Choosing the right rigging equipment for a project is one of the most important decisions a rigging team makes. The wrong choice — whether in type, capacity, or configuration — can result in equipment failure, load damage, or a serious incident. This guide explains the key factors to consider when selecting rigging equipment, and how to match the right tools to the demands of each project.
What Factors Determine Which Rigging Equipment to Use?
Five key factors determine the correct rigging equipment for any project: the weight and dimensions of the load, the load’s centre of gravity and available lift points, the required lift height and radius, the environmental conditions on site, and the sensitivity of the load’s surface to damage. Each of these must be assessed before the rigging configuration is selected.
Selecting the Right Sling Type
Sling type is one of the first equipment decisions in any rigging configuration. The main options are wire rope slings, chain slings, and synthetic web slings. Wire rope slings are the most common choice for heavy industrial lifts — they offer high strength-to-weight ratio, abrasion resistance, and flexibility. Chain slings are preferred where heat, cutting hazards, or rough surfaces would damage wire rope. Synthetic web slings are the best choice for sensitive or finished surfaces where scratching must be avoided, but they have lower temperature limits and are vulnerable to cutting. The choice depends on load characteristics and site conditions.
How Do You Determine the Required Sling Capacity?
The required sling capacity depends on both the load weight and the rigging angle. As the angle between the sling and the vertical increases, the tension in each sling leg increases — often dramatically. At 45° from vertical, each sling carries approximately 141% of its share of the total load. At 60° from vertical, this increases to 200%. This means that a sling rated for 2 tonnes in a vertical lift may only be suitable for a 1-tonne load if rigged at 60°. Always calculate sling tension based on the actual rigging angle, not just the total load weight.
When Should a Spreader Beam Be Used?
A spreader beam should be used when the load’s geometry requires the slings to be attached at widely spaced points that cannot be achieved without excessive sling angles, when inward sling forces on the load would cause damage or instability, or when the load is very long and must be lifted from two or more points. Spreader beams allow multiple attachment points to be connected to a single crane hook while keeping sling legs vertical — which maximises the effective lifting capacity of the slings and eliminates inward compressive forces on the load.
What Is the Role of Shackles in a Rigging Configuration?
Shackles connect slings to hooks, spreader beams, and load attachment points. They must be rated for the load they carry and must be correctly installed — with the pin fully tightened and secured. The direction of loading matters: bow shackles (Omega-type) can carry side loads, making them suitable for multi-leg sling connections. Dee shackles must only carry loads in-line with their spine — side loading a dee shackle significantly reduces its capacity and can cause it to fail. Never use a shackle as a permanent connection without an appropriate mousing or locking arrangement on the pin.
For expert guidance on rigging equipment selection for your specific project, contact the Reef Rigging team.
Frequently Asked Questions: Choosing Rigging Equipment
How do I know what capacity rigging equipment I need?
Start with the verified weight of the load. Add the weight of all rigging hardware. Then calculate the tension in each sling leg based on the planned rigging angle. The calculated tension in each sling must not exceed the safe working load (SWL) of the sling at the specified angle. Apply a design factor appropriate to the lift type — for standard lifts, operating at no more than 80% of SWL is common practice to maintain a safety margin for dynamic effects.
Can rigging equipment be mixed — for example, chain slings with synthetic web chokers?
Yes, different types of rigging equipment are commonly used together in a single rigging configuration — for example, a chain sling as the primary lift sling with web slings as softeners to protect a sensitive surface. However, when mixing equipment types, the capacity of the overall configuration is limited by its weakest component. Each piece of equipment must be rated for the load it carries in the planned configuration, and the rigging plan must document the capacity of each element.
Should I use a 2-leg or 4-leg sling configuration?
A 2-leg sling is simpler and distributes the load evenly between both legs when the attachment points are symmetrically positioned relative to the centre of gravity. A 4-leg sling allows more attachment points and is useful for large, distributed loads. However, in a 4-leg configuration, it is difficult to guarantee that all four legs carry equal loads — in practice, a 4-leg sling is often treated as a 3-leg configuration for capacity purposes. For heavy or precision lifts, the rigging configuration should be engineered specifically for the load geometry.