In This Document MODULE DESCRIPTION This module provides information on the safety concerns and

Transcription

1 Crane Safety Fact Sheet In This Document MODULE DESCRIPTION This module provides information on the safety concerns and Introduction necessary precautions you will need to be aware of when working Crane Hazards around cranes. Whose At Risk? Preparing for Usage Crane Inspections OBJECTIVES Lifting Principles After completing this module, the participant will be able to: Power Line Precautions Identify the major causes of crane accidents. Operator Requirements Describe the pre-planning that is required before using a Crane Personnel crane. Summary State the main precautions that need to be taken when working near power lines. Understand the importance of operator and personnel requirements. MODULE OUTLINE 1. Introduction to Cranes A crane is a machine that consists of a rotating structure that is used to hoist and move heavy objects. There are several different types of cranes, including: Mobile Hydraulic Overhead Gantry Tower The primary difference between each crane type is in the boom hoist, load line controls, and load charts. These differences are significant enough that crane operators must receive specific training for each type of crane they are expected to operate. Although a crane operator may be proficient using one type of crane, they cannot be expected to operate other crane types without proper training. Basic Parts of the Crane Structure Hoist: A hoist is used to lift and lower the load. Boom: A boom is an incline spar, strut, or other long member supporting the hoisting tackle. Boom Stops: Boom stops are devices used to limit the angle of the boom at its highest position. Boom Angle Indicator: A boom angle indicator is an accessory device that measures the angle of the centerline of the boom base section to horizontal. Block: Blocks are sheaves or grooved pulleys in a frame with the hook, eye, and strap.

2 Jib: A jib is an extension attached to the boom point which provides added boom length for lifting specified loads Load: A load is the weight of the object being lifted by the crane. This weight includes the load block and hook, wire rope, rigging, boom attachments, and ancillary attachments 2. Crane Hazards Hazards associated with cranes Improper load rating Excessive speeds Lack hand signals Inadequate inspection and maintenance Unguarded parts Unguarded swing radius Working too close to power lines Improper exhaust system Shattered windows No steps, guardrails, or walkways No boom angle indicator Not using outriggers 4 major types of crane accidents Contact with power lines Overturns Falls Mechanical failures Among the causes of crane accidents, contact with power lines occurs the most often and is considered to be the most dangerous. Crane accidents are most commonly caused by: Crane instability. Lack of communication between the operator and jobsite workers. Improper training of operators and jobsite workers. Inadequate maintenance or inspection of the crane. Definitions Instability: Instability is caused by an unsecured load, an exceeded load capacity, or unleveled or soft ground. Lack of Communication: Lack of communication occurs when the point of operation is a distance from the crane or the point of operation is not in full view of the operator. 3. Who s at Risk When crane operations go wrong, many can be at risk. Among those are the crane operators and any persons working at the crane site. Major crane accidents involve injuries, fatalities, and extensive material costs. Crane operators and all personnel working with cranes must: Receive proper training

3 Perform regular equipment inspections to identify any existing or potentially hazardous conditions Perform cautionary maintenance as required by the crane manufacturer and/or supplier to ensure the crane is operating safely 4. Preparing for Crane Usage Before you start up a crane there are many check and inspection procedures to follow through with. Leveling the crane and ensuring the support surface is firm and able to support the load. Contacting power line owners to determine any and all precautions. It is important to know the location and voltage of the overhead power lines before beginning work. Knowing the basic crane capacities, limitations, and job site restrictions, such as the location of power lines, unstable soil, or high winds. Making other personnel aware of hoisting activities. Barricading areas within the swing radius. Ensuring that there are proper maintenance and inspections. Determining the safe areas to store materials and place machinery. 5. Crane Inspections Inspection and maintenance is very important when working with equipment and cranes. Machinery must be inspected by a competent person and records maintained of each inspection. The following are essential to inspect for before a crane is operated: What to inspect and maintain Properly inflated tires with correct air pressure and no leaks Clearance for swing radius Wire rope wear and sheaves Load capacity Secure guardrails and guards Efficient rigging equipment Physical damage to the crane Loose or missing hardware, nuts, or bolts Fluid leaks All crane inspections should be made with extreme caution and must abide by OSHA and the American National Standards Institute. Tires: Tires should be inspected regularly for excessive wear and damage. Employers and operators must comply with the manufacturer s specifications and limitations applicable to the operation of any and all cranes and derricks. If a manufacture s specifications are not available, equipment limitations are based on a qualified engineer competent in this field; such determinations are to be appropriately documented and recorded. Crane attachments should not exceed the capacity, rating, or scope recommended by the manufacturer. Swing Radius: The crane s swing radius must be kept clear at all times. Barrier guards should be set up to indicate the crane s swing radius; this not only protects employees but also others in the area from getting hurt.

