Analisis Kelelahan Akibat Aliran Internal dan Beban Eksternal Pada Pipa Bawah Laut Yang Mengalami Freespan

Syarif, Hilman (2014) Analisis Kelelahan Akibat Aliran Internal dan Beban Eksternal Pada Pipa Bawah Laut Yang Mengalami Freespan. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Aliran eksternal dan internal fluida dalam pipa yang dapat menyebabkan vibrasi sehingga berakibat pada kelelahan pada pipa bawah laut telah selesai dianalisis. Analisis dilakukan dengan mempertimbangkan variasi flowrates aliran internal fluida serta panjang freespan. Freespan pipa bawah laut yang digunakan dalam analisis ini adalah yang tidak memenuhi kriteria screening kelelahan menurut DNV RP F-105. Berdasarkan hasil screening, panjang freespan yang harus dilakukan analisis kelelahan lebih lanjut adalah freespan dengan panjang 13 meter atau lebih. Kemudian dipilih tiga freespan yang tidak memenuhi kriteria screening kelelahan, yaitu freespan dengan panjang 23 meter, 30 meter, dan 36 meter. Selanjutnya menghitung tegangan pada freespan akibat variasi beban pressure akibat fluida yang mengalir di dalam pipa dan arus yang mengenai pipa. Pressure tersebut didapat dari output software CFD. Pada hasil analisis ini didapatkan bahwa peningkatan flowrates pada inlet berbanding lurus dengan pressure yang dihasilkan oleh fluida sehingga tegangan yang dihasilkan juga bertambah besar. Semakin besar tegangan yang dialami freespan, umur kelelahannya akan semakin kecil. Sehingga bisa disimpulkan semakin besar flowrates semakin kecil umur kelelahan freespan pipa bawah laut. ============================================================================================================== Fluid external and internal flow in the pipeline which can cause vibration resulting in subsea pipeline fatigue has been completely analyzed. Analysis is done by considering the variation of fluid internal flow flowrates and freespan length. Subsea pipeline freespan used in this analysis are those which do not fulfill the fatigue screening criteria in accordance with DNV RP F-105. Based on screening result, freespan length that must be done the further analysis are freespan with the length of 13 meter or more. Then, three freespan which do not fulfill the fatigue screening criteria are chosen; freespan with the length of 23 meter, 30 meter, and 36 meter. The next step is counting the freespan stress caused by pressure load variation as a result of fluid flowing in the pipeline and flow hitting the pipeline. That pressure is obtained from CFD software output. From this analysis result, it is shown that the enhancement of flowrates at the inlet is directly proportional with pressure produced by fluid, so that stress produced is bigger. The bigger the stress experienced by freespan, the smaller the fatigue life. It can be concluded that the bigger the flowrates, the smaller the fatigue life of subsea pipeline freespan.

Item Type: Thesis (Undergraduate)
Additional Information: RSKe 620.112 6 Sya a 3100014056415
Uncontrolled Keywords: Freespan; aliran internal; aliran eksternal; flowrates; tegangan; umur kelelahan
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ930 Pipelines (General). Underwater pipelines.
Divisions: Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User: Yeni Anita Gonti
Date Deposited: 23 Dec 2020 03:54
Last Modified: 23 Dec 2020 03:54
URI: https://repository.its.ac.id/id/eprint/82338

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