Having looked at different types of spreader beam in the second instalment of this column, here we look closer at the differences between spreader and lifting beams to help users select the best one for their application.
Remember, lifting beams are designed for a bending moment whereas spreader beams that incorporate top rigging are designed for a compressive load. Like many manufacturers in the below-the-hook world, we make more lifting beams than spreader beams.
It’s notable that many of these lifting beams are bespoke and provided with lifting points for a specific type of load. Of Caldwell’s spreader beams, only half are customised accordingly. Standard spreader beams are manufactured up to 130-ton capacity; lifting beams to 40-ton capacity.
The two primary considerations when deciding whether a spreader beam or lifting beam is required are headroom and load stability related to centre of gravity location.
When choosing a lifting device for large loads, a rigger can gain additional capacity using a spreader beam versus a lifting beam because of the increased dead load of the lifting device while considering the rated capacity of the crane or hoist. With a spreader beam, the top rigging will support most of the load in its hardware.
A lifting beam has a lower headroom because of the absence of top rigging, as required by a spreader beam. It is for this reason that many people think of spreader beams being used outside where headroom or vertical clearance isn’t an issue. It’s a fact that traditional lifting beams are commonly used indoors where users have headroom considerations, and the load is balanced and stable.
The stability of a spreader beam is a result of this taller headroom too, plus a lower centre of gravity from the crane hook attachment to the point of the assembly (lifter and load); lifting beams have a single lifting point. To add stability to a lifting beam, a second bail can be used if there are two cranes to vertically hoist the lifting beam and load. Typically, twin bails require two cranes to lift. Twin bails shall not be used for angled top rigging (unless designed for this) due to the angles and forces that the lift beam will see.
Spreader beams are often lighter weight for the loads versus a lifting beam, due to the design and top rigging, as discussed.
Adjustable spreader beams
There are a handful of companies globally that make adjustable spreader beams; The Caldwell Group’s is the Dura-Mod range. These products are a versatile, lightweight alternative to fixed and multiple point below-the-hook solutions up to, say, 170-ton capacity.
Each of these systems will consist of a pair of end fittings and drop links, and two upper and lower shackles to make the shortest possible configuration. From there it is a case of combining intermediate spreader sections to achieve the required span. The single longest component is only 20ft.
If a four-point or rectangular spreader frame is required for an Application, users just need to remove the end fittings and add corner sections – the struts are the same. All such spreaders utilise standard shackles that are available from all major manufacturers. The manufacturer specifies top sling lengths, while the load determines lower rigging.
