safety factor for wire rope slings in stock

Have you wondered why rigging experts always suggest a sling that has a significantly higher breaking strength than the actual weight of the load you are lifting? The manufacturers know that the rigging used in overhead applications need to have room for error. This is known as the Safety Factor.

Northern Strands manufactures wire rope slings rated up to 36,000 lbs and sells round synthetic slings that are rated up to 140,000 lb capacity. This capacity is the Working Load Limit of the sling, which is the maximum amount of weight or force that the sling"s user is allowed to put on the sling. Note: These slings do not break at the working load limit. These slings are designed with a safety factor of 5:1. This means that 5 times as much force as the working load limit has to be applied to the sling before it potentially fails. This means the wire rope slings have a Breaking Strength of up to 180,000 lbs and the round synthetic slings can withhold up to 700,000 lbs.

Wear - Working load limits are based on slings in brand new condition and a safety factor can help account for normal wear and tear until it is deemed unfit for further use.

Uneven loading - Slings are made up of either wires or fibers that must all share the weight of the load evenly. If any situation arises where the sling is bent or wrapped around an object, there is potential that some of the wires or fibers will be taking on a greater share of the load than others.

Visit Northern Strands website to use the sling tension calculator. The Northern Strands Sling Calculator has been designed to assist you in selecting slings with enough load carrying capacity for your lifting applications. It is your responsibility to assure that the slings you use are appropriate for your application. http://www.northernstrands.com/sling-calculator.aspx

Wire rope is often used in slings because of its strength, durability, abrasion resistance and ability to conform to the shape of the loads on which it is used. In addition, wire rope slings are able to lift hot materials.

Wire rope used in slings can be made of ropes with either Independent Wire Rope Core (IWRC) or a fiber-core. It should be noted that a sling manufactured with a fiber-core is usually more flexible but is less resistant to environmental damage. Conversely, a core that is made of a wire rope strand tends to have greater strength and is more resistant to heat damage.

Wire rope may be manufactured using different rope lays. The lay of a wire rope describes the direction the wires and strands are twisted during the construction of the rope. Most wire rope is right lay, regular lay. This type of rope has the widest range of applications. Wire rope slings may be made of other wire rope lays at the recommendation of the sling manufacturer or a qualified person.

Wire rope slings are made from various grades of wire rope, but the most common grades in use are Extra Improved Plow Steel (EIPS) and Extra Extra Improved Plow Steel (EEIPS). These wire ropes are manufactured and tested in accordance with ASTM guidelines. If other grades of wire rope are used, use them in accordance with the manufacturer"s recommendations and guidance.

When selecting a wire rope sling to give the best service, consider four characteristics: strength, ability to bend without distortion, ability to withstand abrasive wear, and ability to withstand abuse.

Rated loads (capacities) for single-leg vertical, choker, basket hitches, and two-, three-, and four-leg bridle slings for specific grades of wire rope slings are as shown in Tables 7 through 15.

Rated loads for a sling in a choker hitch are the values shown in Table 7, 9, 11, 13, 14, or 15, provided that the angle of the choke is 120 degrees or more (Fig. 2). Use the values in Fig. 2 or those from the sling manufacturer or a qualified person for angles of choke less than 120 degrees.

Ensure that slings made of rope with 6×19 and 6x37 classifications and cable slings have a minimum clear length of rope 10 times the component rope diameter between splices, sleeves, or end fittings unless approved by a qualified person,

Ensure that braided slings have a minimum clear length of rope 40 times the component rope diameter between the loops or end fittings unless approved by a qualified person,

Ensure that grommets and endless slings have a minimum circumferential length of 96 times the body diameter of the grommet or endless sling unless approved by a qualified person, and

Perform welding of handles or other accessories to end attachments, except covers to thimbles, before assembly of the sling. Ensure that welded end attachments are proof tested by the manufacturer or a qualified person. Retain the certificates of proof test and make them available for examination.

