Analisis Pengaruh Variasi Jarak Span Dan Laju Pertumbuhan Scouring Terhadap Ultimate Limit State Pada Pipa Bawah Laut Yang Mengalami Multispan

Subagia, Putu Bima Putra (2025) Analisis Pengaruh Variasi Jarak Span Dan Laju Pertumbuhan Scouring Terhadap Ultimate Limit State Pada Pipa Bawah Laut Yang Mengalami Multispan. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kondisi seabed yang tidak rata dapat menyebabkan pipa mengalami freespan. Pipa dalam kondisi operasional harus mampu menahan gaya dari dalam pipa itu sendiri (internal load) dan gaya dari luar pipa (eksternal load).Untuk mengetahui batas maksimal kekuatan pipa bawah laut, dilakukan pendekatan Ultimate Limit State (ULS). Analisis ULS dalam penelitian ini mengacu pada codes DNV RP F105: Free Spanning Pipelines dan DNVGL ST-F101: Submarine Pipeline Systems. laju pertumbuhan scouring terhadap stabilitas pipa. Dari hasil analisis, laju pertumbuhan scouring berdasarkan data aktual diperoleh sebesar 2×〖10〗^(-9) m/s, di mana pipa akan mencapai kondisi keseimbangan dalam waktu sekitar 14 tahun. Tegangan von Mises yang diperoleh dari perhitungan manual untuk panjang span 17 m dan 18 m masing-masing adalah 50,49 MPa, serta untuk panjang 21 m dan 22 m masing-masing 51,89 MPa. Sedangkan dari pemodelan software, tegangan von Mises untuk panjang 17 m dan 18 m sebesar 51,51 MPa, dan untuk panjang 21 m dan 22 m sebesar 52,74 MPa. Berdasarkan analisis local buckling sesuai kriteria DNVGL ST-F101, diperoleh nilai load controlled condition untuk span 17 m dan 18 m sebesar 0,047054, serta untuk span 21 m dan 22 m sebesar 0,047055. Seluruh nilai LCC tersebut masih berada di bawah batas (<1), sehingga pipa termasuk dalam kategori span yang diizinkan karena tidak mengalami local buckling.
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Irregular seabed conditions can cause subsea pipelines to experience freespan. In operational conditions, the pipeline must be able to withstand forces from within the pipe itself (internal road) as well as external forces (external load). To determine the maximum strength capacity of subsea pipelines, the Ultimate Limit State (ULS) approach is applied. The ULS analysis in this study refers to the codes DNV RP F105: Free Spanning Pipelines and DNVGL ST-F101: Submarine Pipeline Systems. This study analyzes the influence of scouring growth rate on pipeline stability. Based on the analysis, the actual scouring growth rate is 2 × 10⁻⁹ m/s, indicating that the pipeline would reach an equilibrium condition in approximately 14 years. The von Mises stress obtained from manual calculations for span lengths of 17 m and 18 m is 50.49 MPa, and for 21 m and 22 m is 51.89 MPa. Meanwhile, software modeling yields von Mises stresses of 51.51 MPa for spans of 17 m and 18 m, and 52.74 MPa for spans of 21 m and 22 m. Based on local buckling analysis using the criteria from DNVGL ST-F101, the load controlled condition (LCC) values for spans of 17 m and 18 m are 0.047054, and for spans of 21 m and 22 m are 0.047055. All LCC values are below the allowable limit (<1), indicating that the pipelines fall within the acceptable span category and do not experience local buckling.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Pipa Bawah Laut, Multispan, Scouring, Ultimate Limit State, Metode Elemen Hingga, Subsea Pipeline, Multispan, Scouring, Ultimate Limit State, Finite Element Method
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC1665 Offshore structures--Materials. T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures T Technology > TJ Mechanical engineering and machinery > TJ930 Pipelines (General). Underwater pipelines.
Divisions:	Faculty of Marine Technology (MARTECH) > Offshore Engineering > 54040-(S1) Undergraduate Thesis
Depositing User:	Putu Bima Putra Subagia
Date Deposited:	27 Jul 2025 11:57
Last Modified:	27 Jul 2025 11:59
URI:	http://repository.its.ac.id/id/eprint/122061

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