United States
Environmental Protection
Agency
United States
Occupational Safety and
Health Administration
EPA550-R-98-008
November 1998
www.epa.gov/ceppo/
EXPERT REVIEW OF
EPA/OSHA JOINT
CHEMICAL
ACCIDENT
INVESTIGATION
REPORT
Napp Technologies, Inc.
Lodi, New Jersey
"Woo DC
tndOSHA
Q Printed OH Tecycledpapcr
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Tbe EPA/OSHA Accident Investigation Program
Under a Memorandum of Understanding, EPA and OSHA have jointly assumed the
responsibilities to conduct chemical accident investigations. The fundamental objective of the
EPA/OSHA chemical accident investigation program is to determine and report to the public the
facts, conditions, circumstances, and cause or probable cause of any chemical accident that results
in a fatality, serious injury, substantial property damage, or serious off-site impact, including a large
scale evacuation of the general public. The ultimate goal of the accident investigation is to determine
the root cause in order to reduce the likelihood of recurrence, minimize the consequences associated
with accidental releases, and to make chemical production, processing, handling, and storage safer.
This report is an outgrowth of a joint EPA/OSHA investigation to describe the accident, determine
root causes and contributing factors, and identify findings and recommendations.
Basis of Decision to Investigate and for Involvement of EPA
An explosion and fire took place at the Napp Technologies facility at Lodi, New Jersey, on
April 21,1995, resulting in deaths, injuries, public evacuations, and serious damage both on and off
she. The accident involved a commercial chemical mixture, a gold precipitating agent identified as
ACR 9031 GPA, owned by Technic Inc. (Technic) of Cranston, Rhode Island and comprised of
sodium hydrosulfite, aluminum powder, potassium carbonate and benzaldehyde (hereinafter "GPA").
EPA and OSHA undertook an investigation of this accident because of the serious consequences and
the characteristics of the substances involved. This investigation was conducted in conjunction with
OSHA's enforcement investigation.
At the time of the accident at the Napp facility, Napp was performing a toll blending
operation. Under a toll arrangement, a company performs chemical manufacturing, blending, or other
operations for other companies. Those other companies may not have the equipment or capacity for
these operations or may have other reasons for outsourcing these tasks. One of the purposes of this
investigation was to identify hazards specific to the toll manufacturing industry that might lead to
chemical accidents, and develop recommendations to prevent accidents and improve safety in the toll
manufacturing industry.
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Executive Summary/Overview
On April 21, 1995, at approximately 7:45 a.m., a violent explosion and fire occurred at the
Napp Technologies, Inc. (Napp) specialty chemical plant in Lodi, New Jersey. Five employees of
Napp ultimately died (four employees were fatally injured at the site, the fifth employee died several
days later due to injuries related to the event). A majority of the facility was destroyed as a result of
the fire, and other businesses near the facility were destroyed or significantly damaged.
Approximately 300 residents in the area were evacuated from their homes and a school. Additionally,
firefighting efforts generated chemically contaminated water that ran off into the streets and nearby
Saddle River.
At the time of the explosion and fire, Napp was conducting a blending operation involving
water-reactive chemicals. The chemical mixing portion of the operation, which should have been
completed in less than an hour, continued for nearly 24 hours. Operators noticed an unexpected
reaction taking place in the blender, producing increasing heat and release of foul-smelling gas over
time.
The joint chemical accident investigation team (JCATT) formed by OSHA and EPA
determined that the most likely cause of the accident was the inadvertent introduction of water/heat
into water-reactive materials (aluminum powder and sodium hydrosulfite) during the mixing
operation. The water caused 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 rapidly react with the other
ingredients and generate more heat. During an emergency operation to off-load the blender of jits
reacting contents, the material ignited and a deflagration occurred which resulted in the deaths of the
Napp employees and destruction of the facility.
The JCAJT identified the following root causes and contributing factors of the event:
• An inadequate process hay-ftrds analysis was conducted and appropriate preventive actions
were not taken.. Napp's process hazard analysis identified the water reactivity of the
substances involved, but was inadequate to identify and address other factors, including
sources of water/heat, mitigation measures, recognition of deviations, consequences of
failures of controls, and steps necessary to stop a reaction inside the blender. Consequently,
appropriate prevention actions were not taken.
• Standard operating procedures and training were less than adequate. Napp's standard
operating procedures (SOPs) and related training did not adequately address emergency
shutdown, including conditions requiring shutdown and assignment of shutdown
responsibility, and operating limits, including the consequences of deviations, abnormal
situations, and corrective steps required.
• The decision to re-enter the facility and off-load the blender was based on inadequate
infbnnatioa Although Napp was aware of, and concerned for, the strong possibility of a fire,
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there was a kck of knowledge or understanding whether off-loading the blender would have
made the situation worse or the potential for violent deflagration.
• The equipment selected for the GPA blending process was inappropriate. The blender used
by Napp for the process was inappropriate for the materials blended.
• Communications Between Napp and Technic were inadequate. Napp was carrying out a
blending operation for another company. Inadequate communication of hazard information
between the companies led to an inadequate process hazard review.
• Hie training of fire brigade members and emergency responders was inadequate. Napp fire
brigade members were not trained to respond to the type of emergency that occurred.
The JCATT developed recommendations that address the root causes and contributing factors
to prevent a reoccurrence or similar event at other facilities:
* Facilities need to fully understand chemical and process hazards, failure modes and
safeguards, deviations from normal and their consequences, and ensure that all relevant
personnel know the proper actions to take to operate the process safely, recognize and
address deviations, return to normal operations, or safely shutdown. This is best achieved
though process hazards analyses, standard operating procedures, and training;
• Guidance is needed to address the unique circumstances surrounding tolling arrangements and
the responsibilities for hazards assessments and communication of process safety information;
• Facilities should ensure that equipment manufacturers' recommendations for proper use of
equipment are followed;
OSHA and EPA should review the lists of substances subject to the Process Safety
Management standard and Risk Management Program regulations to determine whether
reactive substances should be added;
• OSHA needs to review the role of MSDSs in conjunction with HazCom, HazWoper, and
PSM Standards to clarify that MSDSs should not be used beyond their intended design.
Industry should consider additional consensus standards or guidelines to address MSDS
consistency and use; and
• OSHA and EPA should consider whether additional guidance or outreach is needed for users
to understand the limitations of MSDSs and industry awareness that more than the MSDS is
needed to conduct full process hazards analyses.
U.S. EPA Headquarters
Mai! code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
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Table of Contents
1.0 Background
1.1 Facility Information 1
1.2 Process Information 3
1.3 Chemical Information 5
2.0 Description of the Accident 9
2.1 Events Preceding the Blending Operation 9
2.2 Preparations for Blending 9
2.3 Blending Operation 12
2.4 The Explosion and Fire 15
2.5 Emergency Response 16
2.6 Napp Fire Brigade Members and Emergency Responders 17
3.0 Analyses and Significant Facts 18
3.1 Analyses 18
3.2 Significant Facts ; 18
4.0 Causes of the Accident 21
4.1 Possible Causes of Chemical Reaction 21
4.2 Most Likely Causes of Chemical Reaction 24
4.3 Root Causes and Contributing Factors 26
5.0 Recommendations 29
6.0 Outcomes of OSHA/Napp Technologies Settlement 32
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Appendices
B
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E
Chemical Reactions . . . .
Accidents Involving Sodium Hydrosulfite and Aluminum
References ...
Photoeraohs of Naoo Technoloeies (Figures 4-24)
37
41
45
47
List of Figures and Exhibits
Figure 1
Figure 2
Figures
Exhibit 1
Figure 3A
Napp Layout
P-KBlender
Intensifier Bar
Timeline of Events
Vacuum System
2
4
6
11
14
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1.0 Background
1.1 Facility Information
The Napp Technologies, Inc. (Napp) facility in Lodi, New Jersey, was located on Main Street
in a mixed industrial/residential section of Lodi. Napp shared a block with other businesses and was
directly across the street from homes and retail businesses (see Figure 24).
Operations
Napp's primary business is pharmaceutical manufacturing. However, in limited cases, it also
performs toll blending operations. In a tolling arrangement a company contracts with another
company to perform a specific operation. Typically, the company letting the toll contract lacks the
equipment or capacity to manufacture the chemical product. The raw material is delivered to the toll
manufacturer, who processes it according to customer specifications, and delivers it to the original
company for a fee or toll.
At the time of the explosion, Napp was performing a blending operation to produce
ACR 9031, a gold precipitating agent (GPA) under a toll blending arrangement with Technic Inc.
(Technic) of Cranston RI. Lacking the necessary equipment to blend the ingredients, Technic entered
into a contract with Napp whereby Technic purchased the components of GPA and had them
delivered to Napp to be blended.
The Patterson-Kelley (PK) 125 blender used in the GPA blending operation was located in
the PK-125 Blending Room, located in the Pulverizing and Blending Department on the South side
of the facility, near the main warehouse area (see Figure 1).
Facility Chemical Review Procedures
Consistent with Napp's "New Product Review" standard operating procedure (SOP), new
products that potentially will be used or manufactured at the Napp Lodi facility are subject to an
evaluation of employee health and safety, permit requirements, regulatory compliance (FDA, EPA,
NJDEP, etc.), equipment suitability, process limitations and product characteristics. The New
Process Review is an internal procedure in which management officials, the Regulatory Affairs
Manager, Chemical Manufacturing and Engineering Manager, Operations Director, and Vice
President of Regulatory and R&D participate.
The objective of the "New Product Review" procedure was "to establish a uniform policy
for evaluating potential products before their use or manufacture on this site."
The Regulatory Affairs Manager initially reviews the job request which may be rejected due
to regulatory concerns or company policies. If accepted, the Regulatory Affairs Manager will
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complete the New Product Review form, assemble relevant documentation, and circulate the package
to other Napp management for further review. As part of that management review, the Chemical
Manufacturing and Engineering Manager, the Operations Director, and the Vice President of
Regulatory Affairs individually review (i.e., no concurrent team review) the package for safety,
permitting, and process requirements. The last person to review the package returns it to the
Regulatory Affairs Manager. Each participant in the review indicates his approval or rejection of the
proposal on the New Product Review Form. All of the managers involved in the New Product
Review approved of the processing of the GPA.
According to Napp's accident report: "Material Safety Data Sheets emd other information
provided by Technic formed the primary basis for this review. Instrumental in Napp's acceptance
of the project was the Company's review of its prior successful processing of approximately the
same volume of these materials m the same blender and the absence of any disclosure from Technic
of prior explosions, uncontrolled reactions or other accidents that had previously occurred during
the blending of these materials."
1.2 Process Information
GPA Blending Process
The GPA that Napp was blending is used to recover precious metals, such as gold, from
aqueous cyanide solutions. The primary ingredients of the precipitating agent are aluminum powder
and a reducing agent, sodium hydrosulfite. The precipitating agent also contains potassium
carbonate, an alkali metal, as an activator. The ingredients were mixed in the following approximate
proportions, by weight: 66% sodium hydrosulfite, 22% aluminum powder, and 11% potassium
carbonate. A small amount (8 liters) of benzaldehyde was also to be added to the mixture for odor
control.
To prepare the GPA, according to patent information, the three powdered components are
mixed prior to use. The ingredients may be mixed in a simple cone blender or other mixing device.
The intended blending time, from the time when all dry powders are charged until the time of
unloading, is approximately 45 minutes.
Napp had once previously, in July 1992, blended a batch of ACR 9031 GPA for Technic, Inc.,
in its PK-I25 blender. Before this operation, Napp technical personnel conducted a new product
review. No formal record of this review was made, although production records were retained along
with the Material Safety Data Sheet (MSDS) for each of the components of the GPA. The 1995
blending ingredients were virtually the same as in 1992. The 1995 blending operation was intended
to be the same as in 1992; however, because of operation deviations, the 1995 batch operation was
significantly different.
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Patterson-Kellev 125 Blender
Figure 2 shows a typical Patterson-Kelley V-shaped blender. Patterson-Kelley builds each
blender with options and features as specified by the purchaser. The blender at Napp had a working
capacity of 6 cubic meters (125 cubic feet). It was approximately 6 meters wide (19 feet), including
supports, and 3 meters (10 feet) high. The blender is a double-lobed stainless steel shell shaped like
a heart. It is supported on its widest dimension by a horizontal trunnion attached to support tubes
set in cement footings. It is insulated with a rigid foam material and encased in a steel jacket
containing a water/glycoi mixture for cooling and heating. The two access covers on top of the
blender are used for loading raw materials, and one port is located at the bottom for off-loading
product. A gear to one side of the blender (right side of Figure 2) rotates the shell of the blender
through a 360-degree arc. Several water lines enter the jacket on this side. On the other side (left
side of Figure 2) of the blender, a vacuum tube housing enters the blender. A graphite seal located
inside the vacuum tube separates the seal's cooling water from the internal area of the vacuum tube
and the blender. The purpose of the vacuum tube housing is to: (1) act as a conduit for establishing
vacuum conditions when the blender is used for drying and other operations; and (2) contain other
concentric lines, shafts, etc., including a liquid feed line (added by Napp) and the shaft used to rotate
an intensifier bar (I-bar). The purpose of the I-bar is to enhance the mixing of materials being
blended. The purpose of the feed line is to allow the controlled introduction of liquids to the
materials being blended. The PK-125 blender can be used with or without the I-bar in service. The
I-bar, Figure 3, transverses the inner walls of the blender connecting the inner sides of the blender on
the same plane as the trunnion. See Figures 4-8 showing a larger but similar blender and associated
equipment.
