Fatigue Life Analysis of FSO Anchor Chain with Corrosion Effect

In this study, the authors analyze the fatigue life of the anchor chain used to secure the Gamkonora FSO to the seabed. The objective is to determine the operational lifespan of the anchor chain by considering its fatigue life. The research begins with an analysis of the movement of the Gamkonora FSO under environmental loads in both free-floating and moored conditions to determine the tension in each anchor chain. Next, the anchor chain tension is calculated for various corrosion levels, namely 0%, 5%, 10% and 15%. Subsequently, the tension range and damage ratio values are determined using the T-N curve method based on Palmgren Miner’s failure law, with failure estimation carried out using the rainflow counting method. The numerical modeling results reveal that the largest translational motion behavior of the FSO occurs during heave motion, reaching 1.409 m/m, while the largest rotational motion is observed during roll motion, with a value of 3.463 deg/m when the FSO is fully loaded. The maximum tension recorded in the anchor chain is 1,695.14 kN at heading 90 under 0% corrosion conditions, with a safety factor of 4.53. Furthermore, the cumulative damage value from the T-N curve is obtained, with the largest value recorded as 0.0702. Based on the cumulative damage, the fatigue life of the anchor chain is estimated to be 14.25 years during its operational lifespan

Analisis Umur Kelelahan Rantai Jangkar Fso Pengaruh Korosi Pada Studi Kasus Fso Di Papa Terminal

Dalam tugas akhir ini penulis menganalisis umur kelelahan rantai jangkar (anchorchain) yang digunakan untuk menambatkan FSO Gamkonora ke dasar laut. Analisis ini dilakukan untuk mengetahui masa operasi rantai jangkar dengan mempertimbangkan umur kelelahan. Penelitian dimulai dengan melakukan analisis mengenai pergerakan FSOG amkonora akibat beban lingkungan dalam kondisi free floating dan tertambat untuk mendapatkan besar tension pada setiap anchor chain. Selanjutnya menghitung besar tensionanchor chain pada semua variasi korosi, yaitu 0%, 5%, 10%, dan 15%. Setelah itu dilakukan perhitungan tension range dan menghitung nilai cumulative damage menggunakan metode TNCurve berdasarkan hukum kegagalan Palmgren Miner dengan mengestimasi kegagalan menggunakan metode rainflow counting. Dari hasil pemodelan numerik yang dilakukan, didapatkan bahwa perilaku gerak translasional terbesar pada FSO yaitu sebesar 1.409 m/m untuk gerakan heave dan gerak rotasional terbesar adalah 3.463 deg/m untuk gerakan roll saat kondisi FSO muatan full load. Untuk hasil tension terbesar pada anchor chain yaitu 1695.14 kN pada heading 90 saat kondisi 0% terkorosi dengan safety factor 4,53. Setelah itu didapatkan nilai cumulative damage dari T-N Curve dengan nilai terbesar 0,0702. Berdasarkan cumulative damage tersebut, umur kelelahan anchor chain yaitu 14,25 tahun selama umur operasi ====================================================================================================================================== In this final project the author analyzes the fatigue life of the