Two cranes working in tandem on a heavy lifting project, showcasing expert rigging and precision cranage services in South Africa.
When a lift exceeds what a single crane can safely achieve — whether due to weight, geometry, or site restrictions — rigging teams turn to tandem lifting. A tandem lift uses two cranes working in precise coordination to share the load and complete the operation safely. This guide explains what tandem lifting involves, when it is required, and what makes it one of the most technically demanding operations in industrial rigging.
What Is a Tandem Lift?
A tandem lift is any lifting operation in which two cranes work simultaneously to move a single load. Each crane takes a calculated share of the total weight based on its position relative to the load’s centre of gravity. Every movement — vertical, lateral, or rotational — must be executed in perfect synchronisation. If one crane moves faster than the other, or if the load shifts unexpectedly, weight distribution changes instantly, placing unplanned stress on both machines. This is what makes tandem lifting so demanding: there is very little margin for error.
When Is Tandem Lifting Required?
Tandem lifts are typically required in the following situations:
- The load exceeds the capacity of a single available crane — combining two cranes allows the team to manage loads that no single machine on site can handle.
- The load is too long for a single crane to manage — vessels, beams, and columns that are 20 to 50 metres in length often require two pick points to keep the load stable.
- Site access prevents positioning a single large crane — two smaller cranes positioned at different access points can sometimes achieve a lift that one large crane cannot reach.
- Precise orientation during installation is required — tandem lifts allow the load to be rotated from horizontal to vertical (or vice versa) in a controlled manner.
How Is a Tandem Lift Planned?
Tandem lifts require a formal rigging plan that includes the following elements:
- Load weight and centre of gravity — the exact weight of the load must be verified and the centre of gravity calculated or physically established. An error here directly affects how weight is distributed across both cranes.
- Crane capacity and configuration — each crane’s rated capacity must be sufficient for its share of the load, including a defined safety factor. Both cranes must be derated to a maximum of 75% of their single-crane capacity when used in tandem, per standard industry guidelines.
- Rigging geometry — the positions of the lift points, the angle of slings, and the height of the load at each stage must be modelled before the lift begins.
- Communication protocol — a single banksman or lift supervisor gives all commands. The two crane operators must be briefed, confirmed ready, and moving only on instruction.
What Are the Safety Requirements for Tandem Lifts in South Africa?
Under South African law, tandem lifts are classified as critical lifts. The Occupational Health and Safety Act and its Lifting Machine Regulations require that critical lifts are carried out under a formal lift plan that has been reviewed and signed off by a competent person before operations begin. Both crane operators must hold valid operator certificates, and all rigging equipment must carry current load test certificates.
In addition to regulatory requirements, professional rigging companies follow guidelines from organisations such as the Crane Owners Association of South Africa (COA) and international standards such as ASME B30.5 when planning tandem lifts.
What Types of Loads Are Commonly Lifted in Tandem?
Reef Rigging has completed tandem lifts involving industrial boilers, pressure vessels, steel tanks, long-span structural beams, processing vessels, and heavy manufacturing plant. These projects span industries including food and dairy, chemical processing, tyre and rubber manufacturing, and steel fabrication.
Learn more about our cranage and heavy lifting services, or contact the Reef Rigging team to discuss a tandem lift requirement.
Frequently Asked Questions: Tandem Lifting in Industrial Rigging
How do you calculate the load sharing in a tandem lift?
Load sharing in a tandem lift is calculated based on the position of each crane’s pick point relative to the load’s centre of gravity. The closer a crane is to the centre of gravity, the greater its share of the load. These calculations must be performed by a competent person and documented in the lift plan before the operation begins.
What is the maximum capacity reduction for a tandem lift?
Industry practice requires that each crane in a tandem lift operates at no more than 75% of its rated single-lift capacity. This derating accounts for dynamic load variations that occur when two independent machines move simultaneously. The exact derating factor may vary based on the lift plan and the specific equipment being used.
Can any two cranes be used for a tandem lift?
Not necessarily. For a tandem lift to work safely, both cranes must be positioned to allow the required rigging geometry, the operators must be experienced with tandem operations, and communication between the two must be clear and unambiguous. The lift plan will specify whether the proposed crane combination is suitable for the load and site conditions.
What happens if the load shifts during a tandem lift?
If the load shifts during a tandem lift, the weight distribution across the two cranes changes. This can cause one crane to be overloaded while the other is underloaded. The immediate response is to stop all movement and reassess — which is why experienced operators who can recognise changes in load dynamics quickly are essential for tandem operations.