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IJOCE (International Journal of Offshore and Coastal Engineering)
Published by Institut Teknologi Sepuluh Nopember Surabaya
ISSN : -     EISSN : 25800914     DOI : -
Core Subject : Engineering,
Engineering
IJOCE, International Journal of Offshore and Coastal Engineering, is an academic journal on the issues related to offshore, coastal and ship science, engineering and technology. Published quarterly in February, May, August, and November.
Arjuna Subject : -
Articles 109 Documents
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Wave Simulation Based Recurrent Neural Network Long-Short Term Memory (RNN-LSTM) Wimala Lalitya Dhanistha; Fajar Sebastian; Haryo Dwito Armono
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//j225800914.v10i1.9913

Abstract

The Recurrent Neural Network Long-Short Term Memory (RNN-LSTM) algorithm was used to perform 6-hour time series forecasting for the variables significant wave height (Hs), maximum wave height (Hmax), zero-crossing period (Tz), and peak period (Tp) in a sea wave simulation using five datasets, each with a duration of ten years and from various locations. The ability of the RNN-LSTM algorithm to simulate sequential data, including time series, led to its selection. According to the research findings, the five RNN LSTM simulations produced fairly good forecasts for Tz (MAPE below 11%) and good forecasts for Hs and Hmax (MAPE below 9%). However, they had trouble simulating Tp (MAPE up to 34.06%). The tendency for Tp data to have a higher standard deviation (up to 2) than other variables and Tp's lower correlation with the other variables are factors that make Tp forecasting challenging. We find that RNN-LSTM can forecast Tp with moderate accuracy, but it can produce dependable forecasts for Hs, Hmax, and Tz
Mooring Chain Fatigue Analysis at the Single Point Mooring Ardjuna Marine Terminal Due to the Combination of Wave, Current, and Wind Loads Using the Fracture Mechanics Method Rafi Manaf Mawardi; Daniel Mohammad Rosyid; Rudi Walujo Prastianto
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//j225800914.v10i1.9915

Abstract

Mooring chain failure in Single Point Mooring (SPM) systems is a critical risk in offshore operations due to cyclic and complex environmental loading. The combination of waves, currents, and winds produces stress fluctuations that trigger crack initiation and propagation that can potentially lead to structural failure. This study analyzes the fatigue behavior of mooring chains in SPM at Ardjuna Marine Terminal, Java Sea, using a fracture mechanics approach. Cracks are modeled as semi-elliptical surface cracks, and the crack propagation rate is predicted using Paris Law based on Stress Intensity Factor (SIF) evaluation through numerical simulations. The motion responses of SPM and FSO are analyzed using Executive software, while the mooring chain stress analysis is performed using Dynamic simulation software. The results show a maximum SIF value of 1821.8 MPa√mm with a deviation of 1.6% from the analytical solution. The crack propagation rate increases from 2.65×10⁻⁸ to 3.02×10⁻⁵ mm/cycle, resulting in a total fatigue life of 8.3 years. These findings emphasize the importance of fracture mechanics-based evaluation to support inspection and maintenance strategies for SPM mooring systems.
Responses Analysis of Tubular Joints in Offshore Substation Jacket due to Settlement During the Roll Up Process Wildan Malika Candra Alfatih; Daniel Mohammad Rosyid; Rudi Walujo Prastianto
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

Abstract

The Offshore Substation plays a crucial role in ensuring the success of Offshore Wind Farm systems in the clean energy transition. During the fabrication stage, the jacket structure used as the Offshore Substation undergoes a fabrication process known as roll-up. During this roll-up process, ground settlement at the fabrication yard may occur, causing the jacket structure to tilt and increasing the risk of structural failure, which can reduce the effectiveness of the jacket structure’s integrity. In this study, a roll-up analysis of the jacket structure was conducted using SACS software with variations in roll-up angles of 0°, 30°, 45°, 60°, 75°, and 96.4°. The analysis results indicate that during the roll up process under settlement conditions, several critical areas were identified, particularly at the K-joint and X-joint, with maximum unity check (UC) values of 0.994 and 0.982, respectively. Further investigation was carried out through a local analysis using finite element software. The local stresses obtained were 264.6 MPa at the X-joint and 323.9 MPa at the K-joint. Since the stress at the K-joint exceeded the allowable stress, a thickness increase of 10 mm was applied to the brace experiencing the maximum stress. As a result, the stress was reduced by 172.29 MPa and was brought below the allowable stress limit.
Local Stress Analysis on Pipeline End Manifold (PLEM) Due to Pipeline Walking in Subsea Pipeline Rizki Cahya Illahi; Daniel Mohammad Rosyid; Rudi Walujo Prastianto
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//j225800914.v10i1.9917

Abstract

The Pipeline End Manifold (PLEM) is a key component in offshore oil and gas subsea systems that serves as a distribution point for fluid flow from subsea pipelines. One phenomenon that can affect its structural integrity is pipeline walking, which is the progressive axial movement of a pipeline caused by pressure and temperature cycles during operation. This study aims to evaluate the effect of pipeline walking on the stress and deformation of a PLEM structure. Numerical modeling was carried out using AutoPIPE to determine the axial displacement of the pipeline, while ANSYS based on the finite element method was used to analyze the structural response of the PLEM. The results show that pipeline walking produces a maximum axial displacement of 78.5994 mm. The maximum Von Mises stress of 61.222 MPa occurred in the 10-inch piping section, while the maximum deformation was 0.1305 mm. These values indicate that the structure remains within safe limits and possesses sufficient stiffness under the analyzed loading conditions.
Burst Pressure Assessment of Corroded Steel Pipeline Using DNV-RP-F101 and Finite Element Method with Circumferential Defect Interaction Study Yoyok Setyo Hadiwidodo; Asta Razqi Damarjati; Herman Pratikno
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//j225800914.v10i1.9918

