When it comes to lifting heavy loads, selecting the right type of slings or straps for rigging is crucial to ensure both efficiency and safety. Each type of lifting sling, whether it’s made from wire rope, chain, nylon, or polyester, has specific advantages and limitations. Understanding these will help you choose the best rigging slings for your application. In this article, we’ll explore the different types of lifting slings, their benefits, and their safety features, as well as maintenance and inspection tips to keep your equipment in good, safe condition. This article is a toolbox topic / informational article explaining the various types of rigging, their application and safety items. For a general safety overview about rigging see our Rigging Safety Toolbox Talk
Types of Lifting Slings
Wire Rope Slings
Wire rope slings are one of the most robust and durable lifting solutions, often used in heavy-duty applications like construction and industrial lifting. These slings have individual metals strands braided together to form a semi-flexible rope.
- Benefits: Wire rope slings have higher temperature limits and are resistant to wear, making them suitable for rugged environments. They are able to provide sufficient strength for lifting heavy loads and are cut-resistant, which adds to their durability. Wire ropes are safer than chain slings. Their braided design makes a sudden catastrophic failure of the sling unlikely. Under failure, wire ropes will begin to tear as each individual cable fails, allowing crews and operators time to react.
- Drawbacks: Despite their durability, wire rope slings can be difficult to inspect properly due to the internal wear that may not be immediately visible. Corrosion and broken strands are common issues if not well-maintained. Wire ropes are less flexible than synthetic straps or chains, which makes them more difficult to store properly. Be sure not to bend or kink the sling hen rapping them up for storage.
Safety Tip: Always inspect wire rope slings for broken wires, corrosion, or kinks before using them to prevent failure during lifting operations. Take the sling out of service if kinks, broken stands and substantial corrosion is found.
Synthetic Slings (Round Slings & Straps) (Nylon and Polyester Slings)
Synthetic slings, which include nylon slings and polyester slings, are lightweight, flexible, and designed to prevent damage to loads with sensitive surfaces. They come in two configurations: Round slings and straps. Round slings have an inner core surrounded by a flexible jacket. Their flexible, cylindrical design prevents binding and pinching. Straps are wide and flat. They come with loop eyes on each end, with hooks and shackles. Straps are less flexible than round slings. They are prone to twisting pinching and folding when pulled against small openings and uneven surfaces. Always take care to keep straps straight and flat when using them for rigging operations.
Nylon and Polyester Slings
- Nylon Slings: These heavy-duty nylon slings are resistant to strong alkalis and basic chemicals, making them ideal for industrial environments where chemical exposure may be a concern. Nylon slings also stretch slightly under load, which can help absorb shock loading.
- Drawbacks: Nylon is susceptible to damage from acids and bleaching agents, making it unsuitable for certain applications. Also, the stretching effect can lead to reduced load stability.
- Polyester Slings: Polyester slings or polyester web slings offer similar benefits to nylon slings but are more resistant to acid exposure and don’t stretch as much, providing better load stability. Polyester is often chosen for lifting applications where chemical resistance and load control are crucial.
- Drawbacks: Polyester slings are more susceptible to cuts and abrasion compared to chain or wire rope slings, so they require extra protection in rough environments.
Safety Tip: Use wear pads, softeners or corner guards when lifting sharp-edged materials to prevent cutting or tearing of synthetic slings. Inspect synthetic slings for tears, cuts, abrasion, burns or punctures. Take the sling out of service when any of these issues are found. If the sling is missing its tag or the tag is illegible, it must be taken out of service. Never use synthetic slings with knots in them. Never use wet synthetic slings for lifting operations. Wet slings stretch much easier under load and do not have the design capacity of a dry sling.
Chain Slings
Chain slings are industrial lifting slings fabricated from alloy steel.
- Benefits: Chain slings are cut resistant and provide excellent durability, making them ideal for heavy loads and environments where high temperatures or harsh conditions exist. Chain slings are more flexible than wire ropes making them easier to store.