1.3 Chemical Information
The chemicals involved in the explosion were sodium hydrosulfite, aluminum powder,
potassium carbonate, and benzaldehyde. The properties and hazards of these chemicals are discussed
below.
Sodium Hydrosulfite
Sodium hydrosulfite (sodium dithionite), Na^O^ is a whitish, crystalline solid, with
moderately strong reducing properties. It is principally used in dying and bleaching operations.
The National Fire Protection Association (NFPA) (NFPA 49, Hazardous Chemical Data,
1994) rates chemical hazards on a scale of 0 (lowest degree of hazard) to 4 (highest degree of
hazard). NFPA rates sodium hydrosulfite as 2 for health hazards (moderate) and notes that
combustion byproducts may include sulfur dioxide. Sodium hydrosulfite is rated 1 for flammability
and described as a combustible solid. NFPA rates it as 2 for reactivity and notes that exposure to
moisture from humid air or small amounts of water can result in spontaneous chemical reactions that
may generate sufficient heat to initiate thermal decomposition. The U.S. Department of
Transportation (DOT) lists sodium hydrosulfite (49 CFR Part 172) in Hazard Class 4.2
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(spontaneously combustible materiaJ), Packing Group EL Packing Group n is assigned to materials
that present a "medium degree of danger." The shipping label "SPONTANEOUSLY
COMBUSTIBLE" is required for sodium hydrosulfite.
Sodium hydrosulfite is unstable in the presence of water, heat or humid air, giving off sulfur
dioxide gas and other sulfur products in an exothermic reaction. Once initiated, the decomposition
process of sodium hydrosulfite supports continued decomposition due to the generation of heat in
the exothermic reaction. Therefore, once the decomposition has been initiated, it cannot be
extinguished with smothering agents. To quench the decomposition, the temperature of the material
must be lowered below the decomposition temperature.
The material safety data sheet (MSDS) for sodium hydrosulfite supplied by Technic notes in
the event a container feels hot or begins to smoke it should be removed to an open area and "flood
with water."
The decomposition temperature of sodium hydrosulfite is identified on the MSDS as 130 C.
Under Reactivity Data, the material is described as "stable" although moisture and heat in excess of
50 C are identified as conditions to avoid.
Aluminum Powder
Aluminum powder is light grey or silvery colored. Air dispersions (dust clouds) of aluminum
particles, when mixed in proper proportions and exposed to a small amount of ignition energy, will
bum with such rapidity that if contained an explosion may occur Aluminum powder has a number
of uses related to its flammability and explosivity when dispersed in air, including use in explosives,
propellants, and pyrotechnics. As a component of explosives, aluminum powder is used to increase
explosive power.
NFPA (NFPA 49, 1994) rates aluminum powder as 0 for health hazards, indicating health
hazards are minor. Under 'Tire and Explosive Hazards," NFPA 49 describes aluminum powder as
a "[fjlammable solid if finely divided. Forms explosive mixtures in a dust cloud in air. Bulk dust
when damp with water may heat spontaneously. Hazard greater as fineness increases." The rating
for flammability hazard is 3, the rating that applies to liquids and solids that can be ignited under
almost all ambient temperatures. Aluminum powder has a rating of 1 for reactivity hazards. DOT
lists aluminum powder, uncoated, on its Hazardous Materials Table in Hazard Class 4.3 (dangerous
when wet material), Packing Group n ("medium" degree of danger). The shipping label
"DANGEROUS WHEN WET" is required for uncoated aluminum powder.
Sax's "Dangerous Properties of Industrial Materials" fifth edition, (page 352) indicates that
aluminum powder is a moderate explosion hazard when finely divided as dust and dispersed with
gaseous SOj, under appropriate conditions.
Water will react with aluminum dust to produce hydrogen gas, especially under alkaline
conditions. Aluminum is normally protected by an oxide coating, but the coating is readily dissolved
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by alkaline agents such as bicarbonate. Once the oxide coating is removed, the aluminum becomes
very reactive. The oxide coating normally reforms rapidly and exothermically on contact with air.
The uncoated condition is ideal for aluminum to become pyrophoric, i.e., burst into fire spontaneously
under appropriate conditions.
The MSDS for aluminum powder, uncoated (atomized), as written by Valimet, Inc., and
supplied by Technic to Napp states:
Under Section IV: Fire and Explosive Data:
"Special Fire Fighting Procedures: A void water "
Under Section VI: Reactivity Data:
"Incompatibility (Materials to Avoid): Water, acids, alkalis.
Hazardous Decomposition Products: Exothermic reaction with water, acids, alkalis
to generate hydrogen and heat"
Benzaldehyde
Benzaldehyde is a colorless liquid. Benzaldehyde readily oxidizes to benzoic acid. To prevent
contact with air, an inert gas blanket over the material is required.
Benzoic acid is a white crystalline material. When benzoic acid is heated above its melting
point, some formation of benzoic anhydride and water takes place. When heated above 370C, it
decomposes to benzene and carbon dioxide, with small amount decomposing to phenol and carbon
monoxide.
Potassium Carbonate
Potassium carbonate is usually in the form of white crystalline granules. Because of its
alkaline chemical nature, it is commonly used to raise the pH of mixtures and solutions. Potassium
carbonate has some acute health hazards (irritant to all body tissue, possibly leading to tissue
destruction), giving it an NFPA health hazard rating of 2. NFPA fire and reactivity ratings for the
material are 0, indicating that it is a stable compound.
Gold Precipitating Agent
The MSDS for the gold precipitating agent supplied by Technic, Inc. notes:
"Flammabiliry Data: Contact with small amounts of water or humid atmosphere will cause
a chemical reaction. The heat generated from this reaction is
sufficient enough to ignite combustible material. . . Flood the
material with water to ensure complete wetting, as this procedure will
control the auto-ignition of the material.
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Extinguishing Media: Water spray should be used to extinguish fire
Usual Fire Fighting Procedures: Use water to keep fire exposed containers cool."
Unusual fire fighting techniques are asserted not to be applicable. Hazardous decomposition
products specified are limited to oxides of sulfur, carbon dioxide and carbon monoxide.
Incompatibles identified by Technic are limited to "oxidizing agents or materials, strong acids and
moisture.
2.0 Description of the Accident
2.1 Events Preceding the Blending Operation
In January of 1995, Technic contacted Napp to inquire about the timing of an order of GPA.
In February 1995, Napp informed Technic that the next available date to make GPA would be March
23, 1995. In preparation for that job, Napp decided to perform a new product review. The
Regulatory Affairs Manager, Chemical Manufacturing and Engineering Manager, Operations
Director, and the Vice President for Regulatory and R&D participated in the review which included
the evaluation of the processing information available from 1992, the MSDS prepared by Technic for
its GPA, the MSDSs of the components of the mix, as well as other information. They noted the
water-reactive nature of the components of the GPA
In March of 1995, in preparation for the blending of one batch of GPA, Technic began
procurement of the various raw materials and made arrangements for their shipment to Napp. A
slight delay in the scheduled blending of the GPA pushed the production date into April. On April
7, Technic sent Napp a purchase order, a duplicate of the GPA MSDS already in Napp's possession,
and a sign-off by Technic's Director of Operations on the formulation sheet (batch recipe ticket)
indicating that it was "OK to blend." The delivery of materials to Lodi commenced in March and was
completed with the delivery of aluminum powder on or about April 4, 1995. The components of the
blend included 1,800 pounds of powdered aluminum, 900 pounds of potassium carbonate, 5,400
pounds of sodium hydrosulfite, and eight liters of benzaldehyde. The blended GPA was to be
packaged into 18 plastic-lined 55-gallon drums, supplied by Technic.
2.2 Preparations for Blending
Preparations for the processing to be performed commenced on Monday, April 17,1995 when
the PK-125 blender was rinsed with deionized water. Thereafter, the rinsewater was discharged. The
intensifier bar was removed from the vessel, dismantled by mechanics, and cleaned.
The maintenance foreman instructed a maintenance employee to remove and change the
packing gland associated with the intensifier bar on the PK-125 blender. This activity was standard
procedure whenever there was a scheduled product change for one of the Napp P-K blenders. After
removing the old packing gland and its housing, the maintenance employee observed water next to
a bearing. Based on this observation, the maintenance foreman instructed the maintenance employee
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to drain the water out of the area, replace the packing, and seal the blender. As part of the procedure
to check the integrity of the seal and packing gland, the maintenance employee ran the blender and
its intensifier bar for 15 minutes and visually inspected the interior of the blender to assure that the
water-cooled seal and packing gland were not leaking. The mechanic found no evidence of leakage.
The blender was given a final rinse, and the rinsate was checked for the presence of
contamination. Quality Control personnel "released" the blender and the room in which it was housed
to Operations personnel and the cleaning log was signed signifying completion of the cleaning
process, approving both for use in preparing the next product, the GPA.
On April 19, prior to charging the materials, the first shift supervisor conducted a process
review with operators on duty. It was a Standard Operating Procedure that any operator engaged
in materials processing must complete a detailed review with the shift supervisor of the process and
its hazards prior to commencing work. The review, which typically takes 45 minutes to an hour, was
done for each operator involved in the Technic process, and included a discussion and review of the
equipment set-up, the steps to be undertaken in the process, and a complete review of the MSDSs
for GPA and each component of the mixture. The shift supervisor and two operators found a minor
water leak from a water pipe in the back of the PK-125 room (not associated with the blender). The
shift supervisor stopped the leak, dried up any water that remained, and covered the floor drains in
the room to prevent contact of GPA with water in the sewer system in the event of a spill. A sign
informing workers that water reactive chemicals were being processed in the PK-125 room was
placed at the entry to the room.
At approximately 10:30 p.m. on April 19, the shift supervisor conducted a process review
with the night shift crew. Exhibit 1 shows the timeline of events beginning at this point.
The process review with the operators concluded at approximately 11:15 p.m. The operators
and leadmen then pre-weighed the GPA components, .placing the unopened drums of sodium
hydrosulfite and aluminum powder and bags of potassium carbonate on a digital scale and recorded
the weight of the material and its container on a log. In the course of this activity, it was discovered
that one of the bags of potassium carbonate had been broken and taped over and it weighed less than
the others. To assure proper proportions for the GPA, a calculation was performed and the volume
of the other raw materials was adjusted for the batch to be mixed.
At 3:30 a.m. on April 20, as part of the precharging verification, operators made a final check
to assure the blender was ready (Le., clean and dry) to be loaded. The two operators and a foreman
discovered that the vacuum head area, inside the blender, was wet. They also observed water On the
internal wails of the blender. Another employee saw a wet spot also described as "droplets of water
on the stainless steel" at the intensifier bar shaft seal (connection). They believed this moisture was
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caused by condensation.
Knowing that water reactive materials were to be loaded into the blender, the night shift
foreman directed an operator to wipe off the portions where moisture was found. The blender was
then heated using the water-glycol jacket on the PK-125 to further dry the interior surfaces. The
blender was allowed to cool and was checked to ensure it was ready to be charged with the raw
materials and found to be dry.
23 Blending Operation
Prior to the commencement of loading operations, the operators implemented a standard
operating procedure that required that a vacuum twice be created within the blender and then broken
with inert nitrogen gas. Thereafter, a slight nitrogen pressure was maintained to assure inert
conditions within the blender. At approximately 5:00 a.m. on April 20, operators began to load the
components of the GPA into the blender, but did not finish the work. At 6:00 a.m., a shift change
occurred, and the first-shift day crew arrived to continue blending operations.
A process review of the GPA blend had been conducted for the new operators, and the
hazardous nature of the raw materials was discussed. At approximately 8:00 a.m., the first shift
operators recommenced .loading of the blender alternating proportionately from one component to
the next as had the previous operators. Because loading occurred only through one port of the "V-
shaped blender, and to distribute the materials evenly across the blender, the intensifier bar was
rotated briefly. The loading of the blender concluded at approximately 11:00 to 11:30 a.m. Thursday
morning. During the final charging, the blender was rotated to level (settle) the powders to allow all
of the material to be loaded. An operator noted that the charge was not dusty when the blender was
opened for the final addition. After charging was complete, the level of the powdered components
completely covered the intensifier bar and was almost up to the middle of the vacuum head.
