### U.S. C HEMICAL 

### S AFETY AND 

### H AZARD 

### I NVESTIGATION 

### B OARD



# INVESTIGATION REPORT

C HEMICAL 

## M ANUFACTURING 

## I NCIDENT 

## (9 I NJURED 

## )

Morton International, Inc. Paterson, NJ April 8, 1998

Report No. 1998-06-I-NJPhoto by Bill Tompkins



### KEY ISSUES:

● I NTERNAL H AZARD C OMMUNICATION

AND P ROCESS S AFETY I NFORMATION

● R EACTIVE H AZARD M ANAGEMENT

● P ROCESS S AFETY M ANAGEMENT

## ABSTRACT

This report explains the explosion and fire that occurred on April 8, 1998, at the Morton International, Inc. (now Rohm & Haas) plant in Paterson, New Jersey. The explosion and fire were the consequence of a runaway reaction, which over-pressured a 2000-gallon capacity chemical reactor vessel and released flammable material that ignited. Nine employees were injured, including two seriously, and potentially hazardous materials were released into the community. The key safety issue covered in this report was reactive chemical process safety management. Recommendations concerning this issue were made to Morton International, Inc. (a wholly owned subsidiary of Rohm & Haas Company); Morton International, Inc.’s Paterson, New Jersey Plant; the Occupational Safety and Health Administration (OSHA); the Environmental Protection Agency (EPA); the American Chemical Council; the Center for Chemical Process Safety (CCPS); the Paper, Allied-Industrial, Chemical & Energy Workers International Union (PACE); and the Synthetic Organic Chemical Manufacturer’s Association (SOCMA).
The U.S. Chemical Safety and Hazard Investigation Board (CSB) is an independent federal agency whose mission is to ensure the safety of workers and the public by preventing or minimizing the effects of chemical accidents. The CSB is a scientific investigatory organization; it is not an enforcement or regulatory body. Established by the Clean Air Act Amendments of 1990, the CSB is responsible for determining the root and contributing causes of incidents, issuing safety recommendations, studying chemical safety issues, and evaluating the effectiveness of other government agencies involved with chemical safety. No part of the conclusions, findings, or recommendations of the CSB relating to any chemical incident may be admitted as evidence or used in any action or suit for damages arising out of any matter mentioned in an investigation report. See 42 U.S.C. § 7412(r)(6)(G). The CSB makes public its actions and decisions through investigation reports, summary reports, safety studies, safety recommendations, special technical publications, and statistical reviews. More information about the CSB may be found on the World Wide Web at http://www.chemsafety.gov.
Information about CSB publications may be obtained by contacting: U.S. Chemical Safety and Hazard Investigation Board Office of External Relations 2175 K Street, N.W., Suite 400 Washington, DC 20037 (202) 261-7600
CSB publications may be purchased from:
National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 (703) 487-4600
For this report, refer to NTIS number PB2000-107721
Salus Populi Est Lex Suprema People’s Safety Is the Highest Law

### TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................. .............1

ES.1 INTRODUCTION .............................................................................................................. ..........................1 ES.2 INCIDENT .................................................................................................................. ..................................1 ES.3 KEY FINDINGS .............................................................................................................. ............................2 ES.4 RECOMMENDATIONS ........................................................................................................... ...................8
1.0 INTRODUCTION ............................................................................................................... ...............11

1.1 BACKGROUND ................................................................................................................. ...........................11 1.2 INVESTIGATION PROCESS ...................................................................................................... ................12 1.3 PLANT FACILITIES ........................................................................................................... .........................13 1.4 LAYOUT AND COMPONENTS ...................................................................................................... ............14 1.4.1 Kettle Description ....................................................................................................... ...........................14 1.4.2 Kettle System ............................................................................................................ ..............................15
2.0 DESCRIPTION OF THE INCIDENT ................................................................................................ ..18

2.1 INCIDENT EVENTS ............................................................................................................ ........................18 2.2 EMERGENCY RESPONSE ......................................................................................................... ...............26 2.3 OFF-SITE IMPACTS ........................................................................................................... .........................27 2.4 PROPERTY DAMAGE ............................................................................................................ ....................28
3.0 ANALYSIS OF PROCESS CHEMISTRY ........................................................................................29

3.1 REACTIVE CHEMICAL ANALYSIS ................................................................................................. .........29 3.2 TESTS OF RAW MATERIALS ..................................................................................................... ...............33
4.0 ANALYSIS OF PROCESS DEVELOPMENT PROGRAM ................................................................34

5.0 ANALYSIS OF PROCESS SAFETY MANAGEMENT PROGRAM ................................................38

5.1 PROCESS SAFETY INFORMATION ................................................................................................. .......38 5.2 PROCESS HAZARD ANALYSIS .................................................................................................... ............40 5.3 INVESTIGATION OF PROBLEMS WITH PREVIOUS BATCHES ..........................................................43 5.4 MANAGEMENT OF CHANGE ...................................................................................................... ............45 5.5 OPERATING PROCEDURES AND TRAINING ........................................................................................46
6.0 REGULATORY OVERSIGHT ANALYSIS ........................................................................................49

6.1 REGULATORY COVERAGE ........................................................................................................ ..............49 6.2 MORTON PSM PROGRAM ......................................................................................................... ...............51 6.3 GOOD PRACTICE GUIDELINES ................................................................................................... ...........52 6.4 RECENT CATASTROPHIC REACTIVE CHEMICAL INCIDENTS ........................................................53
7.0 ROOT AND CONTRIBUTING CAUSES ........................................................................................56

7.1 ROOT CAUSES ................................................................................................................ ............................56 7.2 CONTRIBUTING CAUSES ........................................................................................................ ................57
8.0 RECOMMENDATIONS ............................................................................................................ ........59

i9.0 REFERENCES ................................................................................................................. ...............62

APPENDIX A: INCIDENT TIMELINE................................................................................................... ...63

APPENDIX B: DEVELOPMENT TIMELINE............................................................................................69

APPENDIX C: ROOT CAUSE ANALYSIS DIAGRAM............................................................................70

APPENDIX D: MATERIAL SAFETY DATA SHEETS ............................................................................71



### TABLE OF FIGURES
F IGURE 1: A ERIAL V IEW OF THE P ATERSON P LANT ..........................................................................................11 F IGURE 2: P LOT P LAN

............................................................................................................................... ...........13 F IGURE 3: A NNOTATED R ENDERING OF A C HEMICAL R EACTOR H EAD S IMILAR TO K ETTLE S EVEN ..........15 F IGURE 4: S IMPLIFIED P ROCESS F LOW D IAGRAM ..............................................................................................16 F IGURE 5: T EMPERATURE C HART AND D IGITAL D ISPLAY ................................................................................17 F IGURE 6: M ANWAY H ATCH IN P LACE ..............................................................................................................19 F IGURE 7: C ONDENSER AND V ENT P IPING ........................................................................................................20 F IGURE 8: G LASS S ECTION OF 8- INCH L INE TO C ONDENSER ..........................................................................22 F IGURE 9: R UPTURE D ISK A SSEMBLY R ECOVERED FROM K-7 AFTER THE I NCIDENT ....................................23 F IGURE 10: E XTRUDED H EAD G ASKET ................................................................................................................24 F IGURE 11: R ECOVERED I NSPECTION M ANWAY C OVER ....................................................................................24 F IGURE 12: P OST

- ACCIDENT P HOTO OF THE K ETTLE ........................................................................................25 F IGURE 13: B UILDING 11’ S B LOWOUT P ANELS AND W INDOW F RAMES ............................................................28 F IGURE 14: H EAT G ENERATION VERSUS H EAT R EMOVAL R ATE ........................................................................31

ii

## EXECUTIVE SUMMARY

ES.1 I NTRODUCTION

On Wednesday, April 8, 1998, at 8:18 pm, an explosion and fire occurred during the production of Automate Yellow 96 Dye at the Morton International, Inc. (now Rohm & Haas 1 ) Plant (the plant) in Paterson, New Jersey. The explosion and fire were the consequence of a runaway reaction, which over-pressured a 2000-gallon capacity chemical reactor vessel (or kettle) and released flammable material that ignited. Because of the serious nature of the incident, including injuries to nine employees, the release of potentially hazardous materials into the community, and extensive damage to the plant, the U.S. Chemical Safety and Hazard Investigation Board (CSB) initiated an incident investigation. The purpose of the investigation was to identify the root causes of the incident and make recommendations to prevent similar
incidents.



### ES.2 I NCIDENT

The Paterson plant manufactures a series of dye products. Yellow 96 Dye was produced by the mixing and reaction of two chemicals, ortho -nitrochlorobenzene ( o -NCB) and 2-ethylhexylamine (2-EHA). The dye was used to tint petroleum fuel products.

The investigation team determined that the reaction accelerated beyond the heat-removal capability of the kettle. The resulting high temperature led to a secondary runaway

1 1 In February 1999, Rohm and Haas Company, of Philadelphia, PA, purchased Morton International. Morton is currently a wholly owned subsidiary of Rohm and Haas.decomposition reaction causing an explosion, which blew the hatch off the kettle and allowed the release of the kettle contents. The initial runaway reaction was most likely caused by a combination of the following factors: (1) the reaction was started at a temperature higher than normal, (2) the steam used to initiate the reaction was left on for too long, and (3) the use of cooling water to control the reaction rate was not initiated soon enough.

The explosion ejected flammable vapors from the kettle into the second floor of the production building. The explosion and flash fires inside the building injured nine workers. The flashing eruption of chemicals broke through the building roof, ignited and formed a large fireball above the building, and spattered the adjacent neighborhood with a yellow-brown mixture of compounds that included Yellow 96 Dye and o -NCB.

Workers’ injuries included burns, contusions, and twisted joints. Two employees were badly burned and required extended hospitalization. All of the employees were able, some with assistance, to escape the site of the explosion.



### ES.3 K EY 

### F INDINGS

1. Morton’s initial research and development for the Yellow 96 process identified the existence
and described the two exothermic chemical reactions 2 that can occur when the chemicals used to produce Yellow 96 are mixed and heated:

● The desired exothermic reaction, to form Yellow 96, which is initiated at an onset temperature 3 of 38°C (100°F) and begins to proceed rapidly at a temperature of approximately 75°C (167°F), and

2 2 An exothermic reaction, or “exotherm,” generates heat as a by-product of a chemical reaction. Since reactions usually proceed faster at higher temperatures, the heat generated is typically removed from the reacting mixture by a medium such as cooling water, to allow the reaction to proceed at the desired constant temperature.
3 The onset temperature of a reaction is the lowest temperature at which exothermic activity is observed.● the undesired, exothermic reaction that results from the thermal decomposition 4 of the Yellow 96 product, which is initiated at an onset temperature 195°C (383°F).

2. The Paterson facility was not aware of the decomposition reaction. The Process Safety Information (PSI) package, which was used at the Paterson plant to design the Yellow 96 production process in 1990 and which served as the basis for a Process Hazard Analysis (PHA) conducted in 1995, noted the desired exothermic reaction, but did not include information on the decomposition reaction.

3. Neither o -NCB nor 2-EHA, individually, demonstrates exothermic activity at the normal Yellow 96 process temperatures.

4. Two discrepancies in Morton’s Material Safety Data Sheet (MSDS) for the Yellow 96 product were identified:

● The National Fire Protection Association (NFPA) Reactivity Rating was listed as 0 (on a 0 to 4 scale, with 4 being the most reactive). The CSB determined that the proper reactivity rating for Yellow 96 is 1.

● The Yellow 96 boiling point was listed as 100°C. The CSB determined that the boiling point was approximately 330°C, or greater than the decomposition temperature.

5. Morton did not follow up on two recommendations made by its researchers in 1989: (1) to conduct additional reactive chemical laboratory tests to determine “the rate of reaction under the worst reaction conditions ... the rate of decomposition of the finished product ... [and] pressure rise data which could be used to size emergency venting equipment ...” and, (2) to install specific control and safety devices on the Yellow 96 production vessels such as an emergency shutdown system.

3 4 A thermal decomposition reaction occurs when a chemical breaks up into smaller molecules during exposure to an elevated temperature for a sufficient period of time. The liberation of large amounts of heat and generation of high pressure may accompany decomposition reactions.6. In scaling up the process from the laboratory phase to production-scale, Morton revised the process from a semi-batch process, in which the o -NCB was added in incremental stages to the full amount of 2-EHA already in the reactor, to a batch process, in which the entire quantities of the reactants were added to the reactor at the outset, and staged heating was then applied. Morton did not take into account that this change resulted in a potentially more thermally hazardous operation. 5 The heat output from a semi-batch process is easier to control than is that from a batch process. In the batch process, heating the entire mass of reactants at the start of the reaction increases the likelihood of exceeding the heat removal capacity of a kettle.

7. The kettle was not equipped with safety equipment, such as a quench or reactor dump system, to shut down the process in case of a runaway reaction emergency. Also, pressure relief devices (rupture disks) were too small to safely vent the kettle in case of a runaway
reaction.

8. The operators controlled process temperature manually by opening and closing steam and cooling water valves. Operating procedures, however, required that the process run at temperatures (150 to 153°C) that were near the temperature at which the reaction could become uncontrollable (195°C). Thus, normal variations in the operators’ responses to the batch temperature or delays in adjusting valves could result in overheating or undercooling, with the result that the heat generated by the reaction would exceed the cooling capacity of the kettle. In several previous instances, the operators documented on the process batch sheets that the process temperature rose at a faster-than-expected rate and exceeded the upper limit specified in the operating procedures in spite of the operators’ efforts. The temperature of these batches eventually returned to the operating limits. Management did not investigate the causes of these events.

