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Case Study: Heat Exchanger Rupture Incident
YOU MUST USE ATTACHMENT FOR THIS QUESTION!!!
1. Using the information in the CSB Case Study, identify probable direct causes, contributing causes, and root causes of the incident. Explain the reasoning you used to reach these causes. You may make assumptions concerning any missing investigative information as long as you clearly state your assumptions. Discuss how and where your proposed causal factors fit into the causation model on page 356 of the course textbook. For the root causes only, provide recommended corrective actions.
2. Create an Events and Causal Factors chart that follows the timeline of the incident. Be sure to include all causal factors you identified in your discussion, as well as any other conditions and events that are relevant to understanding the accident sequence.
The chart can be created using MS-Word, PowerPoint, or Excel, or it can be hand drawn and scanned.
Completed case study must be a minimum of three pages and maximum of five pages, not including the title page, reference page, and chart. Use APA formatting for all of your assignment, as well as for all references and in-text citations.
CASE STUDY
Heat exchanger rupture and ammonia
release in Houston, Texas
(One Killed, Six Injured)
2008-06-I-TX
January 2011
The Goodyear Tire and Rubber
Company
Houston, TX
June 11, 2008
Key Issues:
• Emergency Response and Accountability
• Maintenance Completion
• Pressure Vessel Over-
pressure Protection
This case study examines a
heat exchanger rupture and
ammonia release at The
Goodyear Tire and Rubber
Company plant in Houston,
Texas. The rupture and release
injured six employees. Hours
after plant responders
declared the emergency over;
the body of an employee was
discovered in the debris next
to the heat exchanger.
INSIDE . . .
Incident Description
Background
Analysis
Lessons Learned
Goodyear Houston Case Study January 2011
2
This case study examines a heat exchanger
rupture and ammonia release at The
Goodyear Tire and Rubber Company
(Goodyear) facility in Houston, Texas, that
killed one worker and injured six others.
Goodyear uses pressurized anhydrous
ammonia in the heat exchanger to cool the
chemicals used to make synthetic rubber.
Process chemicals pumped through tubes
inside the heat exchanger are cooled by
ammonia flowing around the tubes in a
cylindrical steel shell.
On June 10, 2008, Goodyear operators
closed an isolation valve between the heat
exchanger shell (ammonia cooling side) and
a relief valve to replace a burst rupture disk
under the relief valve that provided over-
pressure protection. Maintenance workers
replaced the rupture disk on that day;
however, the closed isolation valve was not
reopened.
On the morning of June 11, an operator
closed a block valve isolating the ammonia
pressure control valve from the heat
exchanger. The operator then connected a
steam line to the process line to clean the
piping. The steam flowed through the heat
exchanger tubes, heated the liquid ammonia
in the exchanger shell, and increased the
pressure in the shell. The closed isolation
and block valves prevented the increasing
ammonia pressure from safely venting
through either the ammonia pressure control
valve or the rupture disk and relief valve.
The pressure in the heat exchanger shell
continued climbing until it violently
ruptured at about 7:30 a.m.
The catastrophic rupture threw debris that
struck and killed a Goodyear employee
walking through the area.
The rupture also released ammonia,
exposing five nearby workers to the
chemical. One additional worker was injured
while exiting the area.
Immediately after the rupture and resulting
ammonia release, Goodyear evacuated the
plant. Medical responders transported the six
injured workers. The employee tracking
system failed to properly account for all
workers and as a result, Goodyear
management believed all workers had safely
evacuated the affected area.
Management declared the incident over the
morning of June 11, although debris blocked
access to the area immediately surrounding
the heat exchanger. Plant responders
managed the cleanup while other areas of
the facility resumed operations.
Several hours later, after plant operations
had resumed, a supervisor assessing damage
in the immediate incident area discovered
the body of a Goodyear employee located
under debris in a dimly lit area (Figure 1).
Figure 1. Area of fatality
Goodyear Houston Case Study January 2011
3
2.1 Goodyear
Goodyear is an international tire and rubber
manufacturing company founded in 1898
and headquartered in Akron, Ohio. North
American facilities produce tires and tire
components. The Houston facility, originally
constructed in 1942 and expanded in 1989,
produces synthetic rubber in several process
lines.
2.1.1 Process Description
The facility includes separate production
and finishing areas. In the production area, a
series of reactor vessels process chemicals,
including styrene and butadiene. Heat
exchangers in the reactor process line use
ammonia to control temperature. Piping
carries product from the reactors to the
product finishing area.
2.1.2 Ammonia Heat Exchangers
Ammonia is a commonly used industrial
coolant. Goodyear uses three ammonia heat
exchangers in its production process lines.