Thereafter, the operators commenced the blending operation according to Napp's procedure, which
called for blending the dry powders as follows: rotate the blender for ten minutes without the
intensifier ban five minutes with the intensifier bar, and ten minutes again without the intensifier bar.
The dry blending was completed by mid-day.
The operators then made preparations to spray charge the benzaldehyde, a procedure
requiring the use of a separate liquid feed tank connected by hoses to a spray nozzle atop the vacuum
head within the blender. Operators noted a "vanilla-like" odor from a liquid feed tank for the blender,
and water was observed inside the tank. Additionally, the operators found water in an internal filter
located on the liquid feed fine near the point of entry into the blender. However, because the
components of the GPA, with the exception of the benzaldehyde, were already in the blender, the
portion of the feed spray line located inside the blender could not be cleaned without contaminating
the materials in the blender. The operators did not consider the liquid feed line to be functioning
properly. The liquid spray head and spray system had not been completely dried prior to the charging
of tiie blender. The operators placed a gallon of isopropyl alcohol (IP A) into the liquid feed tank and
blew inert nitrogen through the tanks and lines into a bucket forcing the IPA through the system, with
the exception of that portion of the line entering the blender and terminating at the spray nozzle.
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They then blew nitrogen through the liquid feed system for 45 minutes to one hour to make certain
the feed tank and lines were dry.
At approximately 2:30 p.m., the operators attempted to charge the benzaldehyde into the
blender. In doing so, the operators placed the benzaldehyde in the liquid feed tank, charged the tank
with nitrogen pressure, commenced rotation of the blender and intensifier bar, and relieved the
pressure into the blender. The operators noted the feed rate was unusually low, and upon inspection,
they noticed that most of the benzaldehyde had ended up in a vacuum line separator bowl and not in
the blender (Figure 3A). Upon consideration of the failure of the liquid feed system to correctly spray
the benzaldehyde into the blender, it was determined to examine the compression fitting to the liquid
feed line to see if it was leaking.
An operator noted that the liquid in the bowl had a few drops of water or IP A on top of the
benzaldehyde. No further analysis was performed on the liquid.
At 7:00 p.m. an employee entered the PK-125 room and smelled an odor described as "rotten
eggs." The employee observed 18 drums which previously contained the raw materials. These drums
sat uncovered. Assuming the residue inside the drums was the cause of the odor, he put the tops
back on the drums.
At 7:30 p.m., a maintenance employee was instructed to troubleshoot the liquid feed system
line. When the employee attempted to open the vacuum line to gain access to the feed line the
employee was splashed with a "stinky" liquid. The maintenance employee received minor chemical
burns and went to the locker room to wash off the chemical.
Between 7:30 and 10:00 p.m., one hatchway on the PK-125 blender remained open to the
atmosphere. During this period the operators continued to run a nitrogen purge through the vacuum
line into the blender so as to maintain an inert blanket in the head space of the blender.
At approximately 10:00 p.m., another maintenance employee completed the disassembly of
the exterior portion of the vacuum line and took it to another room, where it was washed and dried.
When the employee returned to the PK-125 room the employee smelled an odor that he described
as a "dead animal" smell upon initially entering the PK-125 room. This employee also observed and
smelled the liquid from the separator bowl which had been collected hi a beaker. The employee
described the smell as "awful." The maintenance employee cleaned up the liquid which had earlier
spilled on the floor. By this time, it had been almost ten hours since the ingredients were placed into
the blender (the blending should have taken not more than one hour to complete).
At 10:00 p.m., the maintenance employee informed the shift supervisor about the unusual
odors in the PK-125 room. The maintenance employee finished reinstalling the vacuum line to the
blender, and the shift supervisor went to the lab to obtain more benzaldehyde to inject into the blend.
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#1
FIGURE SA: TYPICAL VACUUM COLLECTION SYSTEM AS SUPPLIED
BY PATTERSON-KELLEY. # I SHOWS APPROXIMATE LOCATION or
INLET FROM BLENDER VACUUM LINE; #2 SHOWS VACUUM
SEPARATOR BOWL.
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-15-
Between midnight and 4:30 a.m. on April 21, 1995, the third shift attempted to inject
benzaldehyde into the batch on two occasions; each attempt failed. Operators observed the
benzaldehyde running back into the vacuum separator. During each attempt to add the liquid, the
blender was rotated for about two minutes with the intensifier bar running. Suspecting that product
was blocking the spray tip of the nozzle and preventing the injection of the liquid, operators opened
the blender twice and removed and washed the spray nozzle. Operators reportedly observed a slight
dusty powder wafting within the head space of the blender. This was reported to the shift supervisor,
who then checked the inside of the blender and directed the operators to remove and clean the nozzle.
After the final attempt to charge benzaldehyde into the vessel it was determined that no fresh
benzaldehyde remained. It was by then approximately 5:00 a.m. and coming to the end of the third
shift. The shift supervisor told the operators to perform a lock and tagout of the blender.
The shift supervisor noted that a pressure gauge on the blender was reading five pounds per
square inch (psi). Inasmuch as the blend was to take place under atmospheric conditions, in a blender
designed for non-pressurized service, concern arose that the rise in pressure could result in the two
charging ports being blown out of the blender. Because there was a continuous flow of nitrogen into
the blender, the pressure gauge was replaced with an open nipple, and the pressure was released into
the PK-125 room. The nitrogen purge rate was then increased.
The shift supervisor reportedly observed an area of about 8 inches in diameter bubbling and
smoking on the surface of the material inside the blender.
2.4 The Explosion and Fire
As employees arrived at the plant for the morning shift on April 21, they noticed a rotten egg
odor. At approximately 5:30 a.m. the operators of the blender had observed puffs of white smoke
coming from the exhaust nipple affixed to the PK-125. By 6:00 a.m. employees on the first shift had
reported to their assembly areas. Nearly all Napp employees smelled the odor of rotten eggs, which
by then had escaped the building and was noticeable in the parking lot behind the plant. At
approximately 6:15 a.m. the plant was evacuated, through verbal instructions; no audible alarms were
ever activated at the facility.
At about the same time, there was a discussion about whether the GPA should be unloaded
from the blender. At approximately 6:30 a.m., the third shift supervisor placed a call to the Vice
President for Regulatory Affairs (VPRA) and advised him of the situation. After asking a series of
questions for more information, in a subsequent phone conversation at approximately 6:45 a.m., the
VPRA directed the shift Supervisor to discharge the batch "ASAP." The VPRA suggested tumbling
the blender with cooling medium (glycol) circulating in the water jacket. The shift supervisor stated
that he did not want to rotate the blender because that would require capping the exhaust nipple that
had been installed to relieve the pressure buildup inside the blender. The VPRA directed the shift
supervisor to maintain the nitrogen purge into the blender. Additional phone calls were also made
from the plant to other Napp management personnel.
During discussions regarding unloading of the blender and upon review of the GPA MSDS,
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h was suggested that a fire hose would be strung out to the PK-125 room but not charged in order
to prevent accidental discharge of water. Later, an additional hose was made available.
At approximately 7:00 am, the third shift supervisor went outside and approached the plant
employees who had been evacuated to the rear parking lot. Several employees, including the first
shift supervisor, returned to the blending room with him to assist with the unloading of the blender.
Other employees, who were members of the Napp Fire Brigade, reentered the plant to stand by with
fire hoses at the ready, but were instructed by the Production Manager not to charge them with water
unless they were told to do so by another employee who would be closely watching the unloading
operation. The maintenance supervisor stood in a doorway that led from the blending room to a
hallway from which he could see both the unloading activities and the fire brigade member standing
by awaiting a signal to charge the fire hose.
At approximately 7:47 a.m., three loud hissing noises were heard in succession. The noises
were closely followed by a "whoosh" sound, then the explosion. The blender and its two 10-ton
concrete footings were propelled in a westerly direction for a distance of approximately fifty feet. An
employee standing by stated that he heard hissing noises, looked inside the blending room, and saw
the other workers in animated activity. He turned to run, saw two bright flashes of what reminded
him of lightning, and saw a yellow-orange ball of flame "like a snake's tongue" leap out of the room
toward him. He was blown along the length of the corridor and out a passage door, he survived with
minor injuries.
Four of the five employees in the PK-125 blending room were killed in the explosion and
ensuing fire, and the fifth employee died of bums a week later. Four other employees escaped with
minor injuries.
2.5 Emergency Response
At the sound of the explosion, Lodi police, fire, and EMS responded to the scene within
minutes. Information concerning the chemicals stored at the facility was promptly made available to
responders. Nine persons injured in the explosion were transported to a local hospital.
Approximately 300 residents in the vicinity were evacuated from their homes, as well as a nearby
elementary school.
Other responding agencies included EPA, OSHA, United States Coast Guard, Federal Bureau
of Investigation, NJ Department of Environmental Protection (NJDEP), NJ State Police Office of
Emergency Management, Bergen and Passaic County .Health Departments, Bergen County
Prosecutor's Office and the Arson Squad. Hundreds of volunteer fire and ambulance personnel also
responded, as did more than 20 other municipal police.
Continuous air monitoring was conducted by seven NJDEP teams for the duration of the fire.
Downwind monitoring was conducted by NJDEP, Bergen and Passaic County Health Departments.
Observable during the firefighting response was a discharge of the chemical fluore&cein, a
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bright green dye, which was stored at the Napp facility. Fluorescein-contaminated firefighting runoff
water entered the Saddle River through the storm drains and by direct overland flow. Fluorescein-
contaminated runoff also entered the sanitary sewer line feeding the sewage treatment plant. The
Passaic Valley Sewage Commission was notified of the release. Napp Technologies hired a cleanup
contractor to contain firefighting runoff. Evidence of firefighting runoff was seen in the Saddle River
in the form of a bright green discoloration for two miles downstream to its confluence with the
Passaic River.
A USEPA mobile laboratory vehicle was used to acquire downwind air samples of
inorganic/acid gases, organic, and ketones. In addition, water samples were obtained at seven
locations for off-site analysis. Water samples were analyzed for volatile organic compounds, base-
neutral-acids, metals, pesticides, and PCBs.
Fish kills were confined to the Saddle River, for approximately 2 miles downstream to the
confluence with the Passaic River. No fish kills were observed in the Passaic River. The residential
evacuation order for Lodi and the surrounding communities was lifted on April 22 at 8:30 p.m.
2.6 Napp Fire Brigade Members and Emergency Responders
Among the Napp employees involved in the attempt to remove the GPA from the blender
were several who were members of the Napp fire brigade and had been trained in incipient fire
fighting techniques.
Napp fire brigade members and other Napp emergency responders were directed by
management to respond to the ongoing chemical emergency. Nine of the twelve employees who were
inside the building immediately preceding the explosion (during the unloading of the GPA) were also
members of the Napp fire brigade. Training records revealed that some employees were given a
lecture on chemical fires, but no formal training was conducted related to fighting chemical fires or
emergencies. A course on hazardous materials was presented to the fire brigade in November 1993,
but the records note that none of five listed managers, including three of the deceased employees,
attended the session. The same training records indicate that four of the five managers failed to
attend six fire brigade training sessions in 1993 (the fifth manager attended one session), and the same
individuals failed to attend similar training courses, including one on hazardous materials and one on
emergency response in 1994. In 1995 the same individuals missed three fire brigade training sessions,
including one on fire behavior given 10 days prior to the explosion. The Napp Plant Safety Standard
for Fire Protection Organization specifically defines the function of the Plant Fire Brigade as, among
other things, to "answer all fire calls." It also states that the "intent of the Brigade is to fight incipient
stage fires only." It further states that "The Brigade will perform a contain and hold function on any
major interior structural fire until the Lodi Fire Department arrives."
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-18-
3.0 Analyses and Significant Facts
3.1 Analyses
After the accident, investigators analyzed the chemical residues in the blender and the remains
of the blender itself These analyses are discussed in detail in Appendix A. Appendix A also includes
information on the injuries suffered by the victims of the explosion.
The chemical analysis showed the presence of sodium, potassium, and aluminum, consistent
with the blender contents. Phenol and methylphenol compounds were also found in large amounts.
These compounds were probably due to the insulating material remnants which were originally
located in the annulus between the outer wall of the blender and the outer wall of the water-glycol
jacket. These compounds could also be derivatives of the benzaldehyde that was added to the blender
contents.
The analysis of the remains of the blender showed extensive erosion damage in parts of the
interior and around several openings. Ejection of heated material from the inside of the blender is the
likely cause of the erosion The blender also showed extensive damage attributed to impact when the
blender was propelled about 40 feet due to the explosion. The investigators looked in particular for
possible damaged areas where water could have entered the blender. Metallurgical examination of
the water-cooled graphite seal for the vacuum tube showed grooves that could have allowed water
to leak into the blender.
