(3) Wire Rope Sling by CERTEX

7/21/2019 (3) Wire Rope Sling by CERTEX

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WIRE ROPE SLINGS

GENERAL INFORMATION

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Figure 1.

NOMINAL SLING STRENGTHis based upon the nomi-nal (catalog) rope strength of the wire rope used in thesling and other factors which affect the overall strengthof the sling. These other factors include splicing efficien-cy, number of parts of rope in the sling, type of hitch(e.g., straight pull, choker hitch, basket hitch, etc.), diame-ter around which the body of the sling is bent (D/d) andthe diameter of pin used in the eye of the sling (Figure 1).

Figure 2.

SLING ANGLEis the angle measured between a horizon-tal line and the sling leg or body. This angle is veryimportant and can have a dramatic effect on the ratedcapacity of the sling. As illustrated (Figure 2), when thisangle decreases, the load on each leg increases. Thisprinciple applies whether one sling is used to pull at anangle, in a basket hitch or for multi-legged bridle slings.

Sling angles of less than 30 degrees are not recommend-ed.

Figure 3.Choker hitch rated capacity adjustment. For wirerope slings in choker hitch when angle is less than 135.

CHOKER HITCHconfigurations affect the rated capacityof a sling. This is because the sling leg or body is passedaround the load, through one end attachment or eye andis suspended by the other end attachment or eye. Thecontact of the sling body with the end attachment or eyecauses a loss of sling strength at this point. If a load ishanging free, the normal choke angle is approximately 135degrees. When the angle is less than 135 degrees anadjustment in the sling rated capacity must be made(Figure 3).

Figure 4.

As can be seen, the decrease in rated capacity is dramatic.Choker hitches at angles greater than 135 degrees are notrecommended since they are unstable. Extreme careshould be taken to determine the angle of choke as accu-rately as possible.

NOMINAL SPLICE EFFICIENCYis the efficiency of thesling splice. Any time wire rope is disturbed such as insplicing an eye, the strength of the rope is reduced. Thisreduction must be taken into account when determiningthe nominal sling strength and in calculating the ratedcapacity. Each type of splice has a different efficiency,

thus the difference in rated capacities for different typesof slings. Nominal splice efficiencies have been estab-lished after many hundreds of tests over years of testing.

D/d ratio is the ratio of the diameter around which thesling is bent divided by the body diameter of the sling(Figure 4). This ratio has an effect on the rated capacityof the sling only when the sling is used in a basket hitch.Tests have shown that whenever wire rope is bentaround a diameter, the strength of the rope is decreased.Figure 5 illustrates the percentage of decrease to beexpected. This D/d ratio is applied to wire rope slings toassure that the strength in the body of the sling is at leastequal to the splice efficiency. When D/d ratios smallerthan those listed in the rated capacity tables are neces-sary, the rated capacity of the sling must be decreased.

RATED CAPACITYis the maximum static load a sling isdesigned to lift. The tables give rated capacities in tons

of 2000 pounds. Rated capacities contained in all thetables were calculated by computer. Each value was cal-culated starting wth the nominal component ropestrength and working up from there. Due to computerrounding of numeric values, rated capacity values for 2, 3or 4 leg slings may not be even multiples of single leg val-ues and may differ by a small amount. This representsthe state-of-the-art technology and tables found in otherpublications which differ by this small amount shouldnot be construed to be in error. The difference is gener-ally no more than one unit for any sling diameter.


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Figure 5.When a wire rope is bent around any sheave or other circularobject there is a loss of strength due to this bending action. Asthe D/d ratio becomes smaller this loss of strength becomesgreater and the rope becomes less efficient. This curve, derivedfrom actual test data, relates the efficiency of a rope to differ-ent D/d ratios.This curve is based on static loads only andapplies to 6x19 and 6x37 class ropes.

Figure 6.

Figure 7. For bridle slings with legs of unequal length,use thesmallest horizontal angle for rated capacity calculations.

PROOF LOADis a specific load applied to a sling orassembly in a non-destructive test to verify the workman-ship of the sling. All swaged socket or poured socketassemblies should be proof loaded. The proof load isgenerally two (2) times the vertical rated capacity formechanical splice slings. The maximum proof load forhand tucked slings is 1.25 times the vertical rated capaci-ty. Care should be taken to assure that sling eyes are not

damaged during the proof load.EYE DIMENSIONSare generally eight (8) sling bodydiameters wide by sixteen (16) body diameters long.

Whenever possible thimbles are recommended to protectthe rope in the sling eye. Eye dimensions for thimbles arecontained in table 2. Table 2 contains only dimensionsfor thimbles used in standard single part slings. Other spe-cialized thimbles are available. Consult your sling manu-facturer for details.PIN DIAMETERshould not be any greater than the nat-ural width of the sling eye. For any sized eye and type ofsling body, the maximum allowable pin diameter may becalculated as follows:Maximum pin diameter = (2L + W) x 0.2

WhereL = length of eye

W = width of eyeThe minimum pin diameter should never be smaller thanthe nominal sling diameter.GRADE & CONSTRUCTION of wire rope for slings isgenerally accepted to be bright Improved Plow Steel orExtra Improved Plow Steel grade 6x19 or 6x37 classifica-tion regular lay. IWRC rope has a higher rated capacitythan Fiber Core rope for mechanically spliced slings, butthe same rated capacity for hand tucked slings. This isbecause when making a hand tucked splice, the core(IWRC) of the rope is cut in the splice area and doesntadd to the overall strength of the sling. Rated capacitiesof slings using galvanized rope depend on the method ofgalvanizing. The sling manufacturer should be consultedregarding rated capacities for these types of slings.

