Below the hook: In need of TLC

4 August 2023

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It is possible to safely lift curved plate or pipe, as found in many manufacturing applications, with specially designed clamps, writes Dale Kelly, engineering manager at The Caldwell Group.

As we discovered in a recent edition, clamps for lifting come in many designs and are used in hundreds of applications, including working with plate steel, ingots, slabs, concrete barriers, pipe, coil steel, paper bales and paper rolls.

As we also shared, clamps are designed to generate a clamping force perpendicular to the surface of the load. These forces are generated from the clamp geometry by the pulling force on the lifting shackle of the clamp or tightening of a screw. Clamps can be used for attaching loads to a hoist, or for other load-handling purposes, such as anchoring or positioning.

Two final takeaways were that it is important to source them from a reputable manufacturer; and, as modifying clamps isn’t advised without consulting the manufacturer and might not be suitable at all, much of safe operation starts with selecting the right clamp for the job in hand.

So, what then if a need arises, either in a one-off scenario or as part of a production line, to lift and turn single curved plate or pipe from horizontal to vertical and vice versa? There are special clamps to help with just that task.

We call one of our clamps for this purpose the turning, locking, curved surface (or TLC) model, which lifts and turns from 0º to 90º, incorporating a vertical lifting clamp with a ‘lock open’ and ‘lock closed’ feature, facilitating attachment and removal from the load. A specially designed cam jaw is made to safely lift curved surfaces and flat plate.

Remember, the load being lifted must be able to support the amount of squeeze that the clamp applies to the load.

In many manufacturers’ lines, these clamps were designed as enhancements to other clamps that might have been capable of turning a single plate or load from horizontal to vertical and back to horizontal through the same 90º arc. In all these types of clamps, you can expect to find standard versions in 0.5 to 20-ton capacity.

As is often the case, enhancements are originally made as a bespoke solution to an end-use requirement, but then enough applications involving, in this case, curved plate or pipe, emerge and standard production soon follows.

Turning, locking, curved surface clamps are primarily used to lift pipes, but they can also lift any curved surface that meets the clamp’s minimum radius specifications. The minimum radius is different for each tonnage of clamp, but it can lift any size from the minimum radius up to a flat plate. As a clamp gets bigger the minimum radius of plate needs to get bigger. For instance, a 1.0-ton clamp can lift a smaller pipe than the 10-ton version.

There are alternative solutions out there, but it is best to use a clamp that is specifically designed for pipe and curved plate if that is the material handling challenge presented.

It’s worth reiterating that distributors and end users note that there is no need for a specific radius, only a requirement to meet the minimum radius size. If you’re sourcing from a reputable manufacturer, each model should be clearly marked with the minimum radius, serial number, capacity, jaw opening, service class, design category, and all the information required for safe use.

We saw initial interest in the concept in the US, but the international market has consumed several units and export is expected to grow over time. Of course, it is possible that you can find a domestic or local supplier, perhaps one that already provides you with more traditional lifting clamps.

In these clamps, a specially designed cam jaw is made to safely lift curved surfaces and flat plate.