9. In 1996, Morton transferred the Yellow 96 process from 1000-gallon to 2000-gallon kettles and increased the amount of raw materials used per batch by approximately 9 percent

4 5 While this change minimized the potential for toxic effects due to employee exposure to o- NCB, it also resulted in a more thermally hazardous operation.without using their existing Management of Change procedures. Morton did not assess the effects of these changes. While 20 percent of the 25 batches of Yellow 96 made before these changes exhibited temperature excursions, half of the 6 batches made after the changes had temperature excursions.

10. The Occupational Safety and Health Administration (OSHA) Process Safety Management (PSM) standard did not cover the Yellow 96 process. Morton covered the process under its internal PSM program, which was applied to OSHA-regulated processes and certain other processes. The CSB did not find that lack of OSHA PSM coverage directly contributed to causing the incident. The Yellow 96 process would not have been covered by the Environmental Protection Agency’s (EPA) Risk Management Program rule, which went into
effect in June 1999.

11. The OSHA PSM standard covers only a limited number of reactive chemicals. EPA’s Risk Management Program rule does not cover reactive chemicals as a class. These standards provide only minimum requirements for process safety management and provide little guidance on reactive chemical process safety management issues, such as the use of chemical screening techniques, and the proper design of pressure relief, emergency cooling, and safety interlock systems.

12. Morton’s PSM program did not require adherence to a number of industry good practice guidelines for the safe management of reactive chemical processes such as those published by the Center for Chemical Process Safety or Lees’s Loss Prevention in the Process
Industries.

13. Morton also did not effectively implement the requirements of its internal PSM program. The PHA conducted for the process and the operating procedures (batch sheets) did not address the consequences of potential deviations such as excessive heating, a runaway reaction, or the inability to provide enough cooling to maintain temperatures in a safe operating range. Batch sheets did not list the actions operators should take to correct or avoid deviations. Operators’ reports of significant deviations in controlling batch temperature were not acted on by management.

56 Root Causes

1. Neither the preliminary hazard assessment conducted by Morton in Paterson during the design phase in 1990 nor the process hazard analysis conducted in 1995 addressed the reactive hazards of the Yellow 96 process.

Not addressing these hazards resulted in the following design, operational, and training
deficiencies:

● The kettle cooling system could not safely control the exothermic Yellow 96 synthesis
reaction.

● The kettle was not equipped with safety equipment, such as a quench system or a reactor dump system, to stop the process to avoid a runaway reaction.

● Rupture disks were too small to safely vent high pressure in the kettle in the event of either of the two foreseeable runaway reactions.

● Morton converted its Yellow 96 production from a staged, incremental addition (semibatch) process to a staged heating (batch) process without assessing the possible hazards of this change, e.g., the increased difficulty of controlling heat output.

● Operating procedures did not cover the safety consequences of deviations from normal operating limits, such as runaway reactions, or specify steps to be taken to avoid or
recover from such deviations.

● Training did not address the possibility of a runaway reaction and how operators should respond to avoid injury if a runaway reaction could not be controlled.

2. Process safety information provided to plant operations personnel and the process hazard analysis team did not warn them of the potential for a dangerous runaway
chemical reaction.Morton internal memoranda had documented that the desired reaction to form Yellow 96
from o -NCB and 2-EHA was exothermic and that Yellow 96 would begin to decompose rapidly (runaway) at temperatures close to the upper operating temperature. Morton researchers also had identified several situations, such as loss of cooling, which might give rise to temperatures capable of causing violent decompositions. Although information on the reactive hazards was contained in plant files, operators and supervisors were unaware that a dangerous decomposition reaction was possible.

Contributing Causes

1. The hazards of previous operational deviations were not evaluated.

Management did not investigate evidence in numerous completed batch sheets and temperature charts of high temperature excursions beyond the normal operating range. Investigation of these incidents likely would have provided an opportunity to uncover the process’s reactive hazards and correct design and other problems.

2. Morton did not follow their Management of Change procedures to review changes
made in reaction kettle and batch size.

Morton changed the Yellow 96 processing equipment from 1000-gallon to 2000-gallon kettles and also increased the batch size by 9 percent in 1996. Morton did not follow its Management of Change procedures and did not review the changes for possible safety consequences. A Management of Change review likely would have provided another opportunity for Morton to uncover the process’s reactive hazards and correct design problems. The review likely would have also revealed that the changes made resulted in a decrease of 10 percent in the heat transfer area per gallon of reactants. Half of the batches made after this change exhibited temperature excursions versus 20 percent in the batches made before the change.

7

### ES.4 R ECOMMENDATIONS

Morton International, Inc. (a wholly owned subsidiary of Rohm and Haas Company)

Establish a program that ensures reactive chemical process safety information and operating experience are collected and shared with all relevant units of the company.

Morton International, Inc.’s Paterson, New Jersey Plant

1. Revalidate PHAs for all reactive chemical processes in light of the findings of the CSB report and upgrade, as needed, equipment, operating procedures, and training.

2. Evaluate pressure relief requirements for all reaction vessels using appropriate technology, such as the Design Institute for Emergency Relief Systems (DIERS) 6 method and test apparatus and upgrade equipment as needed.

3. Evaluate the need for and install, as necessary, devices, such as alarms, added safety instrumentation, and quench or reactor dump systems to safely manage reactive chemical process hazards.

4. Revise operating procedures and training for reactive chemical processes as needed, to include descriptions of the possible consequences of deviations from normal operational limits and steps that should be taken to correct these deviations, including emergency response actions.

5. Implement a program to ensure that deviations from normal operational limits for reactive chemical processes that could have resulted in significant incidents are documented and investigated and necessary safety improvements are implemented.

8 6 DIERS is a consortium of companies, formed in 1976 by the American Institute of Chemical Engineers, to develop methods for the design of emergency relief systems to handle runaway reactions. The DIERS group has developed computer programs and a bench-scale test apparatus for assessing the venting requirements of runaway reactions and two-phase flow.6. Revise the Yellow 96 Material Safety Data Sheet (MSDS) to show the proper boiling point and NFPA reactivity rating. Communicate the MSDS changes to current and past customers (who may retain inventories of these products).

Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA)

1. Issue joint guidelines on good practices for handling reactive chemical process hazards. Ensure that these guidelines, at a minimum, address the following issues:

● The evaluation of reactive hazards and the consequences of reasonably foreseeable and worst-case deviations from normal operations.

● The importance of reporting and investigating deviations from normal operations.

● The determination of proper design for pressure relief capability, emergency cooling, process controls, alarms, and safety interlocks, as well as other good-practice design features for handling reactive substances.

● The appropriate use of chemical screening techniques such as differential scanning calorimetry.

2. Participate in a hazard investigation of reactive chemical process safety conducted by the CSB. The objectives of the hazard investigation will include:

● Determine the frequency and severity of reactive chemical incidents.

● Examine how industry, OSHA, and EPA are currently addressing reactive chemical hazards. Determine the differences, if any, between large/medium/small companies with regard to reactive chemical policies, practices, in-house reactivity research, testing, and process engineering.

● Analyze the effectiveness of industry and OSHA use of the National Fire Protection Association Reactivity Rating system for process safety management purposes.

9● Develop recommendations for reducing the number and severity of reactive chemical
incidents.

American Chemistry Council; Center for Chemical Process Safety (CCPS); Paper, AlliedIndustrial, Chemical & Energy Workers International Union (PACE); Synthetic Organic Chemical Manufacturer’s Association (SOCMA)

Communicate the findings of this report to your membership.

10

## 1.0 INTRODUCTION

1.1 B ACKGROUND

On Wednesday, April 8, 1998, at 8:18 pm, nine workers were injured in an explosion and fire at the Morton International, Inc. (now Rohm and Haas Company) plant in Paterson, New Jersey. 7 This incident was the result of a runaway chemical reaction during the production of Automate Yellow 96 Dye. Because of the serious nature of the incident, which caused the hospitalization of two employees, the release of chemicals into the community, and damage to the plant, the U.S. Chemical Safety and Hazard Investigation Board (CSB) sent a team to investigate the incident.

Morton International, Inc. is a major salt producer and maker of specialty chemicals for a variety of applications. Morton developed the Automate Yellow 96 Dye product in the 1980s.

11 7 Morton International, Inc. was purchased in the spring of 1999 as a wholly owned subsidiary of Rohm and Haas Company, which is a publicly held Fortune 500 company. Figure 1: Aerial View of the Paterson PlantCombined with other dyes, Automate Yellow 96 produced bright green shades of tinting for fuels. Initial laboratory testing and pilot plant scale-up were conducted at Morton facilities in Hounslow, England in 1986–1989. During this development phase, Morton researchers observed exothermic activity and determined that batch temperature control was key to preventing the reaction from reaching runaway conditions. In 1988 and 1989, the Morton research groups in Paterson, New Jersey, and Ringwood, Illinois, developed a staged heating process for Yellow 96 and reported no temperature control problems during laboratory and pilot-scale work. The first production-scale batch of Yellow 96 was manufactured at Paterson on September 6, 1990.



### 1.2 I NVESTIGATION 

### P ROCESS

The CSB received and shared information with the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA), and local emergency response organizations. The CSB examined physical evidence from the incident, conducted interviews with Morton personnel, and reviewed relevant documents obtained from Morton.

The CSB was assisted in its initial field investigation work by contractors from the Department of Energy’s Oak Ridge National Laboratory and the National Aeronautics and Space Administration’s (NASA) White Sands Test Facility. 8 Calorimetric testing of the Yellow 96 process and process materials was conducted for the CSB by both the White Sands Test Facility and Chilworth Technology, Inc.

12 8 The field phase of the investigation was delayed by approximately 6 weeks due to problems between the CSB and Morton in obtaining proper credentials for the contract investigators. This delay did not affect the CSB’s key findings or conclusions regarding the causes of the Morton incident.

### 1.3 P LANT 

### F ACILITIES

The Paterson facility is located in Passaic County, on a seven-acre site surrounded by other industrial establishments and residential homes. On-site support facilities include offices, laboratories, shops, lunchrooms, and locker rooms. The plant is bordered on the west by New Jersey Route 20 (McLean Blvd.) and on the east by the Passaic River (Figure 1).

The incident occurred in Building 11 (B-11), a three-floor building on the east end of the complex. A facility plot plan is provided in Figure 2. The plot plan identifies the location of each of the process buildings, the K-7 chemical reactor vessel used on April 8 to produce Yellow 96, and the hot box, which was used to preheat the ortho -nitrochlorobenzene ( o -NCB) for use in the Yellow 96 process.

13 SHIPPING OFFICES PAVED PARKING AREA

TANK FARM

LUNCH AND LOCKER ROOMS

LAB AND OFFICES PRODUCTION

MAINT. SHOP WAREHOUSE UTILITY BUILDING 11 PRODUCTION LAB & OFFICES

THERMAL OXIDIZER

PRODUCTIONHAZ WASTEDRUM PAD

ELECT.SUBSTATIONMcLEANBLVD.NJROUTE20

PASSAIC RIVER STORAGE K-7

HOT BOX15
Figure 2: Plot PlanIndustrial dye products were manufactured at the plant via batch processing. Various raw materials were mixed in reaction vessels (kettles) and heat was applied to drive the reaction process. The resulting dyes were further processed after the reaction steps to remove residual chemicals and waste products. The final product was put into drums or transferred to product storage tanks to be shipped off-site or blended with other products to produce different colors as final products.



### 1.4 L AYOUT AND 

### C OMPONENTS

1.4.1 Kettle Description

From 1990 to 1996, Morton produced Yellow 96 in 1000-gallon kettles. In September 1996, Morton switched production to 2000-gallon kettles to minimize color contamination between different dyes produced in the same kettles. Kettle number seven (K-7), which was involved in the incident, was one of the 2000-gallon kettles.

Kettle K-7 was designed and manufactured in 1962 (Figure 3 is a drawing of a kettle similar to K-7). The interior of the kettle was glass lined to prevent corrosion of the carbon steel shell and heads. The inside diameter of the kettle was 78 inches and the height was about 107 inches. The kettle heads were dished, with nominal thicknesses of 7/8 inch and 15/16 inch for the top and bottom heads, respectively. The nominal thickness of the shell was 15/16 inch. A heating and cooling jacket, or outer case, extended from the top head-to-shell weld downward to the middle
of the bottom head and surrounded the outside of the kettle. The kettle had a Maximum Allowable Working Pressure 9 (MAWP) of 100 psig. The MAWP for the jacket was 90 psig. Kettle rupture disks were set at 10 psig. 10

14 9 The Maximum Allowable Working Pressure (MAWP) is the maximum pressure at which a vessel is designed to operate safely. Typically, vessels are operated at pressures significantly below the MAWP to provide a margin of safety.
10 Rupture disks are emergency safety devices designed to open to relieve high pressure in vessels and protect equipment and personnel from catastrophic failure of the vessel.Nozzles were located in the jacket and on the top head of the kettle to provide piping connections. The nozzle at the bottom of the vessel served as a drain. The most pronounced feature of the top head was a 30-inch-diameter bolted closure. A glass-coated, single-speed agitator was attached to the top surface of the bolted closure. The bolted closure contained a 14- by 18-inch elliptical manway secured by four C-type clamps.

The CSB determined that the kettle and jacket design, fabrication, inspection, hydro testing, and registration stamping met the requirements of the American Society of Mechanical Engineers, Section VIII, Boiler
and Pressure Vessel Code.

1.4.2 Kettle System

The entire K-7 process system, with the exception of the thermal oxidizer and pressure-relief catch tank, was located inside Building 11. The kettle extended vertically from the ground level to the second floor. The operators had access to the kettle’s top
head and associated nozzles on the second
floor where the raw materials were added. Valve handles and temperature readout and recording instruments were also located on
the second floor.

