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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; Bayu Iman Fatkurokhim; Handayanu Handayanu
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 1, No 2 (2017)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

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.

Analitical Study of Vertical and Lateral Buckling on Pipeline Using Hobbs Method Yoyok Setyo Hadiwidodo; Muhammad Makki Romadhoni; Herman Pratikno
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 1, No 2 (2017)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

During its operation, the pipeline will receive loads of internal pressure and thermal loads of fluid flowed until the pipes have both vertical and lateral buckling. Numerical analysis of vertical and lateral buckling Hobbs this method on a high friction coefficient and the coefficient of friction (0.3 ≤ φ ≤ 0.7) as well as the length of buckling as many as 20 variants were then performed comparisons, as well as axial tension comparison with DnV RP L110. So we get the relationship of temperature increase with the length and amplitude buckling. The data which is used is the gas pipeline Labuhan Maringgai-Muara Bekasi PT. Perusahaan Gas Negara (Persero) Tbk., Including the outer diameter of the pipe = 0.8128 m, plate thickness = 0.015875 m, thermal linear expansion coefficient = 11 x 10-6 m / oC, etc. So the higher coefficient of friction, temperature rise of 13.4%, 13.4% reduced buckling length, and axial tension increased to 12.95%. For the comparisons, the coefficient of friction does not affect the length of buckling on the vertical buckling. Comparison with DnV RP F110, increased coefficient of friction will increase the voltage axial (Seff) of 0.00024% and up 13.4% axial stress (P0) Hobbs.

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; Jousie Rebecca; Murdjito Murdjito
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 1, No 2 (2017)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

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.

Impact of Reclamation Development on Sedimentation and Current Pattern in East Coast Surabaya (Pamurbaya) Suntoyo Suntoyo; Mohammad Iqbal Hidayah; Hasan Ikhwani
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 1, No 2 (2017)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

Reclamation is an effort to establish a new land area either in coastal areas or in the middle of the ocean. In Pamurbaya area a number of property projects both housing and apartments is still continuing. Environmental impacts of the coastal reclamation project is in the potential increase of flooding. The changes include the extent of the cluster, the composition of river sediments, the tidal pattern, the pattern of ocean currents along the coast and damaging the water system. This study examines changes in current patterns, morphology, and sedimentation rate due to the reclamation modeled using Delft3D software. The pattern of current flow after the reclamation has changed. Basic surface changes that occur before and after reclamation in each crossection is by difference, crossection 1 = +0.22 m, crossection 2 = -0.19 m, and crossection 3 = +0.11 m. The sign (+) shows the occurrence of sedimentation, while (-) is erosion. The condition after the reclamation in crossection 1 is sedimentation, crossection 2 is erosion, and crossection 3 is sedimentation. The difference in intensity is very small, therefore the erosion and sedimentation which took place after reclamation is not too significant.

The Influence of Slopes to the Stability of Stones in front of Seawall Haryo Dwito Armono; Danny Indra Setyawan; Muhammad Zikra
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 1, No 2 (2017)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

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.

Risk Analysis of Decommissioning Process: Case Studies of Lima-Compresor Platform Arif Windiargo; Daniel Mohammad Rosyid; Murdjito Murdjito
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 4, No 1 (2020)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i1.8705

The process of petroleum exploration and exploitation is a crucial activity in the fulfillment of energy needs in the world. The process of petroleum exploration and exploitation is currently centred on shallow water regions in the continental shelf. In the process of petroleum exploration and exploitation in shallow waters, the structure of which is commonly used is the jacket structure. In Southeast Asia there are about 1300 platforms, of which 80% is over 20 years old. When the platform has reached its operational limit, according to the ministerial regulation of ESDM number 1 year 2011 The platform must be decommissioning in accordance with existing technical standards. In the process of demolition, there are certainly risks and hazards that can interfere with the process of decommissioning. It is necessary to do a risk analysis to map the risks that can occur while preparing the mitigation steps. In this study, risk analysis arel conducted by determining the activity that has a significant degree of hazard where it is concluded that activities that have a significant risk level are activities related to construction, lifting, maintenance, well service, and maintenance. From each activity that has a significant hazard level, there was a process of determining the cause of risk using the Fault Tree Analysis (FTA) method while determining the barrier that serves to prevent a risk occurring. The next is to determine the impact that can be inflicted from risk by using the Event Tree Analyis (ETA) method while determining the barrier that serves to prevent and reduce the impact that occurs when there is a peril. These two FTA and ETA diagrams are combined to create a Bowtie diagram to explain in detail the risk management performed at each stage of the decommisiioning process.

