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All Journal IJOCE (International Journal of Offshore and Coastal Engineering)
Fajar Rachmadiarto
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Engineering

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Line Clashing Probability Analysis of Catenary Anchored Leg Mooring with Quadraple Marine Hose Configuration Gumilang Alhafiz; Murdjito; Eko Budi Djatmiko; Fajar Rachmadiarto
International Journal of Offshore and Coastal Engineering Vol. 10 No. 1 (2026)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v10i1.9920

Abstract

Global efforts to reduce carbon emissions have encouraged the adoption of lighter and more flexible offshore structures in support of Sustainable Development Goal (SDG) 13 and the International Maritime Organization (IMO) climate initiatives. This study investigates the technical performance of a Catenary Anchored Leg Mooring (CALM) terminal system connected to a Floating Storage and Offloading (FSO) facility using four subsea hose configurations of the Chinese lantern and lazy S types. Due to their flexibility, subsea hoses are susceptible to clashing under extreme environmental conditions, potentially causing damage and reducing operational reliability. Dynamic simulations were conducted to evaluate tensile forces, minimum bending radius, bending moments, shear forces, torsion moments, and the probability of hose clashing. Prior to the analysis, buoy stability was assessed following modifications to the hose configuration. The results indicate that the additional hose arrangement increased the buoy draft by 14.9% to 2.73 m. Under Accidental Limit State (ALS) conditions caused by anchor chain failure, structural loads on the hoses increased significantly, while the minimum bending radius decreased by 6%. Furthermore, the probability of hose clashing was substantially higher in ALS conditions than in Ultimate Limit State (ULS) conditions, demonstrating that anchor chain failure significantly increases the risk of subsea hose interaction and potential damage.
Operability Analysis During Topside Platform Removal with Dynamic Method Due to Wave Load Muhammad Zakaria Al Amin; Murdjito; Eko Budi Djatmiko; Fajar Rachmadiarto
International Journal of Offshore and Coastal Engineering Vol. 9 No. 2 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i2.8929

Abstract

Topside removal is one of the main activities in the offshore platform decommissioning process, with one of the methods in this process being reverse installation-single lift. Corrosion, one of the common problem factors in steel structures, is used as a parameter to reduce the strength of topside structures. In the structural strength analysis with a thickness reduction of 1.5mm, the maximum unity check values for members and joints are 0.854 and 0.602, respectively. Meanwhile, the dynamic analysis results show that the hoisting line and sling tension increase with increasing wave height and period. The response to increasing tension due to wave loads increases exponentially. The beam seas loading direction produces the highest tension response due to the roll motion response to the crane barge. The shortest hoisting line influences tension due to the higher stiffness value, which results in velocity and acceleration in the topside movement as a pendulum, thereby increasing the snap force. This pattern also applies to the dynamic amplification factor (DAF) and factor of safety (FOS) sling values. The distribution fitting results on the DAF value, 3-Parameter Lognormal, is the correct distribution model with a correlation value 0.999. So, the operational operability in the range of conditions for this research model is 89.4%.
Co-Authors Eko Budi Djatmiko Gumilang Alhafiz Muhammad Zakaria Al Amin Murdjito