Do not use wire rope clips to fabricate wire rope slings, except where the application precludes the use of prefabricated slings and where the sling is designed for the specific application by a qualified person,

Use damaged slings only after they are repaired, reconditioned, and proof tested by the sling manufacturer or a qualified person using the following criteria:

Ensure that wire rope slings have suitable characteristics for the type of load, hitch, and environment in which they will be used and that they are not used with loads in excess of the rated load capacities described in the appropriate tables. When D/d ratios (Fig. 4) are smaller than those listed in the tables, consult the sling manufacturer. Follow other safe operating practices, including:

Ensure that multiple-leg slings are selected according to Tables 7 through 15 when used at the specific angles given in the tables. Ensure that operations at other angles are limited to the rated load of the next lower angle given in the tables or calculated by a qualified person,

When D/d ratios (see Fig. 6) smaller than those cited in the tables are necessary, ensure that the rated load of the sling is decreased. Consult the sling manufacturer for specific data or refer to the WRTB (Wire Rope Technical Board) Wire Rope Sling Users Manual, and

Ensure that the load applied to the hook is centered in the base (bowl) of the hook to prevent point loading on the hook, unless the hook is designed for point loading,

Before initial use, ensure that all new swaged-socket, poured-socket, turnback-eye, mechanical joint grommets, and endless wire rope slings are proof tested by the sling manufacturer or a qualified person.

Permanently remove from service fiber-core wire rope slings of any grade if they are exposed to temperatures in excess of 180 degrees F (82 degrees C).

Follow the recommendations of the sling manufacturer when you use metallic-core wire rope slings of any grade at temperatures above 400 degrees F (204 degrees C) or below minus 40 degrees F (minus 40 degrees C).

Scope. This section applies to slings used in conjunction with other material handling equipment for the movement of material by hoisting, in employments covered by this part. The types of slings covered are those made from alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope (conventional three strand construction), and synthetic web (nylon, polyester, and polypropylene).

Cable laid endless sling-mechanical joint is a wire rope sling made endless by joining the ends of a single length of cable laid rope with one or more metallic fittings.

Cable laid grommet-hand tucked is an endless wire rope sling made from one length of rope wrapped six times around a core formed by hand tucking the ends of the rope inside the six wraps.

Cable laid rope sling-mechanical joint is a wire rope sling made from a cable laid rope with eyes fabricated by pressing or swaging one or more metal sleeves over the rope junction.

Equivalent entity is a person or organization (including an employer) which, by possession of equipment, technical knowledge and skills, can perform with equal competence the same repairs and tests as the person or organization with which it is equated.

Master link or gathering ring is a forged or welded steel link used to support all members (legs) of an alloy steel chain sling or wire rope sling. (See Fig. N-184-3.)

Diagam howing Two slings with indicators for sling width, overall length, bearing to bearing length, and fabric length. Further indicators point to both male handles, handle eye, female handle, and slot depth

Diagram indicates Forms of Hitch and Kind of Sling. Eye&Eye Vertical Hitch. Eye&Eye Choker Hitch. Eye&Eye Basket Hitch (Alterates have identical load rations). Endless Vertical Hitch. Endless Choker Hitch. Endless Basket Hitch (Alternateve have identical load ratings). Notes: Angles 5 deg or less from the veritcal may be considered vertical angles. For slings with legs more than 5 deg off vertical, the actual angle as shown in Figure N-184-5 must be considered. Explanation of Symbols: Minimum Diameter of Curvature. Represents a contact surface which shall have a diameter of curvature at least double the diameter of the rope from which the sling is made. Represents a contact surface which shall have a diameter of curvature at least 8 times the diameter of the rope. Represents a load in a choker hitch and illustrates the rotary force on the load and/or the slippage of the rope in contact with the load. Diameter of curvature of load surface shall be at least double the diameter of the rope.

Diagram indicates Form of Hitch and Vertical Hitch. Kind of Sling. Eye&Eye Vertical Hitch Not Applicable. Eye&Eye Choker Hitch Not Applicable. Eye&Eye Basket Hitch (Alternates have identical load ratings). Endless Vertical Hitch Not Applicable. Endless Choker Hitch Not Applicable. Endless Basket Hitch (Alternates have identical load ratings). Notes: For vertical angles of 5 deg or less, refer to Figure N-184-4 ""Basic Sling Configurations with Vertical Legs"". See Figure N-184-4 for explanation of symbols.

Proof test is a nondestructive tension test performed by the sling manufacturer or an equivalent entity to verify construction and workmanship of a sling.

Strand laid endless sling-mechanical joint is a wire rope sling made endless from one length of rope with the ends joined by one or more metallic fittings.

