OSHA Hazard Information Bulletins
May 14, 1996
MEMORANDUM FOR: |
REGIONAL ADMINISTRATORS |
FROM: |
MICHAEL CONNORS
DEPUTY ASSISTANT SECRETARY |
SUBJECT: |
Hazard Information Bulletin - Chemical Exposures from
Industrial Valve and Piping Systems |
The purpose of this Hazard Information Bulletin is to heighten public
awareness of the potential for death, physical injury, and/or illness
resulting from the unexpected release of chemicals during refinery and other
chemical process operations. OSHA recognizes that non-compliance with
existing requirements is the exception, rather than the rule, in these
industries. This bulletin is intended to bring to the attention of
employers, employees, and OSHA field personnel fatal accidents that have
occurred in industrial operations, and the methods that can be employed to
reduce the risk of such accidents. In addition, this bulletin is intended to
alert OSHA's field compliance personnel to such hazards so that the scope of
future inspections adequately addresses these risks. This document is not
intended to impose additional compliance requirements on affected employers.
Fundamentally, employers and employees must be alert to the fact that
working with a "closed system" does not always ensure safety. Operations
involving the opening of valves or pumps on otherwise closed systems or
working on such equipment that is not isolated or locked/tagged out are
particular sources of danger. When a normally closed system is opened, the
potential exists for releasing hazardous chemicals into the workplace in
unknown concentrations.
Examples of Accidents:
The Agency reviewed previous fatality inspections involving the opening of
valves or piping systems and found numerous incidents where one or more
workers had died. Some examples of these types of accidents included:
In 1988, two workers were operating a sodium turnstate purification
system. One worker attempted to pump a sodium sulfhydrate solution into a
tank and accidentally opened the valve to another tank which contained an
acidic solution (pH 2.9). The mixture of the two compounds generated and
released hydrogen sulfide gas to which the deceased was exposed.
In 1988, a refinery employee received a fatal exposure to hydrogen
sulfide gas while draining the contents of a knockout drum to an oily water
sewer, rather than activating a closed system to pump out the drum. The
worker failed to observe procedures calling for the use of a closed system,
and the valve to the sewer was not locked out.
In 1993, employees were working in a coker unit that thermally
cracks heavy residual feed through a process called delayed coking. The
workers were preparing to switch the feed to the core drum, which
necessitated opening and closing a number of valves. Three workers were
involved with opening and closing the valves, each working at a different
location. As the operation was proceeding, a loud noise was heard and a
vapor cloud was observed in the vicinity of the pumps feeding the process.
The vapor cloud ignited, fatally burning two of the workers.
In 1993, workers were draining refrigerant oil from collection traps
on an anhydrous ammonia refrigeration system. The employees were using hand
tools to open the valves and drain off the oil when they were severely
exposed to anhydrous ammonia, resulting in two fatalities.
In 1994, an employee was killed when disconnecting a line from an
ammonia valve. The line had not been adequately isolated, causing the
release of liquid ammonia which struck the worker's face and body.
In 1994, one worker was killed and one worker was injured while
attending to pumps in a muriatic acid unit. While working on the pumps, an
over-pressurization of one of the process tanks occurred, causing a rupture
which sprayed the workers with muriatic acid.
In 1994, a tragic fatality apparently caused by exposure to hydrogen
sulfide was reported by the Billings, Montana, Area Office. The accident was
associated with opening a valve to a sewer cup during the draining of a fuel
gas knockout drum in a hydro treating unit of a petroleum refinery. Normal
work procedures included periodically opening a valve that carried a
water-gas mixture to a separator which removed and vented hydrocarbon gases
to a flare. During the preceding winter, the piping to the separator froze,
and the drum was temporarily drained to the sewer. The Agency believes that
due to unclear procedures, the temporary practice of draining some of the
water-gas mixture to the sewer in some instances may have been continued, or
was incorporated by some workers into the normal draining procedures. The
deceased is thought to have opened the valve to the sewer believing it to be
part of the draining procedure, resulting in the release of toxic amounts of
hydrogen sulfide that killed the worker.
Common Factors and Problems
A common theme running through these fatalities is that they involved
situations where a closed industrial system was opened through a valve or
pump either to perform maintenance work, vent by-products, or remove
condensate. The hazards inherent in these operations should be addressed by
one or more of the following measures:
1. Performing a process hazard analysis to address the hazards of
the process and engineering and other control measures to ensure worker
safety, including a complete evaluation and assessment of process systems
handling waste products, by-products, and/or unreacted process components.
