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Analysis of Sling Tension on the Lifting Process of Riser Support Jacket on Installation Phase Mahardi, Rifki; Hadiwidodo, Yoyok Setyo; Prastianto, Rudi Walujo
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 1 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i1.20463

The increasing exploration and exploitation of oil and gas in the deep sea has led to an increasing need for new technologies to support these activities. In this study, a riser support structure in the form of a jacket is used to support the riser so that the stress can be minimized. Like the jacket structure in general, this riser support structure can be installed using various methods, including the lifting method. This study discusses the stress in the sling when the lifting process is carried out. The crane barge used in this study was first modeled using MOSES Software to determine how the barge moves when the lifting process is carried out. The result of the barge movement analysis is a Response Amplitude Operator (RAO). In the sway, heave and roll movements, it is known that the maximum value is at 90° heading, while in other movements, it varies. The riser support structure is modeled using SACS Software to determine the center of gravity, then the sling length is calculated. From the calculation, the sling length at lifting point 1 is 34,10 m, lifting point 2 is 34,14 m, lifting point 3 is 36,08 m, and lifting point 4 is 36,10 m. The lifting model is input into the OrcaFlex Software to analyze the sling stress. The analysis was performed in five loading directions, namely 0°, 45°, 90°, 135°, and 180°. The maximum stress occurs in the loading direction of 90°, with the result that sling 1 is 1932,70 kN, sling 2 is 1905,65 kN, sling 3 is 1161,64, and sling 4 is 1193,65 kN.

Bivariate Archimedean Copulas to Solve Complex Dependency in Marine Engineering Problems Ramadhani, Adhitya Ryan; Pranowo, Waskito
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 7, No 2 (2023)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v7i2.19334

Climate change has made offshore installations suffer severe consequences from extreme marine hazards. These offshore installations were designed to withstand extreme natural hazards. Marine natural hazards commonly occur interdependently. Thus, a multivariate model to capture this complex dependence structure is necessary. Practically, modelling marine natural hazards is usually assumed to be mutually independent or correlated by a multivariate Gaussian distribution. However, this biased assumption is not relevant to capture the real dependence structure between marine parameters. Copula functions are used to model the complex dependence structure between marine parameters. A simplified case study is selected to illustrate the modelling between wave height and wind speed. Results are compared with the traditional joint probability approach to demonstrate the advantage of copula functions. The use of copula functions provides a better result to model any complex dependence structure between correlated variables.

The Role of Merak Vessel Traffic Service (VTS) in the Implementation of Traffic Separation Scheme (TSS) in Sunda Strait Purnama, Ananda Firsta Tea Relevania; Umaroh, Atika Khoirul; Nugroho, Setyo
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22074

Merak Vessel Traffic Service (VTS) is pivotal in Indonesia's critical maritime traffic network, particularly within the bustling Sunda Strait. This waterway holds immense strategic importance, serving as the primary link between Java and Su-matra Islands and intersecting with the vital Indonesian Archipelago Sea Lane. The Indonesian Government implemented a Traffic Separation Scheme (TSS) in July 2020 to enhance safety and navigation. Despite three years of TSS implementation, concerns persist regarding compliance and safety within the Sunda Strait. This research employs qualitative methods to address these concerns, chiefly in-depth interviews with VTS operators. The overarching objective is to gain profound insights into the intricacies of TSS implementation and the array of challenges it faces. The findings reveal several significant challenges. These include the lack of robust law enforcement and insufficient socialisation efforts regarding TSS regulations, concerns related to weather conditions impacting maritime operations, limitations in VHF radio modulation affecting communication, and issues surrounding vessel compliance with directives from VTS operators. In light of these challenges, future recommendations should prioritise strengthening law enforcement mechanisms, intensifying educational initiatives, improving communication technology, enhancing weather monitoring capabilities, and exploring ways to strengthen vessel compliance with VTS instructions.