Strand laid grommet-hand tucked is an endless wire rope sling made from one length of strand wrapped six times around a core formed by hand tucking the ends of the strand inside the six wraps.

Strand laid rope is a wire rope made with strands (usually six or eight) wrapped around a fiber core, wire strand core, or independent wire rope core (IWRC).

Inspections. Each day before being used, the sling and all fastenings and attachments shall be inspected for damage or defects by a competent person designated by the employer. Additional inspections shall be performed during sling use, where service conditions warrant. Damaged or defective slings shall be immediately removed from service.

In addition to the inspection required by paragraph (d) of this section, a thorough periodic inspection of alloy steel chain slings in use shall be made on a regular basis, to be determined on the basis of

experience gained on the service life of slings used in similar circumstances. Such inspections shall in no event be at intervals greater than once every 12 months.

The employer shall make and maintain a record of the most recent month in which each alloy steel chain sling was thoroughly inspected, and shall make such record available for examination.

The thorough inspection of alloy steel chain slings shall be performed by a competent person designated by the employer, and shall include a thorough inspection for wear, defective welds, deformation and increase in length. Where such defects or deterioration are present, the sling shall be immediately removed from service.

Proof testing. The employer shall ensure that before use, each new, repaired, or reconditioned alloy steel chain sling, including all welded components in the sling assembly, shall be proof tested by the sling manufacturer or equivalent entity, in accordance with paragraph 5.2 of the American Society of Testing and Materials Specification A391-65, which is incorporated by reference as specified in § 1910.6 (ANSI G61.1-1968). The employer shall retain a certificate of the proof test and shall make it available for examination.

Safe operating temperatures. Employers must permanently remove an alloy steel-chain slings from service if it is heated above 1000 degrees F. When exposed to service temperatures in excess of 600 degrees F, employers must reduce the maximum working-load limits permitted by the chain manufacturer in accordance with the chain or sling manufacturer"s recommendations.

Worn or damaged alloy steel chain slings or attachments shall not be used until repaired. When welding or heat testing is performed, slings shall not be used unless repaired, reconditioned and proof tested by the sling manufacturer or an equivalent entity.

Slings shall be removed from service if hooks are cracked, have been opened more than 15 percent of the normal throat opening measured at the narrowest point or twisted more than 10 degrees from the plane of the unbent hook.

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.

Cable laid and 6 × 19 and 6 × 37 slings shall have a minimum clear length of wire rope 10 times the component rope diameter between splices, sleeves or end fittings.

Safe operating temperatures. Fiber core wire rope slings of all grades shall be permanently removed from service if they are exposed to temperatures in excess of 200 °F. When nonfiber core wire rope slings of any grade are used at temperatures above 400 °F or below minus 60 °F, recommendations of the sling manufacturer regarding use at that temperature shall be followed.

All welded end attachments shall not be used unless proof tested by the manufacturer or equivalent entity at twice their rated capacity prior to initial use. The employer shall retain a certificate of the proof test, and make it available for examination.

Sling marking. Each metal mesh sling shall have permanently affixed to it a durable marking that states the rated capacity for vertical basket hitch and choker hitch loadings.

Sling testing. All new and repaired metal mesh slings, including handles, shall not be used unless proof tested by the manufacturer or equivalent entity at a minimum of 1½ times their rated capacity. Elastomer impregnated slings shall be proof tested before coating.

Safe operating temperatures. Metal mesh slings which are not impregnated with elastomers may be used in a temperature range from minus 20 °F to plus 550 °F without decreasing the working load limit. Metal mesh slings impregnated with polyvinyl chloride or neoprene may be used only in a temperature range from zero degrees to plus 200 °F. For operations outside these temperature ranges or for metal mesh slings impregnated with other materials, the sling manufacturer"s recommendations shall be followed.

Once repaired, each sling shall be permanently marked or tagged, or a written record maintained, to indicate the date and nature of the repairs and the person or organization that performed the repairs. Records of repairs shall be made available for examination.

Sling use. Employers must use natural and synthetic fiber-rope slings that have permanently affixed and legible identification markings stating the rated capacity for the type(s) of hitch(es) used and the angle upon which it is based, type of fiber material, and the number of legs if more than one.

Safe operating temperatures. Natural and synthetic fiber rope slings, except for wet frozen slings, may be used in a temperature range from minus 20 °F to plus 180 °F without decreasing the working load limit. For operations outside this temperature range and for wet frozen slings, the sling manufacturer"s recommendations shall be followed.