Analyzing the Effect of Variation in Shielding Gas Flow Rate and V Groove Type Towards Tensile and Metallographic Testing of GMAW Weld Joint of ASTM A53 and A36 Herman Pratikno; Andrea Novia Samiyono; Wimala Lalitya Dhanistha
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 4, No 1 (2020)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i1.8706

Steel is a metal that commonly used in fabrication, engineering, and reparation activities in the structure construction industry. ASTM A53 steel is a low carbon steel with 0.25% to 0.3% of carbon content so it has a high weldability. ASTM A36 steel is a low carbon steel with carbon content of 0.25% to 0.29% and is often used in the floating building industry. This study aims to determine the effect of shielding gas flow rate and V-groove type to the tensile strength of A53 steel welded with A36 steel by Gas Metal Arc Welding (GMAW) method. The shielding gas level used is 100% CO2 with flow rate variations, including 15 liters/minute, 20 liters/minute, and 25 liters/minute. The groove types used are Single V-Groove and Double V-Groove. Tensile strength test result showed that in the welding process in this study, specimen with 25 liters/minute flow rate on the Double V-Groove had the highest tensile strength value of 516.73 MPa, with the narrowest HAZ width of 0,87 mm on A36’s HAZ and 1,22 mm on A53’s HAZ, and the smallest percentage of ferrite in the microstructure as much as 56.34% and 43.66% pearlite.

Influence of Pre-Weld Heat Treatment and Aging Post-Weld Heat Treatment on Tensile Test and Microstructure of Aluminium 6061 Weld Joint Herman Pratikno; Tin Rachmatullah; Hasan Ikhwani
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 4, No 1 (2020)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i1.8701

Aluminium 6061 is an aluminium composition with Al-Mg-Si alloy which is often used for offshore structure material due to its high strength, good ductility and good corrosion resistance as well as its mechanical properties that can be enhanced by heat treatment. The purpose of this paper is to show the effect of heat treatment variations, in the form of preheating and aging PWHT, on tensile strength and microstructure of aluminium 6061 welding connection with GTAW process using electrode ER 5356. The pre-heat temperature variations used were 80°C, 100°C, and 120°C and the aging PWHT temperature variations used were 180°C and 260°c. The result shows that specimen with preheat treatment temperature of 120°C and aging pwht temperature of 260°C had the largest ultimate strength of 246.74 MPa and yield strength of 125.21 MPa. The highest percentage of Mg2Si formed was also found on the same specimen with a percentage of 48.84% in weld metal, 58.75% in HAZ, and 43.54% in base metal.

The Effect Analysis of Coating Thickness Variation and Mixed Composition of Zinc - Graphite on Epoxy Coating with Steel Plate ASTM A36 Herman Pratikno; Andry Febrianto; Wimala Lalitya Dhanistha
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 4, No 1 (2020)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i1.8707

Steel has an important role in the world of marine manufacturing industry. Steel for offshore buildings needs to be reviewed in terms of controlling metal corrosion. The coating method can be used in mobilization areas and splash zones of offshore buildings that have high corrosion rates due to sustained friction loads in the marine environment. This study used steel plate ASTM A36, which is a low carbon steel, and analyze its adhesion strength, abrasion resistance, and corrosion rate prediction by varying the coating thickness of 100μm, 200μm, and 300μm, with a mixture of Zinc-Graphite on epoxy coatings of 2%, 6%, and 10 %. In the Pull-Off test the highest value of adhesion strength was obtained at a mixture of 2% and coating thickness of 100μm with a value of 8.73 Mpa. In the highest abrasion test values was obtained with a variation of 10% mixture and coating thickness of 300μm with a value of 0.91 Wear Cyces per Micrometer. Whereas in the three-cell electrode test the highest value was at a 100% mixture variation and coating thickness of 300μm with a value of 0,00010 mmpy.

Analysis of Inspection Scheduling on Free Spanning Subsea Pipeline Using Risk Based Inspection (RBI) Method Daniel Mohammad Rosyid; Abizar Giffari; Yoyok Setyo Hadiwidodo
International Journal of Offshore and Coastal Engineering (IJOCE) Vol 4, No 1 (2020)
Publisher : DRPM (Direktorat Riset dan Pengabdian kepada Masyarakat) ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j2580-0914.v4i1.8703

The subsea pipeline system of PT. X located at north of West Java transports natural gas with 19 kilometers long and 16 inches standard pipe size. The rough seabed causes free span problem. The system will be threatened by a structural failure of fatigue due to Vortex Induced Vibration (VIV) and local buckling as the effects of free span. In this Final Project, a total of 136 free spans on subsea pipeline system due to the uneven seabed are analyzed. The screening will be done for spans with length and diameter ratio more than 30 to figure out the free span which pass the screening and know the risk level of the subsea pipeline due to free span. The result for fatigue screening due to VIV, spans with a length more than 25 meters did not pass the screening. Local buckling occurred at the longest free span with a length of 62 meters. The level of risk to structural failure caused fatigue due to VIV has the highest level in terms of business and the environment, namely in the medium category. The level of risk to local buckling failures for safety, environmental, and business terms was in low category.

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Journal Mail Official
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Kota surabaya,

Jawa timur

INDONESIA