Crack Location Effect on the Weld Connections of FPSO Helideck Structure Toward Safety Management

Abstract In the oil and gas industry, ensuring the structural integrity of Floating Production, Storage, and Offloading (FPSO) units is critical for maritime operational security and meeting energy demands. The helicopter deck (helideck) of an FPSO, which supports helicopters for personnel and cargo transport, is subject to significant static and dynamic loads, as well as harsh environmental conditions. Helideck structures, consisting of numerous truss/beam elements, are prone to cracking at welded joints. This study investigates the influence of crack locations on the strength and durability of welded connections in FPSO pipe stiffeners. A numerical analysis was conducted using the Finite Element Method (FEM), and the model was validated through a mesh convergence study, ensuring accurate stress intensity factor (SIF) calculations. The Linear Elastic Fracture Mechanics (LEFM) approach is used to analyze the characteristics and propagation rate of cracks at different weld locations. The analysis shows that cracks at the weld toe reached a critical depth after 158 load cycles, compared to 817 cycles for cracks at the weld crown. These results underscore the higher vulnerability of weld toe cracks to rapid propagation, highlighting the need for targeted design and maintenance strategies to ensure the safety of FPSO helidecks.