Splicing. Spliced fiber rope slings shall not be used unless they have been spliced in accordance with the following minimum requirements and in accordance with any additional recommendations of the manufacturer:

In manila rope, eye splices shall consist of at least three full tucks, and short splices shall consist of at least six full tucks, three on each side of the splice center line.

In synthetic fiber rope, eye splices shall consist of at least four full tucks, and short splices shall consist of at least eight full tucks, four on each side of the center line.

Strand end tails shall not be trimmed flush with the surface of the rope immediately adjacent to the full tucks. This applies to all types of fiber rope and both eye and short splices. For fiber rope under one inch in diameter, the tail shall project at least six rope diameters beyond the last full tuck. For fiber rope one inch in diameter and larger, the tail shall project at least six inches beyond the last full tuck. Where a projecting tail interferes with the use of the sling, the tail shall be tapered and spliced into the body of the rope using at least two additional tucks (which will require a tail length of approximately six rope diameters beyond the last full tuck).

For all eye splices, the eye shall be of such size to provide an included angle of not greater than 60 degrees at the splice when the eye is placed over the load or support.

Removal from service. Natural and synthetic fiber rope slings shall be immediately removed from service if any of the following conditions are present:

Attachment of end fittings to webbing and formation of eyes. Stitching shall be the only method used to attach end fittings to webbing and to form eyes. The thread shall be in an even pattern and contain a sufficient number of stitches to develop the full breaking strength of the sling.

Safe operating temperatures. Synthetic web slings of polyester and nylon shall not be used at temperatures in excess of 180 °F. Polypropylene web slings shall not be used at temperatures in excess of 200 °F.

Each repaired sling shall be proof tested by the manufacturer or equivalent entity to twice the rated capacity prior to its return to service. The employer shall retain a certificate of the proof test and make it available for examination.

Wire ropes are essential for safety purposes on construction sites and industrial workplaces. They are used to secure and transport extremely heavy pieces of equipment – so they must be strong enough to withstand substantial loads. This is why the wire rope safety factor is crucial.

You may have heard that it is always recommended to use wire ropes or slings with a higher breaking strength than the actual load. For instance, say that you need to move 50,000 lbs. with an overhead crane. You should generally use equipment with a working load limit that is rated for weight at least five times higher – or 250,000 lbs. in this case.

This recommendation is all thanks to the wire rope safety factor. This calculation is designed to help you determine important numbers, such as the minimum breaking strength and the working load limit of a wire rope.

The safety factor is a measurement of how strong of a force a wire rope can withstand before it breaks. It is commonly stated as a ratio, such as 5:1. This means that the wire rope can hold five times their Safe Work Load (SWL) before it will break.

So, if a 5:1 wire rope’s SWL is 10,000 lbs., the safety factor is 50,000 lbs. However, you would never want to place a load near 50,000 lbs. for wire rope safety reasons.

The safety factor rating of a wire rope is the calculation of the Minimum Break Strength (MBS) or the Minimum Breaking Load (MBL) compared to the highest absolute maximum load limit. It is crucial to use a wire rope with a high ratio to account for factors that could influence the weight of the load.

The Safe Working Load (SWL) is a measurement that is required by law to be clearly marked on all lifting devices – including hoists, lifting machines, and tackles. However, this is not visibly listed on wire ropes, so it is important to understand what this term means and how to calculate it.

The safe working load will change depending on the diameter of the wire rope and its weight per foot. Of course, the smaller the wire rope is, the lower its SWL will be. The SWL also changes depending on the safety factor ratio.

The margin of safety for wire ropes accounts for any unexpected extra loads to ensure the utmost safety for everyone involved. Every year there aredue to overhead crane accidents. Many of these deaths occur when a heavy load is dropped because the weight load limit was not properly calculated and the wire rope broke or slipped.

The margin of safety is a hazard control calculation that essentially accounts for worst-case scenarios. For instance, what if a strong gust of wind were to blow while a crane was lifting a load? Or what if the brakes slipped and the load dropped several feet unexpectedly? This is certainly a wire rope safety factor that must be considered.

Themargin of safety(also referred to as the factor of safety) measures the ultimate load or stress divided by theallowablestress. This helps to account for the applied tensile forces and stress thatcouldbe applied to the rope, causing it to inch closer to the breaking strength limit.

