Ensuring continuous uptime: Safely deferring crane inspection

Crane inspection case study

Asset type: Crane
Location: North Sea

Project challenges
LR’s Asset Integrity Services team has carried out slew ring deferral work for over five years for the client, as well as carrying out additional lifting integrity work on their assets such as cranes, lifeboat davits, Written Schemes of Examination and failure investigations.

On the platform, situated off the east coast of Scotland, both the slewing bearings on the East and West cranes were approaching 20 years' service. Annual inspection is deferred by interpreting condition monitoring data to support a case that the integrity of the bearing is satisfactory. The condition monitoring results had begun to affect the overall trend of data negatively indicating that the bearings required inspection and potentially replacement.

Additional significant remedial works had been planned for both cranes, however, the sequence of events dictated that the West crane was taken out of service first. A Certificate deferring removal of the East crane's bearing for inspection was required to allow for continuous crane capacity during the West crane’s downtime. Without crane availability the platform could not bring on materials critical for the day-to-day operation of the asset.

Scope of work
We conducted the assessment of data relevant to deferring the removal of the East crane’s slew bearing for inspection. We considered the most recent sets of data and the overall trend of information in order to approve or deny a Certificate for deferral before expiry of the previous deferral period.

LR approach
The methodology for this project was applied in scopes involving deferral of maintenance and/or utilisation of specialist inspection data. The results from the initial assessment were not supportive of a deferral, therefore, working collaboratively with the client's Technical Authority and their mechanical handling sub-contractor, we prescribed the frequency and content of condition monitoring results for the East crane. The Frequency of Grease analysis was increased to reflect the upward trend of wear metal content and particle size, and sampling was also spread evenly across the agreed six-month period.

A six-month deferral was considered appropriate and granted to the client. Safe operation of the crane in accordance with the Lifting Operations and Lifting Equipment Regulations with reference to the Technical Guidance on the safe use of lifting equipment offshore was also established.

Our expertise in this area led to the collation and assessment of condition monitoring data, thus a comprehensive understanding and interpretation of the Technical Guidance resulted in a smooth and efficient spread of activity over the six-month period. Our effective interpretation of the results meant our prescribed course of action ensured the crane did not have to be taken out of operation. AIS Lifting continued to interface with the client during the deferral period to provide a record that conditions of deferral had been met within the deferral period.

Continued availability of the crane enabled the continuation of supply boat operations, drilling and well services, maintenance operations and in this case maintenance of the platform's West crane.

If a temporary crane had to be installed the hire costs could have been in excess of 50,000GBP.


  • Continued availability of the crane
  • Avoided interruption to operations
  • Avoided hire costs of temporary crane
  • Assurance that the crane was fit for purpose and compliant