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COMMERCIAL SAFETY PRODUCTS |
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Chemical Exposures from Industrial Valve and Piping Systems.
- INFORMATION DATE : 19960514
- RECORD TYPE : Hazard Information Bulletin
- SUBJECT : Chemical Exposures from Industrial Valve and Piping Systems.
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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