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Cranes and Rigging
- 2. Cranes Are Everywhere Cranes, derricks, and jib hoists are used in almost every setting Cranes can be found on most construction sites
- 3. Crane Hazards Crane, sling, or hook could fail if overloaded Load could flip, turn, or release suddenly if not attached correctly People or objects could be struck by the load
- 4. Crane Capacity Rated capacity clearly marked on each side of the crane If more than one hoisting unit, each hoist must be marked with rated capacity Markings clearly legible from the ground
- 6. Crane Inspections Daily inspections include: Operating mechanisms to ensure proper working order Air or hydraulic systems for leaks Hoist chains/ropes for wear, twisting, distortion Deformed, cracked, or corroded components Loose bolts or rivets Wear on brakes, chain drive sprocket
- 7. Crane Inspections Annual inspections Must be conducted by 3rd party Copy must be provided to the safety department
- 8. General Operating Rules Only trained, designated operators are permitted to operate cranes A crane must not be loaded beyond its rated capacity Follow all safe operating procedures
- 9. General Operating Rules Lifts greater than 20,000 lbs requires lift plan Lifts of man baskets requires lift plan
- 10. Attaching the Load Hoist chain/rope free of kinks or twists Do not wrap hoist chain/rope around the load Attach the load to the load block hook with slings or other approved devices
- 11. Hooks Safety latch or clip Load in center of hook’s curve Picking up load with the hook’s tip causes it to open up and weaken Replace hooks that are bent open or
- 12. Moving the Load Be sure the hook and hoist are directly over the load Ensure that chains/ropes/slings are not twisted Ensure that the load is well secured and balanced When traveling, keep the load close to the floor
- 13. Hoisting Safety Avoid sudden acceleration or deceleration Watch for obstructions Never leave controls with load suspended Do not use cranes for side pulls Never lower the load below the point where less than five full wraps of rope remain on the hoisting drum
- 14. Hoisting and People Never carry loads over people Do not hoist, lower, or travel a load when an employee is on the load or hook When two or more cranes are lifting a load, put one qualified person in charge
- 15. Hand Signals Hoist up Hoist down Stop Travel
- 16. Sling Types Eye to eye versus endless Steel chains Wire rope or steel cable Metal mesh Fiber rope (natural or synthetic) Synthetic mesh
- 17. Operator Sling Inspections Each day before use by a trained operator Check slings and attachments for damage Immediately remove damaged and defective slings from service
- 18. Thorough Sling Inspections At least weekly, recorded in a log Chains Wire rope Metal mesh Fiber rope Synthetic web
- 19. Sling Rules Never load beyond rated capacity Label properly Never shorten with knots, bolts, or any other device Protect from sharp edges Attach securely to the load
- 20. Sling Rules (Cont.) Protect hands and fingers Use care when pulling a sling Never drag a sling Do not use a damaged or defective sling
- 21. Sling Storage Hang slings on a wall. Never leave on the ground. Never expose to water, welding sparks, chemicals, etc.
- 22. Sling Hitches Vertical Choker Basket
- 23. Sling Angles Ratings based on a vertical hang Slings hung >= 5° angle from vertical Slings used at angles should be checked for capacity
- 24. Assume 1,000 lb. Load lifted with 2 slings Slings vertical: 500 lb. Each Slings 45° from vertical: 707 lb. Each Slings 60° from vertical: 1,000 lb. Each Angle Examples 1,000 lb. 1,000 lb.
- 25. Summary Only trained and authorized operators allowed to use a crane Inspect both crane and slings before use Properly secure the load and try to keep slings vertical Keep all people away from a load while it is being hoisted or moved
Editor's Notes
- In this training session we will discuss the basics of crane and sling use. We will focus on the specific hazards and safe work procedures that are associated with the cranes at our facility. This session will focus on: Safe crane operating procedures Inspections of cranes and slings The appropriate use of slings
- Cranes are part of almost everyone’s life. They can be found everywhere from huge tower cranes used in construction, cranes found at shipyards, and gantry cranes found in facilities working with heavy metals. Small cranes, derricks, and jibs can even be found in garages at home or on the back of work trucks or vans to load/unload heavy materials. Cranes, when used correctly, play an important role in material handling and in preventing us from having to use our backs to move or lift loads. However, a crane can also cause serious damage to facilities and people if they are not respected and used with caution.
