SLINGS, CHAINS, and WIRE ROPE

SLINGS, CHAINS, and WIRE ROPE

Are generally one of six types: Chain Wire Rope Metal mesh Natural fiber rope Synthetic fiber rope Synthetic web

Used to lift heavy or large objects Slings can have 2, 3, or 4 legs.

Improper use of, or the use of damaged or faulty equipment can result in shifting loads that: Are Dropped Are damaged Damage equipment Injure personnel Damaged sling Remnants of Injured

Angles The angle between the sling legs and the horizontal should be maximized. Sling angle Horizontal Load

Angles The rated capacity of the sling decreases as the angle formed by the sling leg and the horizontal line decreases. 60° 1,000 lbs. 30° 1,000 lbs.

Angles In other words: the smaller the angle between the sling leg and the horizontal, the greater the stress on the sling leg. This greater stress means the sling cannot support as much load. However, heavier loads can be safely moved if the weight of the load is distributed among more sling legs.

60° 1,000 lbs. 577 lbs. Angles 90° 1,000 lbs. 500 lbs. 30° 1,000 lbs.

Vertical Hitch This hitch is made directly from the crane hook to the load. One eye is engaged directly to the load (usually attached by means of a hook) while the other eye is engaged to the lifting hook.

Choker Hitch The sling passes entirely around the load with one loop passing through the other to form a slip noose or "choker". The remaining eye is engaged to the lifting hook. Note that the angle of choke can result in a reduction to the rated capacity for that operation.

Basket Hitch This hitch is made by passing the sling under the load and having both eyes going to the crane hook. The sling surrounds the load while each eye is engaged to the hook (or hooks) above. Note that the sling-to-load angle can result in a reduction to the rated capacity for that operation.

Bridle Hitch: Two or more legs coming from one collection point.

3-leg and 4-leg Bridles: If the load is balanced on each leg the rating of the bridle can be used. Sling angles and center of gravity will affect rated capacity of sling. Best to size by considering an unbalance on legs and each not carrying the same amount.

Slings: Page 39 For a sling to have no affect on the capacity rating the diameter of the object the sling wraps around (D) must be at least 15 times the diameter of the sling (d). Diameter of the rope (d) Diameter of the load (D) D/d ratio ≥ 15

For a sling to have no affect on the capacity rating the diameter of the object the sling wraps around (D) must be at least 15 times the diameter of the sling (d).

The smaller the D/d ratio the larger the de-rating of the sling capacity. D/d Ratio The capacity of a wire rope sling can be greatly affected by being bent sharply around pins, hooks, or parts of a load. The wire rope industry uses the term “D/d ratio” to express the severity of bend. “D” is diameter of curvature that the rope or sling is subjected to and “d” is the diameter of the rope. The minimum D/d ratio is usually taken as 20 which correspond to 92 % efficiency. As wire ropes are usually at lease 8 % stronger than the catalogue strength, the bent sling at D/d = 20 is therefore considered 100 % efficient. In case wire rope slings are used for smaller D/d ratio, sling capacity shall be decreased based on wire rope efficiency as per following graph. This curve is based on static loads and applies to 6-strand class 6×19 and 6×37 wire ropes. Based on above graph, if the shackle or object has 2 times the diameter of a wire rope sling (D/d = 2) the basket sling capacity must be reduced by 35 % as shown below. To increase d/d ratio and sling capacity, use wide body shackle. If D/d ratio is 5 after using wide body shackle, sling capacity shall be reduced by about 20 %. Load hooks must have sufficient thickness to ensure proper sling D/d ratio, particularly when using slings in an inverted basket hitch; that is the sling body is placed into the hook and the sling eyes are facing downward.

Sling in Choker Configuration Reduces the lifting capability of a sling since the rope component’s ability to adjust during the lift is affected. Only use a choker hitch when the load will not be seriously damaged by the sling body, or the sling damaged by the load. Use when the lift requires the sling to hug the load.

