Anyone who has driven by a large construction site where a huge crane is moving pipes from one side of a newly constructed building to another realizes that it’s no easy task. Moving large pieces of equipment from one place to another can be an extremely tedious undertaking that involves careful planning. The basic principles of science play a massive role in deciding what types of transport materials are best suited for the loads being relocated. One of the main components involved in the transport process is called a “rigging sling”. Rigging slings may seem as though they make up a small portion of the large cranes they are used with, but they perform an essential function. In order to better educate people about the small, but mighty, rigging sling, we’ve composed a quick guide to the sling and what it can do for you.
What is a Rigging Sling?
Rigging slings are a significant piece of lifting equipment that ensures that the materials being transported, whether it’s copper pipes or an industrial air conditioning unit, are not damaged as they are hoisted. They are often used in combination with lifting equipment such as cranes, hoists, and forklifts. There are several types of rigging slings, as well as several ways in which they can be arranged to best serve the needs of the project.
There are four different kinds of rigging slings. These include:
- Wire Slings: These are the most common type of rigging slings. They are most often used in construction projects where heavy loads and rugged conditions exist, such as within mines, oil rigs, and elevators. These are popular due to their flexibility, strength, and fatigue resistance. As the name suggests, they are made of wire strands wrapped together to create a rope of sorts. Most are treated to prevent rust and corrosion.
- Chain Slings: Chain slings are made of, well, chains, that contain an alloy that combines several different types of steel, making them one of the strongest sling options. An advantage of chain slings is that they can be used repeatedly without breaking down as quickly as a wire sling. Chain slings are often used in heavy-duty lifting, in steel mills or heavy machine shops, or with machinery requiring repetitive lifts.
- Mesh Slings: These slings are a combination of chain and wire. These are usually used when lifting objects that are hot or that have sharp edges. Machine shops and steel warehouses usually use these for their materials. In addition, they also usually have wide load-bearing surfaces.
- Synthetic Slings: Synthetic rigging slings are usually made of nylon and polyester fibers that have been woven together. This makes them extremely flexible and lightweight, but they are usually far less resistant to damage than other forms of slings. They are usually used with more expensive or delicate loads to resist scratches, such as yachts, cars, or large pieces of décor. They are most often used with custom applications as well.
How Do Rigging Slings Work?
Rigging slings can be arranged in a variety of ways to best fit the materials that are requiring transport. They are wrapped around the item being lifted in one of four patterns and are attached with hooks. The combination of both the hook and the sling is referred to as a hitch. These patterns are known as vertical, choker, basket, and bridle arrangements.
A vertical rig sling is fairly self-explanatory in that the sling is attached directly to the item being lifted in order to move it vertically. The only downside to this type of rigging is that the item can swing from side to side when suspended. This is usually used when only one lighter-weight object is being moved.
Choker hitches are wrapped around an object in a circular pattern and have an adjustable knot at the top. This is used with evenly balanced loads that require a strong grip. It is vital that the load’s weight is distributed evenly in order to ensure that it does not slip to one side when it is being transported.
Basket hitches have the unique capability to split the weight between both sides of the sling. They are typically used alongside lifting beams to add additional support. Much like the choker hitch, the weight of the load has to be distributed evenly, so often, basket hitches are used with piles of lumber or pipes.
Bridle arrangements are used when two or more hitches are needed to lift an object. This is created with two vertical hitches so that the weight can be distributed more evenly, and therefore, more safely. Bridles are used with especially heavy objects.
Now that we know both the types of slings that exist and the different arrangements of hitches that can be used, let’s explore what factors can affect the rigging process.
What Factors Affect Rigging Slings?
You might not expect it, but there is quite a bit of science involved in the rigging process. The physics of the load being transported will decide both the rigging sling material as well as the arrangement of the hitch. Key characteristics of the load include the weight, volume (length, width, height), center of gravity, location radius and lift height.
For instance, knowing the center gravity of the object being moved is vital, since the rigging hitch has to be placed directly over this point, otherwise, the entire load could topple over. If the wrong sling is chosen for the object’s particular center of gravity, the results could be catastrophic. Knowledge of simple machines like levers and pulleys is also essential so that the behavior of the rigging sling and hitch can be predicted.
Other factors that can affect the rigging sling include weather, the lift angles, and the rated capacity of the sling. If a rigging engineer attempts to lift an object that exceeds the expected capacity of the sling, it could break, and drop an object that is potentially several tons in weight. The weather is important as well since windy weather could weaken the slings or change the lift angles.
The process of choosing a rigging sling is dependent on a myriad of conditions. Though the methods of choosing the correct rigging sling for your project can seem tedious, Rowe Transfer has over 130 years of experience to make the decision easier.
Rigging Made Easy at Rowe Transfer
Rowe Transfer is here for all of your rigging, transportation, warehousing, and crating needs. Whether you need a several-ton piece of machinery lifted up several stories, or simply a place to keep your equipment during a massive renovation, we are the company to call. Our century of experience, coupled with our incredibly knowledgeable staff provides you with top-of-the-line services that are guaranteed to best fit your needs. If you have a question about what we can do for you, or if you require a quote, call us at 865-523-0421, or visit our website.