What Is Rigging? How Heavy Machinery Is Safely Lifted and Moved

Moving heavy machinery involves much more than attaching it to a crane. There are many factors to consider including the weight, potentially unbalanced center of gravity and numerous delicate parts.

As such, prior to moving this type of equipment (or any equipment) the weight of the object must be assessed, secured and controlled.

This evaluation process of preparing, securing and controlling loads for safe lifting, moving or placement is referred to as "rigging."

What is Rigging?

Rigging is the preparation, securing and control of a load that can be safely lifted, moved or placed. In addition to describing the process of preparing a load for lifting, the term "rigging" can describe the slings, shackles, hooks etc. used to attach a load to a crane, hoist or lifting apparatus.

Rigging is commonly used to move:

• Motors and generators

• Pumps and compressors

• Conveyors

• Tanks and pressure vessels

• Manufacturing equipment

• Structural steel

• Prefabricated building components

Every load is different. Its weight, shape, balance, lifting points and final destination must all be considered before movement begins.

How Is a Rigging Plan Developed?

Developing a plan for a successful rigging operation takes place prior to the actual load leaving the ground. 

The individuals involved in developing this plan must determine exactly what type of load is being moved; where it will end up; and under what environmental conditions the load will be moved.

Load Weight

The weight of the load must either be previously known or accurately estimated. All components of the rig including: slings, shackles, hooks, and lifting devices must have sufficient rated capacity to withstand all forces applied upon them during a lift.

Center of Gravity

Loads must be attached at points which allow them to remain balanced. Incorrectly rigged loads will likely swing, pivot or otherwise unexpectedly apply forces against the rigging system after having been lifted.

Lifting Attachments

Individuals involved in the development of the rigging plan must first determine acceptable attachment points capable of supporting the weight of the load.

Travel Route

Various obstacles can influence travel directions such as doorways; overhead utilities; surrounding machinery; flooring conditions and available clearance space.

Landing Location

Upon completion of the lift, personnel involved in the landing portion of the project must prepare the final landing point to enable safe lowering and disconnecting of the equipment, followed by connection and assembly.

In an industrial setting, planning for both internal and external routes becomes increasingly complex as the amount of clearance decreases.

Common Rigging Gear and Lifting Equipment

Rigging devices and lifting devices serve somewhat different functions. Rigging devices connect, secure, and control the load. Lifting devices supply the necessary energy to move the load.

Slings

Slings connect a load to a crane, hoist or other lifting mechanism. Wire rope slings are among one of the most popular forms. Other examples include alloy chain slings and synthetic slings.

Selection of a particular type of sling will depend upon both the load being lifted and/or operating environment. 

Synthetic slings are generally lighter than wire rope slings and do not damage finished surfaces however they are subject to cut by sharp edges. 

Slings may also be configured as verticals; chokers or baskets depending upon both shape, balance & approved lifting locations on the load.

Hooks and Shackles

Hooks and shackles make connections between slings/lifting devices & loads. Both items must be correctly selected, secured and rated based on their expected loading.

Hoists and Chain Falls

Hoists and chain falls provide controlled lifting power. They are commonly used to raise, lower and precisely position machinery, particularly inside industrial facilities where crane access may be limited.

Cranes are generally used for larger lifts or when equipment and structural components must be moved across an open site.

Spreader Bars and Lifting Beams

Spreader bars and lifting beams distribute weight across multiple lifting points. They help stabilize long, wide or unusually shaped loads and can reduce the inward pressure placed on the load by the slings.

Although they perform similar functions, they handle forces differently and must be selected based on the load and planned lifting arrangement.

Who Is Involved in a Rigging Operation?

A rigging operation may involve several professionals with different responsibilities.

The rigger selects and installs the gear used to secure the load. The signal person communicates movement instructions when the operator cannot clearly see the load or landing area. The crane operator controls the equipment performing the lift.

One person may be qualified to perform multiple roles, but the responsibilities are not automatically interchangeable. Clear communication between everyone involved helps keep the load controlled throughout the move.

Why Proper Rigging Matters

A load that appears stable on the ground can behave differently once suspended. It may swing, rotate or place unexpected force on individual rigging components.

Qualified riggers must be able to select appropriate equipment, inspect its condition, recognize potential hazards and properly secure the specific load being moved. OSHA requires employers to ensure that riggers are qualified for the work they perform.

Rigging equipment used for material handling must also be inspected before use. Damaged or defective equipment must be removed from service, and rated working-load limits cannot be exceeded.

Conclusion

Successful rigging requires more than lifting power. It depends on careful planning, properly rated equipment and experienced professionals working together to keep every load controlled. 

Whether installing machinery, relocating equipment or positioning structural components, proper rigging helps ensure the job is completed safely and accurately.