuric acid and sulfur trioxide, filled the exhaust ventilation system (vent system) connected to the tank and eventually released into the storage building. The release of oleum created a cloud of sulfuric acid mist that filled the building and flowed out of the facility into the community.

As the oleum storage tank overflowed, the storage building filled with a dense mist, and liquid oleum spilled from the vent system. Faced with an uncontrolled release, the INDSPEC incident commander declared a plant-wide emergency, notified local fire departments, and requested mutual aid services. Facility personnel evacuated.

While INDSPEC emergency responders managed the onsite incident, at 5:14 pm community emergency responders ordered the evacuation or shelter-in-place of about 2,500 nearby residents from the towns of Petrolia, Bruin, and Fairview. The evacuation order continued until about 2:00 am.

KEY ISSUES:
• TEMPORARY CHANGE EVALUATION
• SAFEGUARD EVALUATION
• PROCESS HAZARD ANALYSIS

ROOT CAUSES:
1. The facility did not evaluate the significance of a change to the emergency power supply.
2. The facility gave operators only verbal instruction on the use of the emergency power supply.
3. The oleum transfer work practice was never recorded in written operating procedures.
4. PHA teams were unable to evaluate the consequences of emergency power supply use.

Image credit: CSB