Runaway Chemical Reaction
Morton International Runaway Chemical Reaction
Morton International, Inc.
📍 Paterson, NJ
May 8, 1998
0
Fatalities
9 (chemical burns and respiratory exposure)
Injuries / Affected
Organosulfonyl Chloride (Runaway Exothermic Reaction During Specialty Chemical S
Chemical Involved
3
CSB Recommendations
📋 Incident Summary

On May 8, 1998, a runaway exothermic reaction occurred during specialty chemical synthesis at the Morton International facility in Paterson, New Jersey, injuring nine workers. The incident involved the synthesis of an organosulfonyl chloride compound. During the synthesis, the reaction went out of control, generating excessive heat and pressure that resulted in a chemical release and fire.

The CSB investigation found that Morton International had not conducted an adequate reactive hazard assessment for the synthesis process. The potential for the reaction to become self-sustaining and to generate uncontrollable heat and pressure under the production conditions used had not been characterized through calorimetric testing or documented in process safety information.

While no fatalities resulted, the incident injured nine workers and demonstrated the same fundamental failure pattern that would later cause the fatal T2 Laboratories explosion in 2007 (CS-062): an exothermic chemical synthesis operated without an adequate understanding of the runaway reaction hazard under loss-of-control scenarios.

🔎 Key Findings
Finding 01
Runaway Exothermic Reaction During Organosulfonyl Chloride Synthesis
The synthesis reaction generated more heat than could be removed by the cooling system, leading to a temperature increase that accelerated the reaction further. The runaway produced excessive pressure and caused the chemical release and fire.
Finding 02
Reactive Hazard of Synthesis Not Characterized Through Calorimetric Testing
Morton International had not characterized the reactive hazard of the organosulfonyl chloride synthesis through calorimetric testing. The potential for self-sustaining exothermic reaction under production conditions was unknown.
Finding 03
Cooling System Not Designed for Worst-Case Exothermic Scenario
The reactor cooling system was not designed to control the heat generated during the worst-case exothermic scenario — total loss of temperature control during peak reaction. The cooling system was sized for normal operation, not for the runaway reaction heat load.
Finding 04
Nine Workers Injured — Chemical Burns and Respiratory Exposure
Nine workers were injured in the release and fire resulting from the runaway reaction. The injuries included chemical burns from the released organosulfonyl chloride and respiratory exposure from the toxic release.
Finding 05
Incident Preceded the 2007 T2 Laboratories Fatal Explosion
The Morton International runaway reaction involved the same fundamental failure pattern — uncharacterized reactive hazard, inadequate cooling for worst-case exotherm — that caused the fatal T2 Laboratories explosion nine years later. The lessons from Morton were available but not applied industry-wide.
🔍 Root Causes
1
Runaway Reaction Potential Not Identified Through Reactive Hazard Assessment
The fundamental cause of the incident was the failure to characterize the reactive hazard of the synthesis through calorimetric testing. Without this assessment, the potential for runaway reaction under production conditions was unknown.
2
Cooling System Inadequate for Worst-Case Reaction Scenario
The reactor cooling system was not designed for the worst-case exothermic scenario. A cooling system for an exothermic synthesis must be capable of controlling the heat generated during the peak reaction rate under all foreseeable conditions, including loss of temperature control.
3
No Emergency Response Procedures for Developing Runaway
Operating procedures did not include emergency response steps for a developing runaway reaction. Workers had no established response protocol when the reaction began to go out of control.
☑ CSB Recommendations
→ Morton International / Specialty Chemical Manufacturers
Conduct calorimetric reactive hazard assessment for all exothermic synthesis reactions; characterize the heat of reaction, adiabatic temperature rise, and cooling requirements for worst-case scenarios; ensure reactor cooling systems are designed for the worst-case exotherm.
→ Chemical Manufacturers / AIChE / CCPS
Publish and promote reactive hazard assessment methodologies specifically for batch chemical synthesis operations; make calorimetric testing a standard practice for all new synthesis processes involving exothermic reactions.
→ OSHA
Consider requiring reactive hazard assessment for all chemical synthesis processes involving exothermic reactions in chemical manufacturing; address the gap between PSM coverage thresholds and reactive hazard potential at facilities below PSM thresholds.
💡 Lessons Learned
The Morton International and T2 Laboratories incidents are separated by nine years but share an identical failure pattern: exothermic synthesis process, uncharacterized runaway reaction potential, inadequate cooling for worst-case exotherm, no emergency response procedure for developing runaway. The pattern persisted from 1998 to 2007 — and beyond — because the lesson of characterizing runaway reaction potential through calorimetric testing was not consistently adopted as a standard practice across the industry.
Reactor cooling systems for exothermic synthesis must be designed for the worst-case heat generation rate — which occurs during a runaway, not during normal operation. Sizing a cooling system for normal heat generation and then operating it for exothermic synthesis is equivalent to designing a fire suppression system for normal temperature and then expecting it to suppress a fire. The cooling system design basis must account for the runaway reaction scenario explicitly.
Emergency operating procedures for exothermic synthesis operations must include specific actions for operators to take when temperature begins to rise unexpectedly. The key decision points — when to increase cooling, when to terminate the batch, when to use emergency quench — must be defined in advance and trained, not left to real-time judgment under stress. Without pre-defined response protocols, operators have no framework for managing a developing runaway.
PHA: Process Hazard AnalysisPSI: Process Safety InformationSOP: Operating ProceduresTRN: Training
🔨 Safety Meeting Toolbox Talk
►Has calorimetric reactive hazard testing been conducted for all exothermic synthesis reactions at your facility? Are the heat of reaction and adiabatic temperature rise documented in PSI for each synthesis?
►Are reactor cooling systems for exothermic syntheses designed for the worst-case heat generation rate during runaway — not just normal operating heat loads? Has this design basis been verified?
►Do operating procedures for exothermic synthesis include specific emergency response steps for a developing temperature excursion? Are these steps trained and periodically drilled?
Immediate Action Items
✓Identify all exothermic synthesis reactions at your facility; verify that calorimetric testing has been conducted and that heat of reaction and adiabatic temperature rise are documented in PSI.
✓Review cooling system design basis for all reactors conducting exothermic synthesis; verify cooling capacity is adequate for the worst-case runaway heat generation rate.
✓Update operating procedures for exothermic synthesis to include specific emergency response steps for temperature excursions; train operators on recognition and response protocols for developing runaway conditions.
✓Implement real-time temperature monitoring with alarms for all exothermic synthesis operations; set alarm setpoints based on safety-critical temperature thresholds identified in reactive hazard assessment.
🔗 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.
Supporting documents in our library →
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.
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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.
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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.
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