How do you calculate the load capacity of a Spreader Beam?

Capacidades de los balancines de carga

What are the OX Spreader Beams?

They consist of a modular construction of mechano-welded parts based on round section tubes that join together forming a whole that works with compression and that supports buckling with a high safety factor complying with the most demanding EUROCODE and DNV standards .

How are the Spreader beams used?

It is used to lift a load with a crane with different lifting configurations of capacity of a Spreader Beam depending on the points of attachment necessary to distribute the load without damaging the load, from 2, 4 or multiple lifting points.

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Basic concept of the application of the Spreader beams

It is the fundamental concept of the spreader beam, a mechanical structure that separates two legs of a sling, grommet or chain, all of which could only work at a straight tension and converts them into two suspended elements separated by a certain length and they spread the load between them.

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In the tables capacity of a Spreader Beam in our catalog (available for download at the bottom) are developed three typical work configurations: 20, 30 and 45º. Considering the angle that forms the top slings with the vertical one (In case of having the complementary angle it is only necessary to subtract it from 90º to have it). The tables are valid for any value equal to or less than the said angle with the vertical.

The choice between one or another configuration capacity of a Spreader Beam will be due to the height available under hook and considering the length of the entire set of lifting accessories, the height of the load itself and the obstacles and height to be overcome.

On the other hand, it is necessary to consider that the configurations that lose more height are more slender and have a more contained weight. On the other hand, configurations that lose less height are more robust and heavy, which may limit the operation due to the available crane capacity, apart from being more expensive.
Therefore we have a wide range of options capacity of a Spreader Beam to accommodate the product to each application.

What is the range of capacity of a Spreader Beam?

In the tables capacity of a Spreader Beam it is necessary to look for the first product that meets the capacity of a Spreader Beam to the necessary length, then verify that the available height is sufficient considering the formulas shown in the figure of question Nº3. In case the available height is insufficient we would go to the upper model that will allow a greater angle and therefore a lower lost height.

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Case study capacity of a Spreader Beam

In the synoptic table capacity of a Spreader Beam we see the choice of a separator for a load of 150 tons at 20 meters with a free height under hook, discounting the height of the separator and the load of 25 meters.

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1. We check the capacity of a Spreader Beam SB-170 that supports up to 170 tons and check that it reaches that capacity at 20m but only at 20º.

2. We verify by the formula of question # 3 that for the 20º configuration we require a height of 1.37X, that is, 27.4 meters of height, which exceeds the predetermined height requirement in this example case. So we must dismiss this model.

3. We would pass by checking the SB-170/250 that supports up to 250 tons At 45º it reaches 162 tons but only up to 12 meters. At 30º it reaches 152 tons but at 17 meters. Finally at 20º it reaches 170 tons at 20 meters but at 20º the same thing happens as in section 2 and we must also dismiss it.

4. Now check the SB-250. We directly dismiss the configuration at 20º because it does not give the height. And we find that the capacity at 30º at 20 meters is up to 250 tons for what it meets.

5. We now check the height and it gives us that it is 0.87X, that is 17.4 meters, therefore it meets the requirement.

6. Once the model of the tube sections of SB-250 has been chosen, it is possible to consider placing terminals of smaller capacity so as not to force the use of shackles for a total capacity of 250 tons for only 150 tons. And at the same time reduce the weight itself. For this purpose there is the product “Cone adaptor”.

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In this capacity of a Spreader Beam case it is about completing the length of 20m,
If we discount the two terminals of SB-170 of 1 meter and the two cones of also 1 meter, we have 16m left that can be completed with 4 sections of 4 meters.

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What more applications can we make with a Spreader beams?

In next newsletters we will develop the Corner Unit or Spreader Frames that allow joining 4 spreader beam forming a rectangle that allows to have 4 attachment points in a single stage of spreader suspended by a four leg sling.

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