Evaluation of injuries suffered by the victims indicate that the explosion at the Napp faculty
was a deflagration rather than a detonation A deflagration releases energy at a lower rate, generates
lower overpressures, and is less destructive than a detonation.
3.2 Significant Facts
Other facts considered by the accident investigation team in determining the causes of the
accident are listed below.
Napp's Analysis of Hazards of Blending Operation
• The GPA was blended on one previous occasion by Napp in July 1992, using the same PK-
125 blender. The manufacturer of the blender states that the blender is not designed to mix
water reactive substances.
• Technic provided Napp with MSDSs for components of the GPA and an MSDS for the GPA
* The MSDSs noted that aluminum and sodium hydrosulfite are water reactive.
• TheMSDS for the GPA recommends "flooding with water" to control auto-ignition of the
material.
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• Napp's "new product review" procedure was conducted primarily based on information
included in the MSDSs. Review was conducted individually (i.e., not by a team) by four
managers of Napp to determine equipment suitability and health and safety concerns.
» Napp management was aware of the water reactivity of the materials in the blending
operation.
Sources of Water and Heat
Literature review and a limited laboratory study of the hazards of the GPA mixture revealed
that small quantities of water were capable of inducing a runaway reaction at relatively low
temperatures. Further, the presence of aluminum powder in the mixture provided a substantial
increase in the amount of heat released during decomposition (see Appendix B).
The following were possible sources of water and heat in or around the blender at the time
of the accident, which were evaluated by the JCAIT as potential initiators of the event.
* The seal of the intensifier bar was water-cooled.
• Water was observed on internal surfaces of the blender prior to charging; a drying procedure
was subsequently performed.
• Water was used to clean the blender.
* Water was noted in the liquid feed tank and feed line filter just before the feed line entered
blender.
• The coolant in the blender jacket was a water/glycol mixture.
• Water was seen in the packing gland area/bearings of blender prior to the blending operation.
• Although the blender was blanketed with nitrogen, the ports were opened and atmospheric
humidity could have been a source of water.
• The intensifier bar moving at a high speed through dry powders my have been a source of
frictional heat.
* Particulate matter between bearing surfaces at the intensifier bar shaft in the packing gland
area may have been a source of frictional heat.
Deviations from Napp's Expected Maintenance and Operating Procedures
• During a routine maintenance procedure, water was noted between a packing gland and
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-20-
bearings inside the PK-125 blender. Because this location was inside the vacuum section of
the intensifier bar, no water should have been present. The water was dried and the gland re-
packed.
At 3:30 a.m. on April 20, two operators and a foreman found that the vacuum head area
inside the PK-125 blender was "wet." Water (droplets) was observed on the intensifier bar
shaft connection as well as on the inside walls of the blender. The moisture was removed and
the blender dried.
The quantities of the ingredients were recalculated because Napp lacked the proper amount
of potassium carbonate.
Operators noted that the level of dry ingredients was above the level of the intensifier bar and
up to the middle of the vacuum head. According to Patterson-Kelley, the level should be no
higher than the middle of the intensifier bar.
At 10:00 am on April 20, operators detected a vanilla-tike odor in the liquid feed tank (used
to contain liquids prior to injection into the blender).
Water was observed in the liquid feed tank and its filter system. All parts of the injection
system external to the blender were cleaned and dried. Because the powdered ingredients
were already in the blender, the components of the injection system inside the blender could
not be cleaned or dried without contaminating the charged material.
At 2:30 p.m. on April 20, operators were unable to inject benzaldehyde, the sole liquid
component of GPA, into the blender. For approximately 14 hours, operators attempted to
clear the liquid feed line and re-inject the benzaldehyde, while intermittently operating the
intensifier bar and rotating the blender. The intensifier bar was used far longer than specified
in the Napp procedure, in order to properly blend material.
At 7:00 p.m. on April 20, an operator smelled a "rotten egg" odor inside the PK-125 room.
The operator assumed it was from open drums which originally contained the raw materials
which had been charged into the blender.
Two distinct liquids, assumed by Napp employees to be benzaldehyde and drops of water or
IP A, were seen in the vacuum separator bowl. No analysis to determine the components of
the liquid was performed.
At 9:30 p.m. on April 20, a maintenance employee noted an unpleasant odor inside the PK-
125 room.
By 4:30 a.m. on April 21, bubbling was reportedly observed on the surface of the materials
in the blender.
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U.S. EPA Headquarters Library
Mail code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
• At approximately 6:00 a.m. on April 21, workers were verbally notified to leave the building.
Arriving day shift employees were directed to remain in the rear parking lot of the building.
Conditions at the Time of Employee Reentry to Unload Blender
• Bubbling (in an area approximately eight inches in diameter) and smoking were noted on the
surface of the material inside the blender approximately three hours earlier.
* The blending operation is normally conducted at atmospheric pressure. However, an exhaust
nipple was relieving pressure from the nitrogen blanket and off-gas products of the batch from
within the blender. Blender could not be tumbled and cooled due to the open vent.
• A strong sulfur smell was noted in the blending area.
• With the exception of 12 employees which were directed to assist in the off-loading of the
blender, the facility remained evacuated.
Lack of Notification of Local Community Immediately Preceding Accident
• Napp solely used verbal notifications to evacuate the building. Use of an internal alarm would
have automatically notified local emergency responders.
• During the attempt to remove the contents of the blender, Napp did not charge fire hoses that
were laid out and held by Napp employees in case of ignition. The fire water system included
a device that would automatically notify local fire officials if a pre-set flow rate was met.
Since the system was not utilized, no alarm was initiated.
• The Napp facility was located hi a residential area, with homes and other businesses nearby.
Napp did not provide any warning to local community of an on-going chemical emergency.
4.0 Causes of the Accident
4.1 Possible Causes of a Chemical Reaction
The reports of unusual odors in the blending room and building, bubbling and smoking noted
on the surface of the material in the blender, and pressure buildup in the blender all suggest that the
explosion and fire were triggered by an unwanted and uncontrolled chemical reaction occurring in
the blender.
The GPA was successfully blended by Napp and other companies without incident on several
occasions prior to this accident. Based on this history and an evaluation of the chemical components
of the GPA, the JCATT believes the raw materials by themselves will not normally react with each
other in the absence of an outside initiator such as water and/or heat. The JCATT eliminated outside
sources, including sabotage and "Acts of God," as possible causes, as there was no evidence to
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support these possibilities.
The predominant reactions taking place most likely were:
• The exothermic reaction of sodium hydrosulfite with water;
*
• The exothermic reaction of aluminum powder with water,
• The exothermic thermal decomposition of sodium hydrosulfite, which would have been
initiated by heat from the exothermic reactions with water; and
• The exothermic oxidation of hot aluminum powder, which would have been initiated when
air contacted the blender contents.
The oxidation of hot aluminum powder could have resulted in a deflagration. The chemical reactions
of sodium hydrosulfite, aluminum, and benzaldehyde are discussed in detail in Appendix B. Brief
descriptions of other accidents in the past involving sodium hydrosulfite or involving aluminum
powder are presented in Appendix C.
Reaction Initiation
Based upon the nature of the chemicals in the blender at the time of the accident, and the
circumstances of the accident, the JCAIT investigated possible sources of water and heat as the
initiator of the reaction. The following table identifies the possible sources of heat and water in the
blender system. These sources are discussed in more detail following the table.
Initiator
Water
Water
Water
Water
Water
Water
Water
Water
Heat
Heat
Possible Source .
Water used to clean blender/inadequate drying
Water used to clean liquid feed line
Leak of coolant from blender jacket
Moisture from raw materials
Water in nitrogen
Atmospheric humidity entering blender
Water in liquid feed tank
Water-cooled seal failure
Shear from intensifier bar through dry powder solids
Paniculate material in internal bearings of blender
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-23-
Based upon eyewitness testimony, the reaction seemed to be localized (as a hot spot) rather
than a generalized reaction of the materials in the blender. The eight-inch wide bubbling area noted
in the Description of the Accident also suggests that the hot spot was more near the center of the
blended material rather than along the sides of the blender. The JCATT therefore considered the
various sources of water/heat, as discussed below, to determine which ones would likely have led to
a reaction in the location observed.
Inadequate drying of blender before use. Water was used to clean the inside of the blender
before it was used. If water remained in the blender, it would have reacted with the raw materials.
However, before the raw materials were added, water found in blender was drained and fully dried.
While the bubbling noted towards the middle of the blender reveals that the reactions did not take
place at the walls of the blender (where any moisture would have been located prior to use), it is
likely that any moisture in the blender before it was used would have been distributed throughout the
batch.
Leak of coolant from blender jacket into the raw materials. A water/glycol mixture is used
in the outer jacket of the blender to cool or heat the blender. A breach in the integrity of the blender
wall could have allowed the water/glycol mixture to migrate from the jacket into the contents of the
blender. The 1C ATT conducted metallurgical analysis of the blender after the accident. This analysis
revealed one crack near the off-loading port; however, the crack was considered to be from impact
damage. (See Appendix A for additional details.)
Moisture from raw materials. Moisture present in any of the raw materials could have been
sufficient to initiate a reaction. However, no signs of reactions (odors, heat) were detected by the
operators charging the blender with raw materials. Also, Napp performed a quality assurance check
on the raw materials, and no moisture was noted.
Moisture in nitrogen. Nitrogen was used throughout the blending process to inert the
headspace in the blender and to prevent atmospheric moisture from reacting with the materials in the
blender. Any moisture in the nitrogen would have been carried into the blender, and it would likely
have caused reactions on the surface of the material in the blender. However, this nitrogen source
included a filter to extract moisture from the supply. There was no evidence that suggests moisture
was in the nitrogen.
Atmospheric humidity. Atmospheric humidity is known to react with sodium hydrosulfite and
aluminum. Interviews revealed that a nitrogen blanket was placed on the contents of the blender
when the blender was opened to the atmosphere, minimizing the effects of atmospheric moisture on
the feed materials.
Water used to clean liquid feed line. Some information indicated that operators may have
used water or steam to clear the liquid feed line in an effort to add the benzaldehyde. In this case,
water would have been injected into the contents of the blender. However, the JCATT confirmed that
efforts to clean the liquid feed line alter the initial attempt to inject benzaldehyde did not involve
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water or steam.
Water in liquid feed line or tank. Water was noted in the liquid feed tank and line up to the
in-line filter near the line's entry into the blender, prior to the attempts to inject benzaldehyde. The
maintenance employees were not able to clean and dry the portion of the injection system that is
inside the blender because the raw materials were charged into the blender. Several drying/vacuum
procedures were performed prior to charging, yet the liquid feed line within the blender was not
checked to ensure that h was dry. Any water left in this portion of the line could have been deposited
in the blender as the operators attempted to add benzaldehyde. However, given that operators were
not able to inject the benzaldehyde into the blender h is unknown if any water in the feed line actually
entered the blender.
Water-cooled seal failure. Analysis of the graphite water-cooled seal for the intensifier bar
after the explosion revealed wear patterns that could have allowed water to leak through the seal.
Had the seal leaked, it is likely that the water would have been deposited in the material being
blended. However, analysis did not determine whether the seal failed during the blending of the GPA
or during a previous use of the blender by Napp. Before the blending of the GPA, a Napp
maintenance worker noticed water near a packing gland in the blender, which could be a sign of
Mure of the seal. However, even though it is unlikely- based on previous cleaning operations- it is
possible that water used to clean the blender could also have been the source of the water near the
packing gland.
Heat generated bv shear of intensifier bar moving through drv metal powder. The heat
generated by the friction between the intensifier bar moving through the dry metal powders may have
been adequate to initiate or contribute to the thermal decomposition of the sodium hydrosulfite.
Thermal decomposition of sodium hydrosulfite is exothermic; therefore, once the decomposition was
initiated, it could have continued. The intensifier bar was only used while mixing the blender
contents. Overfilling the blender may have reduced the efficiency of the blending operation;
therefore, heat generated would not have been distributed throughout the raw materials within the
blender.
Heat generated due to particulate matter between the bearing surfaces inside the packing
gland for the intensifier bar shaft. The area inside the packing gland for the intensifier bar shaft
contains bearing surfaces. Had any particulate matter been between those bearings, the particulate
matter and the bearings could have become excessively hot due to friction. With this area in contact
with the raw materials inside the blender, heat generated due to the friction would be transferred to
the raw materials. If this heat transfer is sufficient it may have been enough to initiate the sodium
hydrosulfite.
