Analisis Tegangan Dan Kelelahan Akibat Vortex Induced Vibration (VIV) Pada Lokasi Crossing Pipelines Saat Kondisi Operasi, Studi Kasus: 10” Mol LLB-LPRO Lima Field Berlokasi Di Utara Pulau Jawa

Khairunnisa, Azizah (2021) Analisis Tegangan Dan Kelelahan Akibat Vortex Induced Vibration (VIV) Pada Lokasi Crossing Pipelines Saat Kondisi Operasi, Studi Kasus: 10” Mol LLB-LPRO Lima Field Berlokasi Di Utara Pulau Jawa. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penggelaran jalur pipeline untuk pengangkutan minyak dan gas kerap kali mengalami kendala akibat kontur dasar laut Indonesia yang beragam. Salah satu kendala yang sering ditemui pada jalur subsea pipeline ialah free-span. Dalam pengoperasian subsea pipeline, terdapat beberapa fenomena sebagai akibat dari free-span, di antaranya adalah Vortex Induced Vibration (VIV). Analisis statis akan dilakukan untuk mengetahui besar allowable span pada lokasi crossing. Untuk panjang effective span pada arah in-line dan cross-flow akan dilakukan melalui analisis dinamis free-span. Kemudian, akan dilakukan analisis kelelahan untuk mengetahui fatigue life dari free-span. Acuan yang digunakan dalam analisis dinamis dan kelelahan adalah DNV-RP-F105 mengenai Free-Spanning Pipelines dan ASME B31.4 mengenai Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids untuk analisis tegangan pada pipeline. Dari perhitungan, didapatkan tegangan ekuivalen (von Mises) sebesar 129,25 MPa. Tegangan tersebut masih memenuhi batas izin yang ditentukan oleh ASME B31.4 sehingga pipeline dinyatakan aman. Dari screening criteria, crossing pipeline dengan panjang span aktual sebesar 15 m ini dinyatakan tidak mengalami fatigue. Untuk panjang allowable span dinamis adalah sebesar 23 m untuk arah in-line dan 27,5 m untuk arah cross-flow. Panjang span tersebut didapat dari hasil iterasi screening criteria fatigue. Perhitungan umur kelelahan dilakukan menggunakan panjang span 23 m dan didapatkan umur kelelahan sebesar 5 tahun. ======================================================================================================= The deployment of pipelines for oil and gas transportation often experiences problems due to the various contours of Indonesia's seabed. One of the obstacles that is often encountered on the subsea pipeline is free-span. In the operation of the subsea pipeline, there are several phenomena as a result of free-span, including Vortex Induced Vibration (VIV). Static analysis will be conducted to determine the allowable span value at the pipeline crossing location. Effective span lengths in the in-line and cross-flow directions will be carried out through dynamic free-span analysis. Then, a fatigue analysis will be carried out to determine the fatigue life of the free-span. The references used in dynamic and fatigue analysis are DNV-RP-F105 regarding Free-Spanning Pipelines and ASME B31.4 regarding Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids for stress analysis in pipelines. From the calculations, the equivalent stress value (von Mises) obtained is 129.25 MPa. The amount of stress still meets the limits set by ASME B31.4 thus the pipeline is declared safe to be used. From the screening criteria, this pipeline crossing with an actual span length of 15 m is declared not to experience failure caused by fatigue. For dynamic allowable span length is 23 m for in�line direction and 27.5 m for cross-flow direction. This value is obtained from the results of the screening fatigue criteria iteration. The calculation of fatigue life was carried out using a span length of 23 m and obtained a fatigue life of 5 years.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: subsea pipeline, free span, vortex induced vibration, crossing pipeline, tegangan von Mises, screening criteria fatigue, fatigue life
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ930 Pipelines (General). Underwater pipelines.
T Technology > TN Mining engineering. Metallurgy > TN879.5 Petroleum pipelines
Divisions: Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User: Azizah Khairunnisa
Date Deposited: 07 Sep 2021 02:47
Last Modified: 07 Sep 2021 02:47
URI: https://repository.its.ac.id/id/eprint/91768

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