Ground-level valve handles were modified to extend up through the second-story floor grating, allowing the operators to control

15 Figure 3: Annotated Rendering of a Chemical Reactor Head Similar to Kettle Seven Besides the agitator bolted closure, the chemical reactor’s head had the following: (A) a 14- x 18-inch elliptical inspection manway, (B) a penetration for the thermocouple, (C) an 8-inch nozzle to the rupture disks and the 10-inch pressure manifold leading to the catch-all tank, (D) a connection for the liquid condensate return, from the liquid separator, (E) an acid feed line into the kettle, (F) a direct kettle vent line to the B-11 manifold that collected organic vapors and delivered them to the site’s thermal oxidizer, (G) an 8-inch line to the condenser on the third floor of B-11. A raw material feed nozzle is located behind the 15-hp. electric agitator
motor. (http://www .pf audler .com/gle/v essels.html ) A

C B D E

F Geach valve manually from the second floor. The third floor housed the condenser and exhaust piping leading outside to the thermal oxidizer and pressure-relief catch tank.

Temperature in the vessel was controlled by adjusting the flow of cooling water and steam piped to the kettle’s jacket with manually operated valves. The operators determined the degree to which these valves were opened based on their experience in running the process. The timing of switching from heating to cooling or vice versa was also based on the operators’ experience. The cooling-water inlet was located at the bottom and the steam inlet was located at the top of the jacket. The water outlet was shared with the steam outlet at the top of the jacket. Steam that condensed during heating operations was drained from the bottom of the jacket and directed to the boiler condensate return. Figure 4 is a simplified flow diagram of the K-7 reactor system.

16 Figure 4: Simplified Process Flow Diagram SEP

.

T PI

TI

REACTOR K-7 CONDENSER

CATCH TANK

RECEIVER RUPTURE DISKS - 10PSI

COOLING WATER IN CONDENSATE OUT

PRODUCT OUT COOLING WATER

OUT STEAM

IN TO THERMAL OXIDIZER

CW IN CW OUT

MANWAY RAW MATERIAL ADDITION MANIFOLD VACUUM ADDITIONS

LINE

TO VACUUM

PUMPS

RECYCLE OR WASTE TREATMENT

11/12/99 SECOND LEVEL FLOOR VALVE HANDLE EXTENSIONReactor instrumentation provided measurements of reactor temperature, reactor pressure, and cooling water pressure. Reactor temperature was measured by one thermocouple 11 connected to two temperature readouts: a digital display and a circular recording chart. The recording chart could not record temperatures greater than 150°C, although the digital readout continued to display temperatures above 150°C (see Figure 5). The kettle was not equipped with temperature or pressure alarms and there were no automatic shutdown devices.

17 11 A thermocouple measures temperature. A thermocouple is composed of two dissimilar metals fused together; the junction between the two metals generates a voltage that is a function of temperature. Figure 5: Temperature Chart and Digital Display

The round window in the aluminum box contained the temperature chart. The rectangular cutout above and to the left of the chart contained the digital temperature readout.

## 2.0 DESCRIPTION OF THE INCIDENT

2.1 I NCIDENT 

### E VENTS 12

On April 8, 1998, the second work shift began at 4:00 pm. During this shift, Yellow 96 was scheduled to be prepared in K-7, a 2000-gallon jacketed kettle located at the east end of Building 11 (B-11). Plant batches of Yellow 96 had been numbered sequentially from the beginning of production in 1990 and this was to be batch #32. The supervisor assigned two chemical operators to the production and provided them with the batch sheets for Yellow 96.

Operators used batch sheets for step-by-step direction in performing the process. The batch sheets were written and approved by plant management, and supervision and operations personnel. The Yellow 96 batch sheet was nine pages long and had abbreviated safety data sheets (listing only the key health hazards and protective equipment) for the raw materials and products as well as a list of raw materials. 13 The batch sheets outlined the procedures for each step in the process. Operators were required to record the time when each step began and ended, the temperature of the kettle contents, and their initials. Each batch was assigned a sequential lot number. The lead operator performing the process controlled the batch sheets throughout the production of Yellow 96. Upon completion of the batch, the operator returned the sheets to the supervisor along with the temperature recording charts generated during the batch.

Both operators involved in the incident had made Yellow 96 before. The lead operator had 31 years of plant experience and the assistant operator had more than 3 years of experience.

Before beginning batch 32, the operators inspected the kettle through the manway to ensure that it was clean. The lead operator recalled that the temperature of the kettle was approximately 20 to 30°C (68 to 86°F) during and after the inspection. Once the inspection was completed, the

18 12 This narrative can be followed on the Incident Timeline in Appendix A. It describes the actions taken by the operators working on the second floor operating deck of B-11 and the subsequent emergency response activities.
13 Complete Material Safety Data Sheets for Yellow 96, o- NCB, and 2-EHA may be found in Appendix C.19 manway cover was closed and clamped onto the kettle using four C-type clamps (see Figure 6).

The first processing step was the addition
of ortho -nitrochlorobenzene ( o -NCB) to
the kettle. Because o -NCB has a melting point of 32°C (89°F), the drums required for a batch were placed in a hot box for several days to be melted before use. The hot box was an enclosed room, with a steam heater, large enough to contain the drums (the hot box is shown in Figure 2, to the west of Building 11).

The operators prepared to transfer the o -NCB from the drums by ensuring that all kettle valves were closed, except for the vacuum valve, and the agitator was started. A vacuum was used to
draw the o -NCB from the supply drum to the kettle through a combination of piping and flexible hose. This operation was repeated until all drums were empty. The transfer of the

o -NCB was normal, taking approximately 30 minutes (until 5:15 pm) indicating that the vacuum was adequate and the o -NCB was well liquefied. Once the transfer of the o -NCB was completed, the temperature of the o -NCB inside the kettle was reported by the lead operator to be “60-something degrees, almost 70°C” (158°F), while the second operator recalled that it was “about 44°C.” The U.S. Chemical Safety and Hazard Investigation Board (CSB) determined through interviews that the operators did not adjust the initial mix temperature to between 40 to 42°C (104 to 108°F) as required by the batch sheet. This temperature-reduction step would have reduced the initial rate of the reaction to produce Yellow 96.

The next processing step was the addition of the 2-ethylhexylamine (2-EHA). The operators readied the kettle by ensuring the vacuum valves and drain isolation valves to the kettle were closed. They opened the kettle vent to ensure there was no buildup of pressure when the 2-EHA Figure 6: Manway Hatch in Place As seen in this photograph of a similar kettle, four clamps hold the inspection manway hatch in place. 1 2 3
4was added. The operators left this vent valve open for the duration of the operation, allowing the process to be performed at atmospheric pressure (see Figure 7).

Next, the operators added 2-EHA to the kettle. The 2-EHA was pumped into the kettle from an underground storage tank through a meter that stopped the flow when the preset amount of 2-EHA had been pumped. The kettle agitator continued to operate during the 2-EHA addition. The transfer took approximately 25 minutes. After adding the 2-EHA, the operators left the building for dinner, returning at approximately 7:35 pm.

After the addition of the 2-EHA, which was at ambient temperature, the operators stated that the temperature of the mixture was approximately 44 to 48°C (111 to 118°F). Since the onset temperature for the reaction was 38°C, it is likely that the reaction to produce Yellow 96 was already occurring at a very low rate at this time.

2-EHA is a combustible material, with a flash point 14 of 52°C (126°F). o -NCB has a flash point of 127°C (261°F). Thus, both substances were above their flash points during a portion of the normal process and during the runaway incident.

The staged heating procedure used by Morton to produce Yellow 96 started with an initial heatup of the reaction mixture to 90°C, with gradual increases thereafter to 150 to 153°C. With

20 14 Flash point is the minimum temperature at which a liquid gives off sufficient vapor to form an ignitable mixture with air near the surface of the liquid. Figure 7: Condenser and Vent Piping The system’s vent to the atmosphere was through the top of the condensate collection end of the condenser. Condenser Vent

Condensate Returnboth the o -NCB and the 2-EHA now in the kettle, the operators slowly raised the temperature to initiate the reaction by opening and closing valves to allow steam to enter the kettle jacket in short bursts, typically lasting several minutes. This processing step was designed to raise the temperature slowly. The expected reaction time for a batch was 6 to 8 hours.

At approximately 7:40 pm, the lead operator began to raise the temperature of the mixture by introducing steam to the kettle’s jacket. The operating procedures stated that the heating process was necessary to start the exothermic reaction used to produce the dye. To introduce steam to the kettle’s jacket, the operator opened the kettle jacket’s steam-outlet and steam-inlet valves and watched for steam to appear at the steam blow-off line. The steam and cooling-water valves were grouped on opposite sides of the kettle and were operated by hand-wheels on extension rods to the valve bodies below the operating deck. Once the jacket was filled with steam, the steam-outlet valve was closed. The lead operator applied steam to the kettle for about 10 minutes, stopping when the jacket’s pressure gauge read 5 to 10 psig. He repeated this step two more times, watching the digital temperature readout. As the temperature rose, he noticed that the rate of the kettle’s temperature rise was unusually fast. He recalled that the temperature of the batch rose quickly from 70 to 80°C (158 to 176°F) and that the tenths decimal reading on the digital temperature indicator was “moving very fast.” This rapid temperature rise began within the first 15 minutes after the start of heating. The typical heat-up rate during this phase of the process was 1–2 degrees per minute.

At approximately 8:05 pm, with the temperature at 100°C (212°F) and rising rapidly, the operators switched from heating the reactor to cooling by closing the jacket steam valves and opening the cooling water valves.

Three other experienced operators became aware of the problem and came to assist. They inquired if the cooling water was on, and at least one of them confirmed the valve positions. The lead operator re-verified the positioning of the valves to ensure that the cooling-water inlet and outlet valves were full open and that the steam-inlet and steam-condensate valves were closed. The operators stated in interviews that they had heard the sound of the cooling water flowing through the piping, another indicator they used to ensure cooling water flow. The CSB

21confirmed that the valves had been working properly.

Approximately 2 minutes passed. The operators called the supervisor to assist
and he also verified that all valves were configured properly. The temperature chart recorder, which had a maximum reading of 150°C, was now off scale and of no use to the operators, but the digital gauge showed that the temperature continued to rise. The kettle began to vibrate and very turbulent vapor appeared in the glass section of pipe above the kettle leading to the condenser (Figure 8). This vapor was composed of 2-EHA and gases generated by the decomposition reaction.

The kettle’s emergency relief system, consisting of two 6-inch rupture disks set to open at 10 psig, activated. The operators estimated that the temperature at the time the rupture disks vented was about 180 to 190°C (356 to 374°F). Figure 9 shows the recovered dual rupture disk assembly. The rupture disks were installed on the top of the kettle in a 6-inch diameter line that vented into a 10-inch diameter manifold. This manifold dumped the vapor and liquid aerosol flow into a catch tank outside Building 11. A total of 100 gallons of various chemicals were recovered from this tank after the incident. However, without information on

22 Figure 8: Glass Section of 8-inch Line to Condenser

The 8-inch line to the condenser had a glass section above the kettle head in which turbulent, refluxing vapor could be seen in Yellow 96 batch 32.the contents of the tank before the incident, the CSB could not determine which materials were vented during the event.

The batch temperature continued to increase rapidly, passing the Yellow 96 decomposition onset temperature of 195°C (383°F). The kettle began to rumble and shake more violently. One operator noticed that material was being blown up from the kettle and into the condensate return separator, indicating that the boiling of 2-EHA and the generation of gases from the reactions had exceeded the capacity of the condenser. The condenser’s tubes were flooded with liquid, and the system was trying to relieve its pressure by backward flow up the condensate return line and through the condenser vent.

At the point of the disk failure, an operator who was standing near the kettle reported that he saw the digital temperature reading increase from 190 to 260°C in less than 30 seconds. He then shouted to several other operators and started to run towards an exit. As he reached the top of the stairs located in the middle of the second floor, he heard additional sounds, including a gush of air, which he associated with the failure of the glass condensate return separator assembly. At ground level, he shouted a warning to three more workers who were unaware of the danger. They all ran toward an exit.

23 Figure 9: Rupture Disk Assembly Recovered from K-7 after the Incident (both disks blown) Disk 1 Disk 2At almost the same time, the operator and supervisor still at the kettle reported in interviews that they observed the temperature on the digital temperature readout at about 200°C (392°F). They remained unaware that the batch temperature was above the decomposition temperature of the Yellow 96 product. At this point, the operator and supervisor ran toward the second-floor northeast exit. The reaction in the kettle was vibrating the second-floor steel decking and there was a very loud rumbling, which other workers on the site thought was the sound of a train passing.

At 8:18 pm, the pressure in the kettle blew the inspection manway off the vessel. The manway was found 15 feet from the kettle, and the heat and pressure extruded the head gasket of the vessel through the bolted connection of the 30-inch bolted closure with the top head of the kettle (Figures 10 and 11).

From the open vessel manway, a jet of hot reactants erupted, emptying the vessel. The ejected material penetrated the third floor and the roof. An aerosol mixture of gas and liquid shot above the roof and spattered the adjacent neighborhood with a yellow-brown mixture of compounds including Yellow 96 and

24 Figure 10: Extruded Head Gasket This was a result of the heat and pressure that developed during the explosions. Figure 11: Recovered Inspection Manway Cover This photo shows the scars where the clamp tore away. Extruded Head Gasket Clamp Scar Clamp Scaro -NCB. This aerosol plume ignited forming a large fireball above the roof. The recoil from the expanding gases of the explosion twisted the kettle off its mounts. The kettle dropped 4 feet onto the ground level below and was found leaning against a cinder block wall. Figure 12 shows the final resting position of the vessel after the blasts and fire.

As the operator and supervisor reached the second-floor exit landing, the explosion blew them to the mid-level landing and flash fires spread throughout the building. The building’s wall panels and windows were blown out by the blast, absorbing much of the explosion’s energy and preventing greater damage. The lead operator and the supervisor were blown off the mid-level stair landing onto to the ground. They suffered second- and third-degree burns, requiring their hospitalization in intensive care for 5 days. Injuries to the other workers included first-, second-, and third-degree burns, contusions, abrasions, lacerations, and muscle strains.

