Hafizan, Darwin Miqailla (2025) Analisis Kelelahan Pipa Bawah Laut Diameter 8 Inch pada saat Instalasi Berdasarkan DNVGL-ST-F101 dengan Variasi Tension pada Tensioner Selama Kondisi Standby Pipelaying Barge. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Gangguan teknis seperti kerusakan tensioner, sistem tambat, atau peralatan pendukung kapal dapat menyebabkan proses instalasi pipa bawah laut terhenti, sehingga pipa tergantung
dalam kondisi standby. Dalam kondisi ini, pipa mengalami beban siklik akibat gelombang laut yang berulang, yang berpotensi menyebabkan kelelahan material. Penelitian ini bertujuan menganalisis tegangan maksimum dan holding time pada pipa diameter 8 inch selama kondisi standby dengan variasi tension 350 kN, 400 kN, dan 450 kN, berdasarkan standar DNVGL-STF101 yang mengalokasikan 18% umur desain untuk fase instalasi. Hasil analisis menunjukkan tegangan statis maksimum sebesar 242.33 MPa (0.77 dari SMYS) pada tensioner 350 kN, menurun menjadi 218.84 MPa (0.70 dari SMYS) pada 400 kN, dan 205.65 MPa (0.66 dari SMYS) pada 450 kN. Tegangan dinamis tertinggi terjadi pada 350 kN sebesar 231.05 MPa (0.74 dari SMYS), turun menjadi 202.36 MPa (0.65 dari SMYS) dan 177.65 MPa (0.57 dari SMYS) pada variasi berikutnya. Semua nilai masih di bawah batas aman
87% SMYS. Perhitungan kelelahan menghasilkan holding time paling kritis sebesar 91,93 jam pada tensioner 350 kN, meningkat menjadi 512,26 jam dan 2570,76 jam pada 400 kN dan 450 kN. Hasil ini menegaskan pentingnya pemilihan tensioner yang tepat untuk meminimalkan kelelahan dan memperpanjang umur pipa selama instalasi.
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Technical issues such as malfunctioning tensioners, mooring system failures, or supporting equipment breakdowns may interrupt subsea pipeline installation, forcing the pipeline to remain suspended during standby conditions. In this state, the pipeline is subjected to cyclic loading from ocean waves, potentially causing material fatigue. This study aims to
analyze the maximum stress and holding time of an 8-inch pipeline under standby conditions
with tension variations of 350 kN, 400 kN, and 450 kN, referring to DNVGL-ST-F101, which allocates 18% of the design life to the installation phase.
The analysis results show the maximum static stress of 242.33 MPa (0.77 of SMYS) at 350 kN tension, decreasing to 218.84 MPa (0.70 of SMYS) at 400 kN, and 205.65 MPa (0.66 of SMYS) at 450 kN. The highest dynamic stress occurred at 350 kN at 231.05 MPa (0.74 of SMYS), decreasing to 202.36 MPa (0.65 of SMYS) and 177.65 MPa (0.57 of SMYS) in subsequent
variations. All values are still below the safe limit of 87% of SMYS.
Fatigue analysis shows the most critical holding time at 91.93 hours for 350 kN, improving significantly to 512.26 hours and 2570.76 hours for higher tensions. These results emphasize the importance of selecting appropriate tensioner values to minimize fatigue damage and extend the operational life of subsea pipelines during installation.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | statis. dinamis, tegangan, kelelahan, tensioner, static, dynamic, tension, fatigue, tensioner |
| Subjects: | 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: | Darwin Miqailla Hafizan |
| Date Deposited: | 30 Jul 2025 09:39 |
| Last Modified: | 30 Jul 2025 09:39 |
| URI: | http://repository.its.ac.id/id/eprint/123425 |
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