This incident occurred at Synthron, LLC’s Morganton, North Carolina, facility. The company manufactured a variety of powder coating and paint additives by polymerizing acrylic monomers in a 1,500 gallon reactor.

The company had received an order for slightly more of an additive than the normal size recipe would produce. Plant managers scaled up the recipe to produce the required larger amount of polymer, and added all of the additional monomer needed into the initial charge to the reactor. This more than doubled the rate of energy release in the reactor, exceeding the cooling capacity of the reactor condenser and causing a runaway reaction.

The reactor pressure increased rapidly. Solvent vapors vented from the reactor’s manway, forming a flammable cloud inside the building. The vapors found an ignition source, and the resulting explosion killed one worker and injured 14. The blast destroyed the facility and damaged off-site structures.

KEY ISSUES:
• REACTIVE HAZARDS & SAFEGUARDS
• CORPORATE OVERSIGHT
• SAFE OPERATING LIMITS
• EVACUATION PLANNING & DRILLS

ROOT CAUSES:
1. A lack of hazard recognition.
2. Poorly documented process safety information & ineffective control of product recipe changes.
3. Lack of automatic safeguards to prevent or mitigate the effects of loss of control over the reaction.
4. Improper manway bolting practices and poor operator training.
5. Inadequate emergency plans drills.
6. Inadequate corporate oversight of process safety.

Image credit: CSB