Technical Manual - Section 3 (Safety Hazards)

COOLING WATER
Recirculated cooling water must be treated to remove
impurities and dissolved hydrocarbons. Because the water is
saturated with oxygen from being cooled with air, the chances
for corrosion are increased. One means of corrosion
prevention is the addition of a material to the cooling water
that forms a protective film on pipes and other metal surfaces.
HEALTH AND SAFETY CONSIDERATIONS
Fire Prevention and Protection
When cooling water is contaminated by hydrocarbons,
flammable vapors can be evaporated into the discharge air.
If a source of ignition is present, or if lightning occurs, a fire
may start. A potential fire hazard also exists where there are
relatively dry areas in induced-draft cooling towers of
combustible construction.
Safety
Loss of power to cooling tower fans or water pumps could
have serious consequences in the operation of the refinery.
Impurities in cooling water can corrode and foul pipes and
heat exchangers, scale from dissolved salts can deposit on
pipes, and wooden cooling towers can be damaged by
microorganisms.
Health
Cooling-tower water can be contaminated by process
materials and by-products including sulfur dioxide, hydrogen
sulfide, and carbon dioxide, with resultant exposures. Safe
work practices and/or appropriate personal protective
equipment may be needed during process sampling,
inspection, maintenance, and turnaround activities; and for
exposure to hazards such as those related to noise,
water-treatment chemicals, and hydrogen sulfide when
wastewater is treated in conjunction with cooling towers.
ELECTRIC POWER
Refineries may receive electricity from outside sources or
produce their own power with generators driven by steam
turbines or gas engines. Electrical substations receive power
from the utility or power plant for distribution throughout the
facility. They are usually located in nonclassified areas, away
from sources of vapor or cooling-tower water spray.
Transformers, circuit breakers, and feed-circuit switches are
usually located in substations. Substations feed power to
distribution stations within the process unit areas.
Distribution stations can be located in classified areas,
providing that classification requirements are met.
Distribution stations usually have a liquid-filled transformer
and an oil-filled or air-break disconnect device.
HEALTH AND SAFETY CONSIDERATIONS
Fire Protection and Prevention
Generators that are not properly classified and are located too
close to process units may be a source of ignition should a
spill or release occur.
Safety
Normal electrical safety precautions including dry footing,
high-voltage warning signs, and guarding must be taken to
protect against electrocution. Lockout/tagout and other
appropriate safe work practices must be established to prevent
energization while work is being performed on high-voltage
electrical equipment.
Health
Safe work practices and/or the use of appropriate personal
protective equipment may be needed for exposures to noise,
for exposure to hazards during inspection and maintenance
activities, and when working around transformers and
switches that may contain a dielectric fluid which requires
special handling precautions.
III:2-54