MINIMUM SLING BODY LENGTHis the minimumlength of wire rope between splices, sleeves or fittings.Generally the minimum body length is equal to ten (10)times the sling body diameter. This allows approximatelyone and one half (1 1/2) rope lays between splices. Formulti-part slings the minimum body length betweensplices is equal to forty (40) times the component ropediameter.

LENGTH TOLERANCEis generally plus or minus two (2)body diameters, or plus or minus 0.5% of the sling length,

whichever is greater. The legs of bridle slings, or matchedslings are normally held to within one (1) body diameter.Tolerances on poured or swaged socket assemblies aregenerally much closer. Tolerances should always be speci-fied to the sling manufacturer before the order is placed.This eliminates a lot of frustration and confusion later.

WIRE ROPE SLINGS

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HAND TUCKED SPLICE

A HAND TUCKED splice is made by passing the wire ropearound a thimble or forming an eye and splicing the deadend (short end) into the live end (long end) of the rope.Normally, each dead end strand is given one forming tuckand three full tucks around the same strand in the bodyof the rope. One additional full tuck is made when splic-ing more pliable wire ropes such as 6x37 classification.

A forming tuck is made by prying two adjacent strandsapart, inserting a dead end strand into the opening andpassing the strand under one, two, or three adjacentstrands in the body of the rope. The dead end strand isset or locked tightly.

A full tuck is made by inserting a dead end strand underand rotating it one full 360 degrees turn around a strandin the body of the wire rope. The tucked strand is set orlocked tightly. Each subsequent full turn of the dead endstrand around the live end strand constitutes an addition-al full tuck.Setting or locking of a dead end strand is accom-plished by pulling the strand end in under considerableforce. A marlin spike is inserted in the same opening inthe body of the rope ahead of the tucked strand and is

rotated about the axis of the rope back to the start of thesplice or toward the previous tuck. This helps set thetuck.

Certain end usages may indicate the desirability of specialsplices such as the Navy Admiralty Splice or loggingsplice. Splices made by these special methods may alsoattain the efficiencies used in calculating the rated capaci-ty tables where the rope quality and number of tucks areequivalent to that outlined above. Development of suchefficiencies should be confirmed by the sling fabricators

making such splices.Serving or wrapping of wire rope sling splices does notaffect the spicing efficiencies nor rated capacities. Suchservings are optional, although unserved splices are pre-ferred because they permit visual inspection of thespliced area.NOMINAL SPLICE EFFICIENCIESare measured interms of efficiency (where efficiency = actual breakingstrength of spliced termination divided by actual break-ing strength of rope). This efficiency will change fromsplice to splice because of the many variable factorsinvolved in producing the splice. Splice efficiencies givenin table 3 were established so that these normal varia-tions are accommodated. The design factor used inestablishing the rated capacities further assures that thesling will lift the load even in those rare instances whenthe splice efficiency falls slightly below the values givenin the tables. Rated capacities shown in this manual havemet with the most exacting test, that of the test of timeand use in over fifty years of actual field experience.

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GENERAL PRECAUTIONSfor hand tucked slings areabout the same as for any other type of sling. The use ofa swivel on single leg lifts as well as free hanging loads

which may rotate is not recommended. A tag line shouldalways be used to prevent rotation of the sling body.

When the sling body of a hand tucked splice is allowedto rotate, the splice could unlay and pull out, thus causing

the load to drop.

Flemish eye splice.

MECHANICAL SPLICE

MECHANICAL SPLICE slings come in two basic types.One being the Returned Loop and the other the Flemish

Eye or farmers splice. In either case, the splice is complet-ed by pressing (swaging) one or more metal sleeves overthe rope juncture.

The returned loop is fabricated by forming a loop at theend of the rope, sliding one or more metal sleeves overthe short end of the loop eye and pressing these sleevesto secure the end of the rope to the sling body. Thismakes an economical sling and in most cases one that

will give satisfactory service. A drawback to this type ofsling is that the lifting capacity of the sling depends 100%upon the integrity of the pressed or swaged joint. Shouldthe metal sleeve(s) fail, the entire eye will also fail.

The flemish eye splice is fabricated by opening or unlay-ing the rope body into two parts, one having threestrands and the other having the remaining three strandsand the core. The rope is unlayed far enough back toallow the loop or eye to be formed by looping one partin one direction and the other part in the other directionand laying the rope back together. The strands are rolledback around the rope body. A metal sleeve is thenslipped over the ends of the splice and pressed (swaged)to secure the ends to the body of the sling. Nominalsplice efficiencies expressed in table 4 and in the ratedcapacity tables are based on this splicing method. Spliceefficiencies for other splicing methods should be con-firmed by the sling manufacturer.

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Notice that the splice efficiency factor plays no role inthe calculation of the Choker Hitch rated capacity. Thisis because as the rope passes through the eye of the slingin a choke, the weakest part of the sling is in the body ofthe sling at the choke point. Thus the splice being high-er in efficiency, has no effect on the rated capacity,because the efficiency factors are not additive.

Rated capacities for single part, choker and basket hitch-es are calculated exactly the same as for hand tuckedslings except for the nominal splice efficiencies. Therated capacities adjustment table 1 for choker hitchesalso applies for mechanical splice slings. Minimum D/dratio for basket hitches is 25. This larger D/d ratio isrequired because the Nominal Splice Efficiency is higher.GENERAL PRECAUTIONSare no different from otherslings except care should be taken not to deform or dam-age the sleeve.Stainless Steel slings which have sleeves made of a differ-ent grade or type metal than the rope body may experi-ence accelerated deterioration due to an electro chemicalreaction between the two metals.This is particularly evi-dent in salt water or brackish conditions.

