EH-93-6 Take Special Care When Using Cranes
ENVIRONMENT, SAFETY & HEALTH
SAFETY BULLETIN
Assistant Secretary for U. S. Department of Energy
Environment, Safety & Health Washington, D.C. 20585
DOE/EH-0342 Issue No. 93-6 November 1993
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Take Special Care When
Using Cranes
In the decade ending 1992, an average of 10 crane-related injuries and
1,200 lost work days were reported each year at Department of Energy (DOE)
facilities. According to the Bureau of Labor Statistics, 111 fatalities
occurred in the U.S. between 1985 and 1989.
The use of cranes required special attention for every application;
however, the majority of crane-related incidents reported to DOE's Safety
Performance Measurement System and Occurrence Reporting and Processing
System fall into four categories: overhead power lines, rigging and
maintenance, jumping and falling, and shifting or slipping loads.
Accidents in each of these categories generally involve human error and
may be preventable. Effective worker safety training and proper planning
at the job site are critical.
Cranes and Overhead Power Lines
A common cause of crane accidents involves contact with power lines. The
National Institute for Occupational Safety and Health investigated 40
electrocutions that occurred in the United States between 1982 and 1990 in
which vehicles with booms contacted energized power lines. This typically
occurs when the operator fails to have an escort when maneuvering the boom
in areas of congestion or poor visibility, fails to lower the boom while
in transit, or fails to observe the surroundings. Even in such cases as
these when no injuries are reported, damage is sometimes extensive. Both
operators and supervisors may be cited for such things as carelessness,
inadequate supervision, and violation of procedures. In one case,
carelessness resulted in four broken power lines, a grass fire, a fallen
utility pole that damaged a private vehicle, and an interruption in phone
service and electric power in the surrounding area.
Fatal crane accidents are generally the result of electrocution. In a case
considered typical of such accidents, the Occupational Safety and Health
Administration reported that a rigger was electrocuted when working too
close to overhead power lines. While attempting to provide sufficient
clearance for the rigger to place a sling around a 40-foot telephone pole,
the crane operator raised the boom and touched an overhead power line. In
this case, the employee was cited for failing to provide proper safety
instructions and for allowing the workers to operate the equipment too
close to a power line.
Recommendations
1. Lower the boom when in transit.
2. Look carefully before moving the boom, particularly in congested
areas of poor visibility, and request assistance if you cannot see
clearly.(1)
3. Consider any overhead wire to be energized unless the line owner or
utility company tells you that it is not energized.(1)
4. Maintain a minimum clearance of 10 feet between the power line and
any part of the crane or load when working around energized power
lines rated at 50 kV or below.(1)
5. Maintain a minimum clearance between the lines and any part of the
crane or load of 10 feet plus 0.4 inch for every 1 kV over 50 kV, or
twice the length of the line insulator, for voltages above 50 kV.(1)
6. When in transit, with no load and the boom lowered, maintain at
least 4 feet of clearance from lines rated less than 50 kV, 10 feet
from lines rated over to kV, up to and including 345 kV, and 16 feet
from lines rated up to and including 750 kV.(1)
7. Notify your manager whenever the crane will be in use, so that you
will have adequate supervision.
Rigging and Maintenance
One-fourth of all nonfatal crane-related injuries reported occurred when
workers were performing rigging or maintenance activities. More than one-
half of those injuries resulted in fractures and lacerations, and they
were caused by workers catching their fingers either between the load and
the sling or between the sling and the crane hook. Most of the
maintenance accidents were minor, with workers suffering bumped heads,
barked shins, and lacerated fingers. However, carelessness in following
safety procedures during maintenance activities can be as dangerous as
failing to do so during operation.
In one instance, a worker was under a mobile crane tightening the battery
cables when the crane operator, who was not aware that the worker was
under the crane, began to slowly rotate the cab. A bystander signaled an
emergency stop and reverse when he noticed that the worker had become
pinned between the cab and its tracks. This incident resulted in only
minor injuries to the worker. The worker believed that he had time
between "picks" or rotations of the cab to finish his work and attempted
to tighten the battery cables without following the standard safety
procedure, i.e., shutting down the crane before beginning maintenance work
of any kind.
Recommendations
1. Keep your fingers and arms from between the sling and the load and
from between the sling and the hook. Gloves are recommended.(2)
2. Examine the surrounding area carefully before beginning maintenance
activities. Look for obstructions in the area where you will be
bending, straightening, or walking.
