Runaway Chemical Reaction
Synthron Inc. Runaway Polymerization Reaction
Synthron, Inc.
📍 Morganton, NC
Incident: February 2, 2007 • CSB Report: 2008
1
Fatalities
14 (workers and first responders)
Injuries / Affected
Acrylic Resin Emulsion (Runaway Exothermic Polymerization Reaction — Loss of Coo
Chemical Involved
3
CSB Recommendations
📋 Incident Summary

On February 2, 2007, one worker was killed and 14 others — including workers and first responders — were injured when a runaway polymerization reaction caused an explosion at the Synthron Inc. specialty coatings manufacturer in Morganton, North Carolina. Synthron produced acrylic polymer emulsions used in coatings, adhesives, and paper treatment applications.

The runaway reaction occurred in a large batch polymerization reactor. The reaction began generating heat faster than the cooling system could remove it, and the temperature rose beyond control. The uncontrolled exotherm caused the reactor pressure to build until the vessel ruptured catastrophically, releasing the contents and causing the explosion that injured workers and first responders.

The CSB found that Synthron had not conducted an adequate reactive hazard assessment for the polymerization reaction. The company did not know that a cooling failure during the reaction could lead to a runaway exotherm. The reactor was not equipped with emergency cooling or a dump system, and operating procedures did not address the response to a developing runaway temperature excursion.

