Consideration of Collision Damage in FPSO Structural Design

Abstract

Abstract

A collision event may be catastrophic for an offshore facility or a floating production, storage and offloading unit (FPSO). Depending on the size and speed of the impacting ship, anything from damage to hull rupture, oil pollution, flooding, loss of buoyancy, capsizing, and sinking may occur. Supply vessels and tankers frequently visit the FPSO to transport consumables and chemicals and, consequently, there is a risk of collision between two structures. Hence, during structural design, special attention is required to minimize damage from such accidents. This study includes the results of collision impact analyses on side shell, bow and stern structures of FPSO against striking vessel, such as supply boat and methanol tanker. Non-linear Finite Element analysis, using large deformation FEM is applied to analyse the damages to FPSO hull structures. The extent of FPSO hull damage due to the different collision scenarios and impact energy levels are determined using the guidelines contained in the NORSOK Standard. For estimating the structural strength, the maximum stresses from the collision analysis results are compared with the stress limit as per NORSOK Standard with consideration of strain rate enhancement. Finally, the paper summarizes an effective evaluation procedure and design criteria for probable scenarios of impact accidents.

Keywords: Collison damage, impact scenarios, FPSO platforms, hull design