Wire rope life extension analysis

Benefits

• Life extension of wire ropes from one year to two year service
• Enhanced knowledge and understanding of rope wear versus usage rate
• Cost saving of £50-60K per crane analysed on each rope replacement
• Recommended pressure lubrication to aid life extension
• Opportunity to continue analysis to aid further life extension.

Challenge

One of our key customers requested that we carry out a research project to analyse the usage and wear rate of their crane wire ropes, with a view to extending their life from one year to two years.

They recognised the potential cost savings in materials, manpower and crane downtime that could result from extending the life of their wire ropes but required a sound technical justification to mitigate the risks before sanctioning such a change. To ensure that they received quality specialist advice they engaged us, who have been their incumbent mechanical handling specialists for over 40 years, to carry out the research.

We assigned one of our research students at Robert Gordon’s University to lead the study.

Solution

• Utilising our knowledge and understanding of crane wire rope construction we compiled a list of all rope types that were to feature in our analysis project. We then engaged with the technical specialists from the rope manufacturer Bridon to better understand the manufacturing process used
• Each time a rope was returned following use it was subjected to a detailed magnetic inspection with a specific focus on broken wires and loss of metallic area at that point. The results were compared against the discard criteria set out in ISO 4309-2010 to establish if the rope was fit for further use
• For each rope tested the usage rate of the crane over the operating life of the crane was reviewed to establish any trends and aid in the evaluation for extended use
• The results were then compared against those of cranes of similar construction and usage rate that have been operating with a two year wire rope life to provide assurance that our evaluation was not only theoretical based
• Our findings showed that out of the 50 ropes tested 47 (94%) were deemed fit for continued use while the remaining three were shown to have suffered mechanical damage outside normal operating conditions
• The analysis report was reviewed and accepted by both the wire rope OEM and the customer. It offers them further opportunity to continue this analysis approach to aid potential further life extension in the future.

Summary

• Technical literature review for wire ropes
• NDT equipment
• MIPEG load history
• Historical rope inspection data.