With no areas highlighted in the safety case for laydown, operations were using available deck space without knowledge of laydown capacity. This meant that key areas of the platform were potentially overloaded causing safety concerns.
Apollo were tasked with reviewing the the clients’ document management system and performed a structural analysis for each area that operations identified as areas used for laydown. The final report aided the Technical Authorities in understanding capacity and limits which helped define the laydown limits for each area. This was then published in the safety case for the platform for the operations team to utilise, knowing the areas had no structural integrity issues.
The background
The laydown area loading limits for the platform were not clearly identified leading to uncontrolled overloading of the area by the offshore deck crew. There is inconsistent historical data and uncontrolled documents being used by the platform, with no evidence of structural assessments being completed. A structural assessment was therefore required for 31 areas used by platform operations and a set of laydown loading drawings were therefore required to be included in the platform safety case.
The process
Apollo reacted quickly to review the document management system, review inspection reports, review 3D photogrammetry data and complete assessments.
The deliverables
Apollo completed a data recovery from the clients’ document management system. A structural analysis for each area was completed with a stepped loading regime applied with a 10% corrosion allowance applied to all structural sections. Hand calculations, latterly backed up with finite element analysis, was completed on the point load capacity of the deck plate. A design report was then delivered to the client which illustrated the utilisations of the secondary and primary steel for the full spectrum of loading to aid assessment by the TA in future scopes which applied one-of loadings on any of the areas beyond the laydown limit assessed.
What did the client think?
The design report and drawing deliverables deliverable were immediately praised by the client for the thoroughness and clear demonstration of the laydown area capacities with a loading spectrum. The point load capacities were lower than expected for the majority of the laydown areas, so further work was agreed to refine the hand calculations with FE Analysis which resulted in only minor increases in allowable point loads, therefore acknowledged by the client to show that Apollo’s hand calculation assessment technique to have been both appropriate and time-efficient.
The client has followed up with Apollo to assess in the exact same approach the laydown capacities of the 19 laydown areas on another platform due to the “very impressive work”
And for all you engineers who just want the facts:
The Problem
- The laydown area loading limits for the platform were not clearly identified and no evidence of structural assessments been completed with no areas highlighted in the safety case.
The Solution
- A structural analysis for each area was completed. Hand calculations, latterly backed up with finite element analysis, was completed on the point load capacity of the deck plate. A design report was then delivered to the client which illustrated the utilisations of the secondary and primary steel for the full spectrum of loading to aid assessment by the TA in future scopes which applied one-of loadings on any of the areas beyond the laydown limit assessed.
The Outcome
- The design report and drawing deliverables deliverable were immediately praised by the client for the thoroughness and clear demonstration of the laydown area capacities with a loading spectrum. The client has followed up with Apollo to assess in the exact same approach the laydown capacities of the 19 laydown areas on another platform.