4.2 Most Likely Causes of Chemical Reaction
Based on the witness testimony, physical evidence, and analysis, the JCATT has determined
that the reaction and explosion of the sodium hydrosulfite and aluminum powder was most likely
initiated by two mechanisms: water introduced that initiated the exothermic decomposition of sodium
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•25-
hydrosulfite; and heat which caused the sodium hydrosulfite to decompose. The JCAIT believes the
most likely sources of water are the graphite water-cooled seal and the liquid feed line. The most
likely source of heat was the shear of the intensifier bar moving at a high rate of speed through the
dry powder.
Water from failed seal and liquid feed line. The JCAIT estimates that only a small amount of
water was needed to initiate a reaction. If a large amount of water was injected into the material in
the blender, the JCAIT believes a large hydrogen gas bubble would have been formed, causing a
detonation with greater energy then was released in this accident. However, if a small amount of
water was injected into the material in the blender, the reaction would begin a series of exothermic
reactions over a longer period of time (see Appendix B). This theory is consistent with the findings
of the accident investigation.
Through interviews and review of the blueprints of the blender, the JCAIT believes that if the
water-cooled seal for the intensifier bar failed, it is likely that the water would have leaked into the
material in the blender. Analysis of the seal after the accident revealed grooves that may have been
deep enough to allow water to leak into the blender.
Additionally, the JCAIT can not rule out that any water in the liquid feed line may have been
delivered into the blender when attempts were made to add benzaldehyde.
Heat generated bv intensifier bar. The heat generated by the friction of the blades of the
intensifier bar running through the dry chemicals in the blender may have been sufficient to initiate
or contribute to the thermal decomposition of the sodium hydrosulfite. Thermal decomposition of
sodium hydrosulfite is exothermic; therefore, it is possible that once the decomposition was initiated,
sodium hydrosulfite in the blender continued to decompose, generating more heat. This reaction
would have continued to create a "hot spot" in the material in the area below the intensifier bar. As
the material was being removed by the Napp employees, the hot spot ignited, setting off the rest of
the material in the blender.
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4.3 Root Causes and Contributing Factors
Root causes are the underlying prime reasons, such as failure of particular management
systems, that allow faulty design, inadequate training, or deficiencies in maintenance to exist. These,
in turn, lead to unsafe acts or conditions which can result in an accident. Contributing factors are
reasons that, by themselves, do not lead to the conditions that ultimately caused the event; however,
these factors facilitated the occurrence of the event. The root causes and contributing factors of this
event have broad application to a variety of situations and should be considered lessons for the
chemical processing industries which operate similar processes, especially the tolling industry.
Immediately following the accident, members of the JCATT collected and recorded the details
on the event and the circumstances leading up to the event, interviewed witnesses, and collected,
photographed (see Figures 4-24) and analyzed physical evidence and documentation. In the following
months, the JCATT conducted engineering analyses of this information using elements of Events and
Causal Factors and Hazard-Barrier-Target techniques and professional judgement to determine the
root causes and contributing factors, and to generate recommendations to prevent a recurrence. The
JCATT concludes that the root causes and contributing factors of this accident are:
• An inadequate hazards analysis was conducted and appropriate preventive actions were not
Through Napp's accident report and interviews with Napp employees, the JCATT learned that
most of the pre-operation hazards assessment as part of the "New Product Review" was based upon
the information presented in the MSDSs for the GPA and its ingredients. MSDSs can provide
adequate chemical hazards information but not necessarily process hazards information. For
example, the information presented in the MSDS for the GPA was for a typical package size (up to
one 55 gallon drum), not for the quantity being blended (22 drums).
Under the New Product Review Procedure using the MSDSs, Napp noted that aluminum,
sodium hydrosulfite, and GPA were water reactive. However, this procedure and the MSDSs did
not reveal or address accident history, identify and account for all of the potential sources of water,
ways to eliminate or control these sources (engineering safeguards or procedures), recognition of
water contamination of the raw materials or GPA, the immediate steps necessary to stop or handle
an unwanted reaction inside the blender, and the proper technology and design of the equipment
necessary to safely and effectively blend water reactive substances. In addition, the procedure did
not identify that heat could also have an adverse affect on the substances in the blender. Without this
information, appropriate prevention actions were not taken.
Napp successfully conducted the blending operation previously (1992) using the same
process, procedures, and equipment and was unaware of any major accidents involving this product
or process. However, Napp did not appear to know about, or at least consider the consequences of,
past accidents that have occurred involving sodium hydrosulfite or aluminum powder.
The lack of an adequate process hazards analysis led to a lack of knowledge or understanding
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that small amounts of water or heat could trigger a self-sustaining exothermic reaction at relatively
low temperatures. This exothermic reaction lead to the catastrophic deflagration and fire. Napp
removed sources of water in the blending room and took steps to ensure the blender and raw
materials were kept dry. However, other sources of water were still present and Napp did not folly
eliminate the possibility that water could contaminate the blending process and operation. Water was
used to cool the mechanical seal in the intensifier bar and a water/glycol mixture was used in the
heating/cooling jacket. Evidence also suggests that water may have been present in the liquid feed
tank and piping system since they were not cleaned and dried prior to the startup of blending
operations. This equipment was cleaned and dried during the blending operation. However, since
the blender was already loaded, the liquid injection piping inside the blender could not be cleaned and
dried. In addition, the intensifier bar offered a potential source of heat input from bearings and mixing
shear (see equipment selection, below).
The JCATT notes that OSHA allows the collection of the MSDSs to suffice for compliance
with its information collection requirements for process safety information, provided the MSDSs
contain information to the extent that enable the employer and employee involved in operating
processes to identify and understand the hazards posed by these processes. Such specific information
criteria include: reactivity data, thermal and chemical stability data, and hazardous effects of
inadvertent mixing of different chemicals that could foreseeably occur. A review of MSDSs alone
for highly hazardous processes in lieu of a formal process hazard analysis would not meet OSHA's
requirements. Industry may not clearly understand this distinction which may have contributed to less
than adequate hazards analyses since MSDSs were relied upon to conduct the company's new
product review. As a result, thermal and chemical stability as well as inadvertent mixing of chemicals
were not adequately addressed in the review process.
• Standard operating procedures and training were less than adequate.
Napp's standard operating procedures (SOPs) failed to adequately address emergency
shutdown, including conditions under which emergency shutdown is required and the assignment of
shutdown responsibility to qualified operators to ensure that emergency shutdown is executed in a
safe and timely manner. Also, the SOPs did not address operating limits, including the consequences
of deviations and steps required to correct deviations. Consequently, employees could not have been
trained on these critical steps, hampering their ability to properly execute the blending process under
the conditions occurring on April 20 and 21.
Napp did not recognize or understand the significance of the abnormal situation beginning on
April 20 and culminating in the explosion and fire on April 21. According to Napp's procedure's, the
blending portion of the process should occur in less than an hour. However, employees attempted
to correct a variety of deviations, including unusual odors, bubbling, pressure buildup, and difficulty
adding the liquid portion, while the blending operation continued for many more hours than normal.
The odors, bubbling on the surface of the contents of the blender, buildup of pressure and venting of
gases from the blender all signaled that an undesired reaction had been initiated and was ongoing.
There were no operating procedures to address the deviations observed, the corrective actions to be
taken, or conditions under which an emergency shutdown should be triggered.
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• The decision to re-enter the facility and off-load the blender was based on inadequate
information.
The lack of a complete understanding of the chemical and process hazards led to a lack of
knowledge of the significance of the conditions present at the time employees re-entered the facility
to off-load the blender. Once the contents of the blender began reacting, the reactions were self-
sustaining. As described above, the reaction had progressed to a point where employees were
evacuated because of the sulfur smell coming from the blender. At the time the decision was made
to unload the blender, Napp was aware of, and concerned for, the strong possibility of a fire.
However, there is no evidence to suggest that Napp was aware that off-loading the blender may have
exacerbated the reaction mechanisms by exposing the contents to air or that the contents could
violently erupt and deflagrate. Any attempt to stop the reactions by smothering or providing a
nitrogen blanket would have been ineffective (see the discussion of chemistry in Appendix B).
• The equipment selected for the GPA blending process was inappropriate.
Napp took steps to eliminate or control sources of water but elected to use blending
equipment that incorporated sources of water in the design (water cooled seal, water/glycol jacket).
Although regular maintenance of seals and cooling jackets helps to prevent failure and leakage, the
possibility of a malfunction still exists, allowing water to contaminate the blender. The Aluminum
Association, in their brochure Recommendations for Storage and Handling of Aluminum Powders
and Paste, recommends "In mixing aluminum powder with other dry ingredients, frictional heat
should be avoided. The best type of blender for a dry mixing operation is one that contains no
moving parts, but rather effects a tumbling action such as a conical blender." The PK-125 blender,
as previously noted, was a closed blender which, for the batch blended, contained a high speed
intensifier bar for mixing. Shear from the movement of the intensifier bar through the dry powders
may have been a source of frictional heat. In addition, paniculate matter between bearing surfaces
at the intensifier bar shaft in the packing gland area may have been a source of frictional heat.
* Communications between Napp and Technic were inadequate.
Inadequate communication between Napp and Technic also contributed to the lack of a
complete understanding of the process hazards and their consequences. There is no standard or
delineation of responsibilities in the toll manufacturing/blending industry which specifically assigns
the responsibilities for input into hazard reviews at the toll manufacturer's facility.
Technic, Inc. is the patent holder of the GPA and is in the best position to know the hazards
of its product. In this tolling operation, Technic contracted with Napp to perform the blending.
Technic provided Napp with MSDSs for the raw materials and the finished product and a batch recipe
ticket. As noted above, MSDSs provide product hazard information but generally do not provide
process hazard assessment information. This investigation showed that Napp did not possess all the
information necessary to make sound judgements regarding the responses to deviations from the
procedures in the blending process. Napp is in the chemical processing industry, however, Napp did
not have in-house expertise regarding the GPA, nor did it have experience in working with water
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reactive materials. Although some of its employees had previously used the ingredients of GPA,
Napp blended the GPA only one other time prior to this event (the previous blend was performed in
1992).
It should be noted that the MSDSs for sodium hydrosulfite and aluminum powder also gave
contradictory emergency response directions. For sodium hydrosulfite, copious amounts of water
should be used, while the MSDS for aluminum clearly stated "avoid water," "reacts with water,"
"exothermic reaction with water ... to generate hydrogen and heat." The MSDS for the GPA
advised the use of "A water spray ... to extinguish fire." The JCATT investigators have located
numerous scientific references, which were presumably readily available to Napp management
personnel as well, indicating that powdered aluminum that is moistened or wetted becomes a very
serious fire hazard. The only information that Napp used to determine the emergency response
procedures for handling emergencies involving the GPA was the MSDSs. However, the MSDSs do
not provide sufficient information to guide a response to an uncontrolled reaction or fire, given the
significant quantity of material in the blender. The recommendation in the MSDS for "small fires"
was to flood with water; however, a small fire was not defined, and the amount of water necessary
to flood the fire was not specified. For a fire involving an agent that is reactive with water, the
addition of an inappropriate amount of water as part of an emergency response can have tragic
consequences.
" The training of fire brigade members and emergency responders was inadequate.
Eight of the twelve employees who were inside the building immediately preceding the
explosion (during the unloading of the GPA) were also members of the Napp fire brigade and trained
to handle fire hoses. Napp was concerned about the potential for fire by arranging for hoses and
personnel to be ready. However, employee training records indicate that the employees standing by
with fire hoses were not trained to deal with chemical fires or emergency response operations
involving chemical fires. Consequently, the lack of training of the fire brigade members and
emergency responders may have contributed to the consequences since the personnel present had no
training to recognize, understand, and assist with a potentially significant emergency situation.
5.0 Recommendations
Based upon the root causes and contributing factors of this accident described above, the
JCAIT provides the following recommendations to prevent accidents like this one from happening
in the future:
FHAs. SOPs and Training
Before handling any substance, facilities should ensure that all chemical and process hazards
and the consequences and deviations associated with the chemical and process hazards are completely
understood, evaluated, documented, and appropriately addressed through preventive measures. This
assessment should also include accident history, chemical incompatibilities and equipment design and
integrity. One way facilities can cany out this evaluation is using a formal process hazard analysis
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(PHA) technique as required under the OSHA Process Safety Management Standard under 29 CFR
1910.119 or the EPA Risk Management Program Rule under 29 CFR part 68. The Center for
Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE) has
prepared guidance on PHA methodologies. In addition, the hazard evaluation can identify failure
areas that need to be addressed by safeguards such as engineering controls, maintenance and standard
operating procedures. The standard operating procedures (SOPs) should address steps for normal
operations (including startups and shutdowns), anticipated deviations from normal, the consequences
of such deviations and the steps to correct them, emergency conditions and steps for emergency
shutdowns and placing the operation into a safe mode. After SOPs have been developed, all
operating personnel, including supervisors, should be trained on the newly developed SOPs. This
training must also include recognition of deviations or upset conditions and their potential
consequences and corrective actions or shutdowns.