Recommendations made by the PHA team, including recommended engineering
changes, should be promptly implemented unless the employer justifiably
rejects the recommendation pursuant to the guidelines contained in OSHA
Instruction CPL 2-2.45A CH-1, "29 CFR 1910.1 19, Process Safety Management of
Highly Hazardous Chemicals -- Compliance Guidelines and Enforcement
Procedures," (September 13, 1994), Pages B-21 and B-22;
2. Assuring a system is under lockout/tagout, including draining
and purging of lines and equipment, prior to working on the system;
3. Assuring that written procedures are clear and provide complete
instructions for the safe performance of work activities;
4. Assuring that employees, including contract employees, are
trained in applicable procedures and safe work practices, and that the
employees understand and adhere to the current operating procedures of the
process.
While the risk of accidents cannot be entirely eliminated, these procedures
and practices will reduce the potential for an accidental exposure to a
hazardous chemical(s).
Applicable Control Measures:
Engineering Controls: Plant systems containing hazardous
chemicals must be completely assessed to assure that valves capable
of releasing the toxic agent to the atmosphere are permitted to be opened
only when absolutely necessary and are then vented using appropriate safety
precautions. The valves must also be capable of being locked/tagged
out.
Sewer systems for draining tanks or drums which present a potential
exposure to hazardous chemicals should be constructed so that they are
closed, vented to a safe location, or not open to the atmosphere.
Alternatively, appropriate respiratory protection should be worn before these
systems are used.
A valve configuration on an industrial process should be such that
only the valves used for routine use as part of the normal process are
readily capable of being opened. If the valves are required to be opened
only for occasional shutdown operations, they must be locked/tagged in the
closed position to preclude erroneous opening during routine plant
operations. Valves that must remain available for immediate use in emergency
operations should be clearly labeled as such so that they are not
accidentally opened during routine process or maintenance
operations.
Monitoring and Detection Equipment:
Operators working on units where there is potential exposure to hazardous chemicals may
need to be supplied with personal monitoring equipment. Alternatively,
stationary monitors could be installed. Personal or stationary monitors must
be capable of sounding an audible alarm or warning.
Training: All current and new employees should receive
training in standard operating procedures covering all aspects of
the job, with emphasis on safe work practices. Where appropriate, training
should also include field observations (on-the-job training) by qualified
supervisory personnel, including verification that workers have satisfied the
training requirements.
Training must include proper procedures for working near areas of
potential exposure to hazardous chemicals and address the hazards of
exposure. While labeling of pipes cannot be required, the hazard
communication standard does require that the employer address the hazards of
unlabeled piping systems in a written hazard communication program and that
the information be provided through training to workers.
Respiratory Protection: Respirators must be provided by the
employer when effective engineering controls are not feasible, or
while they are being instituted, when such equipment is necessary to protect
the health of the worker. The employer must provide respirators that are
applicable for the purpose intended.
Written procedures must be developed for the safe use of respirators
during the performance of operations presenting a potential exposure to a
hazardous chemical(s).
Under circumstances where individuals may be exposed to an unknown
concentration of hydrogen sulfide or some other hazardous chemical, back-up
personnel with appropriate respirators and emergency equipment must be
present.
Applicable Standards:
The following standards may apply according to the nature of the process.
29 CFR 1910.119 -
Process Safety Management
29 CFR 1910.120 -
Hazardous Waste and Emergency Response
29 CFR 1910.132 -
Personal Protective Equipment
29 CFR 1910.134 -
Respiratory Protection
29 CFR 1910.146 -
Confined Spaces
29 CFR 1910.147 -
Lock Out and Tag Out
29 CFR 1910.1000 -
Permissible Exposure Limits for Hazardous Chemicals
29 CFR 1910.1200 -
Hazard Communication
Note: General Duty Clause - In cases where compliance officers encounter
industrial systems that may not fall under the scope of the process safety
standard (29 CFR 1910.119) and a serious hazard is determined to exist, the
general duty clause - Section 5(a)(1) of the OSH Act may apply and require a
process hazard analysis to be conducted. If use of the general duty clause
is anticipated as a result of similar circumstances to those described in
this Bulletin, compliance officers are reminded to refer to the Field
Inspection Reference Manual (FIRM) for guidance.
For more information contact Ray Donnelly, Director for the Office of
General Industry Compliance at (202) 219-8031.
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