Contributory Factors: Loss of Process Control

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

The rupture of a 145-foot-tall distillation column (C-501) used to refine mononitrotoluene (MNT) caused the October 13, 2002, explosion and fire at the First Chemical Corporation (FCC) facility in Pascagoula, Mississippi. The column was thought to be isolated and in standby mode at the time of the explosion (approximately 5:25 am) though it contained a significant amount of MNT.

Debris from the explosion, including metal fragments and packing from the column, was scattered throughout the facility and propelled offsite. One large fragment of the distillation column punctured a nearby para-MNT storage tank and ignited its contents, which burned for almost 3 hours. A 6-ton column segment was hurled 1,100 feet and landed near a crude oil storage tank at a refinery across the highway. Flying glass injured three FCC employees, who were in the unit control room at the time of the explosion. All three employees received first-aid, and one required additional medical treatment.

The FCC fire brigade fought the onsite fires, including the large para-MNT storage tank fire and numerous fires initiated by burning material on ejected column packing. Local community emergency responders provided backup and firefighting support for numerous small fires outside the facility. The sheriff’s department provided traffic control. FCC personnel, the U.S. Environmental Protection Agency (EPA), and the U.S. Coast Guard monitored the air around the facility.

KEY ISSUES:
• EVALUATION OF REACTIVE HAZARDS
• APPLYING LESSONS LEARNED
• LAYERS OF PROTECTION
• WORK PRACTICES
• FACILITY SITING
• COMMUNITY NOTIFICATION

ROOT CAUSES:
1. The FCC Pascagoula facility did not have an adequate system for evaluating the hazards of processing mononitrotoluene (MNT) in its continuous process and did not apply lessons learned from hazard analyses conducted on similar processes in the plant.
2. FCC did not have a system to ensure that the #1 MNT column (C-501) was equipped with sufficient layers of protection to prevent a catastrophic release.
3. The Pascagoula facility had no effective system for ensuring consistent work practices when isolating equipment.
4. FCC did not have an adequate program to prevent leakage from isolation valves in the steam line connected to the #1 MNT column (C-501).

Image Credit: CSB

On the night of October 23, 2009, a large explosion occurred at the Caribbean Petroleum Corporation (CAPECO) facility in Bayamon, Puerto Rico, during offloading of gasoline from a tanker ship, the Cape Bruny, to the CAPECO tank farm onshore. A 5-million gallon aboveground storage tank (AST) overflowed into a secondary containment dike. The gasoline spray aerosolized, forming a large vapor cloud, which ignited after reaching an ignition source in the wastewater treatment (WWT) area of the facility. The blast and fire from multiple secondary explosions resulted in significant damage to 17 of the 48 petroleum storage tanks and other equipment onsite and in neighborhoods and businesses offsite. The fires burned for almost 60 hours. Petroleum products leaked into the soil, nearby wetlands and navigable waterways in the surrounding area.

KEY ISSUES:
• TANK OVERFILL PREVENTION
• COMMUNITY IMPACT
• HAZARD ASSESSMENT
• SAFETY MANAGEMENT SYSTEM
• REGULATION GAPS: NO RISK ASSESSMENT CONSIDERING PROXIMITY TO COMMUNITIES
• REGULATION GAPS: NO ADHERENCE TO RAGAGEP
• REGULATION GAPS: NO REDUNDANT OR INDEPENDENT SAFEGUARDS TO PREVENT OVERFILLING A TANK

ROOT CAUSES:
1. Deficient Management System.
2. Production Pressure.
3. Lack of reliable instruments:Level control failure due to inaccurate available volume calculation.
4. No high-level alarm to notify ship to stop transfer or divert flow.
5. No AOPS with ability to shut down or divert flow into tank.

Image credit: CSB

At 1:33 pm on December 19, 2007, a powerful explosion and subsequent chemical fire killed four employees and destroyed T2 Laboratories, Inc. (T2), a chemical manufacturer in Jacksonville, Florida. It injured 32, including four employees and 28 members of the public who were working in surrounding businesses. Debris from the reactor was found up to one mile away, and the explosion damaged buildings within one quarter mile of the facility.

On December 19, T2 was producing its 175th batch of methylcyclopentadienyl manganese tricarbonyl (MCMT). At 1:23 pm, the process operator had an outside operator call the owners to report a cooling problem and request they return to the site. Upon their return, one of the two owners went to the control room to assist. A few minutes later, at 1:33 pm, the reactor burst and its contents exploded, killing the owner and process operator who were in the control room and two outside operators who were exiting the reactor area.

KEY ISSUES:
• REACTIVE HAZARD RECOGNITION
• HAZARD EDUCATION
• EMERGENCY PREPAREDNESS
• PROCESS DESIGN & SCALE-UP

ROOT CAUSES:
• T2 did not recognize the runaway reaction hazard associated with the MCMT it was producing.

Image credit: CSB