Facilities need to clarify and understand their respective responsibilities for the discovery and
assessment of chemical and process hazards and process safety information in tolling or other
contracting agreements. Both parties must be clear as to who will be responsible for process safety
information, including chemical hazards, technology of the process, consequences of upset conditions,
and identification of any previous incidents involving similar processes. The chemical and petroleum
processing industries should develop basic guidelines to be used in tolling or contracting agreements
the safety of which may depend on sound communication of chemical and process hazards. EPA has
requested that CCPS examine whether guidance for conducting process hazards analyses and safety
information sharing in tolling agreements should be developed.
Recognition and Evaluation of Abnormal Situations
The value of a thorough assessment of the chemical and process hazards using methods such
as a process hazard analysis (PHA) is greater understanding of the range of possible deviations, the
consequences of the deviations, and corrective actions to safely bring the process under control.
Without this information, evaluation and action to correct abnormal situations when they arise may
become guesswork, placing the process, the facility, the employees, the community, and the
environment at risk. Facilities should routinely review their chemical and process hazards assessments
to make sure new information is included, monitor accident histories and lessons learned and consider
applications to their processes, and investigate deviations, no matter how minor, to prevent more
serious consequences.
Proper Use of Equipment
All facilities should ensure that equipment manufacturers' recommendations are followed and
that equipment is installed, operated, and maintained as designed. Equipment manufacturers typically
have a wealth of information regarding the maintenance and recommended uses of equipment they
manufacture. Chemical processors and toll operators should regularly contact equipment
manufacturers for updated information and seek advice should equipment application, installation,
operation or maintenance needs deviate or require modification from equipment manufacturers'
recommendations.
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Many types of industrial vessels or other equipment use mechanical seals to permit external
drive of internal equipment, such as pumps, mixers, or agitators. In certain applications, mechanical
seals must be liquid cooled or purged to prolong seal integrity. While regular maintenance may help
prevent Mure and leakage, the possibility of a malfunction always exists. Faculties should ensure
that liquids used to cool or purge seals are not incompatible with materials processed in the vessels
or other equipment.
OSHA/EPA Review of Highly Hazardous Chemicals List
Appendix A of OSHA's existing Process Safety Management (PSM) standard (29 CFR
1910. 1 19) lists the toxic and reactive chemicals covered by that standard. At the time of the process
safety management rulemaking, OSHA decided to include only those chemicals having the NFPA
(NFPA 49) ratings of 3 or 4 for reactivity. Chemicals rated 3 or 4 are those that are capable of
undergoing detonation or explosive decomposition and generating the most severe blast or shock
wave. NFPA 49 assigns sodium hydrosulfite a reactivity rating of 2 and aluminum powder a
reactivity rating of 1. Because of this tragic event, OSHA is considering adding additional reactive
chemicals to the Appendix A chemical list.
EPA and OSHA have agreed to harmonize their lists of substances under the PSM standard
and the List of Regulated Substances for the Risk Management Program in 29 CFR part 68
promulgated under section 1 12(r) of the Clean Air Act. EPA's current list only addresses toxic and
flammable substances. As part of the upcoming 5-year review of its list, EPA will consider other
hazards, including reactive chemicals.
Review of Integration of Hazard Communication fRoiCom) and Hazardous Waste
Operations and Emergency Response (HazWooer) Standards, with the Process Safety
Management (PSM) Standard
OSHA's HazCom and HazWoper standards, combined with the PSM standard, provide an
integrated approach to worker health and safety. OSHA's Hazard Communication Standard (29 CFR
1910.1200) permits the MSDS for the components of a mixture to serve as the MSDS for the
mixture. Employers that rely upon an MSDS created by other entities must be aware that the MSDS
for raw materials may not identify all hazards which may be encountered when mixing, blending or
processing them with other materials. This may be true even if there is no reaction anticipated or
apparent. Moreover, an MSDS for the final mixture may specifically address the hazards of shipping
container quantities, but may not apply to the hazards of larger quantities in the processing phase.
This accident demonstrates that a review of the MSDS is an inadequate substitute for
performing a process hazards analysis. As noted above, OSHA allows the collection of the MSDSs
to suffice for compliance with its information collection requirements for process safety information
if the MSDSs contain information to the extent that they enable employers and employees involved
in operating processes to identify and understand the hazards posed by these processes. Such specific
information criteria include: reactivity data, thermal and chemical stability data, and hazardous effects
of inadvertent mixing of different chemicals that could foreseeably occur. A review of MSDSs alone
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for highly hazardous processes in lieu of a formal process hazard analysis would not meet OSHA's
requirements. Industry may not clearly understand this distinction which, in this accident, may have
contributed to a less than adequate hazards analyses. As a result, thermal and chemical stability as
well as inadvertent mixing of chemicals were not adequately addressed in the review process.
In addition, many companies rely on MSDSs to communicate hazard and emergency response
information with communities and first responders as required by EPA under the Emergency Planning
and Community Right-to-Know Act. EPA and OSHA will consider whether additional guidance or
outreach in the form of an Alert or other means is necessary to advise industry and first responders
to make sure that MSDSs are not used beyond their intended design, to highlight areas where
information can be misunderstood, and to make sure that hazards information is complete. The
American National Standards Institute (ANSI) in cooperation with the Chemical Manufacturers
Association (CMA) is working to revise an existing ANSI uniform MSDS format. CMA and ANSI
and other industry organizations should also evaluate whether additional consensus standards or
guidelines are needed for MSDS consistency and to avoid misunderstandings (e.g. the difference
between chemical and process hazards) or faulty interpretations of terms (e.g. small fires or small
amounts of water).
As a result of the devastating loss of five emergency responders in this event, OSHA clarified
fcsHazWoper Standard (29 CFR 1910.120) and its Employee Emergency Plans and Fire Prevention
Plans (29 CFR 1910.38) (Memorandum For All Regional Administrators; Subject: Update to
HazWoper Emergency Response Guidance: Coordination with Local Fire Departments; Oct. 30,
1996). This clarification, while written for compliance officers, gives employers guidance for
conducting appropriate emergency response actions as part of their emergency response plans
contained in the subject standards.
Finally, as a result of this accident, OSHA issued a Hazard Bulletin about MSDSs in July 3,
1996, recommending that a process safety analysis be performed for all materials with catastrophic
potential, even if not covered by the PSM standard. The analysis should include a cautious review
of chemical hazards, incompatibilities and a thorough examination of all mechanical equipment.
Standard operating procedures should be developed and the consequences of deviation ought to be
identified. Further, employers that rely on MSDSs created by other parties must be aware that
MSDSs for raw materials may not identify all hazards that might be encountered when mixing or
blending with other materials. This may be true even if there is no anticipated or apparent reaction.
MSDSs for the final mixture may specifically address the hazards of shipping container quantities, but
may not apply to the hazards of the larger quantities needed to make the mixture.
6.0 Outcomes of OSHA/Napp Technologies Settlement
As part of the settlement between Napp Technologies and the Occupational Safety and Health
Administration, Napp agreed to the following hems: 1) conduct a comprehensive review of all SOP's
for worker health and safety issues and compliance with worker safety and health standards; 2)
conduct periodic comprehensive safety and health audits utilizing a qualified independent safety and
health professional and develop action plans to abate all hazards found; 3) contract with a qualified
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safety professional to train Napp Safety Council members (including supervisory, technical and
employee representatives) to perform their duties effectively; 4) create an SOP institutionalizing
review all facility processes to identify those that should undergo a more detailed process hazard
analysis; and 5) designate a responsible management official whose primary responsibility will be to
oversee Napp's safety and health program, worker health and safety issues and compliance with
applicable health and safety standards.
n S EPA Headquarters Library
Mail code 3201
! 200 Pennsylvania Avenue NW
Washington DC 20460
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Appendii A
Results of Analysis of the Accident
Chemical Analysis Results
The results of the chemical analyses of the residues in the blender taken by EPA's
Environmental Response Team revealed the presence of percentage amounts of various metals such
as sodium, potassium and aluminum. This was expected, inasmuch as these metals were part of the
GPA mixture. In addition, the sampling revealed the presence of large amounts of phenol and
methylphenol compounds. Phenol was detected in internal ash samples and in an external crevice ash
sample. To a lesser degree 2-methylphenol and 4-methylphenol were also detected in the ash
samples.
Phenol and the methylphenol compounds were likely due to the insulating material remnants
which were originally located in the annuhis between the outer wall of the blender and the outer wall
of the water-grycol jacket. Additionally, a review of the chemistry of benzaldehyde suggests that the
presence of phenol and phenol compounds can be explained as follows: the aluminum in the blender
had reacted with the water and sodium hydrosulfite, causing an exothermic and reducing atmosphere
to form inside the blender. This resulted in the conversion of whatever benzaldehyde had been
successfully introduced into the blender to a methyl hydroxy (alcohol) intermediate. This material,
hi the reducing environment inside the blender, was transformed to toluene, another intermediate.
The toluene was in turn converted to phenol, and to a lesser degree 2-methyl phenol, and 4-methyl
phenol This reaction is a classic electrophilic aromatic substitution in which methyl groups reform
preferentially onto the benzene ring in the ortho and para positions (relative to the OH group in
phenol), creating phenol, and the 2- and 4-methyl phenol species respectively. This chemistry tends
to eliminate the possibility that phenol, rather than benzaldehyde, had been inadvertently added to the
GPA blend.
Post-Eiplosion Analysis of Blender
After die accident, members of the Materials Reliability Division of the National Institute of
Standards and Technology (NISI) analyzed the remains of the PK-125 blender. A visual examination
of the blender revealed that the outer jacket of the blender was ripped loose at the access ports and
was peeled away from the stainless steel shell of the blender. The damage initially appeared to be the
result of a steam explosion inside the water jacket lining. The shell sustained little gross deformation
except near the bottom unloading hatch assembly area.
The bottom portion of the blender, where the discharge port was located, was severely
deformed, and most of the unloading hatch assembly was missing. Much of this damage was
probably caused by impact when the blender was propelled through the block wall of the blender
room and/or immediately afterwards as it came to rest. The metal surrounding the discharge port was
most likely very hot, which would have facilitated deformation.
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The metal surrounding the access ports had striation marks resembling those typical of
oxyacetylene cuts in steel. The striation marks are believed to be due to erosion that occurred when
material from inside the blender was violently ejected from the loading ports at high temperature and
velocity.
Further visual observations were performed by MIST personnel off-site. The surface of the
stainless steel shell was examined for any visible cracks through which water (from the water jacket)
could have entered the blender. With the exception of a small crack (several millimeters long) located
near the discharge port, there were no visible signs of cracking. This damage is believed to have
occurred during the accident and was not part of the initiating event. No localized areas of melting
or heat tinting were observed.
A metal tube, approximately 400 millimeters (mm) diameter, to which the support flange is
fastened on Lobe A of the blender, is welded to the stainless steel shell inside the blender. This tube
had a sheet metal cover/seal on the end. Through this cover, a series of concentric pipes and shafts
(vacuum tube assembly) enter the blender. The cover, which is approximately 1.5 mm thick, was
severely deformed and bent in a manner suggesting that the concentric pipes were torn or blown out
of the blender in the accident. Inspection of the cover inside the blender showed severe erosion
damage around the opening through which the concentric pipes entered the blender. These erosion
markings are similar to those found on the access ports and indicate GPA material was ejected out
of this opening of the blender as well.
The interior shell near the off-load port is slightly buckled. This deformation most likely
resulted from impact damage during the accident. The damage on the outside of the blender around
the off-load port is more extensive. The wedge-shaped configuration of the damage was probably
caused by the impact during the accident.
The most notable features on the surface of the interior were the erosion marks. These
markings likely resulted from the ejection of heated material from inside the blender during the
accident. The erosion was confined principally to the surfaces of the interior that form the "V
between the two lobes. The erosion occurred mostly within a region that was approximately one
meter wide near the seam between the two lobes of the blender. The heaviest erosion damage is
limited to a region about 200 mm wide near the centerline. The surface at the seam is not eroded.
Erosion appeared on the surfaces adjacent to the seam, in the lobes, and at the top of the lobes
(around ports). In both lobes, it appears that the erosion on the top side of the centerline is most
severe. In addition, the erosion at the tops of Lobes A and B differ: on Lobe B the erosion is dimple-
like around the access port, resembling impact damage, and erosion on Lobe A is wavy lines (flow-
like) cut into the surface of the shell.
The concentric pipes and shafts of the vacuum tube assembly enter the blender (Lobe A)
through the support tube. On the outside of the blender, near the end of the vacuum tube assembly,
is a water-cooled graphite seal that allows the agitator shaft to turn at high speed. Examination of
the seal components showed that the inboard steel ring was fractured and that the inboard graphite
seal had radial fissures and circumferential gouging. The depth of the grooving was measured on a
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replicated surface of the inboard sea!. The measurements were made on an optical microscope with
a calibrated z-axis. Typically, the depth of the grooves varied from 25 to 125 microns. The width
of the groove exceeded 1 mm in some regions; these grooves may have allowed water to pass
through the seal over time.
