Analisis Sisa Umur Pakai Pada Pipa Lepas Pantai Akibat Free Span Studi Kasus : FSO Field Sukowati

Panjaitan, Pricylia Putri Handayani (2026) Analisis Sisa Umur Pakai Pada Pipa Lepas Pantai Akibat Free Span Studi Kasus : FSO Field Sukowati. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5046211001_Undergraduate_Thesis.pdf - Accepted Version Restricted to Repository staff only Download (10MB) | Request a copy

Abstract

Penilaian free span memegang peranan penting dalam menjaga keandalan operasional jaringan pipa bawah laut dari risiko kegagalan akibat kelelahan (offshore). Fenomena getaran yang dipicu oleh pelepasan pusaran air (Vortex Induced Vibration / VIV) menjadi salah satu faktor dominan penyebab kelelahan tersebut. Berdasarkan evaluasi menggunakan standar DNV RP F105, penelitian ini menemukan bahwa 4 dari 15 bentangan bebas yang dievaluasi tidak memenuhi kriteria (screening) offshore. Berdasarkan hasil penapisan kriteria kelelahan (screening criteria offshore), nilai tegangan ekuivalen (Von Mises) pada seluruh bentangan yang dievaluasi berkisar antara 210,47 MPa hingga 225,80 MPa. Tingkat tegangan tertinggi tercatat sebesar 225,80 MPa (rasio 0,54 terhadap allowable stress ASME B3.18) pada span berpanjang aktual 24 m dengan gap 1 m. Sementara itu, nilai terkecil berada di angka 210,47 MPa (rasio 0,51 terhadap ASME B3.18) yang dijumpai pada span 36 m dan gap 0,5 m. Evaluasi kelelahan menunjukkan bahwa 11 bentangan yang diuji memiliki estimasi offshore life yang melampaui design life, sehingga dikategorikan aman beroperasi. Adapun umur kelelahan paling singkat teridentifikasi selama 41 tahun pada span 24 m (gap 0,29m) untuk orientasi In-line.
====================================================================================================================================
Free span assessment plays a crucial role in maintaining the operational reliability of subsea pipeline networks against the risk of offshore failure. Vibration phenomena induced by vortex shedding, known as Vortex-Induced Vibration (VIV), represent one of the dominant factors causing such offshore. Based on an evaluation using the DNV RP F105 standard, this study revealed that 4 out of the 15 evaluated free spans failed to meet the offshore screening criteria. According to the offshore screening criteria results, the equivalent stress (Von Mises) values across all evaluated spans ranged from 210.47 MPa to 225.80 MPa. The maximum stress level of 225.80 MPa (a ratio of 0.54 relative to the ASME B3.18 allowable stress) was recorded at a span with an actual length of 24 m and a 1 m gap. Meanwhile, the minimum value was observed at 225.80 MPa (a ratio of 0.54 relative to ASME B3.18) on a 36 m span with a 0.5 m gap. The offshore evaluation demonstrates that 11 tested spans possess an estimated offshore life exceeding the design life, thereby classifying them as safe for operation. The shortest offshore life was identified as 41 years on a 24 m span (0.29 m gap) in the in-line orientation.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Subsea pipeline, Allowable span, free span, in-line, cross-flow, VIV, umur kelelahan
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:	Pricylia Putri Handayani Panjaitan
Date Deposited:	01 Aug 2026 06:22
Last Modified:	01 Aug 2026 06:22
URI:	http://repository.its.ac.id/id/eprint/141380

Actions (login required)

View Item