"Case Study: Confined Space Entry - Worker and Would-Be Rescuer Asphyxiated (2006-02-i-De)"

Case Study: Confined Space Entry - Worker and Would-Be Rescuer Asphyxiated (2006-02-i-De) is a 22-page legal document that was released by the U.S. Chemical Safety and Hazard Investigation Board on November 2, 2006 and used nation-wide.

Form Details:

  • The latest edition currently provided by the U.S. Chemical Safety and Hazard Investigation Board;
  • Ready to use and print;
  • Easy to customize;
  • Compatible with most PDF-viewing applications;
  • Fill out the form in our online filing application.

Download a printable version of the form by clicking the link below or browse more legal forms and templates provided by the issuing department.

ADVERTISEMENT
ADVERTISEMENT

Download "Case Study: Confined Space Entry - Worker and Would-Be Rescuer Asphyxiated (2006-02-i-De)"

Download PDF

Fill PDF online

Rate (4.4 / 5) 75 votes
CASE STUDY
Confined Space Entry - Worker and
No. 2006-02-I-DE
Would-be Rescuer Asphyxiated
November 2, 2006
This Case Study describes the
Valero Delaware City refinery
asphyxiation death of two
contractor employees who were
preparing to reassemble a pipe on
a pressure vessel while it was
being purged with nitrogen. The
first worker, in an attempt to
retrieve a roll of tape from inside
the vessel, was overcome by
nitrogen, collapsed in the vessel,
and died. His co-worker, the crew
foreman, was asphyxiated while
attempting to rescue him.
The CSB issues this Case Study to
reemphasize nitrogen hazard
awareness and safe work practices
when working in or adjacent to
confined spaces.
Valero Energy Corporation Refinery
Delaware City, DE
November 5, 2005
KEY ISSUES:
INSIDE . . .
Oxygen-deficient Atmosphere Hazards Outside
Incident Description
Confined Space Openings
Companies Involved
Nitrogen Hazard Awareness
Incident Analysis
Other Nitrogen Hazard Reports
Unplanned Confined Space Rescue
Lessons Learned
Recommendations
References
CASE STUDY
Confined Space Entry - Worker and
No. 2006-02-I-DE
Would-be Rescuer Asphyxiated
November 2, 2006
This Case Study describes the
Valero Delaware City refinery
asphyxiation death of two
contractor employees who were
preparing to reassemble a pipe on
a pressure vessel while it was
being purged with nitrogen. The
first worker, in an attempt to
retrieve a roll of tape from inside
the vessel, was overcome by
nitrogen, collapsed in the vessel,
and died. His co-worker, the crew
foreman, was asphyxiated while
attempting to rescue him.
The CSB issues this Case Study to
reemphasize nitrogen hazard
awareness and safe work practices
when working in or adjacent to
confined spaces.
Valero Energy Corporation Refinery
Delaware City, DE
November 5, 2005
KEY ISSUES:
INSIDE . . .
Oxygen-deficient Atmosphere Hazards Outside
Incident Description
Confined Space Openings
Companies Involved
Nitrogen Hazard Awareness
Incident Analysis
Other Nitrogen Hazard Reports
Unplanned Confined Space Rescue
Lessons Learned
Recommendations
References
Valero Refinery Case Study
November 2, 2006
1.0
Incident Description
This Case Study examines the November 5,
top manway (Figure 1), the only open
2005, nitrogen asphyxiation death of two
discharge point on the reactor.
Matrix Service Industrial Contractors, Inc.
(Matrix) employees at the Valero Energy
The nitrogen purge in the reactor continued
Corporation (Valero) refinery in Delaware
to protect the newly loaded catalyst from
4
City, Delaware. Matrix was contracted by
reacting with oxygen in the air
until
1
Premcor, Inc.,
the previous owner of the
emergency responders closed the nitrogen
refinery, to serve as the primary
supply valve the night of the incident.
maintenance contractor during the fall 2005
However, contrary to the Valero refinery
maintenance turnaround (unit shutdown).
safety procedures, a nitrogen purge warning
sign and barricade were not in place in the
Nitrogen, which makes up 78 percent of the
work area.
air we breathe, is non-toxic. The normal