Abstract

Metal loss corrosion is one of the primary degradation mechanisms in steel pipelines in the oil and gas industry. Wall thickness reduction due to corrosion increases hoop stress and reduces the maximum pressure capacity of the pipeline, potentially leading to bursting failure. This study aims to analyze the bursting pressure of corroded steel pipelines using two approaches: the analytical method based on DNV-RP-F101 and the numerical method using the Finite Element Method (FEM) through ANSYS software. The parameters investigated include the defect depth ratio (d/t) and the circumferential spacing between defects. A three-dimensional numerical model was developed considering elastic-plastic material behavior. The results indicate that an increase in defect depth ratio has a dominant effect in reducing bursting pressure, while closer defect spacing intensifies stress interaction and accelerates local plastification. A comparison between DNV-RP-F101 and FEM shows deviations within acceptable engineering tolerance; however, FEM predicts lower failure pressure as it captures stress concentration and plastic distribution in greater detail.
Health and Safety Analysis for Fisherman in East Surabaya, Indonesia Santi Frestiqauli; Daniel Mohammad Rosyid; Wimala Lalitya Dhanistha; Anita Kusuma Wardhani; Shade Rahmawati; Madea Eka Silfiani
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//j225800914.v10i1.9919

Abstract

The number of fishermen in Indonesia has continued to decline in the last decade as reported by the Statistics of Marine and Coastal Resources 2021. In 2010 the number of fishermen was recorded at 2.16 million people. But in 2019, the number was recorded at only 1.83 million people. Thus, there was a decrease in the number of fishermen by 330,000 people in 2010-2019. The fisheries sector is one of the most dangerous industries. In contrast, the health and safety of the people, especially fishermen are too far below occupational health and safety feasibility standards. This research used job safety analysis method for hazard identification and risk assessment for fisherman activities during preparation, operation, and pasca-operation. Data were collected through observation and interview 30 fishermen in East Surabaya. Results of observations divided by three activities shows that fishermen don’t prepare themselves with safety kit or safety equipment, including for personal protective equipment. The conclusion is most potential hazards could be minimized by using personal protective equipment. To minimize the risk of fatality, fishermen should carry a first aid kit, and communication devices and should be accompanied when going to sea. There are future research and program to increase fisherman awareness prior to safety.
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//j225800914.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.
Analysis of Residual Fatigue Life on Jacket Platform Structure Due to Subsidence Effect As Achmad Daffa Dhiya’udien Munaf; Nur Syahroni; Handayanu
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//j225800914.v10i1.9921

Abstract

Many oil and gas platforms in Indonesian waters, both those still operating and those that have passed the operating life limit (expired), experience subsidence events, especially in the jacket platform structure. Subsidence around these platforms is caused by massive oil and gas exploitation in producing hydrocarbon reservoirs. This phenomenon poses a risk due to intolerable wave loads, where the waves increase the risk of structural failure, which can impact platform operations. Changes in seabed conditions due to subsidence will also affect the cyclical wave loads received by the platform jacket structure. In this Final Project, the author will analyze the residual fatigue life of the jacket platform structure due to subsidence. This Final Project research aims to analyze the effect of subsidence on the fatigue life of the jacket platform structure. Tests were carried out using cumulative damage and fracture mechanics methods to predict the failure time of the components reviewed in the jacket platform structure under non-subsidence conditions and when subsidence occurs. The analysis results show that the fatigue life of the structure will be reduced when subsidence occurs. With the cumulative damage method, the fatigue life value of the non subsidence condition is 279 years, while the residual fatigue life of the structure in the subsidence condition is 59 years. Meanwhile, using the fracture mechanics method, the value of the fatigue life of the non-subsidence condition is 76 years, and the residual fatigue life of the structure in the subsidence condition is 41 years. These results show a significant decrease in the fatigue life of the structure.
Operational Risk Assessment of a 150,000 DWT Single Buoy Mooring Muhammad Bayu Abisatya; Silvianita sil; Daniel Mohammad Rosyid
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//j225800914.v10i1.9922

Abstract

Single Buoy Mooring (SBM) is a critical offshore facility used for tanker berthing and fluid transfer in oil and gas distribution systems, where complex interactions between vessels, mooring components, mechanical equipment, and dynamic marine environments generate significant operational risks. This study assesses the operational risks of a 150,000 DWT SBM system using a semi-quantitative Hazard Identification, Risk Assessment, and Risk Control (HIRARC) approach integrated with expert judgment. Hazard identification was conducted across all operational stages, including approaching, mooring, fluid transfer, and departing. Risk assessment was performed by evaluating the Likelihood of Failure (LoF) and the Consequence of Failure (CoF), with CoF assessed across safety, environmental, and asset/operational dimensions. Risk ranking employed a worst-case approach by selecting the maximum risk value among the three dimensions. The results indicate that hazards related to mooring chain integrity, pretension control, and swivel sealing systems present high to very high-risk levels. Further analysis using Bow-Tie Analysis highlights escalation pathways and the effectiveness of existing control barriers. The study demonstrates that the integrated HIRARC and Bow-Tie framework provides a practical basis for prioritizing operational risk controls in large-capacity SBM systems under limited historical failure data.

Page 11 of 11 | Total Record : 109

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