25 Figure 12: Post-accident Photo of the Kettle The kettle is leaning against the east-west concrete block wall that divided the building. (The second floor grating is visible at the right edge of the photo.) (The color balance of this photo has been altered in order to show detail in the dark shadows.)

### 2.2 E MERGENCY RESPONSE

The Paterson Fire Department (PFD) arrived at 8:24 pm. The Paterson fire chief assumed command of the fire-fighting effort and called for the Hazardous Materials (HazMat) team. Fire was visible burning through the roof of the building. Before the PFD began their attack, plant personnel assembled the necessary information on the location and materials involved in the fire and the Paterson fire chief determined whether the presence of water-reactive chemicals precluded the use of water to fight the fire.

Once determined safe, water was applied to the fire. The flames were suppressed in about 1 hour, but the PFD continued the water deluge to facilitate the HazMat Team’s entry and initial survey at 9:44 pm. The HazMat Team conducted a primary and secondary search throughout the building, which indicated that all workers had escaped. The PFD team then entered the east end of the building on the second floor with a portable dry chemical fire-extinguishing unit to extinguish the remaining fires. The firewater was stopped as soon as possible to prevent washing contaminants into the Passaic River, which borders the plant’s eastern side. The fire was reported under control at 11:27 pm. The K-7 fire-suppression system, located over the top of the kettle, and the B-11 fixed fire-water deluge system were damaged by the explosion and did not aid fire suppression.

Morton collected on-site approximately 310,000 gallons of contaminated water from firefighting operations and next-day rain. Less than 10,000 gallons of contaminated firewater/stormwater reached the Passaic River, according to an estimate by Morton. 15

26 15 Morton International, Inc., to NJ Department of Environmental Protection, “Discharge Confirmation Report,” May 7, 1998, page 7.

### 2.3 O FF 

### -S ITE 

### I MPACTS

During the fire, the ambient temperature was about 40°F. It was a clear night, with light winds mostly from the northeast, switching to the southeast. These winds blew the plumes of reactants, products, and smoke off the plant site. The fallout was mainly to the west of the plant. Spots were reported on cars in the neighborhood, at an adjacent candy factory, and at a car dealership one-half mile away.

Nearby residents were ordered to shelter in-place during and immediately after the fire-fighting attacks. The shelter-in-place was conducted by the Paterson Police Department and encompassed a 10-block by 10-block area around the plant. The shelter-in-place lasted for approximately 2 to 3 hours.

During and following the fire, air monitoring was performed by various organizations, including the Passaic County Department of Health, Paterson Office of Emergency Management, the Environmental Protection Agency, and Morton. Tests conducted during the fire by the Passaic County Department of Health were negative for benzene, halogenated hydrocarbons, and nitrous compounds.

Workers at two neighboring businesses and fire fighters reported throat irritation and a slight burning in their eyes and on their skin. Several odor complaints were also received from community members.

Approximately 20 hours after the incident, a health warning statement, prepared by the Passaic County Department of Health and issued jointly with the Paterson Mayor’s office, was distributed to the local community. It advised residents to avoid contact with the deposited material, listed steps to be taken in case of health effects, and instructed residents on how to
handle contaminated items.

Wipe samples were taken of visible material deposited on automobiles and buildings near the Morton facility. These samples contained measurable quantities of Yellow 96 Dye and o -NCB.

27

### 2.4 PROPERTY DAMAGE

The open flooring in B-11, in conjunction with the blowout walls and windows, minimized the fire and blast damage to the load-bearing structure of the building.

The blast blew out the windows, doors, and blowout walls of B-11 (Figure 13). While there was some blast damage in the immediate vicinity of this reactor vessel, most of the damage was caused by the ensuing fire. The second blast was outside, above the roof.

Structural consultants subsequently determined that the load-bearing columns were not severely damaged. Overall, the building was still structurally sound and some of the equipment was salvageable.

28 Figure 13: Building 11’s Blowout Panels and Window Frames

## 3.0 ANALYSIS OF PROCESS CHEMISTRY

3.1 R EACTIVE 

### C HEMICAL 

### A NALYSIS

The runaway chemical reaction incident in the Yellow 96 process involved two reactions: (1) the desired synthesis reaction to form the product, and (2) the undesired decomposition reaction of the product.

The heat produced by the exothermic reaction that formed the product exceeded the heatremoval capacity of the kettle and rapidly raised the temperature of the batch. That heat generation caused the vapor pressure of the 2-ethylhexylamine (2-EHA) to rise until it boiled and the reaction released additional gases, pressurizing the vessel. The heat released also raised the temperature of the batch above the decomposition temperature of Yellow 96, at which point the gaseous products of the decomposition reaction resulted in even greater pressure, culminating in the explosion and the final release of material from the kettle.

Chilworth Technology, Inc., of Monmouth Junction, New Jersey, was hired by the the U.S. Chemical Safety and Hazard Investigation Board (CSB) to conduct a battery of calorimetric tests analyzing the Yellow 96 synthesis and decomposition reactions. Two exothermic reactions were observed: Reaction 1, the desired reaction of 2-EHA with ortho -nitrochlorobenzene ( o -NCB) to form Yellow 96 had an onset temperature ( T o ) of 38°C. Reaction 2, the decomposition reaction of the Yellow 96 had an onset temperature of 195°C. (The onset temperature is the lowest temperature at which exothermic activity is observed.) Chilworth also determined that the onset temperatures for the generation of permanent gases were 139°C for the desired synthesis reaction and 201°C for the decomposition reaction. 16

29 16 Chilworth Technology, Inc., to U.S. Chemical Safety and Hazard Investigation Board, Report No. R/2713BR/0400/DYK, “Closed Tube Test (Carius Tube Test) Measurement Results and Interpretation for the Thermal Decomposition of the Formation of Automate Yellow 96,” April 14, 2000.The heat released during the synthesis reaction raised the temperature of the reaction mixture. The rate of the temperature rise depended on the balance between the reaction rate, the heat capacity of the chemicals, and the rate of heat removal by the reactor’s cooling water jacket. To hold a constant temperature in the kettle after the synthesis reaction had begun, the operators manually adjusted the flow of cooling water through the water jacket, trying to balance the heat removal rate with the heat generation rate. Without any indicators for water-flow rate or for cooling-water inlet and outlet temperatures, the operators controlled the kettle’s temperature based on in-house training and experience. The operators also had to take into consideration a time lag in the temperature response of the reaction mixture to the manual adjustments in the cooling-water flow.

The released heat not only raised the batch temperature but also accelerated the reaction rate, making the temperature rise more difficult to control. The accelerating reaction rate made it more likely that the heat generated by the reaction would exceed the rate of heat removal for which the kettle was designed, resulting in a runaway, uncontrollable condition. The runaway condition occurs because the rate at which heat is removed through the jacket increases linearly with increasing temperature, while the rate at which heat is generated by the reaction increases exponentially (see Figure 14).

The reaction rate is determined both by the volumetric concentrations of the two reactants and the temperature. The rate of a reaction increases exponentially with temperature. At the beginning of the reaction, the reactants are at their maximum concentrations. As the reaction proceeds to completion, the starting materials are depleted and the reaction slows down. Therefore, at the start of the batch, with a high inventory of reactants, the influence of temperature on the heat generation rate is greatest and there is the most danger of overrunning the heat removal capacity of the kettle. As will be discussed in Section 4.0, Analysis of Process Development Program, use of a semi-batch process instead of a batch process, could have provided the operators with more control over the reaction.

The operating procedures for Yellow 96 stated that the operators should heat the reactant mixture to 90°C to initiate the reaction; however, in the operators’ experience, following the

30operating procedures resulted in a temperature increase that was difficult to control. The operators believed that the reaction between 2-EHA and o -NCB started as early as 75°C (167°F) and so most operators turned the steam heating off when the reaction temperature reached approximately 70 to 80°C. The CSB confirmed the operators’ observations: calorimetric testing determined that the onset temperature for the Yellow 96 synthesis reaction was 38°C. Therefore, the reaction would proceed slowly even at temperatures lower than was thought by the operators.

The operating procedure required that the operators should begin the heating process from a temperature of 40 to 42°C (104 to 108°F), but the operators usually started heating the initial mixture at whatever the batch temperature was after the addition of the 2-EHA to the o -NCB. The review of completed batch sheets as well as interviews showed that the starting temperature was greater than 40 to 42°C (104 to 108°F) in a number of cases, including batch 32 (as determined in interviews). Since the reaction began at 38°C, starting from a lower temperature and a correspondingly lower initial reaction rate would have given the operators more time to react and possibly control the rising temperature before the heat generation rate overran K-7’s

31 Figure 14: Heat Generation versus Heat Removal Rate If the reaction temperature exceeds point A, the rate of heat generation exceeds the rate of heat removal and the reaction will run away. (HSE, Designing and Operating Safe Chemical Reaction Processes, page 10) TemperatureRate of heat production/removal Heat production Heat removal

Acooling capacities. The operators had been able to do just that during previous batches that exhibited temperature excursions (see Section 5.3).

If the cooling water is incapable of removing all of the heat generated by the reaction, the temperature rises and accelerates the reaction rate. In batch 32, the accelerating synthesis reaction continued to generate heat, raising the temperature. As a result of this heating, the residual 2-EHA in the kettle began to vaporize rapidly as was observed in the 8-inch glass line between the kettle and the condenser by the operators.

In some batch operations evaporation and condensation (refluxing) can be an effective heatremoval technique. Heat generated by the reaction is used to boil a solvent or other materials in the reactor. This vaporized material is then cooled and converted back to liquid in a
condenser. The heat is thus transferred to the water used to cool the condenser and removed from the process. The Yellow 96 researchers in the United Kingdom considered using evaporation and condensation as a heat-removal mechanism but it was not considered in the Paterson plant design. Vaporization and condensation, however, did occur in batch 32, but the vaporization proceeded at too fast a rate for all the materials to condense, while additional noncondensable gases were also being generated. Operators had seen vigorous refluxing during the reaction in only one previous batch (batch 31), a high-temperature excursion beyond the normal operating limit.

As the reaction temperature approached 195 ° C (383 ° F), the undesired exothermic decomposition reaction of Yellow 96 began producing more heat and noncondensable gases, which further pressurized the vessel. The pressure in the vessel rose higher than the rupture disk pressure setting (10 psig). At about 180 to 190 ° C (356 to 374 ° F), the rupture disks vented, allowing material to escape to the catch tank and to the atmosphere. However, the venting area available through the rupture disks was insufficient to relieve the pressure being generated by the reaction, so the pressure in the kettle continued to rise. The 8-inch glass line to the condenser (see Figure 9) and the glass 2.5-inch condensate return line shattered, also venting reactants.

32The pressure resulting from the Yellow 96 decomposition continued to increase rapidly and
exceeded the kettle ’ s ability to relieve through the several now-opened lines. This pressurization eventually caused the manway inspection hatch to be blown off. The expanding vapors and thedecomposition gases propelled the reaction mixture through the third floor and roof as a twophase flow of vapors and liquid. 17



### 3.2 T ESTS OF 

### R AW 

### M ATERIALS

NASA ’ s White Sands Test Facility 18 and Chilworth 19 conducted differential thermal analysis 20 tests for the CSB on the two raw materials. No exothermic reactions or pressure spikes were detected for the individual reactants until temperatures were above the maximum Yellow 96 operating temperature (160 ° C). After the incident, the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA), and Morton analyzed the unused raw materials and determined that the reactants used were within the expected quality range. These tests confirmed that the runaway reaction was not the result of contamination from
the raw materials.

33 17 An analogy for the eruption of two-phase flow from the kettle is the release of gas, liquid, and foam observed when a container of carbonated beverage is shaken and then opened.
18 NASA, White Sands Test Facility, “ NASA Analyses of the Reaction of ortho -Nitrochlorobenzene with 2-Ethylhexylamine, ” September 1998. 19 Chilworth Technology, Inc., to U.S. Chemical Safety and Hazard Investigation Board, Report No. R/2713/0600/BC, “ Differential Scanning Calorimetry of 2-Ethylhexylamine, chloronitrobenzene and Automate Yellow 96 (Crude and Pure), ” June 2, 2000.
20 Differential Thermal Analysis (DTA) is a preliminary screening test, similar to the Differential Scanning Calorimetry (DSC) performed by Morton in 1987. DTA is used to determine whether an exotherm occurs, the exothermic onset temperature, and the amount of heat generated. The DTA test used small samples, e.g., several milligrams. The sample is heated at a controlled rate. The onset temperature, T o , is the temperature at which the sample first shows an observable thermal response due to reaction or decomposition.

## 4.0 ANALYSIS OF PROCESS DEVELOPMENT PROGRAM

The Yellow 96 process went through several research phases at different branches of Morton. (The Timeline in Appendix B summarizes important dates in the development and production of Yellow 96.) The company began its research with small-scale reactions in 1986 at their Hounslow, England, facility. Larger experimental batches of Yellow 96 were produced in 1987 and 1988. Morton researchers observed exothermic activity in these tests. Morton contracted Brunel University in the United Kingdom to perform differential scanning calorimetry (a typical screening test for exothermic activity) on the reaction in 1987. In these tests, “ the material was found to decompose with considerable generation of heat at above 220 ° C. ” 21 Morton developed a semi-batch, staged addition process to control the exothermic reaction rate in these early
trials. The researchers added the ortho -nitrochlorobenzene ( o -NCB) to the 2-ethylhexylamine (2-EHA) in four equal portions and allowed the reaction to run its course and subside between

o -NCB additions. 22

In 1989, the researchers at Hounslow wrote a review of the process in which they made a number of recommendations regarding the reaction control and safety. This review was faxed to the Paterson plant on April 28, 1989. 23 Among other things, the researchers recommended controlled cooling-water addition directly into the reactor as an emergency method to stop a runaway reaction.

