Describe the essential parameters for performing a pre-use inspection of a mobile crane on a construction site, emphasizing the critical components that must be checked to ensure safe operation.
A thorough pre-use inspection of a mobile crane is absolutely critical for ensuring safe operation on a construction site. This inspection is not just a formality; it's a vital process to identify any potential defects, malfunctions, or unsafe conditions that could lead to accidents, injuries, or property damage. The inspection must be carried out by a competent person, usually the crane operator, before each shift or whenever the crane has been moved or adjusted. The essential parameters that must be checked include:
1. Documentation and Certification:
Crane Logbook: The crane's logbook should be readily available and must be reviewed. The logbook contains crucial information, such as previous inspections, maintenance history, and any reported defects. A review ensures all previous defects are rectified and logged accordingly, and that the crane is certified for the work being done. It should be checked to verify that the required routine maintenance is up to date.
Inspection Certificates: The crane's annual and periodic inspection certificates should be valid, up-to-date, and aligned with the crane type. These certificates confirm that the crane has undergone required checks by qualified inspectors and is safe for use. If there are any pending inspection requirements, then the crane should not be used.
Operator Certification: Verify that the crane operator holds the required certifications to operate that type of crane. Check that this certification is valid and up-to-date.
2. Structural Integrity:
Crane Frame: Inspect the crane's frame for any signs of damage, cracks, deformations, corrosion, or excessive wear. Pay close attention to welds, joints, and bolted connections. Look for signs of stress.
Outriggers and Stabilizers: Examine the outriggers and stabilizers to ensure that they are in good working order. Check for any bends, cracks, or damage. Ensure that they extend fully and evenly and that they lock correctly, and that the pads are correctly placed and suitable for the ground conditions.
Turntable and Slew Ring: Inspect the turntable and slew ring for any cracks, signs of wear, loose bolts, or damage. Ensure the slew mechanism operates smoothly and without any unusual noise or play.
3. Boom and Jib:
Boom Sections: Check all boom sections for straightness, dents, cracks, and corrosion. Look for signs of damage on the welds and connections. Look for any excessive wear or damage.
Jib Sections: Inspect the jib sections, if present, for the same damage and wear as the boom. Check that all pins and bolts are correctly in place.
Boom and Jib Extension: Verify that the boom and jib extension mechanisms are working properly and that the boom and jib extend and retract smoothly, without jerking, and lock securely at each designated length.
Wire Ropes and Sheaves: Inspect wire ropes for kinks, broken wires, wear, corrosion, and proper lubrication. Check that the wire rope is correctly seated on the sheaves and that the sheaves move smoothly, and are in good condition. Make sure the termination points of the wire rope are secure.
4. Hoist System:
Hoist Drums and Brakes: Inspect hoist drums for any signs of damage, cracks, or wear. Ensure that the hoist brake operates properly, locks the load, and holds securely, and check that the control mechanism for the hoist is working smoothly.
Hoist Cable: Inspect the hoist cable for any kinks, broken wires, wear, corrosion, and proper lubrication, just like the boom wire ropes. Check the termination points of the cable to ensure they are secure.
Load Hooks: Inspect the load hook for any signs of wear, cracks, or deformation. Verify that the safety latch is working properly. Check that all rigging attachments are secure and free from damage.
5. Hydraulic System:
Hydraulic Hoses and Lines: Examine all hydraulic hoses and lines for any leaks, kinks, cuts, bulges, or signs of wear. Check all hose connections to make sure they are secure and not leaking.
Hydraulic Cylinders: Inspect all hydraulic cylinders for leaks, damage, or signs of wear. Check that the cylinders fully extend and retract smoothly.
Hydraulic Oil Levels: Verify that the hydraulic oil levels are at the correct level according to the manufacturer's recommendations.
Pump and Valves: Listen for any unusual noises from the hydraulic pump and check all hydraulic control valves for smooth operation, checking they are correctly functioning and are free from leaks.
6. Electrical System:
Wiring and Connections: Inspect all electrical wiring and connections for any damage, loose connections, or exposed wires. Check that the insulation is in good condition and that all wiring is securely routed.
Electrical Panels and Controls: Check all electrical panels and control boxes for damage, and ensure that all controls operate smoothly, and that all safety interlocks function correctly. Check emergency stop buttons are working.
Lighting and Indicators: Ensure all lights, indicators, and alarms are working properly.
7. Safety Devices:
Load Moment Indicator (LMI): Verify that the LMI system is functioning correctly and is properly calibrated. If the crane has an overload protection system, it must be checked that it is working properly, the load display must be working correctly, and be visible to the operator.
Anti-Two-Block Device: Check that the anti-two-block system is working correctly and is free from any obstructions. This system prevents the hook from contacting the sheave.
Emergency Stop Buttons: Test all emergency stop buttons to make sure they bring all crane operations to a stop immediately.
Warning Devices: Ensure that all warning devices, such as alarms and horns, are working correctly.
8. Operator Controls and Cab:
Control Levers: Check all control levers and pedals for proper functionality and smooth operation. The crane operator needs to make sure that the controls are correctly operating.
Operator Seat and Restraints: Ensure that the operator's seat is in good condition and that all safety restraints, such as seatbelts, are working correctly.
Visibility: Ensure that the operator's visibility from the cab is not obstructed by any damage, equipment or dirty windows. Windshield wipers, mirrors and glass surfaces must be clean and in good order.
Operator Manual: Ensure the operator's manual is present and readily available.
9. Tires and Undercarriage:
Tires: Check the tires for proper inflation, wear, and damage. Look for any bulges, cuts, or foreign objects embedded in the tires. Ensure that the wheels are securely mounted.
Undercarriage: Inspect the undercarriage, chassis, and drive system for any damage or wear. Make sure all guards and covers are securely in place.
10. Function Tests:
Full Operational Cycle: Perform a function test that includes all operational functions of the crane including lifting, lowering, slewing, and telescoping. These checks need to be done with no load, then with a small test load.
Brake Test: Test the hoist and slew brake systems under load, to ensure they are holding properly.
Emergency Stop Test: Test all emergency stop systems to ensure they are working as required.
During the inspection, the operator should record any findings in the crane's logbook. Any defects or malfunctions identified during the pre-use inspection must be rectified before the crane is put into service. If the defects are of a serious nature, the crane must be taken out of service until such time as it is rectified and signed off by a competent person. Regular pre-use inspections, are a critical component of a safe construction site, and reduce the likelihood of catastrophic incidents and ensures that the crane is safe to operate. By adhering to these essential parameters, the risk of accidents is reduced, ensuring the safety of all workers on site.