The ammonia cooling system supplies the
heat exchangers with pressurized liquid
ammonia. As the ammonia absorbs heat
from the process chemical flowing through
tubes in the center of the heat exchanger, the
ammonia boils in the heat exchanger shell
(Figure 2). A pressure control valve in the
vapor return line maintains ammonia
pressure at 150 psig in the heat exchanger.
Ammonia vapor returns to the ammonia
cooling system where it is pressurized and
cooled, liquefying the ammonia.
Figure 2. Ammonia heat exchanger
Goodyear Houston Case Study January 2011
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The process chemicals exiting the heat
exchanger flow to the process reactors. Each
heat exchanger is equipped with a rupture
disk in series with a pressure relief valve
(both set at 300 psig) to protect the heat
exchanger from excessive pressure. The
relief system vented ammonia vapor through
the roof to the atmosphere.
2.2 Ammonia Properties
Anhydrous ammonia is a colorless, toxic,
and flammable vapor at room temperature. It
has a pungent odor and is hazardous when
inhaled, ingested, or if it contacts the skin or
eyes. Ammonia vapor irritates the eyes and
respiratory system and makes breathing
difficult.
Liquefied ammonia causes frostbite on
contact. One cubic foot of liquid ammonia
produces 850 cubic feet of vapor. Since
ammonia vapor is lighter than air, it tends to
rise. The vapor can also remain close to the
ground when it absorbs water vapor from air
in high humidity conditions.
The Occupational Safety and Health
Administration (OSHA) and National
Institute for Occupational Safety and Health
(NIOSH) limit worker exposure to ammonia
to 25 and 50 parts per million (ppm),
respectively, over an 8-hour time-weighted
average. Ammonia is detectable by its odor
at 5 ppm.
Goodyear Houston Case Study January 2011
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3.0 Analysis
3.1 Emergency Procedures
3.1.1 Onsite Emergency
Response Training
Goodyear maintained a trained
emergency response team, which
attended off-site industrial firefighter
training, conducted response drills based
on localized emergency scenarios, and
practiced implementing an emergency
operations center. Other employees
received emergency preparedness
training primarily as part of their annual
computer-based health and safety
training.
Although Goodyear procedures required
that a plant-wide evacuation and shelter-
in-place drill be conducted at least four
times a year, workers told the Chemical
Safety Board (CSB) that such drills had
not been conducted in the four years
prior to the June 11th 2008 incident.
Operating procedures discussed plant-
wide, alarm operations and emergency
muster points for partial and plant-wide
evacuations; however, some employees
had not been fully trained on these
procedures.
3.1.2 Plant Alarm System
Although Goodyear had installed a plant-
wide alarm system, some workers reported
that the system was unreliable, as in this
case, when workers were not immediately
made aware of the nature of the incident.
Emergency alarm pull-boxes located
throughout the production unit areas sound a
location-specific alarm. However, ammonia
vapor released from the ruptured heat
exchanger and water spray from the
automatic water deluge system prevented
responders from reaching the alarm pull-box
in the affected process unit. Supervisors and
response team members were forced to
notify some employees by radio and word-
of-mouth of the vessel rupture and ammonia
release.
3.1.3 Accounting for Workers in
an Emergency
Facility operating procedures also outlined
Goodyear’s worker emergency
accountability scheme. Supervisors were to
account for their employees using a master
list generated from the computerized
electronic badge-in/badge-out system.
During the incident however, a malfunction
in the badge tracking system delayed
supervisors from immediately retrieving the
list of personnel in their area. Handwritten
employee and contractor lists were
generated, listing the workers only as they
congregated at the muster points or sheltered
in place. Later, EOC personnel compared
the handwritten lists against the computer
record of personnel who remained badged in
to the production areas.
Additionally, although emergency response
team members were familiar with the
employee accountability procedures, not all
supervisory and security employees, who
were to conduct the accounting, had been
trained on them. In fact, some of the
employees responsible for accountability
were unaware prior to the incident that their
jobs could include this task in an emergency.
Since the fatally injured employee was a
member of the emergency response team,
area supervisors did not consider her
absence from the muster point unusual.
Goodyear Houston Case Study January 2011
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The Emergency Operations Command
(EOC) declared all Goodyear employees
accounted for at about 8:40 a.m. Accounting
for the contract employees continued until
about 11:00 a.m., at which time the EOC
ended the plant-wide evacuation and
disbanded. Only the immediate area
involved in the rupture remained evacuated.
At about 1:20 p.m., an operations supervisor
assessing the damage to the incident area
discovered the victim buried in rubble in a
dimly lit area and contacted City of Houston
medical responders.
3.2 Maintenance Procedures
Training requirements for operators in the
production area included standard operating
procedures specifically applicable to the
rupture disk maintenance performed on
June 10:
• Use of the work order system
including obtaining signature
verification both before the work
starts and after job was completed;
and
• Use of lockout/tagout procedures for
equipment that was undergoing
maintenance.