ZINC OR RESIN POURED SOCKET

TYPE TERMINATIONS

While some people may debate whether zinc or resinpoured sockets are truly slings, they are generally includ-ed in the sling category. This type of termination has tra-ditionally been the method for determining the ropesactual breaking strength.All other types of end termina-tions have been compared to poured sockets. Their effi-ciency is therefore established to be 100% for all gradesand constructions of rope.Choker hitches are not used as much with poured sock-ets as with the other more general types of slings. Whensuch slings are used in a choker hitch, the rated capacityadjustment table 1 applies.Rope assemblies with poured attachments are generallyused as a straight tension member where the rope bodydoes not contact the load and is otherwise kept free from

distortion or physical abuse. In such cases the minimumrecommended design factor is 3.0. If the assembly is usedas a sling then a design factor of 5.0 should be used tocalculate the rated capacity. Rated capacities for theseslings used in basket hitches are the same as mechanicalspliced slings and use the same D/d ratio factors.Length tolerances for poured attachments can be some-

what more stringent than other types of slings. The man-ufacturer should be contacted and agreement reachedbefore the order is placed. Tolerance as small as plus orminus 1/8is not out of the ordinary for this type ofassembly. Specifications such as type of fitting, pin orien-tation, whether zinc or resin is to be used and type ofapplication should also be supplied to the manufacturer

when ordering these types of assemblies. Those inexpe-rienced in the socketing process should not try to fabri-cate assemblies without first getting expert training. It is

far better to leave fabrication of this type of assembly tothe experts. The following socketing methods are gener-al in nature and have withstood the test of time. Slight

variations to these methods will produce equal results.

The two procedures, while achieving the same endresult, differ significantly. It is highly recommended thatall poured sockets whether they be zinc or resin, beproofloaded.

CABLE-LAID WIRE ROPE SLINGS

Cable-Laid Slings are fabricated from a machine made

rope comprised of seven small wire ropes. The cable-laidbody is typically 7x7x7, 7x7x19, or 7x6x19 ClassificationIWRC. This construction makes for a pliable rope andsling. These slings are used where flexibility and resis-tance to kinking and setting are more important thanresistance to abrasion. Since the rope is made up of manysmaller wire ropes, the slings can bend around smallerdiameters without taking a permanent set or a kink. Themany small wires are susceptible to abrasion.The rated capacity adjustment Table 1 for choker hitchesapplies to cable-laid slings as well. Note the difference inthe efficiency factor for calculating vertical choker hitchrated capacities.Rated capacity for a basket hitch is based on a D/d ratio of10, where d is the diameter of the cable-laid fabric.Tolerances and minimum sling lengths are also figuredusing the cable-laid fabric diameter.

BRAIDED MULTI-PART SLINGS

Multi-part braided slings or Multi-Parts as they are known,are generally hand fabricated slings which are braidedfrom 2,3, 4 and up to as many as 48 pieces or parts of rope.Generally 4,6, 8 & 9 parts are the more common.They canbe either flat or round and offer the ultimate in flexibilityand versatility. These are truly the heavy weights of thelifting industry. This book covers only the round typeslings. They snug up tightly to the load in a choker hitchand resist kinking and setting. Loads in excess of 4000 tonshave been lifted with multi-part slings.Nominal Splice Efficiency for multi-part slings is 0.70 forcomponent ropes 3/32through 2 diameters. For largercomponent rope slings, consult the sling manufacturerfor splice efficiencies.Because of the multi-rope component construction, multi-part slings react differently than standard wire rope slingsin a choker hitch therefore the nominal splice efficiencyis present in the equation. The adjustment Table 1applies to multi-part slings also.Rated Capacity for a basket hitch is based on a minimumD/d ratio of 25, whered = component rope diameter.Length tolerances for component ropes of 3/8 diameterand smaller are plus or minus 10 component rope diame-ters, or plus or minus 1.5% of the sling length whicheveris greater. The legs of matched slings shall be within 5component rope diameters of each other. For componentrope diameters 7/16 and larger, the tolerance is plus orminus 6 component rope diameters, or plus or minus 1%of the sling length whichever is the greater. Legs ofmatched slings shall be within 3 component rope diame-ters of each other.

Minimum Sling Length between loops, sockets or sleevesis recommended to be 40 times the component ropediameter of the braided body.

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GROMMETS

Grommets are a unique type of sling. They form a com-plete circle and automatically double the number of lift-ing legs. Several types are available, such as strand laidhand tucked, strand laid mechanical, cable laid handtucked and cable laid mechanical. Grommets work wellin basket and choker hitches and general applications

will find them used in this manner. Another uniqueadvantage to grommets is that the load contact pointsmay be rotated or moved around the sling to even outthe wear points. The only area that should not come intocontact with the load is the splice area. The sling manu-facturer will usually mark the area of hand tucked grom-mets with paint to help the user more easily identify thesplice area.Tolerances for grommets are generally plus or minus 1%of the circumferential length or 6 body diameters

whichever is greater.A minimum circumference of 96 body diameters is rec-ommended. This measurement is normally an inside cir-cumferential measurement. The requirement for a mini-mum circumference of 96 times the body diameter forgrommets and endless slings was based on the require-

ment to have at least three free rope lays on either side ofthe tuck of a hand spliced endless grommet prior tobeing bent around a hook or pin five times the bodydiameter. To eliminate the possibility of confusion, thisrequirement was adopted for mechanically spliced end-less grommets as well. Consult the sling manufacturer forsmaller circumferences.