This process review memo also included the recommendation that accelerating rate calorimetry testing be performed to determine “ the rate of reaction under the worst reaction conditions ... the rate of decomposition of the finished product ... [and] pressure rise data which could be

34 21 CSB-NJ249, CSBINSP002548, Morton Internal Memorandum, R. Pollington to C.J. Bird, et al., “ Thermal Stability of Yellow 152, ” April 8, 1988.
22 During much of the development work, Morton referred to the Yellow 96 material as “ Liquid Yellow 152 ” or

“ Sudan Yellow 152. ”
23 CSB-NJ248, CSBINSP002476, fax message, A. Pearce to J.J. Fuerholzer, April 28, 1989.used to size emergency venting equipment .... ” 24 Morton did not perform these additional tests or install the recommended safety equipment.

In late 1989, Morton transferred its research effort on Yellow 96 to the United States. Initial research was conducted at the Paterson plant. Paterson revised the process from semi-batch to a full-batch process in order to minimize employee exposure to o -NCB. In the batch process, the
full amounts of o -NCB and 2-EHA were added to the reactor first, and heat was then applied to initiate the reaction and drive it to completion. This procedure, with one total addition of

o -NCB versus the four partial additions in the semi-batch process, was used throughout Yellow 96 production at Paterson. Morton did not take into account that switching from their initial, semi-batch process to the full-batch process resulted in a more hazardous condition.

In Inherently Safer Chemical Processes, the Center for Chemical Process Safety notes: “ Semibatch or gradual addition batch processes [Morton ’ s initial process design] limit the supply of one or more reactants, and increase safety when compared to batch processes in which all reactants are included in the initial batch charges [Morton ’ s production process]. For an exothermic reaction, the total energy of reaction available in the reactor at any time is
minimized. ” 25 The U.K. Health and Safety Executive (HSE) writes in a recent publication that semi-batch processes “ reduce the quantity of reactant present and controlling the addition rate may stop the reaction in the event of a hazard arising. ” 26 At the start of the batch process, when the reactant concentrations were at their maximum levels, the influence of temperature on the rate of heat generation was greatest, and there was the most danger of exceeding the heat removal capacity of the kettles.

Paterson ’ s research did not specifically test for the exothermic reactions and their lab-scale work did not reveal the runaway potential of these reactions. After receiving additional

35 24 CSB-NJ249, Morton Internal Memorandum, R. Pollington to C.B. Bird, et al., “ LY 152 Process Review, ” April 8, 1989.
25 Center for Chemical Process Safety. Inherently Safer Chemical Processes, A Life Cycle Approach ; American Institute of Chemical Engineers: New York, 1996, 44.
26 Health and Safety Executive. “ Designing and Operating Safe Chemical Reaction Processes, ” HSE Books: Norwich, U.K., 2000, 16

– 17.documentation from Hounslow alerting them to the possibility of a runaway exothermic reaction, including the process review memo noted above, Paterson researchers performed further experiments and determined that they could adjust the temperatures of the reaction to

“ reduce the potential for overheating the mixture. ”

Morton also conducted research at its Ringwood, Illinois, semiworks facility, producing six trial batches of material, in sizes of 80 to 425 gallons. In these pilot-scale batches, Morton was able to control the exothermic reaction within operating limits.

Paterson staff used a “ Premanufacturing Process Review Checklist ” as a guide for bringing Yellow 96 to full-scale production in 1990. The Yellow 96 checklist contained an information package (process transmittal) received from the Ringwood semiworks facility. The information included batch sheets from the Ringwood batches, material safety data sheets (MSDSs) for the materials used in the process, and several memos and notes relating to the process. The memos noted the presence of an exothermic reaction but stated that the process could be controlled by correctly following the operating steps.

Morton did not conduct a preliminary hazard assessment when they brought Yellow 96 to production in 1990. Preliminary hazard assessment and Process Hazard Analysis techniques were in use throughout the chemical process industries at this time and had been gathered and published by the Center for Chemical Process Safety in 1989, 3 years before OSHA ’ s promulgation of the Process Safety Management rule. 27,28

The observations by the Morton researchers of the several laboratory and pilot-scale batches performed in the United States were the determining factor in Paterson ’ s analysis of the safety of the process. To design a safe reaction process, certain basic information is required. The

36 27 Center for Chemical Process Safety. Guidelines for Hazard Evaluation Procedures, American Institute of Chemical Engineers: New York, 1985.
28 Center for Chemical Process Safety. Guidelines for Technical Management of Chemical Process Safety, American Institute of Chemical Engineers: New York, 1989.empirical ability to control the process in laboratory and pilot plant should have been augmented by additional key engineering work, such as:

● Conducting additional calorimetric testing when the process was changed from staged
addition of o -NCB to staged heating of the entire reaction mass.

● Calculating a heat and mass balance to determine if there was sufficient heat removal capability in the reactors to handle foreseeable events and to determine the influence of
reactor vessel size on this function.

● Determining the worst case venting scenario and sizing the reactor ’ s safety relief devices accordingly. The pressure relief devices on the Paterson reactors had been sized for the scenario of an external fire that would boil xylene in the kettle. Morton did not run calculations to determine if the relief devices could safely vent the pressure generated by a runaway exothermic reaction or if the reaction vessels were strong enough to safely contain the maximum expected pressure.

37

## 5.0 ANALYSIS OF PROCESS SAFETY MANAGEMENT PROGRAM

Morton ’ s Process Safety Management (PSM) program did not require adherence to a number of industry good practice guidelines for the safe management of reactive chemical processes. Morton also did not effectively implement important requirements of their internal PSM program. Deviations in the following areas were important factors leading to the accident:

● Process Safety Information

● Process Hazard Analysis

● Investigation of Problems with Previous Batches

● Management of Change

● Operating Procedures and Training



### 5.1 P ROCESS 

### S AFETY 

### I NFORMATION

Paterson facility personnel were not aware of the existence of the decomposition reaction. The Process Safety Information (PSI) package, which was used by the Paterson personnel to design the Yellow 96 production process in 1990 and which served as the basis for a Process Hazard Analysis (PHA) conducted in 1995, noted the desired exothermic synthesis reaction, but did not include information on the undesired exothermic decomposition reaction.

The Yellow 96 process safety information package did not contain details of the research on the exothermic reactions performed at Hounslow nor did it contain the recommendations made by Hounslow for process safety, control, and additional testing in the “ LY 152 Process Review ” memo, which had been faxed to Paterson on April 28, 1989. Inclusion of this information in the process safety information package was a requirement of Morton ’ s PSM program.

38Morton ’ s Material Safety Data Sheet (MSDS) for Yellow 96 Dye stated that the National Fire Protection Association (NFPA) Reactivity Hazard Rating 29 for this material was a 0 (on a 0 to 4 scale, with 4 being the most reactive). The U.S. Chemical Safety and Hazard Investigation Board (CSB) has determined that the proper reactivity rating for Yellow 96 Dye is 1. 30,31 The reactivity rating is a ranking of the “ degree of susceptibility of materials to energy release. Some materials are capable of rapid release of energy by themselves, through self-reaction or polymerization, or can undergo violent explosive reaction through contact with water or other extinguishing agents or with certain other materials. ” 32 The NFPA defines 0 materials as

“ materials that in themselves are normally stable, even under fire conditions, ” while 1 materials

are “ normally stable, but ... can become unstable at elevated temperatures and pressures. ” 33 The NFPA ratings are used by emergency responders, employees, and customers, as an indicator for the degree of hazard associated with a chemical. Erroneous information regarding reactive hazards can result in errors in handling or responding to emergencies. In this incident, the difference did not affect the emergency response activities.

The Yellow 96 Dye MSDS also stated that the compound ’ s boiling point was 100 ° C. The CSB determined that the boiling point is actually much higher, approximately, 330 ° C, which is greater than the decomposition onset temperature of 195 ° C. While not contributing to causing the incident, the foregoing MSDS discrepancies are examples of shortcomings in Morton ’ s Process Safety Information package.

39 29 NFPA704, “ Standard System for the Identification of the Hazards of Materials for Emergency Response, ” 1996 edition, pages 704

– 707. The NFPA hazard rating system is intended to provide basic information for fire fighters and emergency responders. In addition to reactivity, the NFPA system rates fire and health hazards on the same 0 to 4 scale.
30 Chilworth Technology, Inc., to U.S. Chemical Safety and Hazard Investigation Board, Report No. R/2785/0600/BC, “ Instantaneous Power Density via Differential Scanning Calorimetry, ” June 26, 2000.
31 Based on determination of the Instantaneous Power Density (IPD) of Yellow 96 per the method of NFPA 704, 1996 edition.
32 NFPA704, “ Standard System for the Identification of the Hazards of Materials for Emergency Response, ” 1996 edition, pages 704

– 707.
33 Ibid., pages 704

– 708.

### 5.2 P ROCESS 

### H AZARD 

### A NALYSIS

Process hazard analysis (PHA) is a structured, in-depth examination of a chemical plant process. The objectives of a PHA are to:

● identify the factors in the process that have the potential to cause undesired events (process hazards);

● uncover the foreseeable sequences of events (scenarios) that could lead to the realization of these hazards;

● evaluate the consequences of these scenarios should they occur;

● propose improvements, as warranted, to equipment and procedures that either reduce or eliminate the hazards, prevent the scenarios from occurring or mitigate their consequences.

The PHA conducted for the Yellow 96 process did not address the consequences of potential deviations such as excessive heating, a runaway reaction, or the inability to provide enough cooling to maintain temperatures in a safe operating range.

The formal PHA for Yellow 96 was conducted in January 1995, approximately 4 years after the first batch was produced at Paterson. The PHA was performed using the “ What If? ” method of analysis. The PHA team analyzed the raw material storage tanks; the weigh tanks; the kettle vessel/agitation/instrumentation; the kettle condensers, receivers, piping, valves, and pumps; the elevator and pallet jack; the water scrubber; the dye coupling tanks; and the various site support systems. The PHA did not specifically address the processing of Yellow 96 in K-7 but generally covered all of the reactor kettles, both 1000- and 2000-gallon capacity.

As noted earlier, the Paterson Plant received a number of memos from the Ringwood facility that indicated the potential for a thermal runaway in the Yellow 96 process. Ringwood stated,

“ If the batch [ ortho -nitrochlorobenzene ( o -NCB) charge to the kettle] is left to warm, then it

40will exotherm strongly upon the addition of the 2-ethylhexylamine. ” 34 In another memo, referring to the first 100-gallon, pilot-scale batch, Ringwood noted, “ The concern about exothermic conditions as expressed by... [the Morton Hounslow facility] had been seen previously during the initial R&D [research and development] work. This can easily be handled by starting the reaction at ambient temperature and proceed with staged heat-up with holds at predetermined temperature ranges. ” 35

When the question, “ What if runaway reaction occurs? ” was asked, the PHA team recorded the hazard and consequences as “ Not Applicable. ” The PHA team relied on the information from the Ringwood pilot plant and the success of the pilot batches and the apparent success of the Paterson batches to reach this conclusion. As noted earlier, PHA team members stated that they were not aware of the work done in Hounslow to characterize the exothermic reactions although
this work had been sent to Paterson in 1989. The PHA team did not take into consideration the potential for a runaway reaction, although the potential was evident in the product development
information.

An effective PHA program requires examination of deviations from normal operations that could turn an exothermic reaction into a runaway situation. The PHA team should have
considered such deviations as: “ What if the o -NCB is warmer than specified prior to 2-EHA
addition? ” and “ What if the predetermined temperature ranges of the staged heat-up process cannot be met due to equipment or instrumentation malfunction? ” The PHA addressed the question of the failure of the heating system, but it did not ask the question, “ What if there is inadequate cooling? ”

The PHA team did not consider the potential ramifications of the high temperature excursions in batches 3, 5, 14, and 15 (see Section 5.3

– Investigation of Problems with Previous Batches). Investigation of these occurrences would have provided an opportunity to correct design problems, which likely would have prevented the incident.

41 34 CSB-NJ250, CSBINSP002395, Morton Internal Document, Automate Yellow 96, Process Suggestions.
35 CSB-NJ250, CSBINSP002414, Morton Internal Memorandum, M. Friswell to J.J. Fuerholzer, May 18, 1989.As a result of not recognizing the potential for a runaway reaction, the PHA team did not consider the need for additional safeguards, such as the ones Hounslow recommended in the 1989 process review memo. These recommendations included: temperature alarm, agitator failure alarm, level alarm, pressure alarm, and emergency cooling water addition directly into
the reactor. 36

The late Frank P. Lees, an internationally recognized process safety expert, stated, with regard to emergency safety measures: There are a number of emergency measures that can be taken if a process deviation occurs which threatens to lead to a runaway reaction. The prime

measures are: (1) inhibition of reaction; (2) quenching of reaction; (3) dumping. The reaction may be stopped by the addition of an inhibitor, or short stop. This involves the use of an inhibitor specific to the reaction in question.... Quenching involves adding a quenching agent, usually water under gravity, to the reaction mass to cool and dilute it.... The third method is dumping, which involves dropping the reactor charge under gravity into a quench vessel beneath which contains a quench liquid. Other methods, which can be used to slow the reaction but are not generally ranked as prime emergency safety measures, include: (1) shut-off of feed; (2) direct removal of heat; (3) indirect removal of heat; (a) full normal cooling; (b) emergency cooling. 37

The Hounslow recommendations of 1989 did suggest controlled quenching of the reaction with water as an emergency safety measure. The Lees publication does not list the measures actually used at Paterson (direct removal of heat and full normal cooling) as prime emergency safety

42 36 CSB-NJ249, Morton Internal Memorandum, R. Pollington to C.B. Bird, et al., “ LY 152 Process Review, ” April 8, 1989.
37 Lees, Frank P. Loss Prevention in the Process Industries; Hazard Identification, Assessment and Control, Volume 1, 2 nd Edition, Butterworth-Heinemann: Oxford, 1996, 11/59

– 60.measures. Quenching with water may not have been appropriate given the fact that the process was being run above the boiling point of water (condenser and relief vents would have had to be sized to safely handle the water vapor generated as the heat of reaction was removed from the kettle); however, this is another example of a possible safety improvement that should have been considered during the process design effort.