🔎 Key Findings
Finding 01
Runaway Polymerization Caused Reactor Pressure to Build — Vessel Ruptured
The exothermic polymerization reaction generated heat faster than the cooling system could remove, causing temperature to rise uncontrollably. The resulting pressure increase caused the reactor to rupture catastrophically.
Finding 02
Reactive Hazard of Polymerization Under Loss-of-Cooling Not Assessed
Synthron had not characterized the reactive hazard of the polymerization reaction under loss-of-cooling conditions. The potential for a cooling failure to lead to a catastrophic runaway was not identified, documented, or controlled.
Finding 03
No Emergency Cooling or Dump System on Reactor
The polymerization reactor had no emergency cooling system capable of controlling the runaway exotherm after normal cooling was overwhelmed, and no dump system to safely remove the reacting contents from the reactor during a runaway.
Finding 04
14 Workers and First Responders Injured — 1 Killed
One Synthron worker was killed and 14 others — workers and emergency first responders — were injured in the explosion. The first responders arrived while the runaway was developing, placing them in the blast zone when the reactor ruptured.
Finding 05
Operating Procedures Did Not Address Runaway Response
Synthron's operating procedures for the polymerization reaction did not include steps for responding to a developing temperature excursion or runaway. Operators had no established protocol for managing an out-of-control reaction.
🔍 Root Causes
1
Runaway Polymerization Potential Under Cooling Loss Not Identified
The fundamental cause of the explosion was the failure to identify and characterize the runaway polymerization hazard through reactive hazard assessment. Without this identification, no protective measures were implemented.
2
Inadequate Engineering Safeguards for Runaway Scenario
The reactor had no emergency cooling, dump system, or pressure relief system adequately sized for the runaway polymerization heat generation rate — leaving the vessel without protection when the normal cooling system was overwhelmed.
3
First Responders Arrived During Runaway Development
Emergency first responders arrived at the facility during the period when the runaway was developing. Without knowing the nature of the emergency, responders were positioned in the blast zone when the reactor ruptured.
☑ CSB Recommendations
→ Synthron Inc. / Polymer Manufacturers
Conduct reactive hazard assessments including calorimetric testing for all exothermic polymerization reactions; install emergency cooling or dump systems sized for the worst-case runaway heat generation rate; develop emergency response procedures for developing runaway temperature excursions.
→ Specialty Coatings and Polymer Industry
Establish reactive hazard assessment as a standard requirement for all batch polymerization operations; require cooling system design to account for worst-case runaway heat generation; train all reactor operators on runaway recognition and emergency response.
→ Emergency Responders
Develop pre-incident plans for chemical manufacturing facilities in the jurisdiction; establish staging protocols that position first responders at safe distances during chemical manufacturing emergencies until hazard assessment is complete.
💡 Lessons Learned
The Synthron explosion was the T2 Laboratories pattern again, applied to an emulsion polymerization facility: exothermic batch synthesis, uncharacterized runaway potential, inadequate cooling for worst-case exotherm, no emergency response procedure, catastrophic reactor failure. In 2007 — the same year as the T2 Laboratories explosion (CS-062) — two separate facilities with essentially the same failure pattern caused fatal explosions. The industry-wide failure to adopt reactive hazard assessment as a universal practice for exothermic batch reactions was killing workers in parallel at different facilities.
Emergency cooling systems and dump systems for exothermic batch reactors are engineering safeguards of last resort — they are designed specifically for the runaway scenario when normal cooling is insufficient. For any exothermic polymerization or synthesis reaction, the question "what happens if the normal cooling system cannot control the reaction temperature?" must be answered with an engineering safeguard, not an operating procedure. Procedures cannot remove heat from a runaway reactor; engineering systems can.
First responder safety at chemical manufacturing facilities requires pre-incident planning that establishes safe staging distances for unknown chemical emergencies. When responders arrive at a batch reactor facility and the nature of the emergency is unknown, they must stage at a safe distance until the hazard is identified. The Synthron explosion killed one worker and injured responders who arrived during the runaway development — illustrating the consequence of inadequate pre-incident planning and staging protocols for chemical manufacturing emergencies.
PHA: Process Hazard AnalysisPSI: Process Safety InformationSOP: Operating ProceduresTRN: Training
🔨 Safety Meeting Toolbox Talk
►Has calorimetric reactive hazard testing been conducted for all batch polymerization reactions at your facility? Are the heat of polymerization and the adiabatic temperature rise documented in PSI?
►Are emergency cooling systems or dump systems installed on all polymerization reactors? Are these systems designed for the worst-case runaway heat generation rate, not just normal operating conditions?
►Do operating procedures for polymerization reactions include specific emergency response steps for a developing temperature excursion? Are operators trained to recognize early indicators of a developing runaway?
►Have you coordinated with local emergency responders on pre-incident staging protocols for your facility? Do responders know to stage at safe distances until the hazard is identified during a chemical manufacturing emergency?
Immediate Action Items
✓Identify all batch polymerization and exothermic synthesis reactions at your facility; verify that reactive hazard assessments have been conducted for each and that the worst-case runaway scenario is documented in PSI.
✓Review emergency cooling and dump system capacity for all polymerization reactors; verify that these systems are designed for the worst-case runaway heat generation rate.
✓Update operating procedures for all polymerization reactors to include specific emergency response steps for developing temperature excursions; train all operators on these steps.
✓Coordinate with local emergency responders on pre-incident planning for your facility; establish safe staging distances and hazard communication protocols for chemical manufacturing emergencies.
🔗 PSM Failures Behind This Incident

This incident traced to breakdowns across 4 PSM elements (PHA · PSI · SOP · TRN). Each represents a documented gap that process safety documentation and consulting can close before a similar event occurs at your facility.

Process Hazard Analysis (PHA)
A structured PHA or HAZOP study exists to identify exactly these scenarios before they occur. When PHA is absent, superficial, or overdue for revalidation, hazards operate unseen until they kill someone.
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Process Safety Information (PSI)
Accurate, complete Process Safety Information is the foundation every other PSM element depends on. When PSI is missing or wrong — chemistry data, equipment specs, P&IDs — the entire hazard analysis is built on a flawed base.
Supporting documents in our library →
Operating Procedures (SOPs)
Operators cannot reliably hold safe operating limits without clear, current, enforced procedures. Deviation from acceptable operating conditions is a direct consequence of SOP failure.
Supporting documents in our library →
Training & Operator Competency
Workers must understand process hazards — not just the steps on the page. Training records, refresher frequency, and verified competency are all OSHA PSM requirements.
Supporting documents in our library →
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