Sling in Choker Configuration Never choke a load so that any part of one eye or splice is in the part of the sling that passes through the other eye to form the choke. Always pull the choker hitch tight before the lift is made. Never pull down on the choke when the lift is being made. Never use only one choker hitch on a load that can shift or slide out of the choke.

Sling in Choker Configuration – IMPORTANT! The pin of the shackle must be placed through the eye of the sling and the other end of the sling through the shackle to form a loop. Remember the saying “Pin in the eye, it’s ready to fly” RIGHT WRONG

Synthetic Web Slings

Synthetic Web Slings Strength: can handle load of up to 300,000 lbs. Convenience: can conform to any shape. Safety: will adjust to the load contour and hold it with a tight, non-slip grip. Load protection: will not mar, deface, or scratch highly polished or delicate surfaces.

Synthetic Web Slings Long life: are unaffected by mildew, rot, or bacteria; resist some chemical action; and have excellent abrasion resistance. Economy: have low initial cost plus long service life. Shock absorbency: can absorb heavy shocks without damage. Temperature resistance: are unaffected by temperatures up to 180oF.

Synthetic Web Slings Made from: Nylon Polyester Aramid Some use a combination of nylon and polyester Some manufactures have proprietary material

Synthetic Web Sling Damage Surface and Edge Cuts Holes, Snags, and Pulls Abrasions Heat or Chemical Broken/Worn Stitching Knots Illegible or Missing Tags

Synthetic Web Sling Damage Surface and Edge Cuts Broken fibers of equal length indicate the sling has been cut by an edge Red core warning yarns (if used) may or may not be visible but are not required to show before removing from service. Protect the sling by using wear pads or other devices to prevent damage from edges or corners.

Synthetic Web Slings Surface and Edge Cuts

Synthetic Web Sling Damage Holes, Snags, and Pulls Look for punctures or areas where fibers stand out from the rest of the sling surface. Avoid sling contact with protrusions during lifts and while transporting or storing.

Synthetic Web Sling Damage Abrasions Look for areas on the sling that look and feel fuzzy. This indicates that the fibers have been broken from contact and movement against a rough surface. Never drag slings along the ground. Never pull slings out from under loads that are resting on the sling. Use wear pads between slings and rough surface loads.

Synthetic Web Slings Abrasions

Synthetic Web Sling Damage Heat or Chemical Look for melted or charred fibers anywhere along the sling. Heat and chemical damage can look similar and they both have the affect of damaging the fiber and thus affecting the capacity. Look for discoloration and/or fibers that have been fused together and that may feel hard or crunchy. Never use nylon or polyester slings where they can be exposed to temperatures in excess of 200°F.

Synthetic Web Sling Damage Heat or Chemical

Synthetic Web Sling Damage Broken/Worn Stitching Stitch patterns have been engineered to produce the most strength out of the webbing. If stitching is not fully intact the strength of the sling may be affected. Look for loose or broken threads in the main stitch patterns Never pull from beneath loads where stitch patterns can get hung up or snagged. Never overload the slings or allow the load edge to directly contact the stitch pattern while lifting.

Synthetic Web Sling Damage Broken/Worn Stitching

Synthetic Web Sling Damage Knots Compromise the strength of all slings by not allowing all fibers to contribute to the lift as designed. Can reduce the sling strength by up to 50%. Look for knots. They are pretty obvious. Never used slings that are knotted.

