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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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Ultimate Strength of the Buoy Structure due to the Loads Arise from the Tanker and Mooring Lines Murdjito Murdjito; Handayanu Handayanu; Resy Agatya
International Journal of Offshore and Coastal Engineering Vol. 1 No. 1 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i1.2893

Abstract

A study was conducted to evaluate the ultimate strength of a 40 ton buoy induced by the dynamic loads arising from a 120,000 DWT Aframax tanker and mooring lines. The buoy is operated at Bangka Strait offshore oil terminal. The eva­luation was commen­ced by analyzing the motion characteristics of the buoy and tanker due to environmental excitations, both in free floating conditions. This is continued by the simulation and time-domain analysis of con­nected buoy and tanker to observe the hawsers and mooring line tension intensities. The correspon­ding results show the largest tension occurs in the in-line configu­ration with the tanker in ballast condi­tion, where hawsers tension reaches 1282.58 kN with a safety factor of 2.23 and mooring line tension 1974.18 kN with a safety factor of 3.20. The resulting tensions were further applied as input data for structural modeling using FEM to find out the stresses develop on the buoy structure. Results of this modeling reveal the maximum value of stress experienced by the buoy structure is approaching 184.28 MPa, which is below allowable stress of 200 MPa. Following this, the ultimate stress of 450 MPa will be violated by 143% incremental load above the maximum, namely 3,116.67 kN and 4,797.26 kN due to the hawsers and mooring line. This fact suggests that the structure is unlikely to experience ultimate failure if merely operated in the current operational site.
Effects of Rudder Position on the Ship Maneuvering Wisnu Wardhana; Imam Rochani; Benedictus Johanes Belalawe
International Journal of Offshore and Coastal Engineering Vol. 1 No. 1 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i1.2870

Abstract

The performance of the rudder on a ship affects the ability of the vessel to maneuver effectively. In the current study evaluation is made on the rudder mounted on a twin screw fast boat with LOA of 59.2 m and Vs of 28 knots. This paper discusses the forces acting on the rudder and the velocity distribution of the fluid flow due to the position of the rudder in 3 variations (X/L = 80%, X/L = 100%, X/L = 120%). The analysis undertaken in this study is based on CFD method. Analysis of the effectiveness of the mane­uvers is performed by considering the magnitudes of the drag force and value of the lift force generated by the rudder, as well as a decrease in the fluid velocity u on the rudder area. On the variation of X/L = 120% with rudder angle 35°, the rudder produces a the largest value of total drag force and lift force, in the order of each 761 kN and 1,230 kN. The decrease of fluid velocity u most significan­tly also occurs in variation X/L = 120%, with a value of 10.0 m/s on the portside rudder and 9.3 m/s on the starboard rudder.
The Design of Mooring Dolphin Layout and Mooring Line Tension Analysis Haryo Dwito Armono; Yoffan Ramadhan; Sholihin Sholihin
International Journal of Offshore and Coastal Engineering Vol. 1 No. 1 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i1.2871

Abstract

Some marine industries choose to set up their activities in the coastal area northern part of Java Island, Indonesia, by considering the calmness of the Java Sea environment. A special terminal for liquid bulk cargo to transport fuel oil is being planned for construction in Sedayu Lawas village, Lamongan district, East Java Province. The ship carrying cargo oil require a pier and jetty in sufficient depth for loading and unloading. The jetty need to be enhanced to support more equipment for ship to port, which include breasting dolphin, mooring dolphin, trestle, and cause­way. In this respect a study is carried out to review the stress analysis of the mooring lines (ropes) attached to jetty for various mooring dolphin layout and arrangements. The metocean data such as wind and tides in the areas were processed and analyzed. The layout of the ship and mooring dolphin rope angle were designed in accordance with OCIMF code. The stress analysis of mooring rope for various layout mooring dolphin has been analyzed to determine whether the design layout is safe during operation. The rope stress were analyzed using time domain dynamic analysis for 10,800 seconds. The safety of ship during loading for various rope condition were presented. It is suggested that all ropes should be attached to mooring dolphin for ship and port safety.
Risk Assessment of Onshore Pipeline in Area Gresik Daniel Mohammad Rosyid; Muhammad Yusuf Jamil; Wahyudi Citrosiswoyo
International Journal of Offshore and Coastal Engineering Vol. 1 No. 1 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i1.2872

