Cranes are old devices—the ancient Greeks and Romans designed cranes to lift and move heavy objects. Buildings such as the Roman Colosseum and the medieval cathedrals of Europe were built using cranes, as were the skyscrapers of cities today.

These days, most industries such as construction, manufacturing, shipping, energy—and nearly all others—use cranes routinely to handle and move materials.

But although we’ve used cranes for centuries, and use them just about everywhere today, cranes can still be dangerous. If not probably balanced, they can topple over when lifting a load, and if a load is too heavy, the load line or crane hook can snap, dropping the load on anything, or anyone, below.

Safe crane operations depend on effective use of technology by trained and careful workers. While the professional crane operator may seem to play the leading role in crane operations, the work of the rigger is just as essential. Without effective rigging, no load can be lifted safely, and an improperly rigged load can slip from its sling, or break the sling, and fall, killing or seriously injuring workers or members of the public. That’s why this training session focuses on safe rigging for crane operations.

Note that this training session is intended for employees with crane rigging responsibilities. Other employees may also benefit from understanding the rigger’s duties. Discuss the use of cranes in your industry.

 

Session Objectives

So what do you need to know to be an effective rigger?

• Experienced, reliable riggers know that they are part of a team that’s performing a difficult job. While they may not be trained crane operators, riggers should know the basics of crane operations, including the limits of the equipment. Often, accidents involving cranes occur because the personnel involved asked a crane to do something it was never designed to do.
• Choosing the right sling or other hardware takes judgment born of experience. But you can learn the basics now, including carefully checking the load limits of any hardware you use.
• Slings or other hardware can break, often at the worst time, when under the stress of a load being lifted. That’s why it is essential that you inspect your equipment with care, using established criteria. We’ll discuss the basics of sling inspection today.
• Finally, you need to know how to rig a load correctly. Again, there is plenty to learn, and your exact method of rigging will vary with the situation, equipment, and load, but this session will provide the basics.

As you probably are hearing, becoming an experienced, safe crane rigger requires continued learning. So, don’t be afraid to ask questions and seek further knowledge, both during this session and on the job.

Crane Standards

• Because crane operations can be hazardous, and complicated, OSHA has adopted rules about safe crane regulations in general industry workplaces, including proper rigging.
• However, concern about crane safety does not end with governmental regulations. The American National Standards Institute, ANSI, in conjunction with the American Society of Mechanical Engineers, or ASME, have issued a series of standards for crane operations that are often used in construction and other industries.
• Other professional organizations have issued standards governing crane organizations in certain industries. For instance, the American Petroleum Institute, the API, lists their crane standards for the energy industry, in API Recommended Practice 2D.

Make sure you are familiar with the regulations, standards, or recommended practices for crane operations or rigging in your industry.

Types of Cranes

So, let’s begin by learning a little more about cranes and crane operations. Modern day cranes come in a variety of forms and sizes, designed for different situations or uses.

• The most basic type of mobile crane consists of a truss or boom mounted on a mobile platform. The boom is hinged at the bottom and can be raised and lowered by cables or by hydraulic cylinders. Truck-mounted cranes are mobile cranes mounted in the bed of a truck, whereas all-terrain cranes have a base or wheel bed much like that of an all-terrain vehicle.
• A telescopic crane has a boom that consists of a number of tubes fitted one inside the other. A powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom.
• The tower crane is fixed to the ground or “jacked up” and supported by a structure, such as a building under construction. These cranes can be tall with a high lifting capacity; they’re the cranes that are often seen standing next to a tall building under construction in the center of a city.
• A gantry crane has a hoist that runs along gantry rails. These cranes are often used in ports and railroad yards to unload large cargo containers and move them from place to place. A close relative of the gantry crane is the overhead or suspended crane, with a hoist that moves along two or more beams.
• Finally, vessel, deck, or offshore cranes are used in cargo operations in the maritime or offshore oil and gas industries.

Be sure you know the basic type of cranes used at your workplace.

Essential Data

No matter what type of crane is being used, certain pieces of information are essential for a safe lift.