The CSB found evidence of breakdowns in
both the work order and lockout/tagout
programs that contributed to the incident.
Although the work order procedure required
a signature before work commenced and
after the work had been completed,
operators reported that maintenance
personnel did not always obtain production
operators’ signatures as required.
Additionally, work order documentation was
not kept at production control stations.
Operators used the lockout/tagout
procedures to manage the work on the heat
exchanger rupture disk, but did not clearly
document the progress and status of the
maintenance. Information that the isolation
valve on the safety relief vent remained in
the closed position and locked out was
limited to a handwritten note.
Although maintenance workers had replaced
the rupture disk by about 4:30 p.m. on
June 10, the valve isolating the rupture disk
was not reopened. No further activities
involving the rupture disk or relief line
occurred on the nightshift or the dayshift on
June 11 and the valve remained closed.
Figure 3 shows the timeline of these events.
Goodyear’s work order system for
maintenance requires the process operator to
sign off when the repairs are completed.
However, whether this occurred during the
June 10 dayshift is unclear, and Goodyear
was unable to produce a signed copy of the
work order.
Goodyear Houston Case Study January 2011
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Figure 3. Event timeline
3.3 Pressure Vessel Over-
pressure Protection
3.3.1 Heat Exchanger Rupture
As Figure 2 shows, a rupture disk and a
pressure relief valve in series protected
the ammonia heat exchanger from over-
pressure. An isolation valve installed
between the rupture disk and the heat
exchanger isolated the rupture disk and
relief valve for maintenance. However,
when the valve was in the closed position,
the heat exchanger was still protected
from an over-pressure condition by the
automatic pressure control valve.
The next day, when operators began a
separate task to steam clean the process
piping they closed a block valve between
the heat exchanger and the automatic
pressure control valve. This isolated the
ammonia side of the heat exchanger from
all means of over-pressure protection.
Steam flowing through the heat
exchanger increased the ammonia
temperature and the pressure in the
isolated heat exchanger. Because the
over-pressure protection remained
isolated, the internal pressure increased
until the heat exchanger suddenly and
catastrophically ruptured.
3.3.2 Pressure Vessel Standards
The American Society of Mechanical
Engineers Boiler and Pressure Vessel
Code, Section VIII (the ASME Code),
provides rules for pressure vessel design,
use, and maintenance, including over-
pressure protection. Use of the ASME
Code was required at Goodyear by OSHA’s
29 CFR 1910.119 Process Safety
Management Standard.1
The ASME Code requires that when a
pressure vessel relief device is
temporarily blocked and there is a
possibility of vessel pressurization above
the design limit, a worker capable of
releasing the pressure must continuously
monitor the vessel. Goodyear’s
maintenance procedures did not address
over-pressurization by the ammonia
when the relief line was blocked, nor did
it require maintenance and operations
staff to post a worker at the vessel to
open the isolation valve if the pressure
increased above the operating limit.
1 OSHA Process Safety Management regulation, 29
CFR 1910.119, is a performance-based process-
safety regulation requiring manufacturers to comply
with recognized and generally accepted good
engineering practices on processes containing greater
than threshold quantities of toxic or flammable
chemicals.
Goodyear Houston Case Study January 2011
8
4.0 Lessons Learned
4.1 Worker Headcounts
On the morning of the incident, Goodyear
erroneously accounted for all its workers
and declared an end to the emergency.
Hours later, workers discovered the
victim buried in the rubble near the
ruptured vessel. Her absence had not
been noted due to lack of training and
drills on worker headcounts.
Companies should conduct worker
headcount drills that implement their
emergency response plans on a facility-
wide basis. Company procedures must
account for breakdowns in automated
worker tracking systems to ensure that all
workers inside a facility can be quickly
accounted for in an emergency. Drills that
simulate such malfunctions should be
conducted to verify that all lines of
responsibility and alternate verification
techniques will account for workers in a
real situation.
4.2 Maintenance Completion
Although maintenance workers had
replaced the rupture disk by about 4:30
p.m. on June 10, the primary over-
pressure protection for the heat
exchanger remained isolated until the
heat exchanger ruptured at about 7:30
a.m. on June 11.
Communicating plant conditions between
maintenance and operations personnel is
critical to the safe operation of a process
plant. Good practice includes formal
written turnover documents that inform
maintenance personnel when a process is
ready for maintenance and operations
personnel when maintenance is completed
and the process can be safely restored to
operation.
4.3 Isolating Pressure Vessels
Goodyear employees completely isolated
an ammonia heat exchanger, including the
over-pressure protection, while steaming
a process line through the heat exchanger.
