cranes
.
General
Safety Requirements:
·
Employers
must permit only thoroughly trained and competent workers to operate cranes.
·
Operators
should know what they are lifting and what it weighs, for example, the rated
capacity of mobile cranes varies with the length of the boom, the boom height,
the boom angle and the boom radius.
·
To
reduce the severity of an injury, the employer must take the following
precautions:
1.
Equip
all cranes that have adjustable booms with boom angle indicators.
2.
Provide
cranes with telescopic booms with some means to determine boom length.
3.
Post
load rating charts in the cab of cab-operated cranes.
4.
Require
workers to always check the crane’s load chart to ensure that the crane will
not be overloaded by operating conditions.
5.
Instruct
workers to plan lifts before starting them to ensure that they are safe.
6.
Tell
workers to take additional precautions and exercise extra care when operating
around power lines.
7.
Teach
workers that outriggers on mobile cranes must rest on firm ground, on timbers,
or be sufficiently cribbed to spread the weight of the crane and the load over
a large enough area.
8.
Direct
workers to always keep hoisting chains and ropes free of kinks or twists and
never wrapped around a load.
9.
Train
workers to attach loads to the load hook by slings, fixtures, and other devices
that have the capacity to support the load on the hook.
10. Instruct
workers to pad sharp edges of loads to prevent cutting slings.
11. Teach
workers to maintain proper sling angles so that sling are not loaded in excess
of their capacity.
12. Ensure
that all cranes are inspected frequently by persons thoroughly familiar with
the crane, the methods of inspecting the crane, and what can make the crane
unserviceable.
13. Ensure
that the critical parts of a crane – such as crane operating mechanism, hooks,
air, or hydraulic system components and other load-carrying components – are
inspected daily for any maladjustment, deterioration, leakage, deformation, or
other damage.
CRANE SAFETY
Planning Before Start-Up
Level the crane and ensure support surface is firm and able to support the load
Contact power line owners and determine precautions. Know the location and voltage of overhead power lines.
Know the basic crane capacities, limitations, and job site restrictions, such as the location of power lines, unstable soil, or high winds.
Make other personnel aware of hoisting activities.
Barricade areas within swing radius.
Ensure proper maintenance and inspections.
Determine safe areas to store materials and place machinery.
CRANE SAFETY
Only people that have trained are permitted to operate cranes
CRANE SAFETY
Barricades around the swing area of a revolving cab must be used when operating a crane in areas where pedestrians or traffic pass close by.
CRANE SAFETY
Never operate cranes closer than 10 feet from power lines. Voltages greater than 50,000 volt require greater distance.
CRANE SAFETY
Before lifting carefully inspect all rigging, slings, hooks, etc.
Report any damage or defects to your supervisor right away.
CRANE SAFETY
When it is necessary to guide a suspended, use tag lines.
Don’t distract the crane operator. Only one signalman at a time.
CRANE SAFETY
Never ride the load, ball or hook.
CRANE SAFETY
Keep out from under suspended loads.
Watch out for materials that could fall on you if hit by the moving load.
CRANE SAFETY
Make sure you provide yourself a way out when directing load drops.
Types of Tower Cranes
Rail Mounted, supported on a carriage running on a parallel set of rails.
Outrigger Mounted
On a fixed base, supported on a concrete base.
Climbing type, supported by floors during the construction of a multi-stored building.
On crawler tracks.
Slewing Tower & Non-Slewing Tower
Slewing: the slewing ring is situated at the bottom of the tower and the whole of the tower and jib assembly slews relative to the base of the crane.
Non-Slewing: The slewing ring is situated at or near the top of the tower and the jib slews about the vertical axis of the tower which itself remains stationary.
(should be tied to the to a fixed structure.)
Horizontal Trolley Jib
Inclined trolley Jib
Luffing Jib
Fixed Radius Jib
Safety Measures - Site
Away from high voltage power lines.
Away from excavation sites.
Prevailing Wind-speeds.
Away from water accumulation – water leaking under the foundation of the crane.
Overlapping levels with other cranes. To avoid collision some one (competent person) should plan the sequence of crane movements.
Safety Measures - PPE
Safety Harness
Helmets
Safety Shoes
Fire Extinguishers
Easily Accessible
Trained
Crane Safety Equipment
Automatic Safe Load Indicator
Load Radius Indicator
Motion Limiting Devices
Overload Cut-out devices
Level Indicator
Anemometer
Machinery Guarding
Zoning Devices (two or more cranes – limit the slew, the trolley motion, or the travel motion
Crane Safety
Lighting Protection (Earthing)
Rail mounted tower cranes should be fitted with an audible travel alarm.
Ladders – Landing (Platform)
Access to and along jibs and counter jibs for inspection and servicing should be made safe. (catwalks should be provided with handrails)
Clear vision from cab
Tower Cranes
Visual Examination
Overload Test (swl raised to sufficient height to ensure that each tooth of the train of gears is subjected to the load then lowered to 100 mm to 200 mm above the ground.
SWL should then be increased by 25 % and this load hoisted sufficiently to ensure that each tooth of the train of gears is subjected to the overload then lowered to 100 mm to 200 mm just clear of the ground.
For horizontal jib cranes with trolleys the trolley should be set at the maximum radius for swl.
Swl (100 mm to 200 mm) – 25 % of swl (100 mm to 200 mm)
Continued
Indicator test:
The crane should never loaded beyond 100 % of its swl.
The radius at which the test load corresponds to 110 % of the swl should be marked and the test load should never be taken beyond this point.
