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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 202 Documents
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Fatigue Life Comparison of Modified and Conventional 3 Leg Jacket Offshore Structure Murdjito Murdjito; Muhammad Nabil Ghiffary; Rudi Walujo Prastianto
International Journal of Offshore and Coastal Engineering Vol. 4 No. 2 (2020)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i2.9306

Abstract

The jacket structure must be adapted to the conditions of the production field to support economic factors. So, the concept of a modular platform for minimal, low-cost facilities is adopted. However, the design differences will affect the performance of the jacket itself, in other words a modular jacket can withstand the same load as a conventional jacket model but has a different structural performance. Therefore, this research discusses the performance comparison, which includes the fatigue life and the natural period, between conventional and modular jacket structures, which in this study are referred to as modified jackets. Conventional jacket as a comparison structure takes the design basis of the modified structure, including the same structural profiles, and environmental loads. In this study, the two jackets will only be modeled on the jacket part and the superstructure will be modeled as a joint load on the three upper ends of the jacket legs. Fatigue life analysis in this study used the full spectral analysis method. By using SACS software, the natural period of modified jacket is 1.756 s and conventional jacket is 1.472 s. While the lowest fatigue life on modified jacket is 44.98 years and conventional jacket is 9125.79 years.
Analysis of Influence of Abrasive Material Variation and Spray Pressure Variation in Coating Epoxy of Astm A36 Steel Toward Impact Resistance and Corrosion Rate Herman Pratikno; Bima Satriya Willy Harsa; Sholihin Sholihin
International Journal of Offshore and Coastal Engineering Vol. 4 No. 2 (2020)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i2.9337

Abstract

Corrosion is a decrease in material quality caused by environmental influences. One of the methods commonly used to control corrosion is coating. In the coating process, the use of spray is the better method compared to roll and brush. Before coating is applied, the choice of abrasive material during the sand blasting process can determine the success of the coating. This research was conducted to analyze the effect of variations in abrasive material and spray pressure on the coating process of ASTM A36 steel material on its impact resistance, corrosion rate, and adhesion forces. Variation of abrasive material used were steel grit and silica. The spray pressure variations used were 2.5, 3.5, and 4.5 bar. The result of corrosion rate testing on variation with steel grit abrasive material and spray pressure of 4.5 bar has the lowest corrosion rate, with the value of 0.00124 mm/a. The highest adhesion strength test result of 9.07 MPa was obtained from variations with steel grit abrasive material and spray pressure of 4.5 bar. Impact test result using a variation with steel grit abrasive materials and a spray pressure of 4.5 bar yield the highest value, with the value of 2.287 joules.
Analysis of Pipe Lay Barge Hafar Neptune Capability in Pipelaying Operation at Offshore North West Java Oil and Gas Field Eko Budi Djatmiko; Ignasius Krisna Armanda; Imam Rochani
International Journal of Offshore and Coastal Engineering Vol. 4 No. 2 (2020)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i2.9338

Abstract

When pipelaying activity is carried out, the most influential factor is the significant wave height. In this final project, the maximum significant wave height allowed for the PLB during the pipelaying process was analyzed with the variation of pipe diameters, which are 8 inches, 10 inches, and 12 inches; variations in the direction of coming waves namely 0o, 45o, 90o, 135o, and 180o; and stinger angle variations. First, static analysis was performed using OFFPIPE software Then, Pipe Lay Barge (PLB) Hafar Neptune modelled with MOSES software and validated with ABS MODU codes. The output was RAO from the Hafar Neptune PLB. Next, dynamic analysis was performed with OFFPIPE software, where the input is static analysis, RAO of Pipe Lay Barge Hafar Neptune, and JONSWAP wave spectrum formulation. The result of the analysis was the significant wave height that could hit the PLB when pipelaying is 3 meters for all pipe diameter variations. For variations in the direction of the wave data, the maximum Hs were 3 meters for 0 ° and 180 °, 2.5 meters for 45 °, 1.5 meters for 90 ° and 135 °.
The Effect Analysis of Coating Thickness Variation and Mixture Composition of Magnesium – Flake Glass on Epoxy Coating on Abrasive Resistance, Adhesion Strength, and Prediction of Corrosion Rate of ASTM A36 Steel Plate Herman Pratikno; Hasan Ikhwani; Yudiardana Tridantoko Susarno
International Journal of Offshore and Coastal Engineering Vol. 4 No. 2 (2020)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i2.9339