Abstract

Pipeline is a transport means to distribute the fluid in the form of liquid or gas. Meanwhile, risk is defined as the combination of the likelihood of failure and the consequences of failure. In this rese­arch, the implementation of risk assessment using the index or scoring models as developed by Muhlbauer is made. Pipeline used for the analysis was located in Legundi - Cerme, Gresik Area. The pipeline has a diameter of 12 inches which distribute gas. Scoring method is based on a sum index composed of damage indices caused by a third party with a score averagely 57.71, with a score of corrosion index averagely 68, index design with a score averagely 75, and the index operation errors with a score averagely 90. Furthermore, leak impact factor calculation is made by considering leak impact factor consisting of product hazard, leak volume, and dispersion, receptors. Estimates for product hazard criteria score is 7, leak or spill volume is 0.4, the dispersion score is 0.8,and score in receptor variation value of between 10.8 up to 15.9. Relative risk score average obtained from the calculation is 9.87, which is the result of dividing the sum by the leak index impact factor.This low value indicates the pipeline to be classified in the low risk level, or has a sufficiently high safety.
Effect of Heat Treatment and Types of Bacteria on Corrosion Resistance At Steel Materials (API 5L and ASTM A53) in the Marine Environment Herman Pratikno; Harmin Sulistyaning Titah; Febrian Ramadhana Sastradimaja
International Journal of Offshore and Coastal Engineering Vol. 1 No. 1 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i1.2876

Abstract

Corrosion is the result of damage to material degradation through a chemical or electrochemical reaction spontaneously and causes a decrease in the quality of the material. One of the causes of corrosion is the presence of bacteria on the material. The danger posed by corrosion is fatality, especially on offshore platforms, namely cessation of production at offshore rigs. This study is an experiment using material carbon steel API 5L Grade B and ASTM A53 commonly used as a base for the manufacture of subsea pipelines. Material to be heat-treated before immersion for corrosion test in artificial seawater (salinity 35‰), which have been added with bacteria and without bacteria. The method used in measuring the rate of corrosion steel data is the weight loss. The highest corrosion rate of the original material ASTM A53 and API 5L with the addition of T. ferrooxidans bacteria are, respectively, 3.63 mpy and 3.50 mpy. While the lowest corrosion rate of ASTM A53 and API 5L both with heat treatment but without adding bacteria are 2.33 mpy and 2.01 mpy. This indicates that the steel API 5L have high levels of corrosion resistance, better than ASTM A53 in the marine environment with bacteria or without bacteria.
Pushover Analysis Pile of ULA Jacket Platform Towards Earthquake Loads by SNI-1726:2012 Silvianita Silvianita; Dirta Marina Chamelia; Alim Bagus Prakoso
International Journal of Offshore and Coastal Engineering Vol. 1 No. 1 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i1.2875

Abstract

The Influence of Slopes to the Stability of Stones in front of Seawall Haryo Dwito Armono; Muhammad Zikra; Danny Indra Setyawan
International Journal of Offshore and Coastal Engineering Vol. 1 No. 2 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i2.7051

Abstract

Seawall is a coastal protection structure to prevent coastal erosion from wave forces. In this research, rubble-mound of stones are used as armor due to the availability of the material in coastal areas and ease of construction. A series of physical model tests with a scale of 1:25 with a variation of four wave heights (H), two wave periods (T), and three different slopes of rubble-mound in front of seawall were performed. Parameters used in the research are stability coefficient (KD),wave steepness (H/gT2), and percentage of damages (Do). The slope variations of rubble-mound were 1:1.15, 1:1.5, and 1:2. The experiments also displayed that the stone stability coefficient (KD) directly proportional with wave steepness (H/gT2). The value of KD for the seawall model with the slope angle of cot = 1.15 is 4.4, cot = 1.5 is 4.28 and cot = 2 is 3.02. From all three variations of slope, the most stable is on the slope 1:2 with the least damage impact on the model. The gentlest slope is the most stable structure.
Analysis of Configuration of Stinger Angle with Depth Variation During Installation On Pipe Diamater 20" in Banyu Urip, Bojonegoro Handayanu Handayanu; Imam Rochani; Juniavi Dini Kumala Putri
International Journal of Offshore and Coastal Engineering Vol. 1 No. 2 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i2.7052

