EH-9301 Vol. 2 Issue No. 1, January 1993 Occupational Safety Observer
JANUARY 1993
Occupational Safety OBSERVER
Hazardous Chemical Exposure
Hazards awareness pays
When working with chemicals of any kind, workers need to
understand both the hazards associated with the substance being
handled and the precautions necessary to avoid harmful exposures.
Workers using hazardous chemicals should be especially aware of
any unusual conditions, such as strange odors or feelings of
irritation, either of which could indicate these chemicals are
being released to the immediate environment. The following
unrelated incidents, which resulted in excessive exposure to
personnel, but fortunately no permanent injuries, illustrate the
significance of these points.
What Happened
One incident occurred when two maintenance workers at the
Paducah Gaseous Diffusion Plant were inadvertently exposed to
hydrogen fluoride. In this case, an airtight compressor cell had
recently been rebuilt and was almost ready to undergo pressure
testing to verify its containment capability. Operations
personnel had been notified of the need to complete the
instrument line connections before testing the cell. This
information was ignored and cell pressure testing, up to a value
of 19 psig, was started before the maintenance workers arrived to
complete the instrument line connections.
The operations staff left the cell pressurized in order to
test the instrument lines after they were reconnected. The cell
began to bleed-off hydrogen fluoride into the work area because
the instrument line connections were incomplete. The maintenance
staff arrived at the work area and within three to five minutes
received severe irritation to their eyes and throats. The
exposures were in excess of published Permissible Exposure Limits
and Threshold Limit Values. Supervisors immediately suspended
all work and secured the area.
In a second incident, five Hanford workers who routinely
transported and handled hazardous and radioactive chemical
samples were inadvertently exposed to unknown chemical vapors Ä
possibly nitrobenzene. The individuals were exposed to the
vapors when they picked up chemical samples from the Plutonium
Finishing Plant. These samples had previously caused a similar
exposure at the originating plant, but the receiving laboratory
was not informed of that incident. Upon smelling the vapors, the
samples were placed in a ventilated storage hood and management
was notified. The Material Safety Data Sheets (MSDSs) were
reviewed, the chemical samples were packaged by the site
Hazardous Materials Team (HAZMAT), and the exposed employees were
sent to the medical aid station. Fortunately, the exposed
personnel were not seriously injured.
In a third incident, during an environmental inspection,
discarded wipes containing 1-1-1 trichloroethane and methyl
chloride (a known carcinogen) residues were discovered in a waste
basket at a Savannah River Site laboratory. Laboratory
personnel indicated that these chemicals were used for routine
cleaning and preservation of gage blocks used in the Measurement
Page 2 Occupational Safety OBSERVER
and Test Equipment Laboratory. The chemicals were last used the
day the wipes were found. The laboratory obtained the
appropriate MSDSs, reviewed the associated hazards, and
immediately tagged the chemical containers to preclude further
use. Subsequently, the chemicals were removed from the
laboratory.
How Can Exposures Like These Be Prevented?
Management and employees should constantly be on the lookout
for potential chemical hazards. Many responsibilities fall on
management. They should:
o Keep employees up-to-date on the status of potential hazards
and provide briefing sessions before non routine work is
performed.
o Establish and enforce the use of effective communication
lines between departments to share pertinent safety and
health status information.
o Analyze chemical processes to identify and evaluate any
associated chemical hazards.
o Identify appropriate protective equipment to be worn during
each process and approved emergency actions to be taken if a
release or exposure occurs. All of this information should
be made available to workers through MSDSs.
o Provide formal training in chemical process hazards
identification to all employees. Follow up refresher
training should also be provided to stress the importance of
continued awareness of chemical hazards.
Employees should apply the information available in MSDSs
and should fully understand process safety considerations,
especially the requirements for, and correct use of, PPE and
appropriate emergency procedures.
High Levels of Toxic Vapors
DANGER: Confined Spaces
Work in confined spaces presents special threats to worker
safety. A recent incident at a county sewage treatment
facility in Virginia offers a compelling illustration of the
dangers of confined-space work.
What happened
On September 24, 1992, three workers employed by a private
contracting company were working inside an 18,000-gallon steel
storage tank. The work involved replacing a deteriorated rubber
liner using EndurabondR, a glue that contains xylene and toluene.
Xylene and toluene are petrochemical compounds found in everyday
products such as nail polish remover and model airplane glue.
They are also highly toxic substances, and inhalation of their
Occupational Safety OBSERVER Page 3
vapors can be fatal in unventilated confined spaces.
The specific circumstances and sequence of events of the
accident are unlikely to ever be determined. On September 25, a
coworker peering into the tank discovered the three workers
lifeless at the bottom of the tank. Fire fighters were called to
the scene, and after sampling the tank's atmosphere, they
determined that it contained a high level of flammable vapors.