The same general precautions apply to grommets asapply to all other types of slings. However, it should benoted that since a grommet is a continuous circle, theD/d ratio becomes a very important consideration. TheD/d ratio must be applied to the lifting pins as well as tothe load. Normally the lifting pins will be the smallestdiameter in the system other than the diameter of thegrommet. No loads should be handled on D/d smallerthan 5 times the sling body diameter. If they must, consultthe sling manufacturer. Rated capacities covered in thissection are based on a D/d ratio of 5.

STRAND LAID HAND TUCKED GROMMET

A Strand Laid Hand Tucked Grommet is made from onecontinuous length of strand. No sleeves are used to makethe joint. This results in a very smooth circular sling.

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Because of the sling body construction, grommet slingsreact differently than standard wire rope slings in a chok-er type hitch therefore the presence of the nominalsplice efficiency factor in the equation. Rated capacityadjustment Table 1 applies.

STRAND LAID MECHANICAL SPLICE GROMMET

Strand Laid Mechanical Splice grommets are made fromone continuous length of wire rope joined by pressing orswaging one or more sleeves over the rope juncture.Thistype of grommet is not as smooth as the hand tucked, butoffers economy and ease of manufacture. An advantage isthat the swaged sleeves give clear indication of the splicearea.

CABLE LAID HAND TUCKED GROMMET

Cable Laid Hand Tucked Grommets are fabricated in thesame manner as strand laid hand tucked grommetsexcept one continuous length of wire rope is used. Thismakes for a flexible smooth sling. The body diametersare somewhat odd sized because the grommet body isbuilt up from a standard diameter component rope.

CABLE LAID MECHANICAL SPLICE

(See Rated Capacity Tables Section)

Cable Laid Mechanical Splice Grommets are fabricatedfrom one continuous length of cable laid wire rope fabric

with the ends joined by one or more mechanical sleeves.They are similar to strand laid mechanical splice grom-mets, but offer greater flexibility.

WIRE ROPE SLINGS

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Dependability In Lifting-Everywhere, Every Time.

Youre in a tough lifting situa-tion. Valuable equipment and thelives of your workers are on theline. You have to meet deadlines,observe regulations and staywithin a budget. The slightestoverlooked detail can put employ-

ees and valuable equipment inharms way. Are you sure youhave every detail covered?

When youre taking on theweight of the world, turn to CER-TEX, the lifting experts, for the

experience and resources tomake your most complex liftingchallenge like just another day atthe office.

CERTEX puts its world-widenetwork into the hands of localcompanieswhoknow your needs

and are close at hand to serveyou.

Lifting Products andServices


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Some Useful Guidelines For the Rigger

On the following pages are some useful tips to help therigger do his job more efficiently and safely. Prevailing

work rules and government regulations place full respon-sibility for proper performance upon the rigger, so it ishis duty to be familiar with the condition and capabilityof all tools and equipment used, as well as techniquesemployed. One basic rule always applies: Alwaysknownever guess.

Each lift may be divided into three parts, providing a con-venient plan for proceeding:

1. The Lifting DeviceKnow its capability and limita-tions, and its condition. When was it last inspected? Ifin doubt about capacity, check the placard.

2. The HitchHere is where the rigger can exerciseingenuitybut its also the easiest place to make amistake.

3. The LoadThe weight must be known. But you mustalso protect the load from possible damage by theslingsand protect the slings from damage by theload.

Is the lifting device adequate?

Check the placard on the crane or hoist, and then answerthree questions:

1. Is capacity adequate for this lift?

2. Will it lift high enough?

3. Is horizontal reach adequate?

Check the hook and reeving.

1. Are sheaves properly rigged? If multi-part reeving, willit support the load?

2. Is the hook the right size so sling eye wont be distort-ed when put over the hook?

3. Check for cracks in bowl of the hook, and for evi-dence of point loading or bending to one side of 15%or more.

Type of Hitch Determines Choice of Sling

Before you select a sling for a specific lift, determine themost effective hitch to do the job, protect the load, andprotect the sling. One of three basic hitches will usuallydo the job.

The type of hitch you select may determine the type ofsling body that will best do the job, as well as the lengthof sling that will be needed. Lifting height, overhead clear-ance and hook travel will affect choice of hitch andlength of sling.

Choose a sling body type which will best support theload while providing adequate rated capacity. The properchoice will provide:

1. Lifting capacity needed.

2. Proper D/d Ratio.

3. Handling characteristics needed for rigging.

4. Minimal damage to the sling.

5. Minimal damage to the load.

WIRE ROPE SLINGS

GUIDELINES FOR THE RIGGER

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Protect the sling during the lift with blocking or paddingat sharp corners or where the sling body would be bentseverely.

Use a spreader bar between legs of a sling to preventexcessive side pressure on the load by the sling duringthe lift.

When attaching a sling to eye bolts, always pull on linewith the bolt axis. When hitching to bolts screwed into orattached to a load, a side pull may break the bolts.

Use a shackle in the sling eye during a choke to protectsling body against excessive distortion. Always put shack-le pin through sling eye, rather than against the slingbodysince sliding movement of sling body could rotatepin, causing it to come loose.

A sliding hook choker is superior to a shackle or unpro-tected eye, since it provides a greater bending radius forthe sling body.

Use blocking or padding to protect hollow vessels, loosebundles and fragile items from scuffing and bending.Remember that blocking becomes part of the lift, andmust be added to total weight on the sling.

When lifting crates or wooden boxes with a basket hitch,be sure load can withstand side pressure as tension isapplied to sling. Use spreader bars and corner protectorsto prevent damage to contents.

When lifting a bundled load with a single sling near thecenter of gravity, a choke is more effective than a baskethitch to prevent unbalance and slipping of the load inthe sling.