Abstract

Steel cannot be separated from the marine manufacturing industry. It is important to control the corrosion rate of steel used for offshore structures. The coating method can be used in mobilization areas and splash zones that have high corrosion rates due to sustained friction loads in the marine environment. The purpose of this study was to analyze the different in adhesion strength, abrasion resistance, and corrosion rate prediction of ASTM A36 low carbon steel plate with coating thickness variations of 300µm, 500µm, and 700µm and Magnesium Carbonate - Flake Glass mixture variations of 10%, 20%, and 30%. In the pull-off test, the highest value of adhesion strength was obtained from specimen with 300µm coating thickness and 10% Magnesium Carbonate - Flake Glass mixture with a value of 5.67 Mpa. The highest abrasion test value was obtained from specimen with 700µm coating thickness and 30% Magnesium Carbonate - Flake Glass mixture with a value of 0.91 Wear Cyces per Micrometer. Whereas in the three cells electrode test, the highest value was found at specimen with 700µm coating thickness and 30% Magnesium Carbonate - Flake Glass mixture with a value of 0,00010 mmpy.
Pipe Stacking Optimization and Sea Fastening Analysis of Linepipe Transport Daniel Mohammad Rosyid; Raditya Danu Riyanto; Carlo Jonathan Sihombing
International Journal of Offshore and Coastal Engineering Vol. 4 No. 2 (2020)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i2.9340

Abstract

Subsea pipeline is a system comprised of multiple linepipes that are welded when installed on location used to distribute fluid such as oil and natural gas. Fabricated linepipes are to be stacked on cargo barge and transported to the installation location. This operation takes significant time and involves numerous linepipes. Optimization needs to be done to make sure the transport operation is executed efficiently. Optimization attempt was done using data from Double Joint Linepipe Transport Operation of Tangguh Expansion Project by Saipem Indonesia. Parameters considered during the optimization process include linepipe qualities during stacking, cargo barge strength and stability, and sea fastening property strength. Roark’s Formulas for Stress and Strain formulas are used in pipe stacking analysis to find stacking limit for each type of linepipes. Stability analysis is done by using DNVGL-ST-N001 as a guide and Maxsurf software for modelling. SACS software is used to analyzed sea fastening properties with guidance from DNVGL-ST-N001. Finally, optimization is done using a multi-criteria optimization method by using values from each analysis as parameters. Optimization results find that pipe stacking method using side support is 8.41% more optimal than standard pipe stacking method from Saipem Indonesia.
Experimental and Numerical Study on Roll Damping Structure of Floating Crane Catamaran in Free Floating and Moored Conditions Eko Budi Djatmiko; Murdjito Murdjito; Muhamad Fadkhurrohman Aziz; Baharuddin Ali
International Journal of Offshore and Coastal Engineering Vol. 4 No. 2 (2020)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i2.9341

Abstract

This research discusses the experimental study of free decay test This research discusses related to the experimental study of free decay test motion roll on the catamaran floating crane structure which is reviewed from free-floating and moored conditions. Experiments were conducted on the facilities of Maneuvering and Ocean Engineering Basin owned by the BTH – BPPT. The structure used as an experiment was a model of the catamaran floating crane with a scale of 1:36. The test is carried out with a horizontal mooring link system Taken from mooring system modelling, spring stiffness is used as a reference for mooring rope stiffness in numerical analysis. The analysis carried out in this final project is to compare the experimental results of the decay test with the results of the analysis using Moses software. From the results of the experiments obtained a comparison of free-floating conditions to tethered to decay tests of 38%, 8%, and 9% for linear damping values, then 93%, 12%, and 13% for quadratic damping values. Comparison of experiment results to numerical results found a difference of 128.39% for decay test 1 for quadratic damping value, then in decay test 2 and decay test 3 against the numerical got difference of 60.80% and 66.83% in linear damping value.
Local Stress Analysis in the Chain Link of Mooring Line That Had Diameter Degradation Eko Budi Djatmiko; Murdjito Murdjito; Rafliansyah Azhar Putera
International Journal of Offshore and Coastal Engineering Vol. 5 No. 1 (2021)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i3.9952