• First, you need to know the weight of the load. This may be found on the container, or in shipping papers or another document.
• Second, you must know the rated capacity of the crane. This is the maximum amount of weight a crane can safely lift. The rated capacity is marked directly on the crane.
• Depending on the type of equipment and the nature of the lift, other factors may also be important, and lifesaving. For instance, a boom extended too far or a lift performed at the wrong angle may result in a crane becoming unbalanced or tipping over.
• Finally, the crane’s load chart is used to determine if a lift can be done safely, in consideration of factors such as load weight, boom length and angle, and lift radius.

A lift should never be attempted if it is not within the capabilities of the equipment or if safety cannot be ensured.

Rigging Hardware Data

In many cases, a professionally, trained and certified crane operator uses data such as rated capacity and the load chart to decide if a lift can be made safely. However, riggers often need to check additional data involving rigging hardware.

• For instance, rigging hardware such as slings or shackles also have rated capacities or load limits that cannot be exceeded. Always check these carefully. They are just as important as the rated capacity of the crane.
• The sling angle will affect the capacity, with capacity lowered as the angle is reduced. A sling at a 30° angle may have only half the lifting capacity of a sling that is at 90°, vertical to the lift line.

Either the crane operator or the rigger should check, and double check, the load limit or rated capacity of the crane hook. Check, too, to be sure that the positive latching mechanism on the hook is in good working order.

• Ratings of crane rigging hardware usually are not hard to find: Most often, they are stamped into the hardware or attached on a label. Never use a piece of hardware if you can’t verify its rated capacity or load limit.

As you can see, it is essential that the crane, load line, hook, and all components of the rigging be designed for the load you plan to lift.

Serious Questions

Even when you know that your equipment is suitable for the weight of the load, there are still some serious questions you need to consider:

• Will the angle of the sling take away any of its capacity?
• Have you rigged the load to the center of gravity of the crane and lift line?
• Are there any sharp surfaces or corners in the rigging that could cause a sling to tear? Should padding be used to protect the sling?
• Will the load be under control along the entire path of the lift?
• Should a tag line be used to guide the load?
• Are there any obstructions along the lift path that must be cleared? Can they be moved out of the way?
• Will the suspended load be clear of all personnel?
• Do unusual environmental conditions such as high winds, rain, or heat need to be considered?

As you can see, there are many factors to keep in mind. That’s why it is smart to discuss each job with everyone involved and make doubly sure you are making the right decisions.

Why Not Just Wing It?

• That seems like a long list of questions that need to be answered. Why can’t you just size up the load, slap on some rigging, and hoist away? Chances are, nothing will go wrong.
• The problem is, crane operations are simply too hazardous to leave to chance. So, the more factors that need to be considered, the more important it is to slow down and make the right decisions.

Sling Selection

• You can begin by choosing the correct rigging hardware, using the rated capacity. At most workplaces, slings are commonly used in rigging. A sling that has been well selected and is properly functioning will keep the load stable and secure during the course of the lift. However, using the wrong sling may lead to a load that sways, slips out of the sling, or causes the sling to snap or otherwise fail under stress.
• While a sling’s rated capacity is essential in choosing the correct sling, other factors are also important, including the material composition of the sling;
• Its size, design, and configuration are important;
• Its condition; and
• Each sling should have a tag that states the rated capacity, the date it was put into service, and its length.

Chain Slings

• Chain slings are commonly used because of their strength.
• Chain slings are able to adapt to the shape of the load.
• Chain slings are often the best choice for lifting materials that are very hot, because these slings can be heated to temperatures of up to 1000°F; however, when alloy chain slings are consistently exposed to service temperatures in excess of 600° F, the working load limits must be lowered in accordance with the manufacturer’s recommendations.
• Care should be taken, however, when using alloy chain slings, because they are subject to damage by sudden shocks or jolts.
• Also, when inspecting alloy steel chain slings, pay special attention to any stretching, cracks, elongated links, and nicks and gouges.

These are all indications that the sling may be unsafe and should be removed from service

Wire Rope Slings

The second type of sling is wire rope slings.

