cranes and slings

Cranes and Slings

• Major Causes of Crane Accidents• Contact with power lines• Overturns• Falls• Mechanical failures

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Crane Hazards

• An unstable load, lack of communication, lack of training, and inadequate maintenance or inspection are major contributors to crane accidents.

• Operators or others working in the area can be victims to “struck by" and "caught in" injuries.

• Contact with power lines causes many accidents.

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Crane Hazards

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• Improper loading• Excessive speeds• No 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 walkways• No boom angle indicator• Not using outriggers

Crane Parts

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Rated Capacities• Make sure the crane operator can see the:

– Rated Load Capacities– Operating Speeds– Special Hazard Warning or Instruction

• APPLICABLE OSHA STANDARD– 1926.1501 (a)(2) Rated load capacities, and

recommended operating speeds, special hazard warnings, or instruction, shall be conspicuously posted on all equipment. Instructions or warnings shall be visible to the operator while he is at his control station.

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Competent Person

• The competent person must inspect all machinery and equipment prior to each use, and during use, to make sure it is in safe operating condition.

• If it needs fixing, take it out of service and don’t use it until it is fixed

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Know the Weight of the Load• Refer to shipping ticket or other documentation• Ensure lift calculations are correct• Ensure load is within load chart rating for boom

length and load radius of crane• 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

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Load Limiting Factors

• Not level • Wind• Side loads• On its wheels• Lifting over the side• Use of extensions, jibs and other attachments• Limits of wire rope, slings and lifting devices

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Load Example – 30 ton crane

• Will lift 60,000 pounds at 10 feet from the center pin of the crane

• Based on level surface, no wind, and outriggers fully extended

• At 25 feet from the center pin with an 80 foot boom, the capacity is only 14,950 pounds

• At 74 feet from the center pin, the capacity is only 4,800 pounds

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Wire Rope Slings

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Adapts to shape of the load

Can damage by sudden shocks

Best choice for hoisting very hot materials

Must have an affixed tag stating size, grade, rated capacity, and sling manufacturer

Alloy Steel Chains

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Chain WearWhen a chain shows excessive wear, or is cracked or pitted, remove it from service

Non-alloy repair links can not be used

Wire Rope Slings• Used to hoist materials

• Selection considerations: strength ability to bend without cracking ability to withstand abrasive wear ability to withstand abuse

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Wire rope

Strand

Center

WireCore

Damaged wire rope

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Broken Strands

Damaged wire rope must be taken out of service

Crushed Rope

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Cover or blunt protruding ends of strands

Protruding Ends

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Wire Rope Clips

When using U-bolt wire rope clips to form eyes, ensure the "U" section is in contact with the dead end of the rope

This is the correct method

Dead End

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Wire Rope Slings Remove From Service

If these happen, remove the wire rope sling from service

Crushing

KinkingBird Caging

Synthetic Web SlingMarkings

• Mark or code to show:– Name or trademark of

manufacturer– Rated capacities for the

type of hitch– Type of material

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Synthetic Web SlingStitching

• Stitching is the only method allowed to attach end fittings to webbing, or to form eyes

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Stitching

Synthetic Web Slings -Remove from Service

• Remove from service if any of these are present:– Acid or caustic burns– Melting or charring of any

part – Snags, punctures, tears or

cuts– Broken or worn stitches– Distortion of fittings

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Heat Damage

Sling Tables

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Sling Stress Example

• From the table, a single branch with a 90 degree loading is rated at 3,250 lbs.

• If there is a safety factor of 4, the chain could lift

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