Abstract

Mooring systems are used to moored ships at a particular area. One of its type is SPM by using a buoy. The system generally uses chains used to tie buoys to the seabed. However, chains that are used continuously can experience degradation in the diameter of the chain connection. The degradation experienced by the connections between the chains will certainly affect the local ( von Mises stress). According to ABS rules, the amount of local stress or von Mises stress that occurs on an object must not exceed 90% of the yield strength of the material. Therefore, it is necessary to do a local stress analysis to determine the extent of degradation of the diameter of the chain connection so that the local stress value does not exceed that allowed. The largest mooring tension value that occurs in the mooring system is 1838,252 kN. The results show that if the chain connection is subject to a tension of 1838,252 kN, the diameter degradation that occurs in the chain connection must not exceed 15% of the initial diameter so that the local or von Mises stress does not exceed 369 MPa (90% of the yield strength of the material 410 MPa).
Analysis of the Effect of Abrasive Material and Polyurethane Coating Thickness Variations on ASTM A36 Steel Towards Corrosion Rate in Sea Water Environment Herman Pratikno; Wimala Lalitya Dhanista; Felita Widya Hapsari
International Journal of Offshore and Coastal Engineering Vol. 5 No. 1 (2021)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i3.9953

Abstract

An unavoidable phenomenon of using steel as the main material in offshore structures and floating vessels is corrosion. One method of preventing corrosion is by coating and using polyurethane is one type of coating that is currently being developed in the maritime industry. But the success of this coating process is very dependent on the surface preparation process. The usual method used is blasting using an abrasive material. This study aims to find the response to the corrosion rate of polyurethane coating with thickness variations of 60 µm, 80 µm, and 100 µm by first blasting using abrasive material variations in the form of silica sand and steel grit. The result of the corrosion rate test showed that the lowest corrosion rate value was obtained in the variation of abrasive material in the form of steel grit. with a 100. µm of polyurethane coating thickness, that is 0,00008 mm/a. While the highest corrosion rate value was obtained in the variation of abrasive material in the form of silica sand with a 60 µm of polyurethane coating thickness, that is 0,02202 mm/a.
Influence Analysis of Shielding Gas Flow Rate and Purity Level Variation on GMAW Welding Process to Microstructure of Alumunium 5083 Nur Syahroni; Yeyes Mulyadi; Sadewa Sechan Winando
International Journal of Offshore and Coastal Engineering Vol. 5 No. 1 (2021)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i3.9954

Abstract

Aluminium is a commonly used material in construction and transportation industries. The advantages of using the aluminium material are its light weight, corrosion resistant, and the capability to form an alloy with another metal. Therefore, the aim of this research is to analyze the influence of shielding gas flow rate and purity level variation to mechanical properties and microstructure of the welded material. The welding process used on this research was the GMAW method. The material used was aluminium 5083 series with 300 mm x 150 mm x 8 mm dimensions. The shielding gases used were high purity (HP) and ultra-high purity (UHP) argon (Ar). The variations of shielding gas flow rate used were 16, 18, dan 20 litre/minutes. Based on the tensile test that has been done, the variation of UHP argon gas with 20 litre/minute flow rate had the best result with yield strength of 217,32 MPa and ultimate strength of 295,83 MPa. The result of the micro photos showed that the GMAW method produced small dots where the dots were Mg2Si formation, which the greater number of smaller size dot produced would increase the mechanical properties of the material.
Experimental & Numerical Studies of Vertical Motion Acceleration Analysis in Helideck on a Catamaran Floating Crane Eko Budi Djatmiko; Murdjito Murdjito; Yunan Setiawan Suwandono; Abdul Ghofur
International Journal of Offshore and Coastal Engineering Vol. 5 No. 1 (2021)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i3.9955

Abstract

This research discusses the operability of vertical acceleration in the helideck. The experiment was carried out at the Maneuvering and Ocean Engineering Basin (MOB) facility of the BPPT-ITS Hydrodynamics Technology Center. The model being tested is the catamaran type with a scale of 1:36 to the original scale. Experimental testing using random waves with a Pierson-maskowitz spectrum with Hs = 2.5 and Hs = 6.37 m. The helideck only performs surge sway and heave tests. Meanwhile, numerical analyzes the effects of regular waves at heading 00 450 900 1350 1800 and obtained RAO for Heave, Roll, Pitch movements. For the analysis of landing operability at Helideck using the Olson and Marine criteria, where the limit of wave height according to Olson is obtained, namely for the incoming wave direction of 00, 900,1800, it should not be done more than 3 meters of wave height, while for conditions 450 and 1350 should not be above 4 meters. . For the HCA category, the critical condition when the direction of the wave of 900 with a wave height of 2 meters. At an altitude of 4 meters is the limit of the wave direction 00 450 1350 1800.

Page 14 of 21 | Total Record : 202

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