Abstract

The selection of subsea pipeline construction methods used depends on the environmental conditions and behavior of the pipe installation system which acquires a variety of loads during installation and may the result in failure. In this case the required angle stinger configuration is in accordance with the criteria to avoid overstress and local buckling on the pipe during installation, the variation of the depth of 15 meters, 18 meters, 20.65 meters, 21.25 meters and 22.25 meters can help analysis the stress on the pipe in each case. The pipeline is 23.4 km north of Bojonegoro. From the results of the analysis, it is known that the configuration of stinger angles used during installation for each water depth is 15 m with stinger angle 8.88 degree, 18.65 m stinger angle 8.88 degree, 20.65 m stinger angle 8.88 degree, 21.25 m stinger angle 8.88 degree and 22.25 m stinger angle 8.88 degree. The result of pipe stress on the overbend area has a value of 85.13% SMYS or 352.42 Mpa when the direction of wave comes 90 degrees, while the sagbend area of the pipe has a maximum stress of 51.01% SMYS or 211.2 Mpa when the direction of wave comes 180 degrees. Local buckling check results in all conditions show safe results during the installation process.
Analysis of the Effect of Welding Sequence Variations on Residual Stresses and Distortions for Welding Pressure Vessels Structures at PT. Petrokimia Gresik using the Finite Element Method Nur Syahroni; Handayanu Handayanu; Bayu Iman Fatkurokhim
International Journal of Offshore and Coastal Engineering Vol. 1 No. 2 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i2.7053

Abstract

The development of oil and gas industry technology has been very advanced, one of the implementation is to connect material materials to support oil and gas industry facilities. Residual stress may occur due to high temperature differences due to welding and also uneven heat distribution. This causes the material to become hard but brittle so that it may cause structural failure in the connection area. In this final project will be simulated welding pressure vessels to determine the structure of residual stresses that occur as well as the influence of Post Weld Heat Treatment on residual stress itself. The material used is aluminum and WPS data coming from the fabrication company. The simulation is divided into 2 steps: thermal and structural analysis. The value of the residual voltage of 1 to pathline pathline 3 is 189 MPa, 124.8 MPa, 100.76 MPa with distortion value of 40.43 mm. Then analyzed Post Weld Heat Treatment referring to AWS D1.1: 2000 to reduce residual stresses that occur. From the results of the Post Weld Heat Treatment value of the residual stress can be reduced significantly. After being treated Post Weld Heat Treatment with variations of temperatures of 200 C, 300 C The maximum residual voltage reduction occurs in pathline 1 to pathline 3 at 125 MPa, 93 MPa, 100 MPa.
The Study of Tandem Offloading Performance and Operability on The Cylindrical Hull FPSO Sevan Stabilized Platform with Variation in Mooring System Configuration Eko Budi Djatmiko; Murdjito Murdjito; Jousie Rebecca
International Journal of Offshore and Coastal Engineering Vol. 1 No. 2 (2017)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v1i2.7054

Abstract

This study has been carried out to evaluate the dynamic behavior of the Cylindrical FPSO Sevan Stabilized Platform (SSP) and the LNG Carrier (LNGC) during the process of tandem offloading. The study includes hydrodynamics modellings, computations, and simulations of both cases SSP and LNGC operated individually and in combination for offloading operations. The SSP is moored with two variations of mooring, namely taut and catenary. Environmental loads are waves with the incorporated winds and currents propagating 90o, 210o, and 330o relative to the SSP headings. Excitation of random waves up to Hs = 4.50 m instigates the relatively low SSP motions in standalone condition. In offloading condition, when LNGC is connected, the SSP motion could magnify as much as 2.0 up to 5.0 times higher than that in standalone condition, but still considered in an acceptable level. The motion quality of LNGC in offloading operation is comparable with the SSP. For various random wave headings with Hs = 4.50 m during offloading operation may generate maximum tensions between 1,600 kN up to 2,600 kN in the casse of catenary mooring, and between 4,700 kN up to 7,000 kN in the case of taut mooring. Even then, this largest tension preserves a safety factor of 2.05 which is well above the limit of 1.67 as required by the governing standards. Finally, the study conclude an operability of as much as 90% could be achieved on SSP and LNGC offloading operation in the Masela Block of the Abadi Gas Field.

Page 12 of 21 | Total Record : 202

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