The workers were dead and removal of the bodies took nearly ten
hours because of the danger of an explosion. Vapors from the
open containers of glue inside the tank were so strong that seven
persons at the scene were affected by vapors emanating from a
tank vent; they received treatment at a local hospital.
Rescuers noted no indication that the victims had tried to
escape the tank. An air monitoring meter that sounds an alarm in
a low-oxygen or toxic environment was found in the tank.
However, its battery was dead, and it was impossible to determine
when the meter ceased operating.
OSHA and state regulations, the contracting company's
policy, and the glue manufacturer's instructions required the use
of supplied air respirators under these working conditions. It
was determined that none of the men were wearing supplied air
respirators. The only protective equipment found was a paper
particulate-filtering mask worn by one man, which in this case
was an inadequate safety precaution.
Company policy required the posting of one worker outside
the tank as a lookout. It cannot be determined if that policy
was followed in this case, or whether one man had been posted
outside the tank, but succumbed to the vapors after entering to
check on his coworkers.
Investigation
Autopsies revealed that all three men died from toluene
overexposure. The county and the state Department of Labor are
conducting investigations to determine how the deaths occurred
and whether safety laws were violated. It appears that neither
company policy nor regulations requiring the use of supplied air
respirators were followed.
The OSHA General Industry Standard 29 CFR 1910 does not
currently include specific requirements that address work in
confined spaces. A proposed standard, 1910.146, is pending and is
likely to become a federal regulation within several months.
However, 29 CFR 1000 requires limiting exposures to Xylene
and toluene to a safe level. Also, Section 5(a)(1) of the OSH
Act (Public Law 91-596) is the general duty clause for workplace
safety and health, and is considered applicable in instances
where a specific standard has not been issued for a particular
working environment. It requires each employer to "furnish to
each of his employees employment and a place of employment which
are free from recognized hazards that are causing or are likely
to cause death or serious physical harm to his employees."
Likewise, the ANSI standard Z117.1, Safety Requirements for
Confined Space, also applies in this instance. Both OSHA and DOE
recognize and are guided by industry-accepted standards when a
specific topic is not covered by federal rulemaking.
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Lessons Learned
Based on preliminary information, there are several lessons
to be learned from this incident:
o The use of common solvents, often found in everyday
products, in a confined space requires heightened awareness
on the part of workers and safety personnel. A familiar
product may be lethal in a confined environment.
o The use of proper respiratory protection equipment is
critical in a toxic or oxygen-limited atmosphere. All
workers, no matter how experienced, must be properly trained
on the use of respiratory equipment and confined space
safety. Managers must ensure that proper respiratory
equipment is available to all workers, and must continually
reinforce the necessity of its use.
o Safety policies alone cannot ensure safe practices in the
workplace. It is critical to have a program to implement
those policies in the workplace, including effective
training, oversight of workers, and work practices that make
safety a top priority.
Lockout/Tagout
Inadequate Lockout/Tagout Can Open the Door to DANGER
Lockout/tagout problems are among the most prevalent at DOE
sites. Workers may sometimes adopt a casual attitude to lockout
and tagout practices, despite lurking hazards. The following
event provides some valuable lessons in properly conducting
lockout and tagout.
An electrician at the Savannah River Site needed to do some
electrical work on lighting fixtures in an office. To isolate
the circuit that served the fixtures, he manually tripped the
associated branch breaker at the panel and taped a DO NOT OPERATE
(DNO) tag over the breaker on the face of the panel. The panel
was 40 years old and lacked individual circuit lockout features.
Once the work was complete and the circuit tested, he told his
supervisor that he was done and went on to another job. At the
end of the shift, the supervisor normally turns off the lighting
circuits at the panel and he noticed both the worker and a
custodian DNO tag inside the panel. Because the supervisor knew
that the job had been completed and found no other evidence of
lockout/tagout, he removed the tags. In doing so, he violated a
cardinal rule of lockout/tagout.
What is this cardinal rule, and what other lessons can be
learned from this event?
o The supervisor should not have removed the tags. OSHA
regulations (Sections 1910.147(e)(3) and
1910.333(b)(2)(v)(C)) require that tags be removed only by
the person who applied them, or under that person's direct
supervision. Although no harm was done in this case,
erroneous removal of a tag could have disastrous
Occupational Safety OBSERVER Page 5
consequences.
o The electrician should have supplemented the tag with
another safety measure. OSHA regulations (Section
1910.333(b)(2)(iii)(D)) require that "tagout only"
applications be supplemented with at least one additional
measure that provides a level of safety "at least equivalent
to that obtained by use of a lock." All circuits, even low-
voltage circuits such as a lighting circuit, can be
dangerous. A tag alone is not an adequate safeguard.