A proof test must be conducted on a wire rope or any other piece of rigging equipment before it is used for the first time.that a sample of a wire rope must be tested to ensure that it can safely hold one-fifth of the breaking load limit. The proof test ensures that the wire rope is not defective and can withstand the minimum weight load limit.

First, the wire rope and other lifting accessories (such as hooks or slings) are set up as needed for the particular task. Then weight or force is slowly added until it reaches the maximum allowable working load limit.

Some wire rope distributors will conduct proof loading tests before you purchase them. Be sure to investigate the criteria of these tests before purchasing, as some testing factors may need to be changed depending on your requirements.

When purchasing wire ropes for overhead lifting or other heavy-duty applications, understanding the safety dynamics and limits is critical. These terms can get confusing, but all of thesefactors serve an important purpose.

Our company has served as a wire rope distributor and industrial hardware supplier for many years. We know all there is to know about safety factors. We will help you find the exact wire ropes that will meet your requirements, no matter what project you have in mind.

A lifting sling has a purpose, which is to move bulky, large, and heavy loads. Slings are used because lifting without them can be difficult and sometimes not even possible. Lifting slings makes a direct connection between the load and the lifting equipment being used. Although these slings are used to make lifting more accessible, they can make lifting more dangerous if the straps are misused. Anytime a sling is used for lifting, it is essential that users take concrete steps and precautions.

A lifting sling should be inspected before every use (including the first time). A damaged sling can break while lifting loads. Dropping loads can harm people, products, and the environment.

Different sling styles and sizes exist, and so not all can be used interchangeably. When it comes to lifting tools, you need the right sling for the job. Webbing slings have a full surface, which can help to protect larger loads.

Never exceed the working limit for a load. All lifting devices, like cranes and hoists, are rated for the weight they can carry. Lifting slings are calculated similarly. If you are lifting an object that is roughly 18 tonnes, you will want to acquire slings that have a WLL (working load limit) of 20 tonnes.

Examine slings for wear, fatigue, crushed or broken wires, kinking, ballooning or "bird-caging", heat damage, etc. Check both before and after using slings to detect any damage or defects. See Hoist wire rope for more inspection tips.

Safe Working Load (SWL) is the limiting safety factor to lift and carry any load safely. It must be clearly marked on any lifting device (hoist, lifts, lifting machines, and lifting tackles).

“No lifting machine and no chain, rope or lifting tackle shall, except for the purpose of the test, be loaded beyond the safe working load which shall be plainly marked and duly entered in the prescribed register, and where this is not practicable, a table showing the safe working loads of every kind and size of lifting machine or chain, rope or lifting tackle in use shall be displayed in prominent positions on the premises”

A table showing the SWL (Safe Working Load) of every kind and size of chain, rope, or lifting tackle in use, and in case of multiple slings, the SWLat different angles of the legs, shall be posted in the storeroom.

Safe Working Load is generally tabulated in the load chart of the crane. Sometimes, it is de-rated(decreased) due to defect in welding, bend in angle, bracing, etc., and condition of clutch, brake, etc. Modern cranes give a digital display of SWL, angle indicator, boom limit switch, and alarm for exceeding load.

The factor of the safety (Safety Factor) of fiber ropes varies from 6 to 12 mm depending on the conditions of use. fiber rope less than 12 mm dia should not be used for a sling or apart of a lifting appliance. Their factor of safety (FS) varies with diameter. The factor of Safety for the hook, wire rope sling, chain, fiber rope, and belt are given in the table below:

The proof test is required as a part of ‘thorough examination’ u/r 60(1) of GFRand no lifting machine or tackle should be used for the first time without this proof test.

In general, the proof load applied to chains, rings, hooks, shackles, and similar gear is twice the SWL. It should be just under the yield stress for the material.

Chain, ring, hook, shackles, swivel, sling, individual components of the hoist, wire rope, chain, pulleys, hooks, eye bolts, pins, axles, bearings, turnbuckles & ringing screws.2 SWL

After the above proof test, the parts are to be examined thoroughly by a competent person for signs of cracks, fatigue, deformation, permanent stretch, etc.

Fiber rope and wire rope are widely used across the groundwater industry. Fiber rope is more commonly used in manual hoisting, such as raising up or lowering down tools. Wire rope is commonly used for mechanical hoisting operations.

