Spreaders, frames and lifting beams are not a new concept, having been used in the construction and engineering industries for some time. The use of beams has a number of advantages over traditional slinging methods. They make the handling of awkward loads simpler while giving an even distribution of the weight across a wider area. They can offer considerable scope for use when lifting particularly unusual loads and, if used correctly, provide a safe, flexible and secure lifting method.
There are a number of applications where the use of beams, spreaders and frames can be advantageous:
• To reduce the headroom required when lifting particularly long loads
• Where a lift using multiple lifting points is required
• To provide a means of handling out of balance loads
• To enable the use of two cranes in tandem or in multiple lifting
• To provide lifting points at adjustable centres.
They come in a variety of shapes, sizes and capacities. Very few are alike; some are adjustable, others give multiple lifting points and can be configured into various sections such as cruciform, rectangular or straight.
Stability
When using a lifting beam, spreader or frame, it is vitally important that care is taken to ensure that the load remains stable when lifted. Particular attention must be paid to the centre of gravity of the load lifted. Problems can arise when the centre of gravity is higher than the lifting point.
The diagram, left, shows the conditions for lifting instability. To achieve a stable condition, it is important that the height of the lifting triangle must be increased in relation to the loading triangle. Thus for stability, A must be greater than B, and D must be equal to or greater than C.
SWL and beam weight
It is important to consider the weight of the beam/spreader itself when assessing the total weight of the load placed on the crane hook. Beams, spreaders and frames should have their safe working load clearly marked, with additional markings on individual lifting points.
Handling
There are a number of considerations for handling loads when using lifting beams, frames and spreaders. A lifting beam attached to a crane hook is a load in its own right, and as such, consideration should be given to how to handle it. It may also be found that a lifting beam on its own presents a particularly unwieldy load, therefore care must be taken when the beam is lifted without a load attached.
When manipulating long loads, on a beam with a single suspension point, it is essential to use tag lines. It is important that the tag lines are long enough for personnel controlling the load to be able to stand well clear of it.
In certain circumstances, a load lifted with a beam or frame could foul the underside of a double beam crane. In these instances, if possible, it is advisable to consider adjusting the limit switch of the crane to prevent the load fouling the beam.
Lifting beams, spreaders and frames are usually designed either for a specific purpose or as general-purpose beams for a specified range of lifts. They can vary massively in shape, size and construction to suit a particular application. As an example, Lifting Gear Hire in the UK supplied a custom counter-balance lifting frame to construction contractor Balfour Beatty to help with a bridge building problem. The design of the bridge was unique to the UK; the only other example of its type in the world is built in the Czech Republic. Due to the construction of the bridge, the concrete sections could only be lifted in place from the side. Balfour Beatty needed to lift 20 of the 2.5t concrete bridge sections, manoeuvre them into position and suspend them 30m above the river while they were fixed securely into place. The solution was a custom built counter-balance lifting frame (above). This example demonstrates the great variety of lifting frame configurations that can be used, and their flexibility in meeting an unusual application.
Modular beams
The introduction of modular beams and spreader systems has increased the flexibility and applications in which such equipment can be effectively used. As the beams can be easily shortened or lengthened to suit the precise requirements of a given load, they offer the rigger flexibility in handling unusual loads. The systems can be used in a variety of configurations, offering considerable flexibility to the user.
For example, Lifting Gear Hire has a range of modular beams capable of lifting loads up to 50t. These beam sections range from 1.5m up to 11m maximum. Designed with safety in mind, the main components of the beam are in compression while lifting. The beams can be made up in a variety of lengths using a simple rigging technique for assembly. The working parameters of the beams also limit the operating angles of the slings in an attempt to minimise operator error and thus limit the hazards from overload or imbalance for the operators. Modular beams in general can offer high strength while remaining relatively lightweight.
Lifting beams will continue to be used in a variety of roles and different industry sectors to raise complex and unusual loads. The risks involved must always be minimised with suitable method statements and lifting plans in place prior to any operation taking place. By using the correct equipment, ensuring the risks are minimised and that staff are suitably trained, the job can be carried out without compromising safety.