The smaller the D/d ratio the larger the de-rating of the sling capacity. D/d Ratio The capacity of a wire rope sling can be greatly affected by being bent sharply around pins, hooks, or parts of a load. The wire rope industry uses the term “D/d ratio” to express the severity of bend. “D” is diameter of curvature that the rope or sling is subjected to and “d” is the diameter of the rope. The minimum D/d ratio is usually taken as 20 which correspond to 92 % efficiency. As wire ropes are usually at lease 8 % stronger than the catalogue strength, the bent sling at D/d = 20 is therefore considered 100 % efficient. In case wire rope slings are used for smaller D/d ratio, sling capacity shall be decreased based on wire rope efficiency as per following graph. This curve is based on static loads and applies to 6-strand class 6×19 and 6×37 wire ropes. Based on above graph, if the shackle or object has 2 times the diameter of a wire rope sling (D/d = 2) the basket sling capacity must be reduced by 35 % as shown below. To increase d/d ratio and sling capacity, use wide body shackle. If D/d ratio is 5 after using wide body shackle, sling capacity shall be reduced by about 20 %. Load hooks must have sufficient thickness to ensure proper sling D/d ratio, particularly when using slings in an inverted basket hitch; that is the sling body is placed into the hook and the sling eyes are facing downward.

Synthetic Web Sling Damage Illegible or Missing Tags Information provided by the sling tag is important for knowing what sling to use and how it will function. If you cannot find or read all the information on the sling tag OSHA requires the sling to be taken out of service. Never set loads down on top of slings or pull sling from beneath the load if there is any resistance, Load edges should never contact the sling tag during the lift. Avoid paint or chemical contact with tags.

Synthetic Web Sling Damage Illegible or Missing Tags

Chain Slings Alloy chains are used because of their Strength Durability Abrasion resistance Ability to conform to the shape of the load

Chain Slings 6 primary types or grades of chain 30 – Proof Coil 40 or 43 – High Test 70 – Transport 80 or A – Alloy 100 – High Strength Alloy 120 – High Strength Alloy Grade 120 not recognized by the National Association of Chain Manufacturers Association.

Chain Slings 120 – High Strength Alloy

Chain Slings There is a big difference in strength between different grades of the same size chain All chain is marked in some fashion to designate it’s grade Alloy chain typically cannot be purchased at hardware or home improvement stores Chains not rated Grade 80, 100, or 120 should never be used for Lifting. Hardware stores typically only stock Grade 30 or 40 chain because it is much cheaper than alloy chain. If you read the labels on the containers the chain is stored in you will see that they are state “Not For Lifting”. Alloy chain and components usually must be purchased or ordered from vendors who specialize in rigging.

8, 80, 800 or A Chain Slings Only “Alloy” (Grade 80, 100 or 120) chain and components may be used for lifting loads. Hardware stores typically only stock Grade 30 or 40 chain because it is much cheaper than alloy chain. If you read the labels on the containers the chain is stored in you will see that they are state “Not For Lifting”. Alloy chain and components usually must be purchased or ordered from vendors who specialize in rigging.

Daily Inspection should be conducted by a competent person designated by the employer.

Periodic Inspection: OSHA specifies that all alloy steel chain slings shall have a thorough periodic inspection, by a competent person, at least once every 12 months. These inspections must be recorded and maintained for each individual sling.

The inspection schedule should be based on frequency of sling use, severity of service conditions, nature of lifts being made and experience gained on service life of slings used in similar circumstances.

Chains Inspection Clean chain prior to inspection, to more easily see damage or defects. Hang chain vertically, if practical, for preliminary inspection. Measure reach accurately (bearing point of master link to bearing point of hook). Check this length against reach shown on tag. If present length is greater than that shown on tag, there is a possibility that the sling has been subjected to overloading or excessive wear.

Chains Inspection To inspect for stretch Compare a used chain with its rated length, or a new chain, or Compare a section of the old chain with the same number of links of a new chain If the length has increased by 3%, carefully inspect the entire length of the chain. If the length has increased by 5% or more, replace the chain.

Chains Inspection – page 45

Chains Inspection Chains do not give any warning when they are about to fail. When chains do fail they are as dangerous as a hand grenade Most causes of chain failure can be detected before failure occurs by performing periodic inspections.

Chains Inspection Make a link-by-link inspection of the chain slings. Check master links and hooks for faults – hooks especially for excessive wear. Slings showing any of the faults described should immediately be removed from service and returned to the manufacturer for repair.