The improper use of fiber rope or wire rope can result in serious incidents involving property damage, injuries, and death. Using the ropes as intended within their safe working load and maintaining them in good condition are critical in preventing rope failures.

Both types of rope include a combination of characteristics that give them certain performance traits depending on design, materials, and composition.

Wire rope is made of steel wires laid together to form a strand. These strands are laid together to form a rope, usually around a central core of either fiber or wire.

The number of strands, number of wires per strand, type of material, and nature of the core depend on the intended purpose of the wire rope. Wire rope that has many smaller wires and strands is more flexible than rope with larger-diameter wires and fewer strands. Wire rope used with sheaves and drums should have many strands to be flexible enough to bend around the sheaves and drums.

Wire ropes are classified by grouping the strands according to the number of wires per strand. The number of wires and the pattern defines the rope’s characteristics.

For example, a 6 × 7 rope indicates the rope is comprised of six strands and each individual strand is comprised of seven wires. This particular rope has large wires and is not very flexible but has good abrasion-resistant qualities. Whereas, a 6 × 19 rope has 19 wires per strand and thus is more flexible.

The more wires in a strand, the more flexible the wire rope. Likewise, the more strands in the rope, the more flexible the rope. However, the more strands in a rope and more wires in a strand, the less abrasion resistant.

Other important requirements to consider when selecting a wire rope are the breaking strength and “safe working load.” These values can be found with the use of a chart.

Most hoisting jobs use a safe working load based on a 5:1 safety factor of the wire rope’s breaking strength. However, this safety factor should be even higher if there is a possibility of injury or death from the rope breaking. For example, elevators are based on a 20:1 safety factor. Critical lifts with a danger to personnel should be calculated on a 10:1 safety factor.

Wire rope inspections are important checks on any type of rigging equipment. Wear, metal fatigue, abrasion, corrosion, kinks, and improper reeving are more important in dictating the life of a wire rope—more so than its breaking strength when new. Therefore, wire rope should be regularly inspected in accordance with OSHA and industry standards.

The frequency of inspections depends on the service conditions. Slings should be inspected each day before being used. Wire rope in continuous service or severe conditions should be inspected at least weekly and also observed during normal operation. For most other applications, wire rope should be inspected at least monthly.

Broken wires: Removing a wire rope from service due to broken wires depends on how the particular rope is being used. Finding one broken wire (or several widely spread) is usually not a problem. Regular breaks are a cause for concern and require a closer inspection. General guidelines for rope replacement due to broken wires are as follows:

Running wire ropes: Six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope lay, where a rope lay is the length along the rope in which one strand makes a complete revolution around the rope.

Pendants or standing wire ropes: More than two broken wires in one rope lay located in the rope beyond end connections or more than one broken wire in a rope lay located at an end connection. Slings: Ten randomly distributed broken wires in one rope lay or five broken wires in one strand in one rope lay.

Rotation-resistant ropes: Two randomly distributed broken wires in six rope diameters or four randomly distributed broken wires in 30 rope diameters. Valley breaks:Wire ropes with any wire breaks in between two adjoining strands should be removed from service.

Abrasion:Wire rope winding over drums or through sheaves will wear. The rope should be replaced if the outer wire exceeds one-third of the original diameter.

Crushed strands: This condition is a result of too many layers of rope wrapped around a drum. There should be no more than two layers of wire rope on the drum, especially if the rope is a type with many small wires (such as 6 × 37). Crushing also occurs by cross winding, which is a result of poor winding procedures when the rope is wound in a pile in the middle of a drum.

Corrosion: This problem is difficult to evaluate and is also much more serious than normal wear. Corrosion will often start inside the rope before it shows on the outside. A lack of lubrication is usually the cause. Wire pitting or severe rusting should be cause for immediate replacement.

Kinks: Kinks are permanent distortions. After a wire rope is kinked, it is impossible to straighten the rope enough to return it to its original strength. If a rope cannot be unkinked by hand, it should be removed from service.

Electric arc:Wire rope that has been inadvertently (or purposely) used as a ground in welding or has been in contact with a live power line will have fused or annealed wires, and must be removed from service.

Metal fatigue: This is usually caused by bending stress from repeated passes over sheaves, or from vibration such as crane pendants. Fatigue fractures can be external or internal. A larger sheave or drum size, or using a more flexible rope, may increase the rope life.