4 Wire Rope Wear and Sheaves: Wire rope should be in perfect operating condition and any damaged rope must be taken out of service. Heat damage, broken wires, and kinking, crushing, or bird caging can distort a wire rope causing it to be taken out of service. Sheaves are the attachments of a crane that rotate the wire rope and act as a pulley, running the rope back and forth. Sheaves must also be maintained and grooves are to be kept smooth to prevent the rope from being damaged. Damaged grooves can cause the rope to fray meaning it must be put out of service. Sheaves should also be equipped with guards to guide the rope back into the groove. Load Capacity: Cranes and crane equipment should have instructions, warnings, and load capacities visibly posted on them. The crane operator must be able to see the rated load capacities, operating speed, and special hazard warnings or instructions while operating. Limitations of loads can depend on the level, wind, side loads, wheels, lifting area, limits of the wire rope, sling and lifting devices, and the use of the extensions and other attachments. Guardrails and Guards: Guardrails, along with handholds and slip resistant surfaces, are essential for runways and steps allow easy access and to prevent operators and personnel from slipping. Guards are used to protect moving parts and personnel from being harmed by those moving parts. Guards should be used where exposed moving parts, such as belts, gears, chains, pulleys, or any other rotating pieces can come into contact with employees or create a hazard. Rigging Equipment: Slings are the rigging equipment used for cranes. The different types of slings that can be used include: alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope, and synthetic web. Slings are used in conjunction with other materials handling equipment to hoist and move materials. Any defective slings should immediately be removed from service. Loading As noted earlier, a crane operator must know all crane limitations, loading capacities, warnings, and instructions before operating a crane. Another factor to pay attention to when operating a crane is to know the weight of the load. Unknown load weight can lead to an overturned crane. To avoid these conditions, ensure that the load is within load chart ratings for boom length and the load radius of the crane. Also, make sure the crane is rated by the maximum weight it will lift at a minimum radius and minimum boom length the further from its centerpoint, the less it will lift. Some operators use load or load-moment indicators to ensure cranes won t be overloaded. But, do not become too reliant on these devices and begin using them in place of personal judgment. These devices do not always work, nor do they always read correctly. 6. Lifting Principles There are four basic principles that cover a crane s mobility and safety during lifting operations. They are: Center of Gravity: The point in the object where its weight can be assumed to be concentrated, or, in other words, the point in the object around which its weight is evenly distributed. The location of the center of gravity of a mobile

5 crane depends primarily on the weight and location of its heaviest components (boom, carrier, upperworks, and counterweight). Leverage: Used to lift crane loads. The rotation of the upperworks (cab, boom, counterweight, and load) changes the location of its center of gravity and leverage point. Stability: Stability is the relationship of the load weight, angle of the boom, and its radius to the center of gravity of the load. Stability is also affected by the support on which the crane is resting. Stability also relies on having a level, firm surface; therefore, unlevel surfaces or soft ground should be avoided, or mats and blocking must be used to maintain stable working conditions. Structural Integrity: Includes its main frame, crawler track and/or outrigger supports, boom sections, and attachments. Other elements include: Load chart capacity in relation to stability Boom angle limitations that affect stability and capacity Knowledge of the length of boom and radius in determining capacity 7. Power Line Precautions Power lines are the most dangerous among crane accidents. OSHA standards require that you stay at least 10 feet away from power lines when operating a crane. When crane work requires being near power lines, all electrical distribution and transmission lines must be de-energized and visibly grounded at every point of work. They also must be grounded and de-energized where insulating barriers, not attached to the crane, have been erected to prevent physical contact with the power line. Equipment or machines shall operate near power lines only when in compliance with the following requirements: For lines rated 50 kv. or below, minimum clearance shall be 10 feet between the lines and any part of the crane or load. For lines rated over 50 kv., minimum clearance shall be 10 feet between the lines and any part of the crane or load, plus 0.4 inches for each 1 kv., or twice the length of the line insulator, but never less than 10 feet. In transit with no load and the boom lowered, the equipment clearance shall be a minimum of 4 feet for voltages less than 50 kv.; 10 feet for voltages over 50kV., up to and including 345 kv.; and 16 feet for voltages up to and including 750 kv. A person shall be designated to observe clearance of the equipment and give a timely warning for all operations where it is difficult for the operator to maintain the desired clearance by visual means. When judging the distance of a power line, the operator to judge can be easily tricked due to the distance and slack of the power line. A good way to practice is to measure out the clearance distance and install visual barriers for the operator and other personnel to use. 8. Crane Operator Requirements Crane operators must be qualified on specific crane types and have on-the-job training. They are required to pass a practical operating examination, which is limited to the specific type of equipment they can operate.

6 Operators are required to meet these physical qualifications: Have vision of at least 20/30 Snellen in one eye, and 20/50 in the other, with or without glasses Be able to distinguish red, green, and yellow, regardless of the position of the colors, if color differentiation is required for operation Must have adequate hearing, with or without hearing aids, for the specific operation Disqualifications are due to a history of epilepsy or of a disabling heart condition. 9. Cranes should only be operated by the following personnel: Designated operators Learners under the direct supervision of a designated operator Maintenance and test personnel, when it is necessary in the performance of their duties Inspectors Only the specified personnel are allowed to enter a crane cab, with the exception of persons such as oilers and supervisors, whose duties require them to do so; and then only in the performance of their duties and with the knowledge of the operator or another appointed person. Hand signals are very important to know when working on the jobsite. It is a requirement that a poster be posted at the jobsite with an illustration of the hand signals that every operator and personnel working with or around cranes must know. Hand signals for crane and derrick operators should be those set by the American National Standard Institute customized for the type of crane in use. 10. Summary Now that you have completed this module, you should be able to: Recognize the major causes of crane accidents Describe the pre-planning that is required before using a crane State the main precautions that need to be taken when working near power lines Understand the importance of operator and personnel requirements.