Chains Inspection Excessive wear - If the wear on any portion of any link exceeds the allowable wear allowed, remove from service. Remove from service if twisted, bent, gouged, nicked, worn or elongated links are observed. Also cracks in the weld area of any portion of the link. Transverse markings are the most dangerous. Severe corrosion, remove from service

Safe Practices Never splice a chain by inserting a bolt between two links. When lifting take up slack slowly and check that all links are properly seated. Do not use a hammer to force a hook over a chain.

Safe Practices Never remove a permanent identification tag attached to the chain by the manufacturer. Make sure chain attachments (rings, shackles, couplings, end links) are designed for use with the chain to which they are fastened.

Safe Practices See that the load is always properly set in the bow of the hook. Loading on or toward the hook ends leads to spreading and possible hook failure. When dragging poles don’t allow the chain to be dragged on the ground. This causes excessive wear to the chain. When not in use hang the chain on a hook to avoid mechanical damage and exposure to corrosion.

Three primary grades Mild Plow Steel Plow Improved steel plow

Three primary grades Mild Plow Is tough and pliable Tensile strength from 200,000 to 220,000 pounds per square inch Desirable for cable tool drilling and other purposes where abrasion is encountered.

Three primary grades Steel Plow Is unusually tough and strong Tensile strength from 220,000 to 240,000 pounds per square inch Suitable for hauling, hoisting, and logging

Three primary grades Improved Steel Plow One of the best grades available Stronger, tougher and more resistant to wear than mild plow or steel plow Tensile strength from 240,000 to 260,000 pounds per square inch Especially useful for heavy-duty service such as cranes with excavating and weight-handling attachments

Classified by four factors Type of core Number of strands (most ropes have six strands) Number of wires per strand Arrangement of wires in a strand and the lay of the strands

Most come in two groups: 6 x 19 and 6 x 37 The six represents for the number of strands in the wire The second number represents the approximate number of wires in each strand 6 x 19: can have 15 to 26 wires in each strand 6 x 37: can have 27 to 49 wires in each strand

Anatomy of a wire rope: Thomas Seale's Patent The original Hallidie cable car on Clay Street was an instant success as a transportation system. Overnight, competitors went into business on other hilly streets nearby. Cable cars differed from overhead tramways because the ropes were subjected to more severe service conditions. Constant starting and stopping of the cars with a sliding grip, combined with numerous deflection sheaves required to allow the underground cable to conform to the surface profile of the streets, destroyed wire ropes in short order. San Francisco quickly became the world's largest wire rope market. One of Hallidies major transportation competitors was wealthy Leland Stanford. He had been involved in numerous successful ventures including the transcontinental railroad. Stanford intended to make his new California Street cable car line the city's finest. To this end, he hired an earthmoving contractor named Thomas Seale to be his superintendent. Born in Ireland, Seale had come to California with his brother during the gold rush, where they attained considerable wealth by grading streets near the San Francisco waterfront. The Seale brothers owned a huge ranch adjacent to Stanford's ranch in Palo Alto. Roebling's three-size construction ropes were not very suitable for cable-car service because the alternately small-sized outer wires invariably wore out first, breaking up and tangling machinery in the underground tubes. English inventors were experimenting with elliptical- and triangular-shaped strands to solve this problem. These so-called flattened strands did provide improvement when tested, but they were very expensive to produce. Ultimately, the enormous demand for wire rope in San Francisco stimulated intense competition between Roebling's company and Hallidie, driving prices downward. The cable car demand next spread all over the United States as other cities installed cable cars in the 1870s and 1880s. The three existing American manufacturers could not cope with the demand, which brought many other companies into the ropemaking arena. In San Francisco, the dilemma of short-rope service was tackled by Thomas Seale, whose solution soon became the accepted answer to the problem of severe outer wear combined with multiple reverse bending over small-diameter sheaves. Seale's patent (#315,077 April 7, 1885) is based upon rearranging the three wire sizes into an entirely different pattern so that all the largest wire sizes are side-by-side on the exterior of the strand. The aim was to achieve increased abrasion resistance without losing flexibility. More important, the patent also described, for the first time, the basic concept of equal-lay stranding, which is inherent in the Roebling three-size approach, but had not been previously explained as the solution to internal cross-wire nicking. Unfortunately, Seale's notes are gone and details of how he devised his famous construction remain unknown.