Analysis of the Effect of Nano-Alumina Addition on Epoxy Coating on Abrasive Resistance, Adhesion Strength, and Corrosion Rate of ASTM A36 Steel Plate Pratikno, Herman; Trisnadi, Wimar Bhara; Sholihin, Sholihin
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22078

The maritime industry is one of the natural resources management industries that uses steel as its fundamental component. Much research and development have been conducted to increase the quality and life span of the steel used. ASTM A36 low-carbon steel is one of the steel variants commonly used on offshore structures because of its advantages. This research was conducted to achieve the additional effect of nano-alumina of 0%, 1,5% and 3% in the epoxy coating on adhesive strength, abrasive resistance and corrosion rate prediction. At pull-off testing, the highest adhesion strength was obtained at a mixed variation of 0% with a value of 7,7022 MPa. At the abrasion resistance test, the highest abrasion resistance was obtained at a mixed variation of 3% with a value of 16.7 grams. The lowest value of the corrosion rate prediction test was obtained on the mixed variation of 1.5% with a value of 0.005410622 mph.

Analysis of the Influence of Infrastructure, Costs, and Services for the Crew's PT. PELNI on Customer Satisfaction Using Principal Component Analysis (PCA) Method Adiarsa, Hilda Emeraldo Ahmad; Huda, Mokhamad Aufal; Buana, I Gusti Ngurah Sumanta
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22073

The presence of efficient port infrastructure is of utmost importance in ensuring the seamless functioning of both cargo and passenger operations. In addition to infrastructure, providing high-quality service by a ship's crew is equally important to derive from the infrastructure. Another factor to consider is whether the cost levied for services and infrastructure meets the community's expectations, as excessive costs without adequate infrastructure and services will result in dissatisfied customers. Therefore, customer satisfaction cannot only be assessed from one aspect but must be seen from various aspects, which in this study will be seen from the infrastructure, costs, and crew services. This research focuses on ships owned by PT. PELNI because this company is one of the largest in Indonesia, leading in great demand for sea transportation services. The research on infrastructure aspects, costs, and crew services includes supporting aspects to link them to customer satisfaction with PT. PELNI will be analysed using the Principal Component Analysis (PCA) method. The principal component (PC) can be utilised for feature selection and variable interpretation for data with several variables and a correlation. The results found that infrastructure (X1) can explain the factor variance of 45.309%.

Burst Pressure Analysis on Corroded Pipeline Using Finite Element Method Sormin, Mahadi Yahya; Hadiwidodo, Yoyok Setyo; Syahroni, Nur
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22077

The oil and gas industry includes exploration, extraction, production or processing, and transportation. One of the important activities in the oil and gas industry is the hydrocarbon transportation system. The most commonly used hydrocarbon transportation facility is the subsea pipeline. Pipes operating in a marine environment can easily corrode. Corrosion will cause a metal loss on the pipe surface and worsen the strength of the pipe. The thinning of the pipe surface due to corrosion will result in localized holes of varying depths and uneven shapes on the outer and inner surfaces. A burst pressure will occur if the internal pressure in the pipe with corrosion defects exceeds the allowable internal pressure limit. Therefore, to prevent burst pressure, it is necessary to evaluate the residual strength of the pipe in order to determine whether the defective pipe with working pressure can continue to operate safely or not. The internal pressure value calculation results are as follows: until the pipe fails, it is considered to burst using an FEA of 19.42 MPa. Meanwhile, the internal pressure value using standard codes DNV-RP-F101 is 18.76 MPa. For the effect of variations in the dimensions of the corrosion defect size, the most influential is the length and depth of the defect due to a decrease in the graph that does not fluctuate. The percentage differences between the failure pressure values resulting from rectangle and semi-ellipsoidal corrosion defects and the burst pressure values from the burst test experiments are 0.61% and 0.15%, respectively.

Gulf of Lampung Bamboo Fixed Net Cages Structural Design Identification Sari, Shila Atika; Hermanto, Mochammad Fathurridho; Kencana, Elsa Rizkiya
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22072

Renewable materials are being discussed and researched more recently. One renewable source of material is plants, either with a long life like wood or a short life like bamboo. In Indonesia, bamboo is widely used also for the structures of fixed net cages. This research aims to analyze the structure of the fixed bamboo net cage installed in the waters of Gulf Lampung. The analysis used in this paper is in place. The in-place analysis will give the unity check and deflection result due to load combined by the standard BKI Guidelines for Aquaculture. Based on the results, the structure has met the standard in operation conditions with the maximum unity check value of 0.52 on the group pile. Nevertheless, the largest unity check value of 1.20 on group piles in storm conditions is due to increased lateral loading. The result of deflection already has good serviceability, with a maximum horizontal deflection value occurring in storm conditions of 0.58 cm and a maximum vertical deflection in operation conditions of 0.89 cm. The structure of the fixed net cages has yet to meet the requirements during storm conditions by unity check.