Frequently, that additional measure is to use lockout bars
which physically prevent movement of the breaker. In this
case, a Work Request to install such lockout bars on the
facility panels was initiated, and the design work is in
progress.
o Inadequate procedures, a lack of training, and a casual
attitude, all of which contributed to this incident, can
combine to create the potential for serious consequences. A
number of regulations, including DOE 5480.19, govern
lockout/tagout processes and are intended to protect
workers. The potential for injury can be limited by
ensuring that lockout/tagout procedures meet these DOE
requirements, that workers are adequately trained in those
procedures, and that management emphasizes strict adherence
to procedures and related requirements.
Industrial Explosion and Fire
Chemical Processes Pose Hazards
In March of 1991, an explosion and fire at a large ethylene
oxide production facility in Texas killed one worker and injured
18 others. Although this accident did not occur at a DOE
facility, lessons learned from this incident are directly
applicable to many of the DOE's laboratory and chemical
separation facilities.
What happened
Ethylene oxide is an unstable and highly explosive chemical
that is used in various industrial applications. The explosion
and fire occurred one day after restarting a distillation unit
that had undergone a turnaround of several weeks. It appears
that the process stalled, allowing reboiler tubes to dry out.
The presence of iron oxide in a polymer in the reboiler caused
the ethylene oxide to break down at a much lower temperature than
it normally would. The reaction generated enough local heat to
trigger auto-ignition. The resulting shrapnel caused a second
fire to start when nearby lines containing methane and other
flammable products were ruptured.
Results of the investigation
The OSHA investigation of the incident identified several
deficiencies in the design and operation of the facility that led
to the explosion and fire. Some of the operations deficiencies,
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and the suggested remedial actions, are relevant to DOE sites:
o Operators were not aware of the critical operating
temperatures and liquid levels during the start-up.
Remedial actions include installation of redundant
temperature instrumentation and level controls, replacement
of the process control room, and routine recorded
calibration and maintenance of instrumentation.
o Formal step-by-step procedures for the start-up of the
reboiler system were not used at the plant. In the future,
formal checklists will be developed to supplement the
existing procedures for routine operations for the facility.
o The facility had not performed a formal process hazards
analysis (PHA) for the production operation. A PHA might
have identified several design deficiencies as well as
operations problems, and allowed for their correction.
Within the next 2 1/2 years, formal PHAs of the facility
will be completed. The results will be made available to
employees, and the recommended remedial actions will be
tracked to completion.
The requirements for performing PHAs for toxic, reactive,
flammable or explosive chemical operations are contained in OSHA
Standard 29 CFR 1910.119, Process Safety Management. Process
hazards analysis is covered in section (e). Subsection (e)(3)
requires the following:
o the identification of process hazards;
o an evaluation of any previous accidents;
o the identification of engineering and administrative
controls;
o the evaluation of consequences of failure of these controls;
o an evaluation of facility siting and adjacent hazards;
o the consideration of human factors; and
o a qualitative evaluation of the potential safety and health
effects to workers in the event of failure of the process
controls.
Subsection (e)(5) requires the establishment of a system to
address the PHA findings and recommendations, and to document and
track the identified corrective actions to completion.
Applying lessons learned to DOE sites
This incident offers several important lessons for DOE
sites. The manufacturer was required to repair the facility,
complete the required corrective actions, and pay $1.5 million in
penalties. These serious consequences demonstrate that it is
Occupational Safety OBSERVER Page 7
critical to perform a Process Hazards Analysis for chemical
operations covered by the Process Safety Management Standard,
OSHA 29 CFR 1910.119. All identified serious hazards should be
corrected before an operation or a particular part of an
operation is allowed to continue.
Identification May Mean Prevention
HAZARD RECOGNITION: Its everybody's job
All employees at DOE sites need to take responsibility for
workplace safety. Several recent incidents at DOE sites
illustrate the importance of worker awareness of potential
hazards. While the incidents are diverse, including a worker
being overcome by toxic vapors, a fire in a construction trailer
and an electric shock, they exhibit a common theme: the need for
continued awareness of hazards in the workplace.
Worker dizzy spell
On October 22, 1992, at DOE's Savannah River Site, a
construction worker became dizzy from breathing unidentified
vapors from a diesel-fueled heater in a plastic-covered hut. The
hut had been erected to cover exposed piping that had been welded
and the heater was being operated to reduce the drying time of
the coal tar coating on the weld. When the worker entered the
hut to check the temperature and refuel the heater, he became
dizzy after ten minutes and exited the hut.
Certain hazards that are inherent to this type of operation
should have been noted. First, fuel-fired heaters without
external exhaust present a danger of carbon monoxide poisoning.
