International Journal of Offshore and Coastal Engineeing
ISSN : 20407459     EISSN : 20407467
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.
Articles 7 Documents
Risk Assessment of Onshore Pipeline in Area Gresik

Rosyid, Daniel M ( Institut Teknologi Sepuluh Nopember ) , Jamil, Muhammad Y ( Institut Teknologi Sepuluh Nopember ) , Wahyudi, . ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (481.622 KB) | 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.

The Design of Mooring Dolphin Layout and Mooring Line Tension Analysis

Sholihin, . ( Institut Teknologi Sepuluh Nopember ) , Ramadhan, Yoffan ( Institut Teknologi Sepuluh Nopember ) , Armono, Haryo D ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (1093.815 KB) | 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.

Effect of Heat Treatment and Types of Bacteria on Corrosion Resistance At Steel Materials (API 5L and ASTM A53) in the Marine Environment

Pratikno, Herman ( Institut Teknologi Sepuluh Nopember ) , Titah, Harmin S ( Institut Teknologi Sepuluh Nopember ) , Sastradimaja, Febrian R ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (852.27 KB) | 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.

Tie-Braces Design Optimization of Breasting Dolphin Structure at Petrochina Marine Terminal

Prastianto, Rudi W ( Institut Teknologi Sepuluh Nopember ) , Puspitorini, Dyah A ( Institut Teknologi Sepuluh Nopember ) , Hadiwidodo, Yoyok S ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (977.67 KB) | DOI: 10.12962/j2580-0914.v1i1.2868

Abstract

This paper discusses about optimization design of breasting dolphin’s structural strengthening with additional tie-bra­ces. The breasting dolphin structure has failed because of the increased load on the export activity of tanker. A strengthe­ning project has been carried out in 2014, but the result is considered overdesign and is not optimal. There­fore an optimization design of breasting dolphin structure is carried out as described herein, by looking for the optimum configuration, outside diameter, and wall thickness. The objective function is to determine the minimum weight of the structure. The independent variables are the outside diameter and wall thickness. The constraints are joint deflection check, member stress check, and joint punching shear stress check. There two type analyses performed. Firstly, in-place analysis of several structures with various tie-braces dimensions. The calcu­lation of the initial tie-braces dimension was performed using parameter’s design according to API RP 2A WSD. Secondly is optimization analysis of output data from the in-place evaluation to determine optimum outside diameter and wall thickness of tie-braces, also the weight of the structure. After optimization analysis conducted it is found optimum structural weight be 261 tons, which is some 3 tons lighter than the previous one of 264 tons.

Pushover Analysis Pile of ULA Jacket Platform Towards Earthquake Loads by SNI-1726:2012

Chamelia, Dirta M ( Institut Teknologi Sepuluh Nopember ) , Prakoso, Alim B ( Institut Teknologi Sepuluh Nopember ) , Silvianita, . ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (855.063 KB) | DOI: 10.12962/j2580-0914.v1i1.2875

Abstract

This study aims at analyzing pushover on pile jacket structure based on SNI-1726:2012 standards for earthquake loads. Push­over analysis or ultimate strength was performed on ULA jacket plat­form operated by PHE ONWJ. The jacket platform is operated in the northwestern part of the Java Sea. Design of earthquake loads on ULA jacket platform structure with large seismic accele­ration was obtained. From seismic analysis, dynamic response occurred on ULA jacket platform is evaluated, with natural struc­ture period of 1.256 seconds. The largest shear base values were in X and Y directions resulted from seismic acceleration of PGA 0.2g. On member check, the critical part happens to be one of the members of WD2, and on joint check, the largest UC occurred on 401L joint, both were due to the aforementioned earth quake ace­leration. Pushover analysis was then performed to obtain the value of RSR (Reserve Strength Ratio). The analysis yields an RSR value which far exceed the limiting criteria of API RP 2A WSD of RSR ≥ 0.8. Therefore it could be concluded that ULA jacket platform structure is within the range of low consequence category.

Effects of Rudder Position on the Ship Maneuvering

Wardhana, Wisnu ( Institut Teknologi Sepuluh Nopember ) , Rochani, Imam ( Institut Teknologi Sepuluh Nopember ) , Belalawe, Benedictus J ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (881.605 KB) | 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.

Ultimate Strength of the Buoy Structure due to the Loads Arise from the Tanker and Mooring Lines

Murdjito, . ( Institut Teknologi Sepuluh Nopember ) , Agatya, Resy ( Institut Teknologi Sepuluh Nopember ) , Handayanu, . ( Institut Teknologi Sepuluh Nopember )

International Journal of Offshore and Coastal Engineeing Vol 1, No 1 (2017): IJOCE
Publisher : Lembaga Penelitian dan Pengabdian Masyarakat

Show Abstract | Original Source | Check in Google Scholar | Full PDF (776.473 KB) | 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.

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