M. Basir, Idham Aulia (2015) Analisis Tegangan Dan Kelelahan Akibat Pengaruh Vortex Induced Vibration (Viv) Yang Terjadi Pada Lokasi Crossing Pipelines; Studi Kasus : Kilo Field Milik Pertamina Hulu Energi Offshore North West Java. Undergraduate 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 disebabkan
oleh beban lingkungan terutama gelombang dan arus laut, hingga rasio gap seabed
(e/D) dan kekasaran dari pipa (k/D). Pada tugas akhir ini, analisis free span yang
dilakukan terdiri analisis tegangan dari pipelines, analisis dinamis free span, serta
analisis kelelahan. Berdasarkan hasil perhitungan tegangan, didapatkan keluaran
berupa tegangan ekuivalen sebesar 116.01 MPa dan masih memenuhi tegangan
yang diijinkan berdasarkan ASME B.31.8.2000 mengenai Gas Transmission and
Distribution Piping System. Untuk hasil perhitungan dari analisis dinamis, keluaran
yang dihasilkan berupa panjang efektif untuk arah cross-flow sebesar 19.79 m dan
arah in-line sebesar 20.25 m, namun yang dijadikan panjang span yang diijinkan
adalah dari arah cross-flow karena mengambil nilai yang terkecil dari keduanya.
Sedangkan untuk analisis kelelahan, perhitungan hanya dilakukan pada arah in-line
dan didapatkan fatigue life (Tlife) yaitu lebih dari 33 tahun dengan jumlah kerusakan
yang terjadi (D) sebesar 1.901x10-8. Adapun acuan validasi yang digunakan dalam
analisis dinamis dan kelelahan dari free span adalah DNV-RP-F105 mengenai Free
Spanning Pipelines.
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In the subsea pipeline system, one of the main 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 consist of the pipelines
stress analysis, dynamic analysis of free span, and fatigue analysis of free span.
Based on the results of stress calculations, we obtain the output of the equivalent
stress is 116.01 MPa and still include in value which is determined of the allowable
equivalent stress by ASME B.31.8.2000 on Gas Transmission and Distribution Piping
Systems. For the calculation of free span dynamic analysis, the resulting output is the
effective length of free span in cross-flow direction equal to 19.79 m and the inline
direction equal to 20.25 m. But for the allowable span length, we used the value
from cross-flow direction because that is the smallest value from both. Whereas of
result of the fatigue analysis of free span, we obtain the value of fatigue life (Tlife) is
more than 33 years, with the total of damage that occurred (D) is about 1.901x10-8.
And the reference of validation that used in dynamic and fatigue analysis the free
span is DNV-RP-F105 about Free Spanning Pipelines.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Additional Information: | RSKe 621.867 2 Bas a |
| Uncontrolled Keywords: | free span, analisis tegangan, cross-flow, in-line, VIV, allowable span, fatigue life |
| Subjects: | T Technology > TC Hydraulic engineering. Ocean engineering |
| Divisions: | Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis |
| Depositing User: | Mr. Tondo Indra Nyata |
| Date Deposited: | 14 Aug 2017 04:17 |
| Last Modified: | 24 Aug 2018 03:41 |
| URI: | http://repository.its.ac.id/id/eprint/48468 |
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