oxygen concentration in air is about 21
Two days before the incident, workers
percent. Nitrogen is frequently added to
employed by Catalyst Handling Services
process equipment to significantly reduce
Corporation (CHSC), the catalyst contractor,
the oxygen concentration inside. This
finished loading the reactor with the new
oxygen-depleted atmosphere inside the
catalyst and placed a temporary plastic tarp
equipment is hazardous because there is not
and wooden cover over the open manway to
enough oxygen to support life (Table 1).
prevent moisture and debris from falling into
Furthermore, an oxygen-depleted, hazardous
the reactor. They also attached a confined
atmosphere might be present outside the
space warning sign to the studs surrounding
equipment near unsealed equipment
the opening. About five hours before the
openings.
incident, a CHSC foreman wrapped red
"danger" tape around the studs.
A few days before the incident, Matrix
installed a temporary nitrogen supply system
2
on the hydrocracker unit
reactor (R1). The
Valero operators opened the nitrogen valve
“about one or two turns” to provide a
3
nitrogen purge
inside R1 as part of the
catalyst loading procedure. The nitrogen
flowed slowly out of the reactor through the
1
Premcor Refining Group Inc., the operator of the
Figure 1. Plastic sheet and plywood disk on
Valero Delaware City refinery, is a wholly owned
R1 manway. Red "danger" tape on the studs
subsidiary of Valero Energy Corporation.
alerted workers of the unsecured confined
2
The hydrocracker unit converts heavy oil fractions
space access opening.
to lighter molecular structure hydrocarbons using
high pressure hydrogen and catalysts.
3
Purging is the process of pumping inert gas, such as
4
nitrogen, into pressure vessels, pipes, and other
The inert nitrogen atmosphere was required to
equipment to remove oxygen or other hazardous
protect the new catalyst from exposure to oxygen
gases.
until the reactor was resealed.
2
Valero Refinery Case Study
November 2, 2006
Table 1. Effects of oxygen deficiency on the human body.
Percent
Oxygen
Physiological Symptoms
23.5
Maximum “safe level’
21
Typical oxygen concentration in air
19.5
Minimum safe level
15 - 19
First sign of hypoxia. Decreased ability to work strenuously. May induce
symptoms in persons with heart, lung, or circulatory problems
12 - 15
Respiration increases with exertion, pulse up, impaired muscular coordination,
perception, and judgment
10 - 12
Respiration further increases in rate and depth, poor judgment, blue lips
8 - 10
Mental failure, fainting, unconsciousness, ashen face, blue lips, nausea,
vomiting, inability to move freely
Six minutes–50% probability of death
6 - 8
Eight minutes–100% probability of death
< 6
Coma in 40 seconds, followed by convulsions, respiration ceases, death
Source: Hazards of Nitrogen and Catalyst Handling, Institution of Chemical Engineers, 2004
To begin work on the hydrocracker unit, a
not amended to limit the work to “set up
Valero hydrocracker unit operator issued a
only.” Furthermore, the nitrogen purge
safe work permit to a Matrix nightshift
status was marked “N/A” on the permit even
boilermaker crew to "install [the] top
though the reactor continued to be purged
5
elbow," or pipe assembly, on R1.
The
with nitrogen.
operator told the Chemical Safety Board
(CSB) investigators that he and the Matrix
At about 11 p.m., two Matrix boilermakers
foreman agreed that the crew would only set
removed the wooden cover and plastic tarp
up the work area, and that the foreman
and cleaned the manway flange surface, a
would return to the control room after lunch
prerequisite to reinstalling the pipe assembly
to get a new permit to perform the
(Figure 2).
installation work. However, the permit was
5
The top elbow assembly included the 12-inch
diameter process pipe mating flange; 12-inch
diameter pipe and elbow; and 24-inch manway
mating flange (See Figure 2).
3
Valero Refinery Case Study
November 2, 2006
A few minutes before the incident, nearby
workers saw the first victim standing next to