Diameter reduction: Any noticeable reduction in diameter is a serious deterioration problem. A wire rope is measured across its diameter at its widest point. Diameter reduction could be caused by one fault or a combination of faults. Wire ropes should be replaced when the reduction in diameter is more than 5% from the nominal diameter.

Wire rope stretch: Any new wire rope will stretch when the initial load is applied. After the initial stretch and a slight stretching over time during normal wear, the rope will begin to stretch at a quicker rate, which means it is approaching time for replacement.

Bird caging: This is a torsional imbalance, which is a result of mistreatment such as pulling rope through tight sheaves, being wound on too small a drum, or sudden stops.

A wire rope is lubricated during the manufacturing process. This provides the rope with protection for a reasonable time if stored under proper conditions. When the wire rope is in service, the initial lubrication will not be enough to last the lifetime of the rope. Therefore, it is usually necessary to apply a lubricant to a wire rope under working conditions. A light mineral oil can be used for lubrication. Never use old crankcase oil.

Fiber ropes are preferred for some rigging applications because they are more pliant. However, they should be used only on light loads and must not be used on objects that have sharp edges capable of cutting the rope. Fiber ropes should also not be used where they will be exposed to high temperatures, severe abrasion, or acids.

The choice of rope depends on its application. Manila is a natural fiber and has relatively high elasticity, strength, and resistance to wear and deterioration. Manila rope is generally the most common natural fiber rope used because of its quality and relative strength.

The principal synthetic fiber used for rope is nylon, which has a tensile strength nearly three times that of manila. The advantages of nylon rope are it is waterproof and has the ability to stretch, absorb shocks, and resume its normal length. Nylon also has better resistance against abrasion, rot, decay, and fungus growth as compared to natural fibers.

Avoid dragging rope through sand or dirt or pulling over sharp edges. Sand or grit between the fibers of the rope cuts the fibers and reduces its strength.

The outside appearance of fiber rope is not a good indication of its internal condition. The rope softens with use. Dampness, heavy strain, fraying and breaking of strands, and chafing on rough edges all weaken the rope considerably.

Overloading a rope may cause it to break. For this reason, fiber ropes should be inspected at regular intervals to determine their condition. Untwist the strands slightly to open the rope so the inside can be examined.

Mildewed rope has a musty odor and the inner fibers of the strands have a dark, stained appearance. Broken strands or broken yarns ordinarily are easy to identify. Dirt and sawdustlike material inside the rope, caused by chafing, indicate damage. In rope having a central core, the core should not break away in small pieces upon examination. If this happens, it indicates the rope has been overstrained.

To prevent rope failures and minimize deterioration and damage: select the right rope for the job, inspect regularly, use as intended, and properly store and maintain.

To help meet your professional needs, this article covers skills and competencies found in DACUM charts for drillers and pump installers. DO refers to the drilling chart. The letter and number immediately following is the skill on the chart covered by the article. This article covers:

Alloy Steel-chain slings differ from wire-rope slings in that components using wire are replaced by link chain. Other sling components are similar. Chain slings are more rugged and flexible, but less shock resistant than wire-rope or braided slings. This size is measured by the link stock.

However, as with ANY wire rope sling, when using a chain link sling in ANY Marine related construction activity…Safety is of the upmost of importance.

Chains should be stored in racks or in designated locations when not in use. Chains should never be stored in damp or dirty places, nor in places exposed to the weather. For long-term storage, they should receive a coating of oil. Should one have any empty chains, the “Ends” should be hooked onto the hoist hook or bull ring.

The total load that can be lifted safely with steel-chain slings depends on how the slings are attached to the load. If all legs of a steel-chain sling are hooked back into the master link, the safe-load capacity of the whole sling may be increased by 100 percent if the capacity of the master link is not exceeded.

The safe-load level of any chain sling is a function of three basic factors: size and number of legs, condition of chain and other components. Let alone the sling angle between legs and horizontal. One should note the dramatic drop in load capacity when a “Double Chain Link Sling” is positioned in an extremely low hook height and wide leg spreads.

In ending, upon the return to the shop ANY chain link slings coming off of ANY Project no matter how short the job was, one should always do the following, at a MINIMUM, prior to storing…said Slings.