• Wire rope slings are composed of individual wires that have been twisted to form strands.
• The strands are then wound to form a wire rope. When wire rope has a fiber core, it is usually more flexible but is less resistant to environmental damage. A core that is made of a wire rope strand tends to have greater strength and is more resistant to heat damage.
• These types of slings can experience cracking of individual strands and kinking, which distorts their geometry.

Rope Lay

Wire rope is often referred to as right lay or left lay. Let’s review these terms.

• Right Lay:

– A right lay rope is one in which the strands are wound around the core in a right-hand direction like a conventional screw thread.

• Left Lay:

– A left lay rope is just the opposite. The strands in a left lay rope form a left-hand helix similar to the threads of a left-hand screw thread. Left lay rope has its greatest usage in contexts where the rotation of right lay would loosen couplings. The rotation of a left lay rope tightens a standard coupling.

Rope Lay

Lay also refers to the direction the wires are wound in the strands in relation to the direction of the strands around the core.

• Regular lay:

– In regular lay rope, the wires in the strands are laid in one direction while the strands in the rope are laid in the opposite direction. Regular lay ropes have good resistance to kinking and twisting and are easy to handle. They are also able to withstand considerable crushing and distortion due to the short length of exposed wires. This type of rope has the widest range of applications.

• Lang lay:

– In lang lay rope, the wires are twisted in the same direction as the strands. Lang lay ropes are more flexible and have greater wearing surface per wire than regular lay ropes. In addition, since the outside wires in lang lay ropes lie at an angle to the rope axis, internal stress due to uses such as bending over sheaves and drums is reduced. This means lang lay ropes can be more resistant to bending fatigue. Lang lay rope is recommended for many excavating, construction, and mining applications, including draglines, hoist lines, and dredge lines.

Wire Rope Sling Selection

When selecting a wire rope sling to give the best service, there are several characteristics to consider: strength; flexibility, or the ability to bend without distortion; and durability, or the ability to withstand wear and abuse.

• The strength of a wire rope is a function of its size, grade, and construction. As a sling deteriorates from use, its strength and lifting capacity are reduced. A sling loaded beyond its strength will fail. For this reason, older slings must be inspected thoroughly before use.
• Generally, more flexible ropes are selected when smaller radius bending is required. Smaller wires bend more readily and therefore offer greater flexibility. However, less flexible ropes should be used when the rope must move through or over abrasive materials, as they are less likely to be damaged.
• Durability should also be considered when selecting a wire rope sling. Padding is often applied to increase the radius of the bend, reducing fatigue. Misuse and abuse also cause deterioration.

It’s important to take good care of your slings and make sure the ways you use, inspect, and store them always follow the manufacturer’s recommendations. Wire rope slings are subject to damage resulting from contact with sharp edges of the loads being lifted. These edges can be blocked or padded to minimize damage to the sling. In addition, standard practice is to hang the slings when not in use, not lay them down

Wire or Metal Mesh Slings

• Another type of sling is a wire or metal mesh sling. These slings are much like chain mail in composition.
• They conform to the shape and contours of a load and are strong and durable.
• And, wire or metal mesh slings are often used in basket or choker hitches, as well as vertical hitches.

When inspecting these slings, be sure to look for any broken welds, cracking or broken brazed joints along the side of the sling, or distortion of the handles. These are signs of a weakened sling.

Fiber Rope Slings

Fiber rope and synthetic web slings are used primarily for temporary work, such as construction and painting jobs, and in marine operations. They are also the best choice for use on expensive loads, highly finished parts, fragile parts, and delicate equipment. Let’s talk about fiber rope slings first.

• Fiber rope slings are flexible, pliant, they grip the load well, and do not mar the surface of the load.
• They should be used only on lighter loads, however, and should not be used if there is a danger that they will cut on sharp edges, or be damaged by abrasive material.
• They also can weaken in high temperatures and may be ruined by exposure to certain chemicals, such as strong acids. The choice of fiber rope type and size depends upon the nature of the load, its weight, and the sling angle.
• Remember that these slings can stretch extensively when wet.
• Always inspect fiber rope slings thoroughly before use. Keep in mind that they generally deteriorate more rapidly than chains or wire rope slings.