Anatomy of a wire rope: Fiber Core: may be made of a hard fiber such as manila, hemp, plastic, paper, or sisal serves as a cushion to reduce effects of sudden strain acts as an oil reservoir to lubricate the wire strands (to reduce friction) used when flexibility of the rope is important

Anatomy of a wire rope: Wire Strand Core: Resists more heat than a fiber core Adds about 15% to the strength of the rope Wire strand core makes the wire less flexible than fiber core

Anatomy of a wire rope: Independent Wire Rope Core: Is a separate wire rope over which the main strands of the rope are laid This strengthens the rope and provides support against crushing Supplies maximum resistance to heat

6 x 19 Wire Rope Classification examples: 6X19 SEALE IWRC (independent wire rope core) 6X21 FILLER WIRE FC (fiber core)

6X36 WARRINGTON SEALE IWRC SLINGS, CHAINS, and WIRE ROPE 6 x 37 Wire Rope Classification examples: 6X36 SEALE FILLER WIRE 6X36 WARRINGTON SEALE IWRC

Length of a Wire Rope Lay The length of the wire rope lay is the distance measured parallel to the center line of the wire rope in that a strand makes one complete spiral or turn around the rope

Lays of a Wire Rope The term lay refers to the direction of the twists of the wires in the strand and the direction the strands are laid in the rope In some instances the wires in the strands and the strands in the rope are laid in the same direction In other instances the wires are laid in one direction and the strands are laid in the opposite direction Consult the operator’s manual for proper application.

Lays of a Wire Rope Right Regular Lay: the wires in the strand are laid to the left, while the strands are laid to the right to form the wire

Lays of a Wire Rope Left Regular Lay: the wires in the strands are laid to the right, while the strands are laid to the left to form the wire rope.

Lays of a Wire Rope Right Lay LANG LAY: the wires in the strands and the strands in the rope are laid in the same direction; in this instance to the right

Lays of a Wire Rope Left Lay LANG LAY: the wires in the strands and the strands in the rope are also laid in the same direction; in this instance to the right

Lays of a Wire Rope – page 48 Left Regular Lay Right Regular Lay Left Lay LANG LAY Right Lay LANG LAY

Wire Rope Sling Care Protect wire rope slings from sharp bends and cutting edges by using corner saddles, padding, or wood blocking Avoid heavy or continuous overloading Avoid sudden jerks which can cause momentary overloads sufficient to break the sling Lubricate slings to prevent rust Hang slings up when they are not in use Inspect and lubricate at regular intervals

Wire Rope Damage Strand core protrusion due shock loading

Wire Rope Damage Broken Wires

Wire Rope Damage Localized wear and deformation created at a previously kinked portion of rope.

Wire Rope Damage Kinked

Wire Rope Damage “Bird-caging” due to torsional unbalance

Wire Rope Damage Dog-legged

Wire Rope Damage Protrusion of core due to shock loading

Wire Rope Damage Crushed

Wire Rope Damage Fatigue fractures caused by repeated sharp bending

Wire Rope Damage Popped Core

Wire Rope Damage Two parallel paths of broken wires indicative of bending through an undersized groove in a sheave

Wire Rope Damage Electrical Contact

Wire Rope Damage Corrosion

Wire Rope Damage More Corrosion and Rust

Wire Rope Inspection: Use marlin spike or similar tool to lift strands so inside of rope can be inspected A proper inspection of the rope on an annual inspection requires the inspector to be able to also look at the wires on the inside of the rope. A marlin spike is needed in order to separate the strands without damaging the individual wires to this can be done. Don’t use things like screwdrivers to pry the strands apart. The sharp blunt edge of a screwdriver will most likely snag wires and break them.