The PHA team also did not question whether the relief device sizing was adequate. Effective PSM programs require that PHA teams consider scenarios that might require pressure relief, such as runaway reactions, loss of cooling, loss of agitation, or errors in the addition of reactants. The necessary venting area is then determined through laboratory testing and calculations. Venting scenarios such as these were not discussed during the Yellow 96 PHA. Instead, the PHA participants relied on the information they had received from the Ringwood pilot plant that a runaway situation was not expected. As a result, the kettle ’ s venting systems were not designed to handle the pressure generation rate of the runaway reaction but had instead been sized for a scenario of an external fire that would boil xylene in the kettle.

After the incident, Morton calculated that a vent area of 116 square inches would have been required to properly vent the two-phase flow mixture that resulted from the decomposition
reaction. 38 On K-7, the 6-inch rupture disk had a venting area of only 28.3 square inches.



### 5.3 I NVESTIGATION OF 

### P ROBLEMS WITH 

### P REVIOUS 

### B ATCHES

A number of previous batches of Yellow 96 had exhibited unexpected exothermic activity as shown by high temperature excursions beyond the normal operating range. These batches exhibited unusual temperature profiles or exceeded the maximum operating temperatures. In

43 38 Morton calculated the required vent area using the DIERS methodology. DIERS (Design Institute of Emergency Relief Systems) is a consortium of companies, formed in 1976 by the American Institute of Chemical Engineers, to develop methods for the design of emergency relief systems to handle runaway reactions. The DIERS group has developed computer programs and a bench-scale test apparatus for assessing the venting requirements of runaway reactions and two-phase flow.each of these incidents, the operators were able to regain control of the batch temperature and complete the batch. Management did not investigate these warning events in the processing history of Yellow 96 and did not consider these previous incidents during the PHA.

Significant prior incidents involving 1000-gallon reactor vessels included the following:

● Batch 3 (1991): 39 The operators noted on the batch sheet “ cooling not controlling temp. ” The operators recorded a temperature of 134 ° C during the step for heating the batch from
90 to 110 ° C.

● Batch 5 (November 1991): The operators noted “ Temp override to 120 ... cooling inadequate to control temp ” during a specified temperature hold at 108 to 110 ° C.

● Batches 14, 15, and 18 (July and September 1994, and September 1995): The temperature recording charts for these batches indicate that the temperature rose quickly and remained off-scale (greater than 150 ° C) for approximately 30 minutes for batches 14 and 15 and 75
minutes for batch 18.

Starting with batch 25 in 1996, Morton began producing Yellow 96 in 2000-gallon reactor vessels. Significant occurrences following this change included:

● Batch 28 (April 1997): The operators noted on the batch sheet “ cooling water of no use, ” when trying to maintain the batch temperature at 110 ° C. The batch sheets indicate that batch temperature rose much more quickly than expected.

● Batch 30 (October 1997): The temperature of this batch rose quickly and remained off the temperature recording chart (maximum temperature of 150 ° C) for approximately 30
minutes.

44 39 Two Morton batch sheets were labeled as batch 3. The batch in question was labeled CSBINSP003200-3213 in the data received from Morton.● Batch 31 (March 1998): As in batch 30, the reactor temperature rose quickly and remained off the chart for approximately 45 minutes. Based on operators ’ comments during interviews, the temperature of this batch reached 180

– 200 ° C.

The operators ’ written notes in the batch sheets, detailed above, should have served as notification to management of the temperature control problems and prompted the supervisors to investigate these problems. However, the operators did not always record high temperatures on the batch sheets and they did not verbally inform supervisors of the temperature excursions when they were able to regain control of a batch. One operator reported in an interview that he had brought these issues to the attention of his supervisor, but no supervisors recalled this contact. Several supervisors were aware that high temperatures had occurred in the past. However, supervisors stated in interviews that high temperatures were considered a quality concern, not a safety issue. The batch sheets for Yellow 96 mirrored this quality concern, stating, “ DO NOT heat batch above 160 ° C or yield and quality will be lower. ”



### 5.4 M ANAGEMENT OF 

### C HANGE

Beginning with batch 25, in 1996, Paterson began producing Yellow 96 in 2000-gallon kettles versus the 1000-gallon kettles that had been used for the first 24 batches. At that time, Paterson also scaled-up the Yellow 96 batch size by approximately 9 percent. The CSB determined that the combination of these two changes resulted in a reduction of approximately 10 percent in available heat transfer area per gallon of material. Therefore, the batches produced in the 2000- gallon kettles had less cooling per gallon of reacting material than batches made in the 1000- gallon kettles. Given the fact that the reaction was being run at temperatures very close to the runaway conditions, it was less likely that the operators would be able to control the process in the larger kettles.

Paterson did not use its management of change procedures to review the safety of these changes even though they met the definition of a change in Paterson ’ s PSM program. The batch sheets

45were never modified to reflect the use of 2000-gallon kettles. The batch sheet in use at the time of the April 1998, incident was last revised in August 1996. It specified the use of a 1000-gallon kettle. The scaled up volumes of o -NCB and 2-EHA were indicated on the batch sheets by crossing-out the old volumes and writing in the increased amounts.



### 5.5 O PERATING 

### P ROCEDURES AND 

### T RAINING

The Yellow 96 batch sheet contained little direction for the operators on how to manage the
exothermic reaction between o -NCB and 2-EHA. As a result, each operator ran the Yellow 96 process slightly differently. This lack of direction had safety consequences, as discussed in the examples below.

● The batch sheet stated, after adding o -NCB to the kettle, to “ Adjust temperature of kettle to
40

– 42 ° C with mixing. ” With an onset temperature of 38 ° C, higher temperatures could lead to early initiation of the reaction and make it less likely that the operators could control the
reaction.

● The batch sheet stated, after adding the 2-EHA, to “ Make sure cooling water is on the condenser then carefully heat batch to 90 ° C. Note: DO NOT overheat or batch will start to
exotherm. ” The next step was to “ [c]arefully give batch small shots of steam to raise the temperature 2

– 3 ° C if necessary. Watch batch temperature carefully as batch will exotherm
from 90 ° C

– 110 ° C over 10 minutes. ” There were no instructions on how much steam to use or how long to apply steam. Consequently, each operator had their own technique and looked for different temperature milestones to determine when to switch from steam to cooling water. The operators who ran batch 32 stated that they let steam enter the vessel jacket to heat up the batch for 5 to 10 minutes with 5 to 10 pounds of steam pressure on the jacket. They did not apply cooling water until the batch reached a temperature of 100 to
110 ° C. This was contrary to the experience of other operators and supervisors who stated

46that the amount of steam admitted into the jacket should be minimal, lasting 1 to 5 minutes, and cooling water should be applied when the batch temperature reached 70 to 80 ° C.

● A note following the final reaction step stated, “ DO NOT heat batch above 160 ° C or yield and quality will be lower. ” Operators and supervisors stated during interviews that they had not been trained regarding the risk of a runaway exothermic reaction in the Yellow 96 process. They believed that temperatures higher than the maximum temperature of 160 ° C would result only in quality problems with the finished product. In addition, the temperature chart could not record temperatures above 150 ° C, limiting Morton ’ s ability to document the temperature profile of a batch and identify abnormal temperature deviations.

The additional steam used in batch 32 raised the reaction rate of the Yellow 96 synthesis reaction to a point at which it was generating heat faster than it could be removed by cooling water. The immediate cause of the incident highlights the dangerous circumstances under which the operators were instructed to run the Yellow 96 process:

● The batch sheet provided incomplete information on how much heating the batch required. New operators were trained on-the-job by working with an experienced operator, but batches of Yellow 96 were made infrequently, and so on-the-job training was infrequent. Each operator used their own experience as their guide.

● There was no instrumentation that operators could use to measure the amount of steam being used or cooling water temperatures to ensure consistency of batch temperatures from
batch to batch.

● While the operators and supervisors knew the batch was sensitive to heat, they were unaware of the possible outcomes of a runaway reaction.

Plant operating procedures (batch sheets) did not address the handling of emergency situations in the kettles. Operators were not sufficiently trained to understand fully, or to react appropriately, to the runaway reaction. Other than the instruction to ensure that the cooling water was on, the operators were given no other direction for emergency situations. They were

47not trained to recognize the hazards associated with the Yellow 96 process and consequently did not recognize when they should have evacuated the building. Operators were instructed to obtain help from supervision when unusual events occurred.

On the evening of the incident, the supervisor, the two principle operators, and two other chemical operators stayed by the runaway kettle while: (1) the rapidly rising batch temperature exceeded the operating procedure limit of 160 ° C, (2) the residual 2-EHA started boiling and the reaction generated additional gases, (3) the violently boiling mixture flooded the condenser, (4) the kettle rupture disks actuated because of the vessel ’ s pressurization, (5) the kettle began rumbling and shaking, and (6) the kettle temperature exceeded the decomposition onset temperature range for Yellow 96 of 195 ° C. After the operators established that heating was off, full cooling was on and the temperature of the batch continued to rise, their presence could not contribute anything to preventing an incident such as the one that occurred.

48

## 6.0 REGULATORY OVERSIGHT ANALYSIS

The Occupational Safety and Health Administration ’ s (OSHA) Process Safety Management (PSM) standard (29 CFR 1910.119) provides only minimum requirements for process safety management and provides little guidance with respect to reactive chemical process safety management. The lack of guidance did not contribute directly to causing the incident. However, additional guidelines in such areas as reporting and investigating deviations from normal operations, the use of chemical screening techniques, and proper design for pressure relief, emergency cooling, and safety interlock systems would likely have helped the Morton Paterson staff to recognize the hazards of the Yellow 96 process and take steps to avoid the incident.



### 6.1 R EGULATORY 

### C OVERAGE

The OSHA PSM standard did not cover the Yellow 96 process. However, Morton included the process under its internal PSM program, which was applied to OSHA-regulated processes and certain other processes. In most respects, Morton patterned its program after the OSHA standard; however, there were significant omissions and differences. Also, the Morton program did not require adherence to a number of industry good practices for the safe management of reactive chemical processes.

OSHA only refers to reactivity hazards as two of the information requirements in the PSM
standard ’ s Process Safety Information element subheading, “ Information pertaining to the hazards of the highly hazardous chemicals in the process, ” 1910.119(d)(1): “ (iv) Reactivity data [and] (vi) Thermal and chemical stability data. ” In addition, the Non-Mandatory Appendix to the standard states,

“ The information to be compiled about the chemicals, including process intermediates, needs to be comprehensive enough for an accurate assessment of the fire and explosion characteristics, reactivity hazards, the safety and health hazards to workers, and the corrosion and erosion effects on the process equipment and monitoring tools. Current material safety data sheet (MSDS)

49information can be used to help meet this requirement which must be supplemented with process chemistry information including runaway reaction and over pressure hazards if applicable. ”

The OSHA PSM standard covers certain reactive chemicals ranked as 3 and 4 under the
National Fire Protection Association ’ s (NFPA) 0 to 4 reactivity ranking system. 40 Reactive chemicals are not covered under the Environmental Protection Agency ’ s (EPA) Risk Management Plan rule. Some reactive chemicals are listed by the EPA because they qualify for inclusion due to their toxic or flammable properties. The raw materials and the Yellow 96 Dye were all assigned a 0 reactivity rating on their respective material safety data sheets. However, as was the case with the Yellow 96 process, many chemicals with low reactivity rankings can be very reactive in combination with other chemicals or at temperatures that are reached only as a result of deviations from normal operating conditions.

In 1995, OSHA received a petition 41 to promulgate an Emergency Temporary Standard (ETS) as the result of an incident at Napp Technologies, Inc., in Lodi, New Jersey, on April 21, 1995, that killed five people. The petition stated that the PSM standard “ fails to comprehensively cover
reactive chemicals ” and requested that OSHA reopen the standard. As of August 2000, OSHA has not acted on this petition.

50 40 In NFPA 704, the NFPA defines “ 3s ” as “ materials that in themselves are capable of detonation or explosive reaction, but that require a strong initiating source or that must be heated under confinement before initiation. ”

“ 4s ” are defined as “ materials that in themselves are capable of detonation or explosive reaction at normal temperatures and pressures. ” 41 Eric Frumin, et al., to Mr. Joe Dear, Asst. Secretary for Occupational Safety and Health, “ Petition for Emergency Revision of Standards on Process Safety Management and Emergency Response, ” October 23, 1995. The petitioners were Union of Needletrades, Industrial and Textile Employees; United Steelworkers of America; Oil, Chemical and Atomic Workers; AFL-CIO; International Association of Fire Fighters and International Chemical Workers Union.

### 6.2 M ORTON 

### PSM P ROGRAM

Morton ’ s written Process Safety Management program did not include a number of OSHA PSM requirements. The U.S. Chemical Safety and Hazard Investigation Board (CSB) also identified areas in which Morton did not implement their PSM program.

Examples of inadequacies in Paterson ’ s PSM program included the following:

● Under the requirements for what the Process Hazard Analysis (PHA) shall address, the Morton program did not include the OSHA requirement for “ The identification of any previous incident which had a likely potential for catastrophic consequences in the workplace. ” As stated earlier, investigation of these occurrences would have provided an opportunity to correct design problems, which likely would have prevented the incident.