Synthetic Web Slings

Synthetic web slings are used for many of the same applications as fiber rope slings and have similar qualities: For instance, both types of slings should not mar the surface of a load. However, they can be much stronger and capable of lifting heavy loads and are more resistant to abrasion and, often, chemicals.

• Synthetic web slings are usually made of nylon, Dacron, or polyester. Each material has slightly different properties. For instance, Dacron is resistant to acids, but can degrade if exposed to bases. Polyester should be used when it is important that stretching of the sling is kept to a minimum.
• Synthetic web slings flexibly conform to any shape and contour with the load to keep it tightly gripped.
• Besides resisting abrasion and some chemicals, they also are generally unaffected by mildew and will not rot or biodegrade. They can be used at high temperatures.

Which Sling Is It?

Before we move on to the rest of this session, let’s review this information on sling materials and types with a short exercise. Match the type of sling at left with the descriptor at right.

Allow trainees to complete the exercise and discuss the answers with them.

Answers:

1. Chain—for heavy or hot loads
2. Wire Rope—lay is important
3. Metal Mesh—similar to chain mail
4. Fiber Rope—for light loads only
5. Synthetic Web—unlikely to biodegrade

Sling Inspection

Let’s move on to sling inspection. Keep in mind that even if you select the right kind of sling, you may still be headed for trouble if the sling is not in good condition. That’s why all slings must be visually inspected before each use. Even if you have just used a sling, you need to inspect it before using it again, as damage may have occurred during the last lift. While exact criteria for inspection will vary with the type of sling and its material composition, some general rules remain. When inspecting any sling:

• Look for excessive wear, including cracks and pitting, which may be demonstrated by worn places; unraveling of the fibers or wires that make up the sling; and places where abrasion has degraded or weakened the sling.
• Slings can also lose their shape and become distorted or stretched. This signals a weakened condition.
• Metal slings or components of slings can corrode. While light rust may be acceptable, excessive corrosion can lead to a broken sling.
• Heat stress or scorching can weaken a sling, or cause it to lose its form or become brittle.
• And finally, certain chemicals can eat away at slings or break down their fibers.

If you have any doubt about the safety of a sling or its ability to lift a load, don’t use the sling. Never take chances during crane or rigging operations.

Chain Sling Inspection

Now let’s discuss some inspection criteria for some of the major types of slings.

• When inspecting a chain sling, it is important to inspect the total length of the sling, as any place may be the proverbial “weak link in the chain.” However, it is especially important to inspect the inside ends of each link, as these bear the weight of the load. You can see this part of the chain by pushing links together so that the inside surface becomes clearly visible. Wear may also occur on the outside of links when the chain is dragged along abrasive surfaces or pulled out from under heavy loads.
• Check for excessive wear, nicks and gouges, and stretching. Links that are noticeably elongated or show cracking are always suspect. According to OSHA rules, a sling that has stretched so that it is now more than 3 percent longer than it was when new is unsafe and must be taken out of service.
• Finally, binding is another warning sign of a weakened sling. Binding is the term used to describe the condition that exists when a sling has become deformed to the extent that its individual links cannot move within each other freely.

Wire Rope Sling Inspection

Many operating conditions affect wire rope life, including bending, stresses, loading conditions, jerking, abrasion, corrosion, sling design, materials handled, environmental conditions, and the history of previous usage. That’s why it’s essential to inspect wire rope slings before each use. Check for:

• Cracking and pitting;
• Excessive wear and kinking;
• Deformation;
• Corrosion or rust;
• Heat stress, which may result in a discoloration of the metal or a drying of internal lubrication;
• Twists or lay of the sling. If 10 randomly distributed wires in one lay are broken, or 5 wires in one strand of a rope lay are damaged, the sling must not be used; and
• Finally, end fittings and other components, which should also be inspected for any damage that could make the sling unsafe.

Fiber Rope Sling Inspection

When inspecting a fiber rope sling before use, start by examining its surface.

