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CRANE SAFETY SLINGS SAFETY RIGGING OPERATIONS

OSHA Office of Training & Education

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OSHA Office of Training & Education

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VERTICAL

CHOKER

OSHA Office of Training & Education

BASKET

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Factor of Safety • A factor of safety is applied to a rigging system after all •

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known loads and strengths have been considered. It is intended to allow for unknown variability of material, deterioration of equipment over time, acceleration and other unforeseeable loads, and the like. The usual factor of safety is 5 (1 : 5)

• The Breaking Strength • Factor of safety = -------------------------------------------• Force to be applied OSHA Office of Training & Education

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SAFE WORKING LOAD MAX. S.W.L. =

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CATALOGUE BREAKING STRENGTH OF ROPE --------------------------------FACTOR OF SAFETY CATALOGUE BREAKING STRENGTH OF ROPE ------------------------5

EXAMPLE: If the wire rope catalogue gives the breaking strength of the rope as 10 tons, the maximum safe working load is’ 10 tons Max. S.W.L. = = 2 tons 5 OSHA Office of Training & Education

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Synthetic Web 7 : 1

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SAFE WORKING LOAD Rule of Thumb of Computing Rope S.W.L. S.W.L. = Rope Diameter x Rope Diameter x 8 EXAMPLE: (a) 1/2 inch diameter rope SWL = 1/2 x 1/2 x 8 = 2 tons (b) 5/8 inch diameter rope SWL = 5/8 x 5/8 x 8 = 3.125 tons (c) I inch diameter rope SWL = 1 x 1 x 8 = 8 tons OSHA Office of Training & Education

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OSHA Office of Training & Education

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OSHA Office of Training & Education

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OSHA Office of Training & Education

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Rigging Equipment Slings Types of slings include alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope, and synthetic web.

Chain

Wire rope

Metal mesh

OSHA Office of Training & Education

Synthetic 12

Sling Inspection Inspect slings:

 Each day before use  Where service conditions warrant Remove them from service if damaged or defective

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Alloy Steel Chains •Adapts to shape of the load •Can damage by sudden shocks •Best choice for hoisting very hot materials •When one link in a chain fails, the load will come down. •Must have an affixed tag stating size, grade, rated capacity, and sling manufacturer

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Identification Tag

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Markings Alloy Steel Chain

It must be marked with grade or manufacturer's mark OSHA Office of Training & Education

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Marking

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OSHA Office of Training & Education

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Inspection of Chain • Must be visually inspected prior to use. • Pay special attention to any stretching •

(any elongation from the original length. The diameter of the worn chain link should be measured at the point of the greatest wear and compare with minimum allowable diameters in tables.

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OSHA Office of Training & Education

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OSHA Office of Training & Education

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Unsuitable Alloy Steel Chain Attachments

Right

Wrong

Job or shop hooks and links, or makeshift fasteners, formed from bolts, rods, etc., or other such attachments, can’t be used OSHA Office of Training & Education

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OSHA Office of Training & Education

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OSHA Office of Training & Education

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OSHA Office of Training & Education

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Wire Rope Slings •Used to hoist materials Core

•Selection considerations:  strength  ability to bend without

cracking  ability to withstand abrasive wear  ability to withstand abuse

Wire

Center

Strand Wire rope

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Elements of Wire Rope

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6 x 25 Wire Rope Each strand contains 25 wires

6 Strands

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Inspections Each day before use, the sling, all fastenings and attachments must be inspected by a competent person Additional inspections performed during use, where conditions warrant Damaged slings must be removed from OSHA Office of Training & Education 34 service

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Wire Rope Slings Remove From Service If these happen, remove the wire rope sling from service

Kinking

Bird Caging

Crushing OSHA Office of Training & Education

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Remove From Service

Immediately remove damaged or defective slings from service OSHA Office of Training & Education

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OSHA Office of Training & Education

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OSHA Office of Training & Education

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At Least 2 wires wraps on the Drum

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Lubrication

Regularly lubricate ropes and chains OSHA Office of Training & Education

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Synthetic Web Sling Markings

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Mark or code to show: Name or trademark of manufacturer Rated capacities for the type of hitch Type of material

OSHA Office of Training & Education

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OSHA Office of Training & Education

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Synthetic Web Slings Fittings •

Fittings must be: At least as strong as that of the sling Free of sharp edges that could damage the webbing

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Synthetic Web Sling Stitching

Stitching

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Stitching is the only method allowed to attach end fittings to webbing, or to form eyes OSHA Office of Training & Education

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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 OSHA Office of Training & Education

Heat Damage 47

Cuts

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Sling Configurations

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