Some riggers will use a double wrap around the load, for360 gripping of the load, to prevent slippage during thelift.

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You can reduce the angle of a choke with a woodenblock, or blocks, between the hitch and the load Thisalso increases the angle between the two legs to improvesling efficiency.

When rigging two or more straight slings as a bridle,select identical sling constructions of identical length

with identical previous loading experience. Normalstretch must be the same for paired slings to avoid over-loading individual legs and unbalancing the load duringthe lift.

Single-part hand-spliced slings must not be permitted torotate when rigged in a straight, vertical hitch. Rotationcan cause the splice to unlay and pull out, resulting indropping of the load.

Anytime a load is lifted beyond arms reach with a single-part load line or straight eye-and-eye sling, use a tagline toprevent load rotation. If a wire rope is permitted torotate, the strands may unlay and the ropes capacity willbe reduced.

Two basket hitches can be rigged with two slings to pro-vide better balance for long loads. Be sure that slings can-not slide toward one another along the load when the liftis made.

Use an equalizing bar with double basket hitches toreduce tendency of slings to slide together, and to keeploads level. By adjusting the hook point and using a come-along or chain block to support the heavy end, the loadcan be kept level during the lift.

Proper Use of Cribbing

Incorrect

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WARNING

Hand-spliced slings should not be usedin lifts where the sling may rotate and

cause the wire rope to unlay.


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Proper Use of Cribbing

Correct

To turn or reposition a load, either one or two liftingdevices may be employed. Always use a choker hitch ora single-leg direct attachment. Never attempt to turn aload with a basket, since the load will slide in the hitch,against the sling bodyresulting in damage to both thesling and the load, and possibly a dropped load.

One Hook Load Turning

To turn a load with one hook, attach the sling directly tothe load ABOVE the Center of Gravity. The lifting hookmust be able to move, or travel, in the direction of theturn to prevent sliding of the pivot edge of the load justas the load leaves the ground. It may be necessary to liftthe load clear to reposition it after the turn is completed,and irregular shapes sometimes will require blocking forsupport during and after the turn.

Two-hook turning is employed when it is desired to turnthe load freely in the air. Main and auxiliary hoists of acrane can often be used, or two cranes can be used.

To turn from side (A) to (B) in 1 & 2 above, attach onside (B) above the Center of Gravity and on side (D) atthe Center of Gravity, then lift both hoists equally untilload is suspended. Lower auxiliary until turn is complet-ed; detach sling at (B) before lowering load completely.

To turn from side (B) to (C) in 3 & 4 above, lift balancedload at (D) directly above the Center of Gravity; thenattach auxiliary at (B) and lift to desired position. Lowerboth hooks simultaneously until side (C) is in desiredposition.

Turning with double choker gives good control, withweight always applied against a tight sling body and nomovement between sling and load. To rig, place botheyes on top of load, pointing opposite direction of turn.Body of sling is then passed under load, through botheyes and over lifting hook. Blocking should be usedunder load to protect sling and facilitate removal.

Lifting unbalanced loads when exact length slings are notavailable can be accomplished by rigging a choke on theheavy end, as right. Length can be adjusted before weightapplies, but once the load comes onto the sling, the hitchis locked in position for the lift.

Center of Gravity of a rectangular object with homoge-nious characteristics will usually be below the junction oflines drawn diagonally from opposite corners. When arectangular object has weight concentrated at one end,Center of Gravity will be situated toward that endawayfrom the intersection of diagonal lines. To avoid anunbalanced lift, the lifting hook must be rigged directlyabove the Center of Gravity.

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To locate the approximate Center of Gravity of an irregu-larly shaped article, visualize it enclosed by a rectangle.

Where diagonals from opposite corners intersect willusually provide a lift point near the Center of Gravity.

Overturning a heavy object onto cribbing, using one lift-ing hook and chainblock. To upend the object, chain-block A and the sling B should exchange positions.

Doglegs, Sets and Kinks

When a loop is pulled through, it forms a kink whichpermanently deforms a wire rope by freezing or locking

wires and strands. This prevents them from sliding andadjusting, and reduces rope strength.

A dogleg is a set which occurs when a wire rope sling ispulled down snug against a load. A dogleg usually can berolled back or turned inside out, and usefulness of thesling restored, since strands can still adjust.

Eye deformation is ordinarily not deterimental to slingstrength as long as there are no broken wires or grossdistortion of the lay of strands.An eye has two legs, sohas adequate strength for the load the body can carry. Asling should be retired when distortion locks the strandsor flattens the rope in the eye so strands cannot moveand adjust.

Riggers Check List

1. Analyze and MeasureDetermine the total weight tobe moved as well as exactly how far it is to move andhow high it must be lifted.

2. Determine the HitchDecide how the load is to beconnected to the lifting hook and how the sling willgrip, or be attached to, the load.

3. Select the SlingIn addition to adequate Rated

Capacity for the angles and hitch involved, the slingbody should be of the type and style best suited tohandling this specific load. Select a sling with properend attachments or eye protection, as well as attach-ment hardware such as clevises.

4. Inspect the SlingMake a good visual check of thesling you select to determine if it is in good conditionand capable of making the lift. Refer to prevailingOSHA and ANSI regulations for inspection criteria.

5. Rig Up, Not DownAlways attach the sling to theload first, then attach it to the hook.

6. Check EverythingBefore attempting a lift, take alight strain on the rigging, checking to see that block-ing, sling and load protection and all safety devices arein place.

7. Stand Clear and LiftLet the lifting device and rigging

do the jobdont use brute strength to preventswinging or movement. Use a tagline, or tether, to con-trol any movement. Keep all hands and toes out fromunder the load when it is suspended.