• Look for dry, brittle, scorched, or discolored fibers. If any of these conditions are found, the sling should not be used.
• Next, check the interior of the sling. It should be fairly clean. The presence of powder or dust on the inside of the fiber rope may demonstrate excessive internal wear; the sling may be unsafe.
• Finally, scratch the fibers with a fingernail. If the fibers come apart easily, the fiber sling probably has suffered chemical damage and must be discarded.

Synthetic Web Sling Inspection

Inspecting slings is an important step in making sure they operate safely.

• Synthetic slings and round slings are prone to acid or caustic burns, holes, wear, cuts, tears, snags, broken stitches, worn stitches, excessive abrasion, embedded particles, and knots. These problem signs are cause for the slings to be removed from service.
• Also, check for broken or worn stitching in the cover that exposes the core fibers and web slings that have visible signs of red threads protruding.
• Finally, heat damage causes the webbing to harden and stiffen, and the sling will often show signs of melting, bubbling, or charring.

Sling Maintenance

You can extend the life of a sling considerably with proper maintenance.

• One relatively simple step is to clean the sling. This will remove material that may be abrasive or produce snags, or that could degrade the sling through a chemical reaction.
• Some damaged slings may be repaired. For instance, nicks or gouges in a chain sling can be filed smooth, but it is essential not to reduce the diameter of a link below the manufacturer’s recommendations. If repairing a sling may render it unsafe, the sling should be discarded.
• Wire rope slings need occasional lubrication. The heavier the loads, the greater the number of bends, or the more adverse the conditions under which the sling operates, the more frequently lubrication will be required.
• Finally, slings should be stored in a well-ventilated, dry storage area. Do not store slings on the ground or allow them to be exposed to the elements when not in use. A storage rack is generally used. Once you are done using a sling, check it for damage, and if none is found, return it to storage.

Shackles, Clips, Eyes, and Other Hardware

• Rigging hardware such as shackles, links, wire rope clips, and end fittings must also be inspected thoroughly and treated with care. Retire hardware if signs of wear or deformation such as cracks, nicks, or gouges are found. Remove the equipment from service if excessive wear of more than 5 percent is detected in the throat or eye of a shackle or more than 10 percent wear is found in other areas.
• Malfunctioning, missing, or improperly installed hardware is also grounds for removal from service. Check latches, swivels, bearings, locking devices, and the installation of wire rope clips and wedge sockets. It’s also essential to retire hardware that has been altered on the job, such as by cutting or welding.

Hooks

The crane hook is a sturdy device capable of enduring great stress, but it, too, must be inspected.

• Hooks must have a safety latch or clip. This prevents the hook from twisting out of the ring or another device they are attached to. If a hook does not have a safety clip or latch, or if the clip is broken, replace the hook or have the safety clip repaired.
• And, hooks may crack, bend, or distort. A hook opened more than 15 percent of the normal throat opening measured at the narrowest point or twisted more than 10° from the plane of the unbent hook must be removed from service. Many times, the hook requires non-destructive testing to ensure there are no stress cracks.

Hitches

Part of the art of the rigger’s work is to employ the proper hitch for a lift. Many types of hitches may be used, depending on factors such as the weight and shape of the load and the sling or slings being used. A few hitches commonly used are:

• The single vertical hitch, where a single sling is used for a vertical lift;
• The bridal hitch, in which two or more slings meet at the crane hook;
• The basket hitch, in which a sling wraps around the load or a part of the load to support it;
• And, the choker hitch, where the hitch tightens around the load as it is lifted.

If you are unsure about which type of hitch is best for a particular lift, talk to the people who know, such as your supervisor, the crane operator, or a more experienced rigger. Never twist a chain or sling to adjust its length—this will compromise its load-bearing capacity. You’ll learn much more about how to hitch particular loads and when to use certain hitches as you gain experience.