Pipeline End Manifold (PLEM) Structural Response Analysis due to the Settlement Process Darobi, Ichwandanny Faturahman; Murdjito, Murdjito; Ikhwani, Hasan
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22076

Pipeline End Manifold (PLEM) is an offshore structure that consists of a simple subsea manifold that combines two or more pipelines into one pipeline. Like other offshore structures, the risk of seabed settlement may occur, and settlement is predicted can increase the stress of pipe and frame members. Stress that exceeds the allowable stress of codes may be a danger. So, stress analysis of the UC ratio of pipe and frame PLEM due to the settlement must be done. Stress analysis is performed using the numerical method with the model in FEM software. UC ratio refers to AMSE B31.8 2010 for pipe and API RP 2A (WSD) 22ed 2014 for the structural frame. From this analysis, the allowable settlement of pipe codes is at a depth below 450.42 mm. The deeper the settlement, the more stress the member frame increases. At a depth of 600 mm settlement, the greatest stress, 133.125 N/mm^2, UC 0.375, is found on member E04(L). According to the pipe codes, the maximum slope is 2.27˚ on the southward slope. The biggest effect of tilt settlement on the member frame is found in the west direction at member E04(U) with a value of 244.6 N/mm^2, UC 0.689, tilt settlement 3˚.

Analysis of the Global Structural Strength of a 35,000 DWT Single Point Mooring (SPM) Buoy Under Wave Loads Kencana, Elsa Rizkiya; Fatkhurrozi, Muhammad; Nugraha, Alvin Aziz; Kelen, Olga Wulandari
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22071

Single Point Mooring (SPM) systems are offshore structures facilitating cargo transfer between tankers and refineries in deeper waters to accommodate larger vessels. The marine environment at SPM sites often features unstable and extreme wave conditions, making it essential to understand the SPM's response to these forces. SPMs include an anchor system with mooring lines secured to the seabed. Evaluating the stress on these lines and the buoy structure under environmental loads is crucial. This research models the SPM structure using dimensional data and mooring line specifications. The hypothesis posits that, based on the significant wave height and 100-year wave period in the Balongan Sea, as well as the minimum breaking load value for a 35,000 DWT SPM, the maximum tension in the mooring lines is 956 kN, which is below 2261 kN. It means safe based on API RP 2KS (2005) standards. Thus, the mooring lines are safe during operations under 100-year environmental loads with a maximum tension of 1732 kN. The maximum stress on the SPM buoy structure is 1.87 MPa and 3.38 MPa in ULS and ALS conditions, respectively.

Strength Analysis of the Floating Pier Structure with Passenger Ship 116 GT (Case Study: Sanur Harbor, Bali Province) Buana, Eliezer Bertram Free; Sholihin, Sholihin; Sambodho, Kriyo
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 8, No 2 (2024)
Publisher : Pusat Publikasi Ilmiah Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i2.22075

The pier is one of the primary means of sea transportation that continues to be developed to support equity activities and advance the community's economy. Bali is one of the main tourist destinations in Indonesia. The construction of the Sanur Floating Pier will create good connectivity between regions in Bali, which can become an additional tourist destination so that tourists can vacation longer in Bali. The purpose of this study was to determine the strength of the floating jetty structure through an analysis of the loading received by the structure and the resistance of the piles so that they can carry out designs related to the installation of strong and safe floating dock piles. In the analysis process, the author uses the help of Plaxis V.8.6 software to model the soil and AutoCAD 2018 as a support system in making the floating dock pile installation layout. The analysis results show that the floating dock can accept the forces acting on the structure. The UE RPD 250 fender and the T-Head MT 20 type bollard are the right choices. The pile has a lateral force value (H) of 1907 kg with a deflection of 0.19 mm. The greater the number of piles installed on the floating pier, the stronger the structure is evidenced by the smaller pile settlement due to soil changes.

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Contact Name
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Contact Email
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Phone
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Journal Mail Official
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Editorial Address
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Location
Kota surabaya,

Jawa timur

INDONESIA