3. Follow lockout/tagout procedures (turn the crane off, lock the main
switch in the off position, and tag of flag it), and place an OUT OF
ORDER sign on the crane in a highly visible place before starting
any maintenance activity. (3,5)
Jumping and Falling
Many injuries are caused when workers jump or fall off cranes while
descending from the cab. In most of the cases studied, the workers were
inexperienced and did not realize the dangers involved in jumping from
even a short height. Workers sustained sprained ankles and twisted and
sprained knees after jumping instead of using the ladder. Some workers
were injured when they fell while climbing up to the cab and carrying
items in their hands. Those workers were often unable to catch themselves
to avoid a fall when their feet slipped.
Recommendations
1. Use the ladder when climbing up to the cab. Keep a firm grip on the
handrails to avoid falling if your feet slip.
2. Use the ladder to climb down -- do not jump.
3. Avoid handling or carrying objects while climbing up or down the
ladder. Anything that cannot be transported via pockets or belts
should be hauled up using a hand line.(3)
4. Take precautions to ensure that loose clothing, such as coats or
rain gear, does not catch on bolts or handles and cause a fall.
Shifting, Slipping Loads
Loads that shift, slip, fall, or knock over other items comprise the
fourth major category of worker injuries. A fatality at a DOE site
illustrates the danger inherent in loaded cranes. In this incident, a
worker was crushed to death when a heavy crane load broke loose and fell
on him. The accident investigation listed numerous causes for the fatal
mishap. A worn, faulty tie-down strap which broke and the close proximity
of the victim to the crane's load were two main reasons for the fatality.
In another incident, a metal staircase slipped out of the hook while it
was being lifted, landing on a worker's foot and fracturing his toes.
Another worker received multiple injuries when an I-beam was knocked off a
truck onto his leg as the load was moved. Several workers suffered back
injuries when they attempted to adjust or turn a load while it was
suspended.
Recommendations
1. Inspect the crane before use, checking for deformed or cracked hooks
and wear on the host chain, sling, and associated equipment. Ensure
that the crane and associated hoisting machinery is inspected
annually by a competent person or by an agency recognized by the
U.S. Department of Labor. (1,3)
2. Ensure that the load is well secured and balanced in the sling or
rigging before it is lifted more than a few inches from the
ground.(3)
3. Position the hood directly over the center of the load to minimize
swinging.(4,5)
4. Keep the hook's load centered, and avoid point loading the hook
unless it is designed for that.(2)
5. Do not attempt to manually shift, turn, or redistribute a load once
it has been lifted, since this increases the risk of accidents and
injuries. If the load is off center or looks as if it will slip,
ask the operator to lower the load back to the ground before you
approach to make adjustments.
6. Wear safety shoes and hard hats, and keep clear of the suspended
load.(2)
7. Check the area in the path of the moving load to ensure that it
will not hit anything, especially if it swings suddenly.
8. Move the loaded hook smoothly, avoid sudden accelerations or
decelerations, which can cause the load to swing.(3,5)
Additional Good Work Practices
The majority of crane-related accidents can be avoided if workers and
supervisors take the following safety precautions before beginning
work.(6)
Supervisors
1. Ensure that workers are trained in all crane safety procedures.
2. Be certain that all hoisting equipment is in good shape and rated
for the weight to be lifted.
3. Ensure that ladder steps, platforms, and walkways have nonskid
surfaces. Keep walking surfaces clean and free of mud and ice.
Workers
1. Do not exceed the rated load capacity and understand the load
charts; exceeding load capacity may cause the crane to tip over.
2. Use a signal person if you cannot see the load you are trying to
move or maneuver.
3. Never suspend a load over or close to people. Make sure the area of
travel or boom movement is clear before maneuvering a load.
4. Keep clear of the crane swing radius when lifting is being done. Do
not stand under suspended loads or in the load's line of motion.
References
(1) 29 CFR 1926.550, "Cranes and Derricks"
(2) American National Standards Institute (ANSI) B30.9-90, Slings
(3) 29 CFR 1910, Subpart N, "Materials Handling and Storage"
(4) ANSI B30.16a-89, Overhead Hoists
(5) ANSI B30.2-90 and B30.2a-91, Overhead and Gantry Cranes
(6) DOE Hoisting and Rigging Manual, Revised Edition, 1993
This Safety Bulletin is one in a series of publications issued by EH to
share occupational safety information throughout the DOE complex. To be
added to the Distribution List or to obtain copies of the publication,
call (615) 576-7548. For additional information regarding the
publications, call Barbara Bowers, Safety Performance Indicator Division,
Office of Environment, Safety and Health, U.S. Department of Energy,
Washington, DC 20585, (301) 903-3016.