Analisis Tegangan Komponen Struktur Jacket Kaki Empat pada Proses Decommissioning Tahap Lifting

Nugraha, Aditya Ferananta (2026) Analisis Tegangan Komponen Struktur Jacket Kaki Empat pada Proses Decommissioning Tahap Lifting. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Struktur jacket kaki empat merupakan struktur anjungan lepas pantai yang paling banyak digunakan dalam kegiatan eksplorasi dan eksploitasi minyak dan gas bumi. Seiring bertambahnya usia operasi, sebuah anjungan akan mengalami masa tidak efektif, sehingga diperlukan penanganan berupa decommissioning atau pembongkaran. Lifting merupakan proses yang sering digunakan untuk kegiatan decommissioning. Penelitian ini bertujuan untuk menganalisis tegangan komponen struktur jacket kaki empat pada proses decommissioning tahap lifting, metode lifting yang digunakan adalah reverse installation proses upending. Pada analisis dinamis, nilai tegangan maksimum sling padeye terjadi pada sling MH-PDY3 dengan nilai 779.97 kN, pada kondisi CoG Shift 1 (X+Y+) saat jacket berada pada deklinasi 18.12o. Sementara itu, nilai tegangan maksimum sling trunnion terjadi pada sling AH-TRN3 dengan nilai 1496.7 kN, pada kondisi CoG Shift 2 (X-Y+) saat jacket berada pada deklinasi 86.83o. Pada analisis kekuatan struktur, nilai unity check maksimum yang terjadi pada connected dan non-connected member masing-masing sebesar 0.68 dan 0.61, sedangkan untuk nilai unity check maksimum yang terjadi pada joint, memiliki nilai sebesar 0.95. Selanjutnya dilakukan analisis distribusi tegangan lokal pada elemen padeye, diperoleh tegangan maksimum sebesar 223.91 MPa, analisis ekstrapolasi dilakukan pada titik tegangan maksimum tersebut, dan diperoleh nilai hot spot stress sebesar 164.96 MPa. Sehingga elemen padeye memiliki nilai unity check sebesar 0.42. Dari analisis yang telah dilakukan tegangan yang terjadi pada struktur memiliki nilai unity check <1.0, sehingga struktur jacket dinyatakan aman selama decommissioning dengan metode reverse installation proses upending
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Four-legged jacket structures are the most widely used offshore platforms in oil and gas exploration and exploitation activities. As their operational lifespan concludes, these platforms reach an ineffective phase, necessitating interventions such as decommissioning or dismantling. Lifting is a commonly employed process in decommissioning activities. This study aims to analyze the component stresses of a four-legged jacket structure during the lifting phase of decommissioning, specifically utilizing the reverse installation method during the upending process. Based on the dynamic analysis, the maximum padeye sling tension occurred at the MH-PDY3 sling with a value of 779.97 kN, under the CoG Shift 1 (X+Y+) condition when the jacket was at a declination angle of 18.12°. Meanwhile, the maximum trunnion sling tension reached 1496.7 kN at the AH-TRN3 sling, under the CoG Shift 2 (X-Y+) condition at a declination angle of 86.83°. In the structural strength analysis, the maximum unity check values for the connected and non-connected members were 0.68 and 0.61, respectively, while the maximum unity check for the joints was 0.95. Furthermore, a local stress distribution analysis was conducted on the padeye element, yielding a maximum stress of 223.91 MPa. An extrapolation analysis performed at this maximum stress point resulted in a hot spot stress value of 164.96 MPa, corresponding to a padeye unity check of 0.42. The comprehensive analysis demonstrates that all evaluated structural components maintained unity check values of < 1.0, thereby concluding that the jacket structure remains structurally safe during the decommissioning process using the reverse installation and upending method.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Decommissioning, Lifting, Reverse Installation, Padeye
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA347 Finite Element Method T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures
Divisions:	Faculty of Marine Technology (MARTECH) > Offshore Engineering > 54040-(S1) Undergraduate Thesis
Depositing User:	Aditya Ferananta Nugraha
Date Deposited:	25 Jul 2026 04:58
Last Modified:	25 Jul 2026 04:58
URI:	http://repository.its.ac.id/id/eprint/137589

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