Wire Rope Measurement Measured across the wires greatest diameter Measure diameter of rope to make sure there is not excessive wear Wire rope diameter is always measured across the widest part of it’s cross section.

Wire Rope Measurement Replace the rope when the diameter is reduced more than the minimum specified below: Wire rope diameter is always measured across the widest part of it’s cross section.

Wire Rope Inspection Records Make periodic inspections of wire rope slings at intervals no greater than 12 months. A good guide to follow includes: Yearly for normal service use Monthly to quarterly for severe service use, and As recommended by a qualified person for special and infrequent service use. Although OSHA's sling standard does not require you to make and maintain records of inspections, the ASME standard contains provisions on inspection records.

Wire Rope Inspection Records

Eyes of Wire Rope Slings Should be properly spliced or swaged and equipped with thimbles to withstand wear

Spliced Eyes of Wire Rope Slings With few exceptions, all spliced eyes must incorporate rope thimbles to maintain rope strength and reduce wear. The efficiency of the connection can be reduced by as much as 10% without a thimble because the rope flattens under load.

Spliced Eyes of Wire Rope Slings The best and most secure splice is the Flemish eye with a pressed metal sleeve. This develops almost 100% of rated breaking strength of the rope.

Cable Clips Most common method to make an eye or attach a rope to a piece of equipment Allows for thorough examination of rope and ease of field installation If done correctly the eye can develop about 80% of rope strength Using wire clips to form slings is not permitted All clips must be drop forged steel – not malleable iron clips

Cable Clips Must have the U-bolt section on the dead end, or short end of the rope The saddle must be on the live, or long end of the rope

Cable Clips – Page 52 The wrong application of even one clip can reduce the efficiency of the connection to 40% of rated capacity Live End Saddle

Cable Clips A rule of thumb to remember when attaching a wire rope clip is to “NEVER saddle a dead horse.” ! WARNING ! It is illegal to use slings with eyes made with rope clips for overhead lifting

Removal from Service [OSHA (f)] Ten randomly distributed broken wires in one rope lay, or five broken wires in one strand in one rope lay (sometimes referred to as the “10-and-5” rule. Wear or scraping of one-third the original diameter of outside individual wires Kinking, crushing, bird-caging, or any other damage resulting in the distortion of the wire rope structure

Removal from Service [OSHA (f)] Evidence of heat damage End attachments that are cracked or worn Hooks that have been opened more than 15% of the normal throat opening (measured from the narrowest point) Hooks twisted more than 10° from the plane of the unbent hook Corrosion of rope or end attachments Missing or illegible identification markings

Removal from Service [OSHA (f)] Missing or illegible identification markings Paragraph (f)(1) was amended per 76 FR effective date June 08, 2011. (f)(1) Sling use. Employers must use only wire-rope slings that have permanently affixed and legible identification markings as prescribed by the manufacturer, and that indicate the recommended safe working load for the type(s) of hitch(es) used, the angle upon which it is based, and the number of legs if more than one.

Sling Safety General Lift and lower slowly and evenly. Never subject slings to shock loads. Small hooks, shackles, and other attachments with small cross sections can have sharp bending radii. This reduces the breaking strength of slings (D/d ratios). When using a sling in a basket hitch, avoid angles of less than 45 degrees. If the sling angle will be small, use a spreader bar.

Sling Safety Synthetic web slings Inspect sling for damage before using. Tag and remove from service if any item fails the inspection. Do not tie or knot ends together. When two slings are used together to “double up” the lifting capacity, the slings must be a matched pair. Otherwise one sling will tighten up first and carry most of the load.

Sling Safety Synthetic rope slings Used rope has reduced breaking strength. This must be considered when calculating the working load limit (WLL) Ropes in a sling reduce the strength of the sling by 50%. (D/d ration is 1 and the reduction in efficiency is 50%). When placing a rope sling around a loads with sharp edges, pad the portion of the sling contacting the sharp edge to prevent any cutting.

SLINGS, CHAINS, and WIRE ROPE

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