Lift Studies: Why a Safe Crane Lift Also Requires Engineering of the Equipment Being Lifted
Lifting heavy industrial equipment involves much more than selecting a crane with sufficient capacity.
A conventional lift plan considers critical factors such as crane capacity, lifting radius, ground conditions, rigging configuration, clearances and site conditions. These are essential elements of any safe lifting operation.
However, there is another important question:
Can the equipment being lifted safely withstand the loads created during the lift?
At Trang Imagineering, our engineers undertake Lift Studies and Lifting Engineering that consider not only the lifting equipment, but also the structural behaviour of the item being lifted.
A Lift Creates Loads the Equipment May Never Experience in Service
Industrial equipment is generally designed for loads encountered during normal operation.
Lifting can create a completely different load case.
A vessel, tank, skid, module, hopper, conveyor section or piece of machinery may be perfectly capable of carrying its normal operating loads but experience significant local stresses or distortion when supported from only a few lifting points.
An engineered lift study may consider:
Equipment weight and centre of gravity
Lift point locations
Sling angles and resulting forces
Local stresses around lifting points
Load distribution between lifting points
Equipment distortion and deflection
Temporary load paths
Dynamic effects
Rigging geometry
Stability during lifting and rotation
Understanding these loads is particularly important when lifting large, flexible or irregularly shaped industrial equipment.
Are the Lifting Points Strong Enough?
A lifting lug should not be assessed in isolation.
The load applied to the lug must ultimately transfer into the surrounding structure.
Depending on the equipment, this can involve checking:
Lifting lugs and trunnions
Welds
Local plate stresses
Supporting beams and stiffeners
Shell stresses
Bolted connections
Buckling and local instability
Overall structural behaviour
Where conventional engineering calculations are not sufficient, Finite Element Analysis (FEA) can be used to investigate complex load paths, local stresses and deformation during the lift.
This is particularly valuable for tanks, pressure equipment, fabricated machinery, process skids and other large industrial structures.
Lifting Beams and Spreader Beams
Sometimes the safest lifting solution is not to make the equipment being lifted stronger.
It is to change the way the lifting loads are applied.
Trang can design special-purpose lifting beams, spreader beams, lifting frames and engineered lifting devices to create a safer and more controlled load path.
A purpose-designed lifting device can be used to:
Reduce sling angles
Control horizontal forces on lifting points
Distribute loads between multiple lifting locations
Maintain equipment geometry
Reduce local stresses
Avoid interference with equipment
Control the orientation of the load
Allow complex or unusual equipment to be safely lifted
For example, a large fabricated vessel may have lifting points capable of carrying vertical loads but may not be suitable for the substantial horizontal forces created by angled slings.
A correctly designed spreader beam can change the rigging geometry and significantly reduce those forces.
In other situations, a custom lifting frame may be required to distribute loads across several structural locations or support an item during lifting, rotation or installation.
Engineering Specialised Lifting Equipment
Specialised lifting devices require engineering in their own right.
Depending on the application, the design may include assessment of:
Beam bending and shear
Compression and buckling
Lifting lugs
Pin and hole bearing
Welded connections
Shackles and rigging interfaces
Load combinations
Stability
Fatigue, where appropriate
Proof load requirements
Relevant Australian Standards may include AS 4991 – Lifting Devices, AS 1418 – Cranes, Hoists and Winches, AS 4100 – Steel Structures, AS/NZS 1554 – Structural Steel Welding, together with other applicable standards and project-specific requirements.
The objective is to develop a lifting arrangement in which the crane, rigging, lifting device and equipment being lifted operate as one engineered system.
Mechanical and Structural Engineering Working Together
Complex lifts are another example of why combining Mechanical and Structural Engineering can produce better project outcomes.
Mechanical engineers understand the equipment, its function, mass distribution and operational requirements.
Structural engineers can assess the load paths, lifting points, supporting structure and temporary stresses generated during lifting.
Together, these disciplines can determine not simply whether a crane can lift an item, but whether the entire lifting system can safely withstand the operation.
Lift Studies for Existing Equipment
Engineering assessment can be particularly valuable when relocating or replacing existing equipment.
Original lifting drawings may be unavailable, equipment may have been modified, corrosion may be present, or existing lifting points may not have been designed for the proposed lift configuration.
A Lift Study can provide engineering confidence before the equipment leaves the ground.
Trang's lifting engineering capabilities can include:
Lift studies
Lifting point assessment
Lifting lug design
Spreader beam design
Lifting beam design
Custom lifting frames
Structural analysis
Finite Element Analysis (FEA)
Equipment centre-of-gravity assessment
Existing equipment verification
Temporary works and lifting support design
Engineering the Whole Lift
A safe lifting operation requires experienced crane operators, riggers and doggers who understand how to execute the lift safely on site.
Engineering adds another layer to that process by considering something that cannot always be determined from crane capacity charts or rigging arrangements alone:
What is happening structurally to the equipment while it is being lifted?
By considering the crane, rigging, lifting device and lifted equipment as an integrated system, potential problems can be identified before the lift takes place.
At Trang Imagineering, we combine practical industrial experience with Mechanical Engineering, Structural Engineering and Finite Element Analysis to develop safe, practical lifting solutions for complex industrial equipment.
Planning a complex or unusual lift? Trang Imagineering can provide Lift Studies, lifting point verification and the design of specialised lifting beams, spreader beams and lifting devices to support a safe and practical lifting solution.