8. Dont Jerk!Lift slowly and with a steady applicationof power.

9. Put It Away!After youve completed the job, checkthe sling for any damage (If its damaged, red tag itimmediately or advise the sling inspector.), then returnit to the sling storage rack for safekeeping until nextusage.

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Kink EyeDeformation

Dogleg


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WIRE ROPE SLINGS

USA Standard Crane Hand Signals

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Use Main Hoist.Tap fist onhead;then use regular signals.

Lower.With arm extendeddownward, forefinger pointingdown, move hand in smallhorizontal circles.

Use Whipline (AuxiliaryHoist). Tap elbow with onehand, then use regular signals.

Hoist.With forearm vertical,forefinger pointing up, movehand in small horizontal circle.

Travel. Arm extended for-ward, hand open and slightlyraised, make pushing motionin direction of travel.

Swing. Arm extended, pointwith finger in direction ofswing of boom.

Travel. (One Track). Lock thetrack on side indicated byraised fist.Travel opposite trackin direction indicated by circu-lar motion of other fist, rotated

vertically in front of body. (Forcrawler cranes only).

Travel (Both Tracks). Use bothfists in front of body, making acircular motion about eachother, indicating direction oftravel; forward or backward.(For crawler cranes only.)

Lower Boom. Arm extended,fingers closed, thumb pointingdownward.

Raise Boom. Arm extend-ed, fingers closed,thumbpointing upward.

Extend Boom (TelescopingBoom). One Hand Signal. Onefist in front of chest withthumb tapping chest.

Retract Boom (TelescopingBooms).Both fists in frontof body with thumbspointing toward eachother.

Retract Boom (TelescopingBoom). One Hand Signal. Onefist in front of chest, thumbpointing outward and heel offist tapping chest.

Raise the Boom and Lowerthe Load.With arm extended,thumb pointing up, flex fin-gers in and out as long as loadmovement is desired.

Extend Boom (TelescopingBooms). Both fists in front of body

with thumbs pointing outward.

Lower the Boom and Raisethe Load.With arm extended,thumb pointing down, flexfingers in and out as long asload movement is desired.


14/27

WIRE ROPE SLINGS

Additional Signals for Bridge Cranes

2-14

2

Temperature, Lubrication, Moisture Are Factors InProper Storage

Care of Slings

The amount of care and proper maintenance a sling

receives will go a long way in determining its service life.Following are guidelines which experience has shownhelpful.Storage: Proper storage requires that slings be kept in anarea where they will not be exposed to water, extremeheat, or corrosive fumes, liquids, and sprays, of being runover or kinked.Slings should never be left beneath loads or lying around

where they may be damaged. All slings, when not in use,should be kept on a rack. Use of a rack minimizes acci-dental damage and allows easier monitoring of condition

between regular inspections. A rack will also save timeby allowing larger slings to be picked up and returned bycrane, thereby reducing manhandling.

Effects of Temperature

All wire rope should be protected from extremes of tem-perature.The accepted rules are: Fiber core slings shouldnever be exposed to temperature in excess of 200F.Steel cored slings should never be used at temperaturesabove 400F, or below minus 60F.It is not always easy to detect when wire rope has beendamaged by heat.The most common visual signs are lossof lubrication and discoloration of wires.The best practice to follow is that if there is the slightestsuspicion that a sling was subjected to high tempera-tures, it should be taken out of service immediately. If it isabsolutely necessary to use slings outside of the abovetemperature range, the sling manufacturer should be con-sulted.

Lubrication

Like any other machine, wire rope is thoroughly lubricat-

ed at time of manufacture. Normally, for sling use underordinary conditions, no additional lubrication is required.However, if a sling is stored outside or in an environment

which would cause corrosion, lubrication should beapplied during the service life to prevent rusting or cor-roding.If relubrication is indicated, the same type lubricantapplied during manufacture should be used.Your slingmanufacturer can provide information on the type oflubricant to be used and best method of application.

Dog Everything. Clasphands in front of body.

Move Slowly. Use one hand togive any motion signal andplace other hand motionlessin front of hand giving themotion signal.(Hoist slowlyshown as example.)

Emergency Stop. Armextended, palm down, movehand rapidly right and left.

Stop. Arm extended, palmdown, hold position rigidly.

Bridge Travel. Arm extendedforward, hand open and slightlyraised, make pushing motion indirection of travel.

Trolley Travel. Palm up, fingersclosed, thumb pointing indirection of motion, jerk handhorizontally.

Multiple Trolleys. Hold up onefinger for block marked 1 andtwo fingers for block marked2. Regular signals follow.

Magnet is Disconnected.Crane Operator spreads bothhands apart palms up.


15/27

Basic Inspection Criteria For Wire Rope Slings

The goal of a sling inspection is to evaluate remainingstrength in a sling which has been used previously to deter-mine if it is suitable for continued use.Specific inspection intervals and procedures are requiredby the Occupational Safety and Health Act (OSHA) and by

ANSI B30.9 Regulations, and the responsibility for perfor-mance of inspections is placed squarely upon the sling userby Federal Legislation.

As a starting point, the same work practices which apply toall workingwire ropes apply to wire rope which has beenfabricated into a sling.Therefore, a good working knowl-edge of wire rope design and construction will be not onlyuseful but essential in conducting a wire rope sling inspec-tion.

But because wire rope is a rather complex machine, noprecise rules can be given to determine exactly when awire rope sling should be replaced. There are many vari-ables,and all must be considered.