- There are many hazards associated with operating a crane. Unfortunately, any accident associated with crane use will probably result in serious damage to equipment, facilities, or personnel. Crane, sling, or hook could fail if loaded beyond its rated capacity. If equipment is not inspected on a regular basis, it could fail even when not loaded to capacity, because it was worn out or damaged. If a load is not properly attached to the slings and the crane, it could flip around, turn side to side, or even release suddenly. This obviously could result in the load falling or striking a nearby object or person. If the crane operator is not paying attention or does not know how to safely operate the load, people or objects could be struck by the load.
- The rated capacity is the amount of weight that the crane can safely handle. This has been certified by an engineer or the manufacturer of the crane. The rating must be clearly marked on each side of the crane. If there is more than one hoisting unit on a crane, then each hoisting unit must be marked with its rated load. All the marking must be clearly legible from the ground or the operator’s station.
- These items must be checked each day by the operator. These same items must also be inspected thoroughly on a monthly basis. The monthly check must be recorded on the inspection log. Hoist, load block, sheave, crane runway, emergency stop, etc., to ensure that everything is properly aligned and in good working order. Inspect air or hydraulic systems for signs of wear or leakage. Inspect the hoist chains or wire rope for signs of wear, twisting, distortion, fraying, broken wires, corrosion, cuts, etc. Check for cracked, deformed, or corroded parts including sheaves, drums, pins, bearings, shafts, gears, rollers, etc. Loose bolts or rivets. Wearing on the brake system, chain drive sprocket, or electrical systems.
- II.Speaker’s Notes: Only trained and designated operators are permitted to operate cranes. Never load a crane beyond its rated capacity. Of course, follow all safe operating and safe work practices.
- II.Speaker’s Notes: Only trained and designated operators are permitted to operate cranes. Never load a crane beyond its rated capacity. Of course, follow all safe operating and safe work practices.
- Prior to attaching the load to the load block hook, make sure the hoist chain or rope is not twisted or kinked. Never use the hoist chain or rope as a sling by wrapping it around the load. This can damage, cut, or kink the hoist chain/rope. Do not attempt to lift the load by the block hook. Attach the load to the block hook with appropriate slings or other approved devices.
- Hooks must have a safety latch or clip. This prevents the hooks from twisting out of the ring or other device they are attached to. If a hook does not have a safety clip, or it is broken, do not use it. Replace the hook or have the safety clip repaired. Hooks are designed to carry the load in the center, which is the thickest part. Never pick up a load with the hook’s tip. Not only is this an unsafe way to attach a load (because it could easily slip and the safety clip cannot be utilized in this case), the hook tip will open up and weaken. Hooks opened more than 15 percent of the normal throat opening measured at the narrowest point or twisted more than 10 degrees from the plane of the unbent hook must be removed from service.
- Before lifting the load, make sure the hook and hoist are directly over the load. If they are not, the load will move, or swing, potentially causing an injury to someone or damaging facilities or equipment. Make sure that the hoist chain/rope and the slings are not twisted around each other. This could cause the load to twist, rotate, or flip once it is lifted. Before moving the load, lift the load a few inches to make sure it is well secured and balanced. Keep the load as close to the floor as possible when traveling. If anything should happen, the load does not have far to go before reaching the sanctity of the ground.
- Sudden acceleration or deceleration can cause a load to swing and put extra stress, or load, on the crane and slings. For obvious reasons, the load should never strike any obstructions. Never leave the controls of a suspended load. Untrained operators might accidentally walk under the load, or the load may begin to fail. Overhead cranes are not typically designed for side pulls. In addition to the extra strain and load that a side pull will put on a crane, the load will eventually swing uncontrollably when it is lifted off the ground. Never lower the load below the point where less than two full wraps of the hoist rope remain on the hoisting drum. Also, never place the hoisting hook on the ground. The weight of the hook keeps the hoist rope in alignment and free of kinks or twists. When the hoist hook is allowed to rest on the ground, the hoist rope can easily go out of alignment or become kinked or twisted.
- Never carry loads over people or allow people to walk under a load. You never know when the crane or a sling might fail. Never hoist, lower, or travel a load when someone is on the load or hook. Obviously this is dangerous, because the employee could easily fall off the load. When two or more cranes are used to lift a load, one qualified person must be in charge in order to analyze the lift, and coordinate the rigging, positioning, and movement of the load.
- Hoist up: Point your index finger up and rotate or spin your wrist. Hoist down: Point your index finger down and rotate or spin your wrist. Stop: Close fist. Travel: Extend your arm with fingers up and motion in the direction of travel you want the control operator to move the load.
