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Padeye Strength Analysis of Topside Offloading Platform due to Loadout Using Lifting Method Prayoga, Ilham Kharisma; Hadiwidodo, Yoyok Setyo; Handayanu, Handayanu
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.v8i1.20455

Abstract

Lifting is one method in the loadout process. Lifting is the activity of moving a structure using the help of a crane. The loadout process moves the structure from the yard to the barge. In this study, a lifting analysis was carried out on the topside offloading platform structure. The analysis also considers the center of gravity shift factor, dynamic load factor (DAF), and other safety factors that occur in the structure during the lifting process. Dynamic load factor using Dynamic Amplification Factor. Cog shift during lifting affects the amount of load being lifted. The most significant load received by the lifting point is 872.507 kN at lifting point 3. During the lifting process, no failure was found in the structural members, as evidenced by the maximum UC value of 0.87. The Padeye used is designed according to the DNV OS-H205 criteria. Several checks on the padeye structure were carried out, comparing the stress that occurred with the allowable stress on several stress reviews, such as tensile stress, shear stress, and bending stress. Local analysis was also carried out on the padeye structure to determine the stress on the padeye structure. Local analysis of the padeye structure was conducted using the ANSYS Workbench software. The results of the regional analysis showed the equivalent von-mises of 164.96 MPa in the padeye structure and 140.04 MPa at the joints, with the allowable stress of ASTM A36 steel material of 250 MPa.
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

Abstract

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.
The Analysis of Electrode Combination Effect on Steel and Stainless Steel Welding (Overview of Tensile and Metallography Test) Ikhwani, Hasan; Abdullah, Faruq; Pratikno, Herman; Sujantoko, Sujantoko; Hadiwidodo, Yoyok Setyo; Yulianto, Totok
International Journal of Marine Engineering Innovation and Research Vol 9, No 1 (2024)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25481479.v9i1.20138

Abstract

The process of building a ship or offshore structure, proper and accurate planning and implementation is required. In the development process, it will go through a stage, namely the construction stage. At the construction stage, the construction of a ship or offshore building will go through a welding phase which functions as a connection of materials to one another. Low carbon steel and stainless steel are materials that are often used in the construction process of ships or offshore structures. In this study, an analysis of the effect of the combination of electrodes on the welding of steel and stainless steel materials was carried out in terms of mechanical properties such as tensile strength, bending strength and metallographic shape. The materials used in this study were A36 steel and 304 stainless steel, while the electrode combinations used were E308L and E309 electrodes. Welding variations used in this study were a combination of E308L (root) and E309 (filler) electrodes, a combination of E308L (filler) and E309 (root) electrodes, E309 electrodes, and E308L electrodes. In the tensile test results it was found that the highest tensile strength value occurred in Specimen 4 with an average value of yield strength and ultimate strength of 389.54 MPa and 522.52 MPa. The tensile strength value is influenced by the amount of chromium contained in the electrode. This is because the higher the amount of chromium causes the amount of ferrite in the material to increase so that the tensile strength value decreases. In the metallographic macro testing results, the best weld profile results were obtained on specimens with the ME 4 material code because the results of the weld profile shape best met ASME Section IX standards. The results of micro metallographic testing showed that welding using the dominant E308L electrode as in Specimen 1 and Specimen 4 obtained a higher ultimate strength value compared to Specimen 2 and Specimen 3. This was due to the influence of chromium on the electrodes used, high chromium causing the formation of a ferrite phase in the microstructure of the material.