OSHA specifies that a wire rope sling shall be removedfrom service immediately if ANY of the following condi-tions are present:

1. Broken Wires: For single-part slings, 10 randomly distrib-

uted broken wires in one rope lay, or five broken wires inone strand of one rope lay. For multi-part slings thesesame criteria apply to each of the component ropes. Forthis inspection, a broken wire shall only be counted once;that is, each break should have two ends.

2. Metal Loss:Wear or scraping of one-third the originaldiameter of outside individual wires.This is quite difficultto determine on slings and experience should be gainedby the inspector by taking apart old slings and actuallymeasuring wire diameters.

3. Distortion: Kinking, crushing, birdcaging or other damagewhich distorts the rope structure.The main thing to lookfor is wires or strands that are pushed out of their origi-nal positions in the rope. Slight bends in a rope wherewires or strands are still relatively in their original posi-tions would not be considered serious damage. But goodjudgment is indicated.

4. Heat Damage: Any metallic discoloration or loss of inter-nal lubricant caused by exposure to heat.

5. Bad End Attachments: Cracked, bent or broken end fit-tings caused by abuse, wear or accident.

6. Bent Hooks:No more than 15 percent over the normalthroat openings, measured at the narrowest point,ortwisting of more than 10 degrees is permissable.

7. Metal Corrosion: Severe corrosion of the rope or endattachments which has caused pitting or binding of wiresshould be cause for replacing the sling. Light rusting usu-ally does not affect strength of a sling, however.

In addition to these seven conditions specified by OSHA,the following are also important:8. Pulled Eye Splices: Any evidence that eye splices have

slipped, tucked strands have moved, or pressed sleevesshow serious damage may be sufficient cause to reject a

sling.9. Unbalance: A very common cause of damage is the kinkwhich results from pulling through a loop while using asling, thus causing wires and strands to be deformed andpushed out of their original position.This unbalances thesling, reducing its strength.

Disposition of Retired Slings:the best inspection programavailable is of no value if slings which are worn out and havebeen retired are not disposed of properly.When it is deter-mined by the inspector that a sling is worn out or damagedbeyond use, it should be tagged immediately DO NOT USE.

This sling should then be destroyed as soon as possible bycutting the eye and fittings from the rope with a torch. Thiswill help assure that an employee will not mistakenly use asling which has been retired from service.

It should also be obvious that a good inspection programwill not only provide safer lifting conditions, but will alsoextend the life of slings and thereby reduce lifting costs.

Federal Work Rules Require Specific InspectionIntervals

Government regulations are also specific on WHEN toinspect.

Both ANSI Standard B30.9 and OSHA require that wire ropeslings receive two types of inspections:a DAILY visualinspection, and additional inspections where service condi-tions warrant.

Daily visual inspections are intended to detect serious dam-age or deterioration which would weaken the sling.Thisinspection is usually performed by the person using thesling in a day-to-day job. He should look for obvious things,such as broken wires, kinks, crushing, broken attachments,severe corrosion, etc.Additional inspections should be performed at regularintervals based on, (1) frequency of sling use, (2) severity of

service conditions, (3) nature of lifts, and (4) prior experi-ence based on service life of slings used in similar circum-stances.

It is required that these additional inspections be carriedout by a designated person who must have good knowl-edge of wire rope. An accurate WRITTEN and dated recordof all conditions observed should be kept. Any deteriora-tion of the sling which could result in appreciable loss oforiginal strength should be carefully noted, and determina-tion made on whether further use would constitute a safetyhazard.

How to Inspect

Precisely how to make proper, adequate inspections is notdetailed by OSHAyet it is in the HOW of inspection thatthe big difference between a good inspection and some-thing less become apparent.

Inspection should follow a systematic procedure:(1) First, it is necessary that all parts of the sling arereadily visible.The sling should be laid out soevery part is accessible.

(2) Next, the sling should be sufficiently cleaned of dirtand grease so wires and fittings are easily seen.Thiscan usually be accomplished with a wire brush orrags.

(3) The sling should then be given a thorough, systematicexamination throughout its entire length, paying par-ticular attention to sections showing the most wear.

(4) Special attention should also be paid to fittings and endattachments,and areas of the sling adjacent to these fit-tings.

(5) When the worst section of a sling has been located,this area should then be carefully checked against theOSHA criteria.

(6) Label or identify slings that are inspected.

(7) Keep records of inspections that include dates and cor-responding conditions of slings.

(8) Dispose immediately of slings that are rejected.

A knowledgeable inspector will also insist on proper stor-age for out-of-use slingsto make his job easier if not forthe good of the slings. Inspections are much easierandprobably more thoroughwhen slings are available forinspection in an orderly arrangement, out of the weather,away from heat and dirt.

WIRE ROPE SLINGS

WIRE ROPE SLING INSPECTION & REMOVAL CRITERIA

2-15

2


16/27

Standard End Fitting CombinationsTo order sling legs, follow the criteria listed in pages 2-1 to 2-15. Choose the correct size from the tables onthe following pages. Determine the length needed and specify the end fittings required from the list of combinationsshown below.

WIRE ROPE SLINGS

Sling Leg Options

2-16

2

Eye & Eye

Eye & Thimble

Eye & Hook

Eye & Slip-Thru Thimble

Thimble & Thimble

Eye & Crescent Thimble

Thimble & Slip-Thru Thimble

Thimble & Hook

Eye and Screw Pin Anchor Shackle

Eye and Open Swage Socket

Eye and Closed Swage Socket

Slip-Thru Thimble & Hook

Slip-Thru Thimble &Slip-Thru Thimble

Eye & Thimble withSliding Choker Hook

Eye & Eye withSliding Choker Hook


17/27

WIRE ROPE SLINGS

1-PART SLINGS/MECHANICAL SPLICE

Single Leg Slings

2-17

2

EXTRA IMPROVED PLOW STEEL IWRC

RATED CAPACITY IN TONS

.RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25

.RATED CAPACITIES BASED ON PIN DIAMETER NO LARGER THAN NATURAL EYE WIDTH OR LESS THAN THE NOMINAL SLING DIAMETER

.RATED CAPACITIES BASED ON DESIGN FACTOR OF 5

.HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USED

.Rated Capacities shown apply only to 6x19 and 6x37 classification wire rope.