● Under OSHA PSM requirements, an operating procedure is required for Emergency
Shutdown. Morton ’ s program simply lists “ Emergency Shutdown ” in a list of required procedures and omitted OSHA ’ s requirements that the procedures should state the conditions under which shutdown is required and the operator ’ s responsibilities. Inclusion of this information in operating procedures and training likely would have led the operators to evacuate sooner, thus preventing their injuries.

Examples of inadequacies in Paterson ’ s implementation of its PSM program included the following:

● Morton ’ s program required that the process safety information package should contain

“ Copies of any laboratory, pilot plant, or other testing work (including that performed outside the company) which pertains to the hazards posed by the chemicals used in the

process. ” There were a number of memos and notes that touched on the exothermic nature of the Yellow 96 process, but the testing results and memos that explicitly discussed the runaway potential were not provided to the PHA team or used to inform operations personnel. Using this information in process reviews and in training would have made personnel more aware of the hazards of the process.

51● Morton ’ s program required information on chemical reactions and equations for primary and important secondary, or side reactions addressing all chemicals associated with the process, including discharge and by-products. Also required, if available, were kinetics data for important process reactions, including order, rate constants vs. time, approach to equilibrium, and kinetics data for undesirable reactions, such as decompositions and autopolymerizations. This information was not compiled for the Yellow 96 process although the information had been developed and was available.

● The change from the 1000-gallon to the 2000-gallon kettle was not approved through a Management of Change process, although the change met Morton ’ s definition of a change. A change of this magnitude should also have been reviewed in a PHA per Morton ’ s procedure. Again, Morton missed an opportunity to assess the hazards of the process and take steps to avoid an incident.



### 6.3 G OOD 

### P RACTICE 

### G UIDELINES

Good practice guidelines, such as the Center for Chemical Process Safety publications, 42,43 were available prior to the startup of Yellow 96 production in 1990. Other guidelines (see References) became available prior to the Yellow 96 Process Hazard Review in 1995. Use of these guidelines would have provided the Morton Paterson staff with information on the means to identify the potential reactive hazards and would likely have led them to take steps to prevent
the incident.

Additional guidelines are now available from the Center for Chemical Process Safety ’ s books on reactive chemicals (see References), Lees ’ s Loss Prevention in the Process Industries 44 and

52 42 Center for Chemical Process Safety. Guidelines for Hazard Evaluation Procedures, American Institute of Chemical Engineers: New York, 1985.
43 Center for Chemical Process Safety. Guidelines for Technical Management of Chemical Process Safety, American Institute of Chemical Engineers: New York, 1989.
44 Lees, Frank P. Loss Prevention in the Process Industries; Hazard Identification, Assessment and Control, 2 nd Edition, Butterworth-Heinemann: Oxford, 1996.the U.K. Health and Safety Executive ’ s booklet, “ Designing and Operating Safe Chemical
Reaction Processes. ” 45 The U.K. guidelines, published in May 2000, are a consensus product of government, industry, and labor. Use of these types of guidance documents by Morton staff could have provided them with sufficient information and awareness of the reactive hazards that likely would have helped them to take actions to prevent the incident.

Government-issued safety guidelines on other topics, such as those issued by OSHA and EPA, have been used extensively by industry. For example, the EPA ’ s Off-Site Consequence Analysis Guidance is used by industry in complying with the EPA ’ s Risk Management Plan requirements.



### 6.4 R ECENT 

### C ATASTROPHIC 

### R EACTIVE 

### C HEMICAL 

### I NCIDENTS

The Chemical Safety Board, and safety professionals in general, currently face limitations in their ability to obtain information on reactive chemical incidents. Detailed analysis of root causes is only available for several major incidents in recent years. Expanded information on the root causes of incidents would provide data on trends in reactive chemical process safety management and on the effects of federal and state regulations and consensus standards on the frequency and severity of reactive chemical incidents.

Napp Technologies Incident 46

The 1995 Napp explosion and fire in Lodi, New Jersey resulted in five deaths as well as injuries, public evacuations, and serious damage both on and off the site. A joint EPA/OSHA team investigated this event. At the time of the incident, Napp was conducting a mixing operation involving water-reactive chemicals. The operation, which should have been completed in less

53 45 Health and Safety Executive. “ Designing and Operating Safe Chemical Reaction Processes, ” HSE Books: Norwich U.K., 2000.
46 EPA/OSHA Joint Chemical Accident Investigation Report, Napp Technologies, Inc., Lodi, New Jersey, EPA 550-R-97-002, October 1997.than 1 hour, continued for nearly 24 hours. Operators noticed an unexpected reaction taking place in the blender, producing heat and the release of a foul-smelling gas. During an emergency operation to remove the contents of the blender, the material ignited and a deflagration occurred that resulted in the deaths of the employees and the destruction of the facility.

According to the EPA/OSHA report, the most likely cause of the incident was the inadvertent introduction of water into water-reactive materials (aluminum powder and sodium hydrosulfite) during the mixing operation. The water caused the sodium hydrosulfite in the blender to decompose, generating heat, sulfur dioxide, and additional water. The decomposition process, once started, was self-sustaining. The reaction generated sufficient heat to cause the aluminum powder to react rapidly with the other ingredients and generate more heat, until the point of deflagration was reached. As in the Morton case, the chemicals and chemical reactions involved in the Napp incident were not covered under the OSHA PSM standard.

Georgia-Pacific Resins Incident 47

In 1997, an explosion at a resins production unit at Georgia-Pacific Resins, Inc. in Columbus, Ohio, killed one worker and injured four others. This explosion was caused by a runaway reaction. As detailed in an EPA Chemical Safety Case Study on this event, “ the runaway was triggered when, contrary to standard operating procedures, all the raw materials and catalyst were charged to the reactor at once followed by the addition of heat. Under the runaway conditions, the heat generated exceeded the cooling capacity of the system and the pressure generated could not be vented through the emergency relief system causing the reactor to explode. ”

The PHA conducted for the Georgia-Pacific process did not consider the failure to control the rate of chemical addition to the process. In addition, the pressure relief system was not sized to handle the pressure rise from such an event. 48

54 47 U.S. Environmental Protection Agency. “ How to Prevent Runaway Reactions, Case Study: PhenolFormaldehyde Reaction Hazards, ” EPA 550-F99-004, August 1999.
48 Belke, James C. “ Recurring Causes of Recent Chemical Accidents, ” proceedings of the International Conference and Workshop on Reliability and Risk Management, September 15

– 18, 1998, page 463.Napp, Morton, and Georgia-Pacific were three of the most significant and highly studied reactive chemical incidents to occur in the United States in recent years but they were not the only incidents:

● In its Safety Alert on the Georgia-Pacific incident, EPA noted six other phenolformaldehyde reaction incidents that had occurred since 1989. 49

● Databases such as the EPA ’ s Emergency Response Notification System, OSHA ’ s incident statistics, and the U.K. Institution of Chemical Engineers ’ incident database contain over 30 events in the last decade that were characterized by keywords such as “ exothermic
reaction ” or “ runaway reaction. ”

55 49 U.S. Environmental Protection Agency. “ How to Prevent Runaway Reactions, Case Study: PhenolFormaldehyde Reaction Hazards, ” EPA 550-F99-004, August 1999, page 2.56 

## 7.0 ROOT AND CONTRIBUTING CAUSES

7.1 R OOT 

### C AUSES

1. Neither the preliminary hazard assessment conducted by Morton in Paterson during the design phase in 1990 nor the process hazard analysis conducted in 1995 addressed the reactive hazards of the Yellow 96 process.

Not addressing these hazards resulted in the following design, operational, and training
deficiencies:

● The kettle cooling system could not safely control the exothermic Yellow 96 synthesis
reaction.

● The kettle was not equipped with safety equipment, such as a quench system or a reactor dump system, to stop the process to avoid a runaway reaction.

● Rupture disks were too small to safely vent high pressure in the kettle in the event of either of the two foreseeable runaway reactions.

● Morton converted its Yellow 96 production from a staged, incremental addition (semibatch) process to a staged heating (batch) process without assessing the possible hazards of this change, e.g., the increased difficulty of controlling heat output.

● Operating procedures did not cover the safety consequences of deviations from normal operating limits, such as runaway reactions, or specify steps to be taken to avoid or
recover from such deviations.

● Training did not address the possibility of a runaway reaction and how operators should respond to avoid injury if a runaway reaction could not be controlled.2. Process safety information provided to plant operations personnel and the process hazard analysis team did not warn them of the potential for a dangerous runaway
chemical reaction.

Morton internal memoranda had documented that the desired reaction to form Yellow 96
from ortho -nitrochlorobenzene ( o -NCB) and 2-ethylhexylamine (2-EHA) was exothermic and that Yellow 96 would begin to decompose rapidly (runaway) at temperatures close to the upper operating temperature. Morton researchers also had identified several situations, such as loss of cooling, that might give rise to temperatures capable of causing violent decompositions. Although information on the reactive hazards was contained in plant files, operators and supervisors were unaware that a dangerous decomposition reaction was possible.



### 7.2 C ONTRIBUTING 

### C AUSES

1. The hazards of previous operational deviations were not evaluated.

Management did not investigate evidence in numerous completed batch sheets and temperature charts of high temperature excursions beyond the normal operating range. Investigation of these incidents likely would have provided an opportunity to uncover the

process ’ s reactive hazards and correct design and other problems.

2. Morton did not follow their Management of Change procedures to review changes
made in reaction kettle and batch size.

Morton changed the Yellow 96 processing equipment from 1000-gallon to 2000-gallon kettles and also increased the batch size by 9 percent in 1996. Morton did not follow its Management of Change procedures and did not review the changes for possible safety consequences. A Management of Change review likely would have provided another

57opportunity for Morton to uncover the process ’ s reactive hazards and correct design problems. The review likely would have also revealed that the changes made resulted in a decrease of 10 percent in the heat transfer area per gallon of reactants. Half of the batches made after this change exhibited temperature excursions versus 20 percent in the batches made before the change.

58

## 8.0 RECOMMENDATIONS

Morton International, Inc. (a wholly owned subsidiary of Rohm and Haas Company)

Establish a program that ensures that reactive chemical process safety information and operating experience are collected and shared with all relevant units of the company (98-006-I-NJ-R01).

Morton International, Inc. ’ s Paterson, New Jersey Plant

1. Revalidate Process Hazard Analyses for all reactive chemical processes in light of the findings of the U.S. Chemical Safety and Hazard Investigation Board (CSB) report and upgrade, as needed, equipment, operating procedures, and training (98-006-I-NJ-R02).

2. Evaluate pressure relief requirements for all reaction vessels using appropriate technology, such as the Design Institute for Emergency Relief Systems (DIERS) 50 method and test apparatus and upgrade equipment as needed (98-006-I-NJ-R03).

3. Evaluate the need for and install, as necessary, devices, such as alarms, added safety instrumentation, and quench or reactor dump systems to safely manage reactive chemical process hazards (98-006-I-NJ-R04).

4. Revise operating procedures and training for reactive chemical processes as needed, to include descriptions of the possible consequences of deviations from normal operational limits and steps that should be taken to correct these deviations, including emergency response actions (98-006-I-NJ-R05).

59 50 DIERS is a consortium of companies, formed in 1976 by the American Institute of Chemical Engineers to develop methods for the design of emergency relief systems to handle runaway reactions. The DIERS group has developed computer programs and a bench-scale test apparatus for assessing the venting requirements of runaway reactions and two-phase flow.5. Implement a program to ensure that deviations from normal operational limits for reactive chemical processes that could have resulted in significant incidents are documented and investigated and necessary safety improvements are implemented (98-006-I-NJ-R06).

6. Revise the Yellow 96 Material Safety Data Sheet (MSDS) to show the proper boiling point and National Fire Protection Association reactivity rating. Evaluate the need for and change, as necessary, the MSDSs for other Morton dyes. Communicate the MSDS changes to current and past customers (who may retain inventories of these products) (98-006-I-NJ-R07).

Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA)

1. Issue joint guidelines on good practices for handling reactive chemical process hazards (98-006-I-NJ-R08).

Ensure that these guidelines, at a minimum, address the following issues:

● The evaluation of reactive hazards and the consequences of reasonably foreseeable and worst-case deviations from normal operations.

● The importance of reporting and investigating deviations from normal operations.

● The determination of proper design for pressure relief capability, emergency cooling, process controls, alarms, and safety interlocks, as well as other good-practice design features for handling reactive substances.

● The appropriate use of chemical screening techniques such as differential scanning calorimetry.

2. Participate in a hazard investigation of reactive chemical process safety conducted by the CSB (98-006-I-NJ-R09).

60The objectives of the special investigation will include:

● Determine the frequency and severity of reactive chemical incidents.

● Examine how industry, OSHA, and EPA are currently addressing reactive chemical hazards. Determine the differences, if any, between large/medium/small companies with regard to reactive chemical policies, practices, in-house reactivity research, testing, and process engineering.

● Analyze the effectiveness of industry and OSHA use of the National Fire Protection Association Reactivity Rating system for process safety management purposes.

● Develop recommendations for reducing the number and severity of reactive chemical
incidents.

American Chemistry Council; Center for Chemical Process Safety (CCPS); Paper, AlliedIndustrial, Chemical & Energy Workers International Union (PACE); Synthetic Organic Chemical Manufacturer ’ s Association (SOCMA)

Communicate the findings of this report to your membership (98-006-I-NJ-R10).