- Drawbacks: When chain slings fail, the links snap without warning. For this reason, they are less safe than wire ropes or synthetic slings, which begin to fray and tear under failure, allowing crews a small amount of time to react. Chain slings are also difficult to inspect. Check for elongated and deformed links. If the chain sling is in a 4 way or 2-way configuration check to see that each leg is the same length. If a leg is longer than the others, there are elongated links, and it should be taken out of service. For these reasons, some companies have safety policies that forbid the use of chain slings.
Safety Features and Certifications
Proof Testing
To ensure safety, all slings should undergo proof testing where the sling is pulled to twice its vertical rating to confirm its strength. This testing ensures that the sling is reliable under load and can handle its rated capacity. This testing is performed by the manufacturer.
Tagging
Slings must have a tag with their working load limit (WLL). This helps operators ensure that the sling is used within its safe capacity, minimizing the risk of failure during a lift. Tags also show the various configurations the sling can be used in and the capacity for each. Common sling configurations are choker hitch, basket hitch, and vertical hitch. Each configuration will have different lifting capacities.
Certifications
All slings should meet or exceed the safety standards set by OSHA and ASME to ensure safe operation. These certifications are essential for rigging in industrial, construction, and cargo control applications.
Lifting Sling Maintenance and Inspection
Regular Inspection
Performing regular inspections is key to ensuring the safety and longevity of lifting slings. Look for signs of wear, fraying, or corrosion in synthetic, wire rope, and chain slings. OSHA requires that each sling has a tag displaying the capacity of the sling. Take the sling our of service when the tag is missing or illegible. Keep records of what slings are onsite and the date the inspection date.
Proper Storage
Store slings in a dry, clean environment, away from direct sunlight or extreme heat, to prevent deterioration. Store Custom nylon slings and heavy-duty lifting straps off the floor to avoid moisture damage.
Cleaning
Clean slings regularly to prevent dirt, grease, or other contaminants from building up and weakening the material. Follow the manufacturer’s instructions to avoid damage during the cleaning process.
Specialty Lifting Solutions.
Custom Nylon Sling:
Custom nylon sling are designed to meet specific lifting needs, providing a tailored solution for unique or complex lifting applications. They are useful for specialized tasks that require non-standard lengths or configurations.
Specialty Slings
Specialty slings are engineered for specific applications, such as boat lifting or moving heavy-duty cargo. These slings are designed with particular materials and configurations to ensure a safe lift.
Bridle Slings
Bridle slings combine the strength and durability of chain or wire rope slings with the lightweight and flexibility of nylon slings. This makes them an ideal choice for lifts that require multiple points of contact with the load.
Industry Applications
- Industrial Lifting: Wire rope and chain slings are commonly used for industrial lifting operations, where durability and high strength are essential.
- Construction: Slings like chain and wire rope are used on construction sites for lifting heavy materials like steel beams.
- Manufacturing: Nylon slings and polyester slings are frequently used in manufacturing environments to handle delicate products.
- Cargo Control: Web slings and round slings provide secure lifting and load control during transportation.
Choosing the Right Lifting Sling
When selecting the best sling for your lifting operation, consider the following:
- Type of Load: The material, size, and weight of the load will determine the appropriate sling.
- Lifting Application: The hitch type and lifting height will influence your choice of sling, as well as whether you need basket hitches, choker hitches, or other configurations. The lifting application also determines what accessories and lifting hardware to use. Don’t pinch or kink a sling in a choked hitch. Use an appropriate shackle or hook instead. Don’t attempt to use a hook through a lift point that is too small for the hook to fully engage.
- Environment: The conditions, such as temperature and chemical exposure, must be considered to select the right sling material, such as chain, nylon, or polyester.
Conclusion
Lifting slings are essential tools for ensuring safe and efficient lifting operations. By understanding the different types of slings available, their benefits, and potential drawbacks, you can make an informed choice for your specific lifting needs. Regular inspection, proper maintenance, and adherence to safety standards are critical to ensuring the longevity and safety of your lifting straps.,
More Rigging Resources:
Rigging Safety – General Safety Toolbox Talk about Rigging Safety
Shackle Safety: Using the correct shackle for your operation