Collision Damage Analysis of FPSO Hull Caisson Protection Structure

Ozgur Ozguc

doi:10.7225/toms.v09.n02.001

Abstract

The protection structures for the Floating Production Storage and Offloading (FPSO) caissons should be sufficiently strong to avoid contact with the caisson pipes even when the protection structure is damaged by the impact of the accompanying vessels. Collision events of protectors of appurtenances such as risers, mooring lines, and seawater lift caissons with supply vessel may cause structural damage to protection structures and even to the appurtenance structures and hull structures. This study introduces the collision impact analyses on three protective structures of FPSO against striking supply vessel whose displacement is 7,500 tons. The capacity of protection structures in view of strain energy has been assessed with simple beam FE models. The striking vessel has been modelled as a small rigid body, and impact simulation has been performed including material and geometric nonlinearities where ABAQUS Explicit tool, which is a commercial explicit code, has been used for non-linear collision analyses with protection structures. The results from the current work will be a guide to understanding the impact response of offshore structures and evaluation approaches, and will provide useful indications for the FPSO hull caisson protection design and operation. In addition, the findings obtained by the current study will be informative in the safe design of FPSO facilities.

Highlights

Collision is a major threat to the safety of a ship or other offshore facilities and can result in significant economic damage, environmental pollution, and death
Caissons for seawater lift and discharge are normally positioned on the side shell structure
External vertical caissons fitted with strainer and submerged lift pump for seawater intake, running along the side shell are used

Summary

Introduction

Collision is a major threat to the safety of a ship or other offshore facilities and can result in significant economic damage, environmental pollution, and death. Because the cost of repairing the offshore structure is higher than that of the striking ship, a number of studies have focused on the method of increasing the crashworthiness of the offshore structure during accidental collision scenarios (ISSC 2018). These collision events could cause substantial damage to an offshore installation and, for a Floating Production Storage and Offloading (FPSO), the puncture of cargo tanks could result in significant spillage of hydrocarbons as well as the loss of life, disruption of safety functions and loss / delay of production. FPSOs are efficient deep-water and ultra-deep-water production facilities and their key benefit is the ability to store and process the hydrocarbons

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