OSHA requirement 29 CFR 1926.154 addresses temporary heating
devices and provides requirements for adequate ventilation,
temperature limits, and clearances from combustible enclosure
coverings. Coatings like the coal tar coating present a special
hazard of airborne toxicity, which may be exacerbated by the use
of heaters to speed drying. The final occurrence report
determined that the heater should have been placed outside the
plastic enclosure, and the plastic should have been removed
before anyone entered, allowing the area to ventilate.
Trailer fire
A fire in a construction-clothing change trailer on October
24, 1992, at Savannah River resulted in a total loss of equipment
and facilities valued at about $35,000. The apparent cause of
the fire was a carton of toilet paper having been placed on the
floor adjacent to a wall-mounted electric heater. A worker
making a routine surveillance noticed an odor of smoke earlier in
the evening. Suspecting an electric heater as the cause of the
odor, the worker turned off the heater on one side of the
trailer, and proceeded with the remainder of the surveillance.
No notice was made of the heater on the other side of the
trailer. Another worker making a surveillance an hour later
noticed flames and turned in an alarm. Despite a prompt response
from fire crews, the trailer was a total loss.
In this case, a series of failures to recognize hazards led
Page 8 Occupational Safety OBSERVER
to the fire. Because the trailer was a temporary facility, it
had no sprinkler system and poor storage space. The lack of
storage space led to the single biggest hazard: the carton of
toilet paper being stored on the floor by the heater. A thorough
review by the surveillance worker who smelled smoke might have
revealed the danger in time to prevent any damage. While each of
these alone may seem like a small issue, in combination they led
to a significant loss of property.
Electric shock
In the third incident, a rigger received an electric shock
while erecting scaffolding. On October 21, 1992, plant
electricians at the Hanford site were planning to re-install
electrical heat trace on a boiler de-aerator drain line, and
riggers were assigned to erect scaffolding under the de-aerator.
While erecting the scaffolding, one of the riggers noticed worn
insulation on heat trace wiring, with a section of bare wiring
showing. Either no question was raised about the possibility of
the heat trace wiring being energized, or the rigger mistakenly
believed that contact with the bare section of wiring could be
avoided. As the scaffolding sections were being handled, contact
was made with the bare wiring, and a rigger received a 110-volt
shock. Fortunately, no serious injury was incurred.
In this case the worker saw the hazard Ä the bare wiring Ä
but underestimated its significance. Neither the on-duty
Operations Supervisor nor the Maintenance Person In Charge was
notified when the scaffolding was being erected. A pre-job
safety walkdown for site-specific hazards identification could
have noted the bare wire, and averted the electrical shock.
What do these incidents have in common?
In each of these incidents, underestimating the significance
of workplace hazards led to significant incidents.
o In the dizzy spell incident, everybody underestimated or
failed to recognize the hazards posed by the combination of
high temperature and possibly toxic fumes inside the hut.
o In the trailer fire, the dangers of electric heaters were
underestimated or not recognized, especially the importance
of never placing combustible materials nearby. In addition,
the surveillance worker underestimated the significance of
the smoke, and so failed to investigate fully.
o In the case of the electric shock, the danger posed by the
bare wire was not recognized and therefore went uncorrected.
Safety regulations should always be followed, but attention
to safety should not stop with the regulations. All workers at
DOE sites share responsibility for preventing incidents like
these. Specific lessons learned from these incidents include:
o Workers need to be vigilant about identifying and reporting
potential hazards in the workplace.
Occupational Safety OBSERVER Page 9
o Management needs to ensure that workers will report all
safety hazards, perhaps by strengthening the positive
response to such reports, and avoiding a punitive response.
o Through training and demonstration, management must continue
to foster a safety culture at all DOE sites.
Recognizing, reporting and avoiding workplace hazards takes
time and initiative, and it may not always be rewarded. But in
order to prevent safety incidents in the future, hazard
recognition must be everybody's job.
Page 10 Occupational Safety OBSERVER
DOE Order 5483.1A, dated June 1983, requires DOE compliance with
OSHA regulations, including those listed in the Observer.
The descriptions of the incidents included in this compendium are
based on information available at the time of publication.
Articles regarding DOE incidents are drawn from ORPS reports,
accident investigation reports, and interviews with site
personnel. The following ORPS reports were used in this issue:
The Occupational Safety Observer
is a publication of the
Office of Environment, Safety and Health.
For more information or corrections to the articles in this
issue, please contact:
Tom Kyriakakis
Operations Management Division (EH-32.1)
U.S. Department of Energy
Telephone: (301) 903-5516
For address changes and mailing list information, please contact:
John Everett
Fax: (206) 528-3552
Telephone: (206) 528-3246