Preparing the Lift

• As you get ready to prepare a load for a lift, protect yourself by donning all required PPE. This may include a hard hat, safety shoes, and work gloves.
• Before lifting the load, make sure the hook and hoist line are directly over the load. If they are not, the load will move or swing, potentially causing an injury to someone or damaging facilities or equipment.
• Also, check to be sure that the hoist chain or line and the slings are not kinked or twisted around each other. This could cause the load to twist, rotate, or flip once it is lifted.

Preparing the Lift (cont.)

• Always attach the sling to the load first, then attach it to the hook. This is called “rigging up the load.” Hooks are designed to carry the load in the center of the hook, which is the thickest part. Never pick up a load with the hook’s tip. A load attached this way can easily slip and the safety clip cannot be utilized. Also, the tip itself will also open up and weaken.
• The hook latch must be closed to secure loose slings. Check once more to make doubly sure that all rigging components and any safety devices are in place and that the load is free of any restraint. • Also, check again to be sure that the path of the lift is clear.
• And finally, the lift and hitch should be tested by lifting the load a few inches, at first, to make sure it is well secured and balanced.

The load should be lifted as close to the floor or ground as possible when traveling. If anything should happen, the load does not have far to fall before reaching the ground.

A tag line may be used to guide a load if necessary, but if operating the line, use extreme caution and stay out from under the load.

Crane Signals

• Throughout lifting operations, it is essential that the crane operator remain in contact with the crew on the loading floor or deck. Hand signals are commonly used.
• Only one member of the crew should give signals to the operator, unless someone else sees an unsafe condition. Then, an emergency stop signal can be given.
• The rigger is often the person appointed to give signals. However, it is essential that everyone on the loading floor recognize the signals and understand where the load is headed. Getting in the way of a load, or standing under it, have gotten many people killed over the years.
• After checking to make sure everyone is clear of the area, the signalman tells the crane operator to hoist the load, by rotating an extended index finger.

The “Nevers”

Now that the load is safely under way, let’s review a list of “nevers” involving crane operations. Accidents and injuries tend to occur when people do something they never should have!

• Never use a hoist chain or load line that is twisted or kinked. Never use the hoist chain or line as a sling by wrapping it around the load. This can damage, cut, or kink the chain or line.
• Do not attempt to lift the load by the block hook. Attach the load to the block hook with appropriate slings or other approved devices.
• Never use a sling or piece of rigging hardware that is not in good condition.
• Never allow a load to be lifted if you are unsure about safety.

The “Nevers” (cont.)

And that’s not all. Here are a few more “nevers.”

• Never allow more than one person to control a lift or give signals to a crane or hoist operator except to warn of a hazardous situation.
• Never work or stand under a suspended load or allow anyone else to.
• And, never turn your back or walk away until a load is completed. Watch the load and rigging with care and be prepared to stop the job if you see an unsafe condition.

What Is? (Fill in the blanks)

1. A type of hitch in which two slings meet at the crane hook is a _____ ____.
2. An essential part of the crane hook that keeps the sling from sliding off is a ____ or ___.
3. A term for describing the pattern of wires in a wire rope is ___.
4. The maximum weight a crane or sling will support is _____ _______.

We’ve discussed quite a few new terms today. Let’s see if you remember some of them. Provide the term described in each of the items.

Allow time for trainees to answer, and discuss the answers with them.

 Answers:

1. Bridle hitch
2. Latch or clip
3. Lay
4. Rated capacity

 Questions or Comments?

• We’ve covered a lot of material, from the basic types of cranes, to sling selection and inspection, to rigging a load. What questions do you have?

Key Points to Remember!

• There is certainly a lot to learn about rigging a crane; that’s why crane rigging is often referred to as an art, and it takes years of practice to be a true expert.
• Because lifts often present new situations that require thought and sound decisions, you should never be bored at work!
• It is important that you continue to learn and find out all you can about the practice of rigging cranes.
• As you learn, keep in mind that you need to be cautious at all times, and think safety. It is up to you to never allow a lift that you even suspect could be unsafe.
• Finally, while unusual lifts may require special thought, even routine lifts can be deadly if a sling fails or if the rigger forgets to fasten the crane hook. That’s why it is essential that you follow all procedures every time, and think safety.