terminals must be proof-tested before placing the slingin initial service.The COMSECOND/COMTHIRDNCBINST11200.11 has rated capacity charts enclosed fornumerous wire rope classifications. You must knowthe diameter, rope construction, type core, grade, andsplice on the wire rope sling before referring to thecharts. The charts provide you the vertical-ratedcapacity for the sling. The test weight for single-legbridle slings and endless slings is the vertical-ratedcapacity (V. R. C.) multiplied by two or (V.R.C. x 2 =sling test weight).The test load for multi-legged bridle slings mustbe applied to the individual legs and must be two timesthe vertical-rated capacity of a single-leg sling of thesame size, grade, and wire rope construction. Whenslings and rigging are broken out of the TOA for fielduse, they must be proof-tested and tagged&fore beingreturned to CTR for storage.Check fiber line slings for signs of deteriorationcaused by exposure to the weather. Ensure none ofthe fibers have been broken or cut by sharp-edgedobjects.SLING SAFE WORKING LOADSThere are formulas for estimating the loads inmost sling configurations. These formulas are basedon the safe working load of the single-vertical hitch ofa particular sling. The efficiencies of the end fittingsused also have to be considered when determining thecapacity of the combination.The formula used to compute the safe workingload (SWL) for a BRIDLE HITCH with two, three,or four legs (fig. 6-17) is SWL (of single-verticalhitch) times H (Height) divided by L (Length)times 2 = SWL. When the sling legs are not of equallength, use the smallest H/L measurement. Thisformula is for a two-leg bridle hitch, but it is stronglyrecommended it also be used for the three- andfour-leg hitches.NOTE: Do NOT forget it is wrong to assume thata three- or four-leg hitch can safely lift a load equal tothe safe load on one leg multiplied by the number oflegs.Other formulas are as follows:Single-basket hitch (fig. 6-18):For vertical legs:SWL = SWL (of single-vertical hitch) x 2.For inclined legs:SWL = SWL (of single-vertical hitch) x H dividedby L x 4.Double-basket hitch (fig. 6-19):For vertical legs:SWL = SWL (of single-vertical hitch) x 4.For inclined legs:SWL = SWL (of single-vertical hitch) x H dividedby L x 4.Single-choker hitch (fig. 6-20):For sling angles of 45 degrees or more:SWL = SWL (of single-vertical hitch) x 3/4 (or.75).Sling angles of less than 45 degrees are notrecommended; however, if they are used, the formulais as follows:SWL = SWL (of single-vertical hitch) x A/B.Double-choker hitch (fig. 6-21):For sling angle of 45 degrees or more:SWL = SWL (of single-vertical hitch) x 3 dividedby 4 x H divided by L x 2.Sling angles of less than 45 degrees:SWL = SWL (of single-vertical hitch) x A dividedby B x H divided by L x 2.When lifting heavy loads, you should ensure thatthe bottom of the sling legs is fastened to the load toprevent damage to the load. Many pieces of equipmenthave eyes fastened to them during the process ofmanufacture to aid in lifting. With some loads, though,fastening a hook to the eye on one end of each slingleg suffices to secure the sling to the load.Use a protective pad when a fiber line or wire ropesling is exposed to sharp edges at the comers of a load.Pieces of wood or old rubber tires are fine for padding.SLING ANGLEWhen using slings, remember that the greater theangle from vertical, the greater the stress on the slinglegs. This factor is shown in figure 6-22.6-9

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