Coroner's Report
This report will not detail the injuries sustained by those Napp employees who perished in the
explosion. However, the physical condition of the victims provides some insight into the nature of
the chemical reactions that occurred inside the PK-125 blender.
Autopsy information provided investigators by the Bergen County Medical Examiner indicates
mat the deceased employees suffered a combination of trauma, burns, and smoke/fumes inhalation.
There were no physical signs that the victims had been subjected to the explosive force of a
detonation. Rather, the physical signs indicated that what occurred was a deflagration, not a
detonation. The main difference between the two is the rate of energy release and the amount of
overpressure generated by the instantaneous and violent reactions of the materials involved. Had a
hydrogen gas explosion occurred, it has been calculated that the entire plant, as well as a significant
portion of the nearby homes, would have been destroyed in the blast. The extent of the damage,
although catastrophic by any standards, was indicative of an explosion with a lower rate of energy
release than that which would have been produced by hydrogen gas. This physical evidence indicates
that the reactions that occurred involved the decomposition of sodium hydrosulfite and subsequent
reaction products interacting with powdered aluminum.
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Appendix B
Chemical Reactions
Sodium Hvdrosulfite
Sodium hydrosulfite decomposes exothermically in the presence of heat, moisture, or air.
Although sodium hydrosulfite is flammable, h is not explosive. Contact with small amounts of water
or moist air will cause a chemical decomposition reaction that generates sufficient heat to ignite
combustible materials. In one reported accident (Bretherick 1990), smoldering started when water
entered a drum of sodium hydrosulfite, which then ignited when tipped over for disposal. In another
case (Bretherick 1990), a batch of sodium hydrosulfite violently decomposed during drying in a
graining bowl. The likely explanation was contamination with water and/or oxidant.
Exposure of sodium hydrosulfite to moisture, either from humid air or traces of water, can
cause reactions that may generate enough heat to initiate thermal decomposition (NFPA 49, 1994).
The reaction of sodium hydrosulfite (Na^OJ with water can produce sodium bisulfite (NaHSO3)
and sodium thiosulfate (Na^OJ (Equation 1). Because sodium bisulfite is an unstable solid
compound (Kirk-Othmer 1983), it most likely decomposes to sodium metabisulfite (Na^Oj) and
water (Equation 2). Sodium metabisulfite may then decompose to sodium sulfite (NajSOj) and sulfur
dioxide (SOz) (Equation 3). Therefore, the bubbling of the GPA materials that was observed by a
supervisor in the early morning of April 21 can be explained by the generation of sulfur dioxide.
Because water is produced in this suggested reaction scenario, the overall reaction becomes self-
sustaining; only a small amount of water is needed to initiate the exothermic reaction. As the reaction .
proceeds, the temperature of the blender and the GPA components would have increased.
(1) 2Na2S2O4 + Hp - 2NaHS03 +
(2) 2NaHSO3 - Na^Oj + H20
(3) 2N32SA -
+ S02 + S
Only catalytic amounts of water are needed to make the decomposition self sustaining. In
closed vessels, decomposition is likely to occur simultaneously with pressure buildup at low
temperatures.
Anhydrous sodium hydrosulfite has a tendency to decompose spontaneously as in the
following equation (Equation 4), forming sodium thiosulfate and sodium sulfite and releasing sulfur
dioxide. Because this reaction is exothermic, the temperature of the GPA components would have
continued to increase. This increase in temperature would have accelerated the decomposition and,
thus, the production of sulfur dioxide, resulting in violent surface bubbling of the reaction mixture.
(4) 2^8204 - NajSOj +
SO
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The reaction is violent above 150 - 190C. Simple geometry influences the mode of
decomposition. In 'heap' samples, insulation, and therefore self heating, is greater than in thin layers
of the chemical. When a sample was heated at 15C per minute, a sudden exotherm of 47 kilojoules
per mole (kJ/mol) occurred at 205C (Gcodhead, 1974). Another investigator performing calorimetry
experiments on sodium hydrosulfite found that there were two large exotherms preceded by a small
one (Tartani and Contessa). The initial decomposition temperature was lowered by SOC (from 1 IOC)
in the presence of 0.5 to 1% water. The investigator concluded that in closed vessels, the two sets
of reactions above (i.e., wet and anhydrous sodium hydrosulfite) occur simultaneously with buildup
of pressure at low temperatures.
The intensifier bar rotating at a high speed, cutting through the aluminum powder and other
GPA materials, may have generated frictional heat. Although tumbling the contents of the blender
may have distributed some of the heat, the use of the intensifier bar may have contributed to the
continuation of the sodium hydrosulfite/aluminum/water reaction.
Aluminum
Aluminum is a strongly electropositive metal and is very reactive, burning rapidly in air when
strongly heated. Finely divided aluminum powder or dusts forms highly explosive mixtures in air
(flash point of 645C). Ignition may be the result of heat, shock or abrasion; it may also be
spontaneous due to humidity or moisture. A severe explosion occurred in a plant producing fine
aluminum powder in 1983 (Bretherick 1990). Fires and explosions have occurred during grinding
and polishing operations where sparks may have set off the reactioa Because of the extreme
exothermic nature of its reaction with air, aluminum is used as a metal fuel. It is incorporated into
explosives to increase the energy released. The use of substantial amounts of aluminum powder
under high temperatures with the reduction of liberated carbon dioxide and water by the metal is used
in conventional explosives enhances the energy release by up to 100%.
In a finely divided form, aluminum will react violently with boiling water to form hydrogen
and aluminum hydroxide; the reaction is slow in cold water. Under ordinary circumstances, aluminum
is passivated by the formation of a layer of aluminum oxide. If this protecting layer is breached,
reactions consistent with its strong electropositive character may occur. In handling fires where
aluminum dust is present, one is warned not to use water. In one case where aluminum dust was
ignited by sparks from a grinding machine, the activation of an automatic sprinkling system and the
reaction of the water with burning metal resulted in the liberation of hydrogen, which, after mixing
with air, exploded (Bretherick 1990). In the Bretherick case, the primary explosion created an
aluminum dust cloud which exploded forcefully, producing more dust and encompassing more
aluminum dust, resulting hi four tertiary explosions in all.
Because of its high affinity for oxygen, aluminum is used in metallothermic reductions of
metal compounds. These reactions produce enormous amounts of heat. For example, hi its reaction
with chromic oxide, molten chromium (melting point 1907C) is formed. Thermite-type reactions may
also occur with non-metals such as sodium hydrosulfite, sulfur dioxide, and carbon oxides. Even
though sodium hydrosulfite is a reducing agent, aluminum has such an affinity for oxygen that it can
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extract oxygen from these compounds. A violent explosion occurred when an 8:3 molar mixture of
aluminum powder and sodium sulfate was heated to 800C (Bretherick 1990). Application of sodium
carbonate to red hot aluminum caused an explosion (Bretherick 1990). At high temperatures,
aluminum powder also reacts violently with sulfur to form aluminum sulfide.
As examples, aluminum powder may react with sodium hydrosulfite or sulfur dioxide,
produced from the decomposition of sodium hydrosulfite, according to the reactions:
4A1 + 3S02 2A1A + 3S
2A1 + NajS204 NajO + A12O3 + 2S
The heats of reactions at 25C are -615.3 kJ/mol Al and -428.9 kJ/mol Al, respectively.1
In another case, butanol attacked an aluminum gasket at 100C, liberating hydrogen
(Bretherick 1990). Other alcohols would react similarly. Benzyl alcohol is produced by the reaction
of benzaldehyde with sodium hydrosulfite. Therefore, conditions may exist in the reaction vessel for
a similar reaction of benzyl alcohol and aluminum powder to occur.
Reactions Occurring in Mixture
The predominant reactions taking place probably were the exothermic reaction of sodium
hydrosulfite with water, or with water and oxygen; the exothermic reaction of aluminum powder with
water, the exothermic thermal decomposition of sodium hydrosulfite, which would have been initiated
by heat from the exothermic reactions; and the exothermic oxidation of hot aluminum powder, which
would have been initiated when air contacted the blender contents. The reaction products expected
are consistent with the results of the chemical analysis of the site (EPA Trip Report, July 5, 1995).
The source of the large phenol concentration noted in the grab samples from the blender does not
seem to be a result of the reactions of the reported mixture materials, but most likely occurred at
some time during initial attempts to blend the GPA components.
Caiorimetrv Studies
The following are the results of accelerated rate calorimetry (ARC) studies of sodium
hydrosulfite and a sample approximating the composition of the GPA. The purpose of the studies
was to measure the heat released from these substances in the presence of water to determine the
hazard posed by these substances. Calorimetric studies obtained from the literature and a limited
study conducted by the Salt Lake Technical Center confirm that the mixture was extremely
hazardous. These studies confirm that small quantities of water were capable of inducing a runaway
reaction at relatively low temperatures and that the presence of aluminum in the mixture provided a
substantial increase in the amount of heat released during the decomposition.
hheheattoffoi
13th edition.
obtained from CRC Handbook of Chemistry and Physics, 73lh edition and Lange's Handbook of Chemistry,
-------
-40-
A review of the literature disclosed a study entitled "Water Influence on Thermal Stability of
Sodium Dithionite" (presented by V. Tartari and S. Contessa at the 5th International Symposium
"Loss Prevention and Safety Promotion in the Process Industries," sponsored by the Societe de
Chimie Industrielle, 28 rue Saint-Dominique, F75007, Paris. This accelerated rate calorimetry (ARC)
study of the effect of water on the decomposition of sodium hydrosulfite (Na^O^ sodium dhhionite)
demonstrated that addition of less than one percent of water to a sample of sodium hydrosulfite
reduced the temperature at which self-heating begins from approximately 111C down to
approximately 60C. Based on these results, the authors conclude that a small amount of water
strongly influences the thermal stability of this material.
Additional, but limited, studies were conducted by the Salt Lake Technical Center using ARC
methods to determine the effects of including aluminum in a mixture containing sodium hydrosulfite
and potassium carbonate. Under these conditions, which mimic the insulated (adiabatic) conditions
in the core of the mixer leading to thermal runaway, the net adiabatic temperature rise for 3.5 grams
(g) of the mixture without the aluminum was 34C. For a comparable amount of the mixture including
aluminum and approximating the composition of the ACR9031 mixture, the temperature excursion
went off scale, and the experiment had to be scaled down. For 0.5 g of the mixture containing the
aluminum, the net adiabatic temperature rise was 486C. From these data, the heats of reaction were
determined. These studies demonstrated that the addition of the aluminum produced an eleven-fold
increase in the amount of heat released per gram of mixture.
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-41-
Appendix C
Accidents Involving Sodium Hydrosulflte and Aluminum
Sodium Hvdrosulfite
The events leading to the explosion at Lodi involved the exothermic reaction of sodium
hydrosulfite with water, followed by thermal decomposition of sodium hydrosulfite. A number of
accidents are reported in the literature involving reaction of sodium hydrosulfite with water and
generation of sulfur dioxide. Exhibit C-l below provides short descriptions of some accidents
involving fires, explosions, or reactions of sodium hydrosulfite, culled from media and other
sources. This exhibit does not include reports of spills of sodium hydrosulfite where no serious
consequences resulted, but evacuations were carried out as a precaution.
Exhibit C-l
Accidents Involving Fires, Explosions, or Reactions of Sodium Hydrosulfite
Location
Savannah, GA
Chemical plant, Wuxi,
Jiangsu, China
Commercial laundry,
Rhode Island
Philadelphia, PA
Accrington Lancashire
UK
Los Angeles, CA
Paper manufacturer,
Madawaska, ME
Trucking Company,
Galveston County. TX
Date
4/1/95
3/24/95
6/14/94
3/23/94
3/5/92
11/28/90
11/6V90
6/9/90
Description
Large fire may have resulted from tank
leaks that caused the mixing of crude
sulfate turpentine and sodium hydrosuifite.
Drums containing sodium hydrosulfite
exploded (no details available).
A small chemical fire was reported in a
storage drum containing sodium
hydrosulfite.
Water, possibly from a roof leak, hit a 30-
gallon drum of powdered sodium
hydrosulfite, generating fumes.
Drum of sodium hydrosulfite came in
contact with moisture and began giving off
sulfur dioxide. Several gallons of water
were used to dilute chemical.
A 35-gallon drum filled with sodium
hydrosulfite burned.
A spill of 5,000 pounds of solid sodium
hydrosulfite led to a release of sulfur
dioxide.
A trailer of sodium hydrosulfite caught fire.
