Analisis Perbandingan Keandalan Antara Steel Catenary Riser Dan Flexible Riser Pada Semi-Submersible Akibat Squall Pada Kondisi Accidental Limit State

Syaputra, Muhammad Desar Eka (2025) Analisis Perbandingan Keandalan Antara Steel Catenary Riser Dan Flexible Riser Pada Semi-Submersible Akibat Squall Pada Kondisi Accidental Limit State. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Permintaan minyak dan gas yang terus meningkat mendorong eksplorasi ke perairan dalam, di mana semi-submersible menjadi pilihan utama karena keunggulan ekonomis dan fleksibilitasnya. Struktur ini dapat menggunakan Steel Catenary Riser (SCR) dan Flexible Riser untuk mentransportasi minyak dan gas, namun seringkali menghadapi tantangan lingkungan yang tidak dapat diprediksi seperti squall, yaitu kenaikan kecepatan angin secara tiba-tiba yang meningkatkan tinggi gelombang serta beban pada sistem tambat dan riser, yang dapat memicu putusnya mooring line atau dikenal dengan istilah Accidental Limit State (ALS). Penelitian tugas akhir ini menganalisis respon gerak (RAO) semi-submersible dalam kondisi free-floating pada gelombang reguler, dampak squall terhadap tinggi gelombang signifikan, von mises stress pada riser akibat beban squall dalam kondisi ALS, serta menentukan riser yang lebih andal menggunakan simulasi numerik dengan perangkat lunak simulasi dinamik dan analisis Monte Carlo. Hasil menunjukkan bahwa respon gerakan terbesar untuk surge pada 0° dan 180° (0,851 m/m) serta 90° (0,818 m/m), heave pada 45° dan 135° (0,533 m/m), roll pada 90° (0,645 deg/m), pitch pada 0° (0,565 deg/m), dan yaw pada 45° dan 135° (0,16 deg/m). Squall dengan raising time 2,5 menit meningkatkan tinggi gelombang hingga 24,55%. Kombinasi squall dan ALS meningkatkan von mises stress pada SCR hingga 26,62% (arah 90°, TR 2,5 menit) dan pada flexible riser sebesar 0,49% (arah 0°, TR 7,5 menit). Dari sisi keandalan, SCR memiliki nilai terendah sebesar 0 dalam variasi tertentu, sedangkan flexible riser tetap andal dengan keandalan 1. Penelitian ini memberikan wawasan penting mengenai dampak squall dan kegagalan mooring terhadap keandalan riser, yang dapat menjadi referensi dalam desain dan operasi sistem riser di perairan dalam.
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The ever-increasing demand for oil and gas is driving exploration into deep waters, where semi-submersible is the top choice due to its economic advantages and flexibility. These structures can use Steel Catenary Risers (SCRs) and Flexible Risers to transport oil and gas, but they often face unpredictable environmental challenges such as squalls, which are sudden increases in wind speed that increase wave heights and loads on mooring and riser systems, which can trigger the breakage of mooring lines or known as Accidental Limit State (ALS). This final project research analyzes the semi-submersible motion response (RAO) in free-floating conditions on regular waves, the impact of squall on significant wave height, von mises stress on risers due to squall loads in ALS conditions, and determines risers which is more reliable using numerical simulations with Monte Carlo dynamics simulation and analysis software. The results showed that the largest motion response for surge at 0° and 180° (0.851 m/m) and 90° (0.818 m/m), heave at 45° and 135° (0.533 m/m), roll at 90° (0.645 deg/m), pitch at 0° (0.565 deg/m), and yaw at 45° and 135° (0.16 deg/m). Squall with a raising time of 2.5 minutes increases the wave height by 24.55%. The combination of squall and ALS increased von mises stress in SCR by 26.62% (90° direction, TR 2.5 minutes) and in flexible riser by 0.49% (0° direction, TR 7.5 minutes). In terms of reliability, SCR has the lowest value of 0 in certain variations, while flexible risers remain reliable with reliability of 1. This study provides important insights into the impact of squall and mooring failures on riser reliability, which can be a reference in the design and operation of riser systems in deep waters.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Flexible riser, Reliability, Steel catenary riser, Squall, Von mises
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User:	Muhammad Desar Eka Syaputra
Date Deposited:	22 Jan 2025 03:19
Last Modified:	22 Jan 2025 03:19
URI:	http://repository.its.ac.id/id/eprint/116545

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