BACKGROUND
In heavy industry, lifting lugs are deceptively simple, yet critical components. These robust metal fixtures, often a reinforced hole, plate, or part of the main structure, provide the connection point for cranes and rigging equipment to lift massive machinery, such as dump truck bodies, transport frames, or entire sub-assemblies. While small, their failure can result in catastrophic consequences, including equipment damage, injuries, fatalities, and site shutdowns.
Given the high stakes, accurate design and rigorous assessment of lifting lugs is essential – an area where specialist engineering firms like CMP Engineers play a vital role.
Based in Brisbane, Queensland, CMP Engineers has developed a strong reputation for its expertise in mechanical failure analysis and design, including lifting lug assessments for clients across the mining, construction, and manufacturing sectors. The company’s role often bridges the gap between safety assurance and real-world practicality, helping clients understand and meet the demanding requirements of standards such as AS4991 (Lifting Devices) and ISO 15818 (Lifting Lugs for Equipment).
CHALLENGE
CMP Engineers was engaged to assess the lifting lugs fitted to a boom section of a mining excavator. The lugs had been found with significant distortion, so CMP Engineers was engaged to determine if they were fit for continued use.
Despite the lugs being part of the OEM design, there were concerns that the lift planned for the boom section would exceed the required factors of safety. ISO 15818 mandates that lifting lugs:
- Must withstand a 1.5x overload without permanent deformation.
- Must not fail before reaching a 4x overload.
The bent lugs were a clear indication that the stresses in the lugs during the lift were not within safe limits.
SOLUTION
CMP assisted the client by utilising Finite Element Analysis (FEA) to simulate the behaviour of the lifting lug design under load.
The FEA clearly indicated that, with the lift as planned, the out-of-plane loading on the lugs generated very high stresses. Worryingly, the lugs appear to have already been used in a similar lift, so this also explained the distortion. Overall, with the applied load resulting in significant out of plane bending within the lug, the lug design would not meet the requirements of the ISO standard and would have an increased risk of a catastrophic lug failure.
In addition to this specific case, CMP has reviewed numerous other lifting arrangements on various equipment designs. In some instances, they had to:
- Reduce the working load limit (WLL) to achieve compliance.
- Reinforce or modify the design to lower the stresses
- Reject the components outright, particularly when attempting to determine compliance for older equipment.
OUTCOMES
CMP’s analysis clearly identified that the lifting lug design would not meet the requirements of the ISO standard for the lift that was planned. Ultimately, a change to the lifting procedure was required.
In general, by engaging with CMP Engineers to review the design of lifting components, our clients can:
- Avoid potential equipment failure and downtime.
- Protect workers from a known high-risk failure.
- Improve internal quality assurance and design protocols for future manufacturing.
Why it matters
With workplace health and safety laws tightening and mine inspectors increasingly enforcing documentation and design compliance, lifting lug certification is more important than ever.
As Peter Hockings, Senior Mechanical Engineer at CMP, notes: “Just because it has worked for 20 years, doesn’t mean it’s safe or compliant with the requirements of the relevant standards. CMP is frequently called in to review equipment with undocumented lugs. A proactive, engineering-first approach reduces ambiguity and ensures organisations meet both compliance obligations and safety expectations.”
Beyond analysis: building better practice
The mechanical engineers at CMP don’t just assess failures – they help prevent them. Through training initiatives, like the Making Metal Work course, engineers like Peter are educating clients and contractors on best practices to avoid structural failures and costly repairs.
Incorporating compliant, load-rated lifting lugs from the outset, rather than improvising later, saves cost, time, and most importantly, it reduces risk. It’s a lesson that smart operators are taking seriously, with CMP leading the way in engineering assurance.
Contact CMP Engineers on +61 7 3839 2045 or email@cmpeng.com.au, or visit www.cmpeng.com.au for more information.