Oil & gas
The White Rose Field Development
Subsea Production System (SPS), located approximately
350 km off the east coast of Newfoundland, will be
developed using subsea wells tied back to a Floating/Production/Storage/Offloading
(FPSO) Vessel. The FPSO will be moored in position
through nine mooring piles. The mooring piles will
be handled using an offshore crane and specially designed
pile lift tool (PLT).
Martec Limited was contracted to carry out a finite
element (FE) analysis of the PLT for the three most
critical load cases to which the lift tool will be
subjected. The PLT is a plated, tubular structure
containing two lifting trunnions. It is designed to
slide over the end of the pile and rest on the upper
ring of the pile. The specialized FE program HyperMesh
was used for pre and post-processing, and the general
purpose FE program ANSYS was used to analyse the pile
lift tool model.
The three load analysed cases
were:
1. Submerged pile in vertical lift position
2. Submerged pile in horizontal lift position, with
pile rotation due to eccentricity
3. Submerged pile in horizontal lift position, no
pile rotation (global stresses only).
For the case with no pile rotation, Martec carried
out a preliminary design and analysis of an anti-pile
rotation bracket.
The results of the PLT analysis indicated that stresses
for all load conditions were within the allowable
limits. However, the stresses for the preliminary
design of the anti-pile rotation bracket were found
to be above the allowable stress. Based on recommendations
from Martec, the final design and analysis for the
anti-pile rotation bracket was carried out by Technip.
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