Affandi, Ari (2019) Analisis Tegangan dan Kelelahan Akibat Pengaruh Vortex Induced Vibration (VIV) Yang Terjadi Pada Lokasi Crossing Pipelines. Studi Kasus : Platform B1C-KCOM Milik PHE ONWJ. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Dalam sistem perpipaan bawah laut, salah satu permasalahan utama yang sangat dihindari adalah free span. Free span tersebut rentan mengalami kegagalan struktur, seperti kelelahan, yang disebabkan oleh vibrasi yang terjadi oleh vortex shedding atau biasa disebut fenomena vortex induced vibration (VIV). Fenomena ini disebabkan oleh beban lingkungan terutama gelombang dan arus laut, hingga rasio gap seabed (e/D) dan kekasaran dari pipa (k/D). Dalam tugas akhir ini, analisis free span yang dilakukan terdiri dari analisis tegangan dari pipelines, analisis panjang allowable span untuk kondisi statis, analisis dinamis free span, serta analisis kelelahan. Berdasarkan hasil perhitungan tegangan, didapatkan tegangan ekuivalen sebesar 82.15 MPa dan masih memenuhi allowable stress dari ASME B31.8. Dan panjang allowable span untuk kondisi statis sebesar 16.07 m. Untuk hasil perhitungan analisis dinamis, panjang efektif span yang didapatkan untuk actual span 12 m sebesar 12 m dan untuk actual span 16.07 m sebesar 16.07 m. Dalam analisa fatigue, kondisi yang dianalisa hanya pada kondisi in-line saja dikarenakan kondisi cross-flow sudah memenuhi criteria fatigue dari DNV RP F105. Fatigue life (Tlife) yang didapatkan yaitu 23 tahun, dengan jumlah kerusakan (Dfat) yang terjadi sebesar 0.92. Adapun acuan validasi yang digunakan dalam analisis dinamis dan kelelahan dari free span adalah DNV RP F105 mengenai Free Spanning Pipelines. ===========================================================================In the subsea pipeline system, one of the most problems that very avoided is free span. Free Span is prone to structural failure, such as fatigue, caused by vibrations that occur by vortex shedding or commonly called the phenomenon of vortex induced vibration (VIV). This phenomenon caused by environmental loads, especially waves and ocean currents, or the effect from seabed gap ratio (e/D) and roughness of pipe (k/D). In this thesis, the free span analysis that we performed consists of the pipelines stress analysis, allowable span length for static condition, dynamic analysis, and fatigue analysis of free span. Based on the results of stress calculations, we obtain the output of the equivalent stress is 82.15 MPa and still include in value which is determined of the allowable stress by ASME B31.8. And allowable span length for static condition is 16.07 m. For the calculations of free span dynamic analysis, the resulting output is the effective span length of free span for actual span 12 m is 12 m and for actual span 16.07 m is 16.07 m. For the fatigue analysis, analyzed only on in-line direction because cross-flow direction has fulfilled the criteria fatigue of DNV RP F105. The value of the fatigue life is 23 years, with the total of damage that occured is about 0.92. And the reference of validation that used in dynamic and fatigue analysis of the free span is DNV RP F105 about Free Spanning Pipelines.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | free span, tegangan, von-Mises stress, in-line, cross-flow, VIV, allowable span, fatigue life. |
| Subjects: | T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures T Technology > TJ Mechanical engineering and machinery > TJ935 Pipe--Fluid dynamics. Tubes--Fluid dynamics T Technology > TN Mining engineering. Metallurgy > TN879.5 Petroleum pipelines |
| Divisions: | Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis |
| Depositing User: | AFFANDI ARI |
| Date Deposited: | 24 Jun 2024 05:23 |
| Last Modified: | 24 Jun 2024 05:23 |
| URI: | http://repository.its.ac.id/id/eprint/68793 |
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