Effects on People
None reported
6 killed, 5 injured
None reported
4 workers injured, 12
evacuated
8 people (company staff)
evacuated
2 firms evacuated
1 1 workers injured
16-block area evacuated;
no injuries
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-42-
Extaibit C-l (continued)
Location
Rail depot, Kensington,
Victoria, Australia
Landfill in Orlando, FL
Chemical plant, Phoenix,
AZ
Chemical plant, Rocky
Mount, NC
Dye plant, Los Angeles,
CA
Henrico, VA
Chemical truck,
Daglingworth,
Gloucestershire, UK
Chemical truck on
highway, Covington, LA
Chemical distribution,
and storage company, NC
Northenden, Greater
Manchester, UK
Liverpool, Merseyside,
UK
Date
4/20/90
1/26790
4/6/89
6/28/89
5/25/89
2/15/89
1/13/89
1/1/89
3/88
1/20/87
H/ll/85
Description
Sodium hydrosulfite leaked from a shipping
container that held ! 22 drums and reacted
with moisture to form a huge toxic cloud.
Firemen neutralized the leak.
Fire started when a small amount of
calcium hypochlorite was added to a drum
containing sodium hydrosulfite.
A drum of sodium hydrosulfite ignited
while in storage.
Rain apparently fell into a rusted 30-gallon
container of sodium hydrosulfite, causing a
chemical reaction that formed a vapor
cloud
Fire of sodium hydrosulfite reported.
Sodium hydrosulfite "ignited itself inside a
35-gallon drum in the parking lot.
Driver of truck carrying drums of sodium
hydrosulfite noticed one on fire. Water was
sprayed onto drums, which then exploded
Sixty-foot cloud of sulfur dioxide formed
A truck carrying 43,000 pounds of granular
sodium hydrosulfite burst into flames.
A fire was blamed on improper cleanup of
a chemical spill. Employees accidentally
punctured a drum of sodium hydrosulfite;
the spill area should have been deluged
with "massive amounts" of water.
A drum of waste sodium hydrosulfite
periodically ignited and released toxic
fumes. Firemen used water to cool the
anm\
A chemical fire broke out in the hold of a
cargo ship. As a drum of sodium
hydrosulfite was being offloaded, some
material was spilled and instantly ignited,
causing • fln«h fire
Effects on People
1300 residents evacuated
Evacuation reported
None reported
16 people treated, 1
hospitalized
Evacuation reported
None reported
Residents told to stay
inside
12 miles of interstate
highway closed, residents
evacuated in a 1-mile
radius
None reported
20 nearby residents
evacuated suffering from
nausea and sore eyes
7 people injured by
inhaling vapor
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-43-
Eihibit C-l (continued)
Location
Dye plant, Leicester,
Leicestershire, UK
Penang, Malaysia
Avonmouth, Avon, UK
Date
10/16/85
11/24/80
6/10/80
Description
Water got into a drum of sodium
hydrosulfite, which ignited, giving off
poisonous fumes.
A vessel carrying 4,800 drums of sodium
hydrosulfite caught fire. Some of the drums
were transferred to barge, but many bad
their lids blown off in the heat Dense
poisonous fumes were given off.
A truck containing 160 drums of sodium
hydrosulfite overturned. Heavy rains
caused severe problems.
Effects on People
1 injury, evacuation
reported, residents
complained
None reported
42 people injured
Sources: Newspaper reports (on-line literature search), United Kingdom's Major Hazard Incidents Data Service
(MfflDAS) database, EPA's Accidental Release Information Program (ARIP) database
Aluminum Powder
The Lodi explosion likely involved the aluminum powder in the mixing vessel. Aluminum
powder has been reported in a number of accidents with fires or explosions. Fine aluminum
powder, like other finely powdered materials, has the potential to explode when dispersed in air.
In addition to dust cloud explosions involving aluminum, there are several reports in which
mixtures of aluminum powder and other chemicals exploded (e.g., an explosion of aluminum
powder and glass-making chemicals in a mixing machine). A case of ignition of aluminum powder
in hot weather is also reported. Exhibit C-2 presents brief descriptions of some accidents that
involved fires or explosions of aluminum powder, culled from media and other sources.
Exhibit C-2
Accidents Involving Fires or Explosions of Aluminum Powder
Location
Glass factory, Pittsburgh,
PA
Aluminum flake
processing plant, Darwen,
Lancashire UK
Date
9/4/93
9/91
Description
A mixture of aluminum powder and
glass-making chemicals exploded in a
mixing machine. The cause of the
explosion is unknown.
An explosion blew the roof off the plant
and caused a fire. The cause of the
explosion is unknown; a possible cause is
failure to stop process while maintenance
was beine carried out
Effects on People
1 worker killed
1 worker killed, 2 injured
-------
Location
Aerojet industry,
Sacramento, CA
Truck on highway, VA
Newburgh, IN
Paruren Lancashire TJK
Mixing plant, Eaton
Township, OH
Aluminum powder
company, Gwynedd,
Anglesey, UK
Chemical works, Widnes,
Cheshire, UK
Aluminum works.
HermMoD, France
Albany, CA
Metatwork plant,
Chicago, IL
Date
7/26/91
7/24/91
5/16790
3/27/89
7/2/86
7/16/83
2/6/83
2/2/80
1/23/78
4/16/53
Description
A compound of potassium perchlorate and
aluminum powder exploded.
Aluminum powder ignited while being
transported in hot weather The nlumjinum
powder was reported to be properly
contained, but the container might have
deteriorated during a heat wave.
A gap in an exhaust duct allowed aluminum
fines and dust to be dispersed in the air.
Welding sparks ignited the dust, creating a
fireball.
An exothermic reaction occurred in an
aluminum powder storage area, starting a
fire which consumed about 40 metric tons
of aluminum. The fire spread to other parts
of the factory and was allowed to bum itself
out
An aluminum powder compound exploded
at a mixing plant, biting the roof off. The
cause of the explosion was unknown.
Explosion in powder collection system sent
fireball hundreds of feet in the air, two
more explosions and a fire followed. All
buildings within 200 yards were wrecked,
and debris blocked rail line.
A dust explosion occurred during filling
operation when aluminum powder was
being put into drums.
Several buildings were destroyed in 3
explosions. Fire raged for 6 hours.
Explosion occurred in building where
aluminum powder was precipitated and
graded. Considerable damage inside and
outside plant
Plant demolished by fire following dust
explosion ignited by polishing mashing
Effects on People
1 worker cut and
seriously burned
None reported
I worker injured
None reported
8 workers injured
5 people injured
1 person killed
None reported
1 person injured
35 people killed, more
man 20 injured
Sources: Newspaper reports (on-line literature search). United Kingdom's Major Hazard Incidents Data Service
(MfflDAS) database. Occupational Safety and Health Administration (OSHA) database
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-45-
Appendix D
References
Aluminum Association. Recommendations for Storage and Handling of Aluminum Powders and
Paste. Washington DC.
Bretherick's Handbook of Reactive Chemical Hazards, Fourth edition, pp. 20-32, 633, 1385,
1810-2. London: Buttenvorths 1990.
CRC Handbook of Chemistry and Physics, 75th ed. Boca Raton, FL: CRC Press. 1995
Dean,! Lange'sHandbook ofChemistry. 13thed. New York, NY: McGraw-Hill Book
Company. 1985.
Dietz, Jr., G., Skomoroski, R., Aluminum Containing Precipitating Agent for Precious Metals
and Method for its use. Patent No. 4,092,154. American Chemical and Refining Co., Inc.
Waterbury, CT. 1978.
Goodhead, K et al. The non-oxidative decomposition of heated sodium dithionite. J. Appl.
Chem. Biotechnol. (24) pp. 71-79. 1974.
ICF, Inc., Production and Use, Accident History, Regulations/Recommendations for Transport
and Handling of Sodium Hydrosulfite and Aluminum Powder. Draft October 13,1995.
ICF, Inc., Analysis of Process Issues and Chemical Reactions Concerning the Accident at Napp
Technologies, Inc. inLodi, NJ. Draft October 16,1995.
Kirk-Othmer 1983. Kirk-Othmer Encyclopedia of Chemical technology, 3rd ed., Vol 22, p. 153-
4; Vol 2, p. 134; Vol 9, p. 562-3. New York: John Wiley and Sons, 1983.
McCowan, C. and Siewert, T., Site Assessment of a Large Blender. MIST, Boulder, CO. May
10, 1995.
McCowan, C. and Siewert, T., Inspection of P-K Blender (Napp Technologies, Lodi, NJ, and
FortDix, NJ). NIST, July and August 1995.
Mclaughlin, Dr. H., Summary of Findings to Date - Napp Technologies Incident Review. Waste
Min Inc., October 4, 1995.
McLaughlin, Dr. R, Final Report - Chemical Safety Issues, Napp Technologies Incident Review.
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-46-
Waste Min Inc., November 2, 1995.
NFPA 1994. National Fire Protection Association, NFPA 49, Hazardous Chemicals Data.
Quincy, MA: NFPA, 1994.
NFPA 1993. National Fire Protection Association, NFPA 651, Standard for the Manufacture of
Aluminum Powder. Quincy, MA: NFPA, 1993.
Occupational Safety and Health Administration. Update to HazWoper Emergency Response
guidance: Coordination -with Local Fire Departments. Memorandum for all Regional
Administrators. October 30,1996.
Sage, G., Analysis ofNapp Technologies Explosion. Syracuse Research Corp. January 13, 1997.
Sax, N and Lewis, R. Dangerous Properties of Industrial Materials. 5th ed. p. 352.
New York: Van Nostrand Reinhold.
SRI 1995. SRI International, 1995 Directory of Chemical Producers, United States of America.
Menlo Park, CA: SRI International, 1995.
Tartani V, Contessa S. Water influence on thermal stability of sodium dithionite. 5th
International Symposium "Loss Prevention and Safety Promotion in the Process Industries"
Societe de Chimie Industrielle, Paris, France.
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-47-
Appendix £
Photos of Napp Technologies Equipment and Facility
Figures 4-24
-------
-------
Figure 4: One of the top loading ports on the 150 cubic foot blender showing how the insulation
jacket is attached (weld) and access door tabs.
-------
Rguie 5: Inside a PK-150 cubic foot blender, looking through top access port, the vacuum head
and spray nozzle configuration can be seen.
-------
Figure 6: The intensifier bar for a PK-150 cubic foot blender shown in its storage position.
U S EPA Headquarters Uorary
Mail code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
-------
Figure 7: The gear drive and bearing that supports one side of a 150 cubic foot blender.
Figure 8: The other side support (intensifier bar drive side) of a 150 cubic foot blender.
-------
Figure 9: The general condition of the 125 cubic foot blender a) the top access ports and
damaged insulation jacket, and b) the flange to which the belt drive attaches.
-------
Figure 10: Top access port: a) looking through a top port and out the bottom off-load port, and
b) close-up view of a top port.
-------
Figure 11: The bottom off-load port of the blender was severely
damaged in the accident: a) the stubs of the flange bolts that held
the door to the port are visible, b) general deformation to the
water jacket and shell.
-------
Figure 12: The striation markings on the top access ports.
-------
Figure 13: The tabs that held the top access port door are bent
down against the stainless steel shell.
-------
Figure 14: The insulation jacket has torn away from where it was attached to the stainless steel
shell and the access door tabs are bent over against the shell.
-------
Figure 15: The inside of the blender: a) area near the bottom off-
load port, b) just inside one of the top access ports.
-------
Figure 16: The gear drive side of the blender, a) the shaft (drive side) and b) the portion of the
gear that fractured and separated from the blender in the accident.
-------
^•V-.,-''-
- - „-•.,'--
- -*r*-%r7l-,^^^:\'::.
Figure 17: The concrete support and bracket that secured the
bearing on the gear drive side of the blender.
Figure 18: The concrete support and rollers that supported the belt
drive side of the blender.
-------
Figure 19: The flange on the belt drive side of the blender: a) the
bolt stubs are visible, b) the flange is bent.
-------
^ ' "*- ."* * V •*£,«*• * Jr J**»-t _ • _
Figure 20: The wheel that supported the blender on the belt drive
side and the shaft components: a) the wheel and shaft, b) the
concentric shafts and tube that went into the interior of the
blender.
-------
Figure 21: Close-up views of the end of the shaft shown in Fiqu^e
20. ~
-------
Figure 22: The end of the shaft, shown in Figure 20, holds the vacuum head, spray nozzle, and the
connecter for the intensifier bar shaft: a) Y-fitting where the vacuum and water spray nozzle
branch off the tube, b) the can that surrounds the vacuum head.
-------
Rgure 23: The intensifier ban a) the shaft of the bar is severely deformed, b) two of the mixing
plates are left, both arc broken away from the shaft.
-------
Figure 24: The Napp facility after the explosion and fire showing location in the plan: where the
processing took place and the location of the facility with respect to residential area in
background.
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