18/27

WIRE ROPE SLINGS


2-18

2

2-Leg Bridle SlingsEXTRA IMPROVED PLOW STEEL IWRC


RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25RATED CAPACITIES BASED ON PIN DIAMETER NO LARGER THAN NATURAL EYEWIDTH OR LESS THAN THE NOMINAL SLING DIAMETERRATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USEDRated Capacities shown apply only to 6x19 and 6x37 classification wire rope.

Standard Style

LE

NGTH


19/27




WIRE ROPE SLINGS


3-Leg Bridle Slings

2-19

2

Standard Style

LENG

TH


20/27




WIRE ROPE SLINGS

4-Leg Bridle Slings

2 Standard Style

LENGTH


2-20


21/27

WIRE ROPE SLINGS

2-21

2

Stainless Steel Type 302 or 304 IWRCRated Capacity in Tons

Rated Capacities Shown Apply Only tp 6X19 and 6X36 Classification Wire Rope

RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25RATED CAPACITIES BASED ON PIN DIAMETER NO LARGER THAN NATURAL EYE WIDTH OR LESS THAN THE NOMINAL SLING DIAMETERRATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USEDRated Capacities shown apply only to 6 x 19 and 6 x 37 classification wire rope.


Single Leg Slings


22/27

WIRE ROPE SLINGS

2-22

2

CABLE LAID SLINGS/MECHANICAL SPLICE

MECHANICAL TYPE SPLICE

RATED CAPACITIES IN TONS

RATED CAPACITIES BASKET HITCH BASED ON D/d OF 10 OR GREATERRATED CAPACITIES BASED ON PIN DIAMETER NO LARGER THAN NATURAL EYE WIDTH OR LESS THAN THE NOMINAL SLING DIAMETER.

RATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLING ANGLES LESSTHAN 30 DEGREES SHALL NOT BE USED


23/27

WIRE ROPE SLINGS

2-23

2


RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25 TIMES THE COMPONENT ROPE DIAMETERRATED CAPACITY IN TONSRATED CAPACITIES BASED ON PIN DIAMETER NO LARGERTHAN NATURAL EYE WIDTH OR LESS THAN THE NOMINAL SLING DIAMETERRATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USEDRated Capacities shown apply only to 6x19, 7x19, and 6x37 classification wire rope.

Lengthof

Sling(SL)

Lengthof

Sling(SL)

Lengthof

Sling(SL)

4-PART BRAIDED SLINGS


24/27

WIRE ROPE SLINGS

2-24

2



RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25 TIMES THE COMPONENT ROPE DIAMETERRATED CAPACITIES BASED ON PIN DIAMETER NO LARGERTHAN NATURAL EYE WIDTH OR LESS THAN THE NOMINAL SLING DIAMETERRATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USEDRated Capacities shown apply only to 6x19, 7x19, and 6x37 classification wire rope.


Length Length

Length


25/27

WIRE ROPE SLINGS

2-25

2EXTRA IMPROVED PLOW STEEL IWRC


RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25 TIMES THE COMPONENT ROPE DIAMETERRATED CAPACITIES BASED ON PIN DIAMETER NO LARGERTHAN NATURAL EYE WIDTH OR LESS THAN THE NOMINAL SLING DIAMETERRATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USEDRated Capacities shown for 1/8" through 3/8" apply only to 7x19 galvanized wire rope.Rated Capacities shown for 3/8" apply only to 6x19, and 6x37 classification wire rope.



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WIRE ROPE SLINGS

2-26

2

RATED CAPACITIES BASKET HITCH BASED ON D/d RATIO OF 25RATED CAPACITIES BASED ON PIN DIAMETER NO LARGER THAN NATURAL EYE WIDTH ORLESSTHAN THE NOMINAL SLING DIAMETERRATED CAPACITIES BASED ON DESIGN FACTOR OF 5HORIZONTAL SLINGANGLES LESS THAN 30 DEGREES SHALL NOT BE USEDRated Capacities shown apply only to 6x19 and 6x37 classification wire rope.

1-PART SLINGS/POURED SOCKETS

RATED CAPACITIES IN TONS


27/27

WIRE ROPE SLINGS

2 27

2

Length of Pendant is measuredas indicated on sketches.Note:When ordering, customershould specify parallel or rightangle (90) socket pins.

SINGLE ROPE LEGS AND OPENSWAGED SOCKETS

SINGLE ROPE LEGS ANDOPEN/CLOSED SWAGED SOCKETS

SINGLE ROPE LEGS AND CLOSEDSWAGED SOCKETS

BOOM PENDENTS WITH SWAGEDFITTINGS

* Values given apply when pendants are used as slings or sling assemblies.When used in a Boom suspension system, other valuesapply; consult rope manufacturer.

Rated Capacity in Tons of 2,000 lbsRated Capacities Shown Apply Only To 6x19 and 6x36 Classification Wire Rope

O pen- Open O pen- Cl os ed C losed- Cl os ed O pen- Open O pen- Cl os ed C losed- Cl os ed

1-PART SLINGS/SWAGE SOCKETS

Open-Open Open-Closed Closed-Closed

(3) Wire Rope Sling by CERTEX

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