- The two primary designs of slings are eye to eye, which is a single line with eyes or other attachments at each end, and endless, which is a continuous loop of line. Slings are made out of various materials to allow for different strengths, heat exposure, chemical exposure, etc. Steel chain slings are fairly common in the workplace and work well for vertical hitches. They can also be damaged by sudden shock loads. Wire rope or steel cable slings are also common and work well for vertical hitches. Metal mesh is basically a strap made out of chain mail. In addition to vertical hitches, it will work well in choker and basket hitches. Fiber rope does not have the strength of steel or chain and can also stretch, so its use is limited to lighter loads. It is also used for temporary and marine work. Synthetic or fiber mesh is also very common in the workplace, and in addition to working well in vertical hitches, it also works well in choker and basket hitches.
- Slings must be inspected each day before they are used by a trained and authorized crane operator. Damage to slings and their attachments might include cracks, deformities (e.g., elongation), twists, corrosion, abrasions and cuts, broken strands or bird nests, loose stitching. Remove damaged slings from service immediately. Tag them as out of service. Have them repaired by the manufacturer or discard them.
- A thorough sling inspection must be conducted and documented each year. This inspection goes much further than the operator’s quick visual inspection. The inspector is actually looking at each link in a chain, every inch of a wire rope, every stitch in a web for any signs of deformity or damage. Chains are checked for link wear, defective welds, deformation, cracks, and increased length. Wire rope is checked for broken strands, kinks, crushing, wear, cuts, bird caging, cracks, and corrosion. Metal mesh is checked for broken welds, wire damage, corrosion, and distortion. Fiber rope is checked for wear, broken fibers, rotting, and distortion. Synthetic web is checked for heat or chemical burns, snags, punctures, tears, broken stitches.
- Never load a sling beyond its rated capacity. All slings should be labeled with their rated capacity. Never shorten a sling by tying a knot, inserting a bolt, etc. This puts extra stress on the knotted area or the links that contain the bolt. Protect slings from sharp edges on the load or nearby objects. Make sure the sling is securely attached to the load. Do the hooks have their safety clips?
- Unless you want a squished, pinched, or otherwise damaged hand, never place it between the sling and the load while the slings are being tightened or the load is started to be lifted. Pull a sling out from under a resting load can stretch, tear, or otherwise damage a sling. Dragging slings can also cause damage. Remember, maintaining slings properly also helps protect your life. Never use damaged or defective slings.
- Storing slings properly will help protect them from damage. Do not leave slings on the ground where they can be run over by forklifts or carts, or have loads set on them that might crush or otherwise damage them. Do not allow slings to be exposed to water, welding sparks, chemicals, or other materials that could damage them.
- Vertical hitch is a method of supporting the load by a single, vertical part or leg of the sling. One end is hooked to the load, and the other end is attached to the hoist hook. A choker hitch is a sling configuration with one end of the sling passing under the load and through the attachment, handle, or eye on the other end of the sling. One end of the sling wraps around and “chokes” the load, and the other end is attached to the hoist hook. Basket hitch is when the sling passes under the load and has both ends, attachments, handles, or eyes on the hoist hook or a single master link. The sling in essence cradles the load. It is important that loads lifted in a basket hitch are properly balanced to prevent the load from slipping. Loads might be lifted with a number of slings using one or more of these different kinds of hitches.
- Slings are designed and rated to hang vertically. If a sling is hung at an angle of 5 degrees or more from the vertical position, it will also be subjected to horizontal loads in addition to the current vertical loads. When using slings at angles, consult the sling manufacturer’s information about the sling’s capacity at certain angles.
- To demonstrate how sling angles impact the load a sling is subjected to, let’s assume we want to lift a l,000 lb. load with 2 slings. Obviously, with vertical slings, each sling will support 500 lb. If the slings are 45 degrees from vertical, each sling will support a total of 707 lb. Five hundred vertical lb. from the load and 207 lb. of horizontal load stress put on the slings because of the angle. Slings at 60 degrees are subjected to 500 lb. of vertical load and another 500 lb. of horizontal load for a total load stress of 1,000 lb. Finally, slings at an angle greater than 60 degrees from the angle will each be subjected to more of a load than the actual weight of the load being lifted. Seventy-five degrees from vertical causes a horizontal load of 1,430 lb. for a total of 1,930 lb. Now, can you see why it is important to keep the slings as close to vertical as possible? If your sling is too short and creates too much of an angle, get a longer sling.