Workers left the pressure relief line
isolated for many hours following
completion of the maintenance.
In accordance with the ASME Boiler and
Pressure Vessel Code, over-pressure
protection shall be continuously provided
on pressure vessels installed in process
systems whenever there is a possibility that
the vessel can be over-pressurized by any
pressure source, including external
mechanical pressurization, external
heating, chemical reaction, and liquid-to-
vapor expansion. Workers should
continuously monitor an isolated pressure
relief system throughout the course of a
repair and reopen blocked valves
immediately after the work is completed.
Goodyear Houston Case Study January 2011
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5.0 References
Occupational Safety and Health Administration (OSHA) Process Safety Management Standard.
29 CFR 1910.119, 1992.
American Society of Mechanical Engineers (ASME). Boiler and Pressure Vessel Code, Section
VIII, Division I, 2004.
Center for Chemical Process Safety (CCPS). Plant Guidelines for Technical Management of
Chemical Process Safety (revised ed.). American Institute of Chemical Engineers
(AIChE), 2004.
CCPS. Guidelines for Engineering Design for Process Safety, AIChE, 1993, p. 539.
Goodyear Houston Case Study January 2011
10
The U.S. Chemical Safety and Hazard Investigation Board (CSB) is an independent Federal agency
whose mission is to ensure the safety of workers, the public, and the environment by investigating and
preventing chemical incidents. The CSB is a scientific investigative organization; it is not an enforcement
or regulatory body. Established by the Clean Air Act Amendments of 1990, the CSB is responsible for
determining the root and contributing causes of accidents, issuing safety recommendations, studying
chemical safety issues, and evaluating the effectiveness of other government agencies involved in
chemical safety.
No part of the conclusions, findings, or recommendations of the CSB relating to any chemical accident
may be admitted as evidence or used in any action or suit for damages. See 42 U.S.C. § 7412(r)(6)(G).
The CSB makes public its actions and decisions through investigation reports, summary reports, safety
bulletins, safety recommendations, case studies, incident digests, special technical publications, and
statistical reviews. More information about the CSB is available at www.csb.gov.
CSB publications can be downloaded at
www.csb.gov or obtained by contacting:
U.S. Chemical Safety and Hazard
Investigation Board
Office of Congressional, Public, and Board Affairs
2175 K Street NW, Suite 400
Washington, DC 20037-1848
(202) 261-7600
CSB Investigation Reports are formal,
detailed reports on significant chemical
accidents and include key findings, root causes,
and safety recommendations. CSB Hazard
Investigations are broader studies of significant
chemical hazards. CSB Safety Bulletins are
short, general-interest publications that provide
new or noteworthy information on
preventing chemical accidents. CSB Case
Studies are short reports on specific accidents
and include a discussion of relevant prevention
practices. All reports may contain safety
recommendations when appropriate.
http://www.csb.gov/�
- Introduction
- 3.0 Analysis
- 4.0 Lessons Learned
- 5.0 References
1.0 Incident Description
2.0 Background
2.1 Goodyear
2.1.1 Process Description
2.1.2 Ammonia Heat Exchangers
2.2 Ammonia Properties
3.1 Emergency Procedures
3.1.1 Onsite Emergency Response Training
3.1.2 Plant Alarm System
3.1.3 Accounting for Workers in an Emergency
3.2 Maintenance Procedures
3.3 Pressure Vessel Over-pressure Protection
3.3.1 Heat Exchanger Rupture
3.3.2 Pressure Vessel Standards
4.1 Worker Headcounts
On the morning of the incident, Goodyear erroneously accounted for all its workers and declared an end to the emergency. Hours later, workers discovered the victim buried in the rubble near the ruptured vessel. Her absence had not been noted due to la…
Companies should conduct worker headcount drills that implement their emergency response plans on a facility-wide basis. Company procedures must account for breakdowns in automated worker tracking systems to ensure that all workers inside a facility c…
4.2 Maintenance Completion
Although maintenance workers had replaced the rupture disk by about 4:30 p.m. on June 10, the primary over-pressure protection for the heat exchanger remained isolated until the heat exchanger ruptured at about 7:30 a.m. on June 11.
Communicating plant conditions between maintenance and operations personnel is critical to the safe operation of a process plant. Good practice includes formal written turnover documents that inform maintenance personnel when a process is ready for ma…
4.3 Isolating Pressure Vessels
Goodyear employees completely isolated an ammonia heat exchanger, including the over-pressure protection, while steaming a process line through the heat exchanger. Workers left the pressure relief line isolated for many hours following completion of t…
In accordance with the ASME Boiler and Pressure Vessel Code, over-pressure protection shall be continuously provided on pressure vessels installed in process systems whenever there is a possibility that the vessel can be over-pressurized by any pressu…