61

## BY THE CHEMICAL SAFETY AND HAZARD INVESTIGATION BOARD

Gerald V. Poje Member

Andrea Kidd Taylor Member

Isadore Rosenthal Member August 16, 2000

6263 

## 9.0 REFERENCES

Barton, J. A., and Nolan, P. F. “ Incidents in the Chemical Industry Due to Thermal-Runaway Chemical Reactions, IChemE Symposium Series, No. 115, 1989. Barton, John and Rogers, Richard. Chemical Reaction Hazards, 2 nd edition, Institution of Chemical Engineers: Rugby, Warwickshire, 1997.
Belke, James C. “ Recurring Causes of Recent Chemical Accidents, ” proceedings of the International Conference and Workshop on Reliability and Risk Management, September 15

– 18, 1998, page 463. Center for Chemical Process Safety of the American Institute of Chemical Engineers. Guidelines for Chemical Reactivity Evaluation and Application to Process Design, American Institute of Chemical Engineers: New York, 1995. Center for Chemical Process Safety of the American Institute of Chemical Engineers. Guidelines for Hazard Evaluation Procedures, American Institute of Chemical Engineers: New York, 1985. Center for Chemical Process Safety of the American Institute of Chemical Engineers. Guidelines for Process Safety in Batch Reaction Systems, American Institute of Chemical Engineers: New York, 1999. Center for Chemical Process Safety of the American Institute of Chemical Engineers. Guidelines for Safe Storage and Handling of Reactive Materials, American Institute of Chemical Engineers: New York, 1995. Center for Chemical Process Safety. Guidelines for Technical Management of Chemical Process Safety, American Institute of Chemical Engineers: New York, 1989. Center for Chemical Process Safety of the American Institute of Chemical Engineers. Inherently Safer Chemical Processes, A Life Cycle Approach, American Institute of Chemical Engineers: New York, 1996. EPA/OSHA Joint Chemical Accident Investigation Report, Napp Technologies, Inc., Lodi, New Jersey, EPA 550-R-97-002, October 1997. Health and Safety Executive. Chemical Reaction Hazards and the Risk of Thermal Runaway, http://www .open.g o v .uk/hse/pubns/indg254.htm , 1999. Health and Safety Executive. “ Designing and Operating Safe Chemical Reaction Processes, ” HSE Books: Norwich U.K., 2000.
Lees, Frank P. Loss Prevention in the Process Industries; Hazard Identification, Assessment and Control, 2 nd Edition, Butterworth-Heinemann: Oxford, 1996. U.S. Environmental Protection Agency. “ How to Prevent Runaway Reactions, Case Study: Phenol-Formaldehyde Reaction Hazards, ” EPA 550-F99-004, August 1999.64 

## APPENDIX A: INCIDENT TIMELINEB-11 evacuationREVISED–7/5/2000Shift starts at1600,April 8, 1998Second-shift foremanassigns Operators1 & 2 to K-7 inin Building 11 (B-11)and gives themAutomate Yellow 96Dye batch sheets.Operators 1 &2 inspect K-7and prepare tostart batch 32of Yellow 96.Three-man teammakes finalpreparation toload orthonitrochlorobenzene( o-NCB).Operators 1 &2 secureinspectionmanway hatchon the head ofK-7.1StartOperator 1 heldover from first shiftin the normalovertime rotation.The B-11supervisor and1st-shift foremanschedulesproduction andwork assignments.K-7 empty andclean.Temperature ofempty K-7 is 20 to30oC (ambient).for the loading of

o-NCB.Inspectionmanway hatch issecured with fourC clamps.Laborer suits up inprotective clothingwith air-purifyingrespirator.Operators 1 & 2suit up inprotective clothingwith supplied air.B-11 is evacuated,except for threeworkers.This is to be the32nd plant batch ofAutomate Yellow 96Dye.This is to be thefourth batch ofAutomate Yellow96 Dye to beprepared in K-7.Kettle 7 (K-7) is a2,000-gallonchemical reactor.Note: All times are expressedas military timeShift foremanschedules forkliftoperator and65REVISED–7/5/2000On second floor,laborer bringsdrums of o-NCBfrom elevator toK-7. (1645)Operator 1aligns valveson K-7 feedmanifold to diptube.K-7 vacuumpulls o-NCBthrough diptube and feedmanifold.(1715)Operators 1& 2 leave B-11for airing outperiod.(1730)K-7 feedmanifold anddip tubeflushed with5 gallons ofdetergentsolution.(1720)21A hand-pulledforktruck is used tobring the pallet ofdrums from elevatorto kettle on secondfloor of B-11.The pallet of drumsis brought to thesecond floor ofB-11 by an elevatorat the west end.Forklift operatorbrings pallet of

o-NCB drums fromhot-box to B-11elevator.K-7 agitator isturned on.Transfer of o-NCBtakes about 25minutes and isuneventful.Rapid smoothtransfer indicatesthat the o-NCB iswell heated andliquefied.A laborer hasprepared a solutionof water anddetergent in5-gallon pail.Pallet of empty drums isreturned to B-11elevator.B-11 unoccupiedfor mandatory 30minutes while"airing out."Team unsuits.Temperature afterloading o-NCB wasreported byoperators as from"about 44" toalmost 70."Vacuum system isworking. Vacuumgauge on head of K-7.No unusual occurrencesnoted.Temperature ofdrums is too hot tohandle with glovedhand."60-something66Shots of steam areadded by openingthe steam-in valvefor a few minutes.REVISED–7/5/2000Operators 1 & 2return to charge2-ethylhexylamine(2-EHA). (1800)2-EHA flowsinto K-7through feedmanifold fromundergroundstorage tanks.(1830)Operator 1adds firststeam to K-7jacket. (1940)Operator 1adds one ortwo more shotsof steam.Operator 1 fillsK-7 jacket withsteam.32Other operators andlaborers return toB-11.Based onexperience,Operator 1 alignsvalves and sets2-EHA feedDigital meter is set for2-EHA charge andcontrols remote pumpat storage tank.Vent to condenserabove K-7 is open.Operators estimatethat loading 2-EHAtakes 25 minutes.At the beginning ofheating, the temperatureof the 2-EHA and o-NCBmixture is at 44oC.0perators knowthat Yellow 96 hasa very difficultexotherm tocontrol.One line in operatinginstructions in batchsheet says only,"heat carefully to90oC."Operators andsupervisors knowthat exotherm ofYellow 96 startsbefore 90oC.Jacket steampressure is 5 to 10psi on dial gauge.Lag time betweentemperature rise inkettle and steamaddition is a fewminutes.There are notemperature orflow indicators onsteam supply.Operators'dinner break.(1900–1935)Exact time dependson operatorexperience andpreference.operatorswork fromexperience anddevelop their ownbatch heatingtechniques.Individualmeter.67REVISED–7/5/2000K-7temperaturerises rapidly to100°to 110°C.(2000)Operatorsinitiate coolingwater flow toK-7 jacket.(2005)K-7 temperaturerises rapidly toover 150°C andkeeps risingrapidly.K-7 starts tovibrate thesecond-floordecking.K-7 temperaturerises to over175°C. (2015)43Operators 1 & 2estimate about 15minutes havepassed sincesteam additionbegan.Operators' pastexperienceindicates that theexotherm ofAutomate Yellow96 may beginaround 75oC.The heat of thereaction of the2-EHA amine andthe o-NCB is nowrapidly heatingK-7.Valves are groupedon opposite sidesof K-7.Operators hearwater flow andsteam bumping inK-7 jacketverifying water ison.Operators estimatethat it takes2 minutes to switchto cooling water.Operator 1 and otheroperators recheckcooling water valvepositions and findthem correct.The cooling waterline-in or line-outhave no temperatureor flow indicators.Operators 1 & 2see shift supervisoron his rounds andcall to him to comeover.Three otheroperators on thesecond floor of B-11are now aware thatK-7 has a problemand start over to see.The shift supervisorarrives and rechecksvalves.Other second-flooroperators havegathered around in theaisle next to K-7.The temperature inK-7 has exceeded theboiling point ofresidual 2-EHA.The experiencedoperators have neverbefore observed asignificant condensatereturn in a Yellow 96batch.Cooling water to K-7confirmed to be fullon. Cooling waterpressure is normal.Turbulent vapor is inthe K-7 condenserline glass and there isdeluge of yellowishcondensate return inthe glass separator.Permanent gases arebeing generated bythe reaction.68REVISED–7/5/2000Two 6-inchrupture disksin series popin 6-inch linefrom K-7reactor head toB-11 catchtank. (2015)K-7temperatureclimbs to over200oC.Remaininggroup ofoperators andshift foremanrun towardB-11 exits bydifferentroutes.Aerosol plume ofK-7 reactants andproducts blowsthrough the thirdfloor and roof ofB-11 and ignites.K-7 contents eruptfrom manway,starting flash firesthat catch workerstrying to escapesecond floor, B-11.(2018)54To this point, theonly pressure relieffor K-7 was the2.5-inch condenservent line throughball valve toreceiver vented tocatch tank.The temperature inK-7 is between180oand 190oC.Heat removal bycondensing vaporsin the condenserand returning refluxto the kettle cannotkeep up withreaction heat.On all otheroccasions, theYellow 96 batcheshad recoveredfrom thesetemperatureexcursions.K-7 rumblingviolently as mix'sboiling rate rapidlyincreases.Last K-7temperaturesobserved werebetween 200oand260oC.K-3 operatorshouts "get out"and runs to stairstoward the westend of B11.An experiencedobserving operatorreads digitaltemperature gaugeat 260oC.Operator 1 andshift foreman atsecond floor eastend door are blowndown steps tolanding.Secondary ignitionof aerosol releaseblows them offlanding ontoground.They suffersevere thirddegree burnsand requireintensive care.Witness observeslarge fire ball aboveroof.Rupture disks areset for 10 psi.There is a loud roar;other plant workersthink that a train ispassing the plant.Manway coveris blown offkettle. (2018)Mixture in K-7 isabove theYellowDye decompositionexotherm onsettemperature of175–195 C.o(2017)69REVISED–7/5/2000Call to PatersonFire Department(PFD) at 2020.Battalion 1arrives onscene at 2024.PFD positions ladder pipetruck and begins placingwater on west end of B-11roof.Fire undercontrol at 2327.PFD repositions ladderpipe truck, increasespressure, and douseseast end of B11 roof.End5Multiple 911 calls.Structure fire on theroof at the east endof B-11.Sounds secondalarm for moreequipment. (2044)Nine injured workersassemble at theMcLean Blvd. plantentrance.Victims are sent byambulance to threearea hospitals, twomost serious to St.Joseph's.All plant personnelaccounted for.Uncertain as towhether chemicalsinvolved are waterreactive.Full protective gearused.Fire knocked down at2144, but water flowmaintained to cover entryteams.Light vapor fires put out withwheeled dry chemical unit.Primary and secondarybuilding searches arecompleted.HAZMAT and fire teamssuit up for entry.All firemen decontaminatedbefore returning. No ill effects.One fireman puncturesboot and is exposed tosite chemicals.Investigative teams begin.Water flow from ladder pipe isstopped to prevent washingcontaminants into PassaicRiver.Fire units remain incase of hot spots.Site secured as acrime scene byPaterson police.70 

## APPENDIX B: DEVELOPMENT TIMELINERevised7/5/2000199611/14/919/13/949/14/951991June/July 198610/2/874/8/884/8/894/28/895/1/895/12/896/25/908/22/909/6/907/27/94January 19954/2/973/31/984/8/98Process Change to2000-gal kettles andincreased batch sizeBatch 5—High Tempoccurrence—1000-gal kettle"Cooling inadequateto control temp"Batch 15—High Tempoccurrence1000-gal kettleBatch 18—High Tempoccurrence1000-gal kettleBatch 4—High Tempoccurrence—1000-gal kettle"Cooling notcontrolling temp"Initial LabExperiments atHounslow, UKDifferential ScanningCalorimetry testing inUK identifieddecompositionexothermMemo, "ThermalStability of LiquidYellow 152,"Discussion of thermalstability work atBrunel UniversityHandwritten Memo—"LY 152 ProcessReview"recommendingadditional testing andsafety instrumentation"LY 152 ProcessReview" transmitted toPaterson/RingwoodDevelopment of stepwise heating processto minimize exposure to

ortho-nitrochlorobenzeneFirst Ringwood Batch—100 gallonsRingwood Batch 90-9495Operator's Note: "Thisbatch wants to run,112-133C"Ringwood SemiworksProcess Transmittalsent to PatersonFirst Paterson batchBatch 14—High Tempoccurrence1000-gal kettlePROCESSHAZARDANALYSISBatch 28—High Tempoccurrence2000-gal kettleBatch 31—High Tempoccurrence2000-gal kettleBatch 32—Explosionand FireK-7—2000-gal kettle71 

## APPENDIX C: ROOT CAUSE ANALYSIS DIAGRAMInjuries andPhysical DamageGas pressureexceeds strengthof manway clampsEmployees presentat kettle sideEmployees attemptto salvage productEmployeesunaware ofhazardsInadequate hazardassessments—failsto identify hazardsInadequate mgmt.of change—fails toidentify hazardsEmployees hadsaved previousbatchesMajority of batcheshad been smaller—better heat transfer(1000 vs 2000 gal)Timing of steam/cooling water hadbeen favorableVenting capacityinsufficient torelieve pressureRunaway reactiongeneratespermanent gasesand boiling of2-EHACoolingwater systemunable to controlheat of reactionReaction heatuprate too fastSteam added attoo high a rateSwitchover tocooling water toolateOperatingprocedures/traininginadequateOperatingprocedures/traininginadequateInadequate design—no heat/mat'lbalanceNot required byMorton PSMprogramDesigers did notidentify properworst-case ventingscenarioPHA team did notidentify properworst-case ventingscenarioInadequateguidance onhazardassessmentsInadequateimplementation ofplant programsREVISED - 7/8/2000Inadequatetransfer ofresearchinformationInadequatetransfer ofresearchinformationInadequateguidance ondesignInadequateguidance onhazardassessments72 

## APPENDIX D: MATERIAL SAFETY DATA SHEETS7374757677787980818283848586878889909192