the studs surrounding the open manway
trying to retrieve the tape with the wire.
One worker saw him kneeling next to the
studs while he worked with the wire.
Nobody saw him enter the nitrogen-filled
reactor, but he either fell in or intentionally
went into the reactor.
Figure 2. Pipe assembly connects 12-inch
diameter process pipe to the reactor top
manway (photo taken after the incident).
While the boilermakers were cleaning the
manway flange surface, a Matrix pipefitter
told them that a roll of duct tape was lying
6
on the distribution tray
(Figure 3) about
five feet below the opening. The
boilermakers knew that reactor cleanliness
criteria prohibited leaving the tape inside the
reactor, so they discussed retrieval options
with their foreman.
Figure 3. Roll of duct tape on the top
distribution tray inside reactor R1 (photo
They considered entering the reactor to
taken after incident).
retrieve the tape, but knew entry would
require a specially trained and equipped
An eyewitness working on the platform of
7
8
crew and confined space
entry permit,
an adjacent reactor saw the boilermaker
which would delay their work, possibly
foreman (the second victim) and the
beyond the end of their work shift. Instead,
nightshift contract administrator looking
they decided to make a long wire hook
through the manway into R1. The
(Figure 4) and lower it through the manway
eyewitness watched the foreman hurriedly
to retrieve the tape.
grab a ladder, insert it into the reactor, and
immediately climb down.
The eyewitness next saw the nightshift
6
A tray is a perforated platform installed inside a
contract administrator approach the ladder,
reactor used to support catalyst material and/or
hesitate, and then heard him urgently call for
distribute the process fluid.
help on his radio. The site emergency siren
7
A confined space is a space that is not designed for
then activated.
continuous occupancy and has restricted means for
entry or exit, but is large enough and configured
such that an individual can enter and perform
Valero Emergency Response Specialists and
assigned work (OSHA, 1994).
Matrix safety personnel arrived on the
8
Permit-required confined space access control
platform in less than two minutes, and saw
prohibits breaking the plane of the confined space
two victims lying motionless inside the
entry point with any part of the body without first
reactor on the tray five feet below the
obtaining an entry permit and applying proper safety
manway. They inserted an oxygen meter
prerequisites (OSHA, 1994).
4
Valero Refinery Case Study
November 2, 2006
through the manway and it immediately
Because the manway opening was only 24
alarmed—the oxygen concentration was
inches and the victims were not wearing
near zero.
safety harnesses, recovering them from the
reactor was very difficult. Rescue workers
10
wrapped a confined space recovery tripod
hoist cable around each victim, and lifted
them out one at a time. In spite of the quick
arrival of the emergency responders, the two
victims were deprived of adequate oxygen
for nearly ten minutes.
Once on the work platform, an emergency
medical technician examined each victim;
however, both were unresponsive and efforts
to revive them unsuccessful. They were
carried down the platform stairs to the
Figure 4. Fifteen foot wire with hook formed
waiting ambulance and transported to the
on end used by the first victim to retrieve the
hospital where they were pronounced dead.
duct tape.
A Valero operator put on his self-contained
breathing air respirator then entered the
reactor to help the two victims. An
Emergency Response Specialist asked a
contractor loading catalyst into the adjacent
reactor to put on his supplied breathing air
9
helmet
and climb down the ladder into the
reactor to help the operator.
9
The contractor was fully qualified and equipped to
10
A recovery tripod is a portable, hand-operated hoist
work in an inert gas environment.
used to lift victims out of a confined space.
5
Page of 22