Tandem Lift Safe Practices

Tandem lifting allows two cranes to lift objects too heavy or too large for one crane to lift. Tandem loading is often employed to place heavy structural beams for bridges, lift long components from horizontal to vertical positions, or move objects near power lines. Small sites can also utilize tandem lifting. Sites with limited space or poor soil conditions might not be able to use a large single crane, but two smaller cranes that sit apart can lift the desired loads. 

Although utilizing two cranes offers excellent lifting solutions, tandem lifts have the potential to become dangerous if not handled properly. A tandem lift requires extensive planning, skillful supervision, and accurate execution. 

Before executing a tandem lift, prepare a written lift plan that discusses aspects like load distribution, lift sequence, and crane position as outlined by OSHA 1926.1432. Tandem lifting plans must be developed by a “qualified person,” and if this person determines that engineering expertise is required, the employer must ensure it is provided. 

The lift must also be directed by a person who meets the criteria for both a “qualified person” and a “competent person.”  A “competent person” can also be assisted by one or more “qualified persons.” Finally, the lift director must review the complete plan in a meeting with all workers who will be involved in the operation.

Lift Factors and Conditions

The goal of a detailed lifting plan is to ensure the lift can be completed safely. For the lift to be safe, the cranes must not be overloaded or side loaded. When a lift involves more than one crane, there are many factors that could cause an overload situation to arise, and they must be accounted for when the plan is developed. Here are a few factors to consider when planning a tandem lift:

Center of Gravity 

It is necessary to know the center of gravity of a load to be able to balance the load correctly and distribute the load between cranes as desired. It is easy to lift, jack, and transport an object whose center of gravity is right in the middle. Tandem lifting becomes more complicated when loads comprise many individual objects with a center of gravity not in the middle. Skids containing products from various suppliers, oilers with pressure vessels located in specific spots, or vessels with varying diameters require personnel to carefully calculate the center of gravity before executing a tandem lift. 

It is also necessary to make provisions for any conditions that could cause a shift in the center of gravity, such as strong winds or fluids in or on the load. If the center of gravity shifts during the lift, the crane nearest the center of gravity could become overloaded. 

Capacities 

There are two possibilities for loading during a tandem lift: equal distribution and unequal distribution. When the load is distributed equally between both cranes, it can be beneficial to use cranes of the same model or the same capacity range. Using two of the same or similar cranes will make it easier to synchronize movements between them, which will help reduce the chance of overloading. 

If the load is not intended to be distributed equally, cranes of different capacities can be used based on the portion of the load that will be carried by each crane. However, using cranes of the same model, even when the load is distributed unevenly, can still make synchronizing movement easier. If the cranes have different movement speeds, the lift plan should define ways to keep the movements synchronized to avoid moving the center of gravity out of the position defined by the plan.

Rigging

Many loads that are being moved with a tandem lift may require the use of additional rigging and lift equipment. Lifting devices, such as equalizer beams, can also help prevent the risk of unintended load distribution due to uncoordinated vertical movements. Equalizer beams can help keep the load distributed evenly in case crane movements become unsynchronized. 

Rigging equipment can also be used to ensure the load is lifted above the center of gravity, rather than below it, for the most stability. Like the cranes, all rigging and lift equipment must have the necessary lifting capacities. Lift equipment can also add significant weight to the load, so the lifting plan must account for the additional weight of any equipment as well as the weight of the load itself.

Side Loading 

Side loading happens when operators lift a load that’s not directly underneath the hoist. Loads can shift from underneath the hoists when doing a multiple lift due to improper coordination. A load out of position will try to position itself directly under the hoist, causing the load to swing horizontally and potentially injuring nearby equipment and personnel. Side loading can also damage crane components like the drums, chain, and sheaves, leading to costly repairs. In the worst-case scenario, the chain can break, causing the load to drop on equipment, personnel, or facilities. 

While crane booms can withstand some side loading forces, it is unsafe to allow horizontal loads or off-center lifts intentionally. The lifting plan should provide ways to avoid side loading, and cranes should be carefully positioned to minimize the side loading risk.

Communication

A tandem lift plan should have a clearly and precisely defined system of communication to avoid any miscommunication and possible unintended movements — you can’t perform a tandem lift without clear communication. The qualified person directing the lift should be the person instructing the personnel who are operating the machines. If necessary, relay persons should be used between the supervisor and operator. The operators and relay persons should know and understand all commands and communications. In case of a crisis, an emergency stop signal should be used by any person who observes an unsafe condition.

Perfect the Art of Tandem Lifting

When operators, planners, and well-suited equipment work in tandem, they can perfect the art of tandem lifting. Tandem crane lifts have the potential to be dangerous, so every precaution must be taken to protect the safety of everyone involved. 

There are many additional factors to consider when planning a tandem lift that has not been described here. The qualified person planning and directing the lift is responsible for identifying all potential hazards and addressing them. The planners should also be aware of any national and local safety regulations, such as derating requirements, and ensure the plan is compliant. Safety is the top priority when executing tandem lifts and all other critical lifts. 

Apart from masterful planning, you’ll also need excellent equipment to execute a tandem lift. Spanco, Inc. retails pre-engineered cranes, and our masterful engineers can customize these lifting solutions — you can easily find a crane that meets your needs. 

All our cranes meet the ANSI, MAA, MMA, and OSHA guidelines and standards and come with industry-leading warranties. Use our system selector tool to find the most fitting cranes for your next lift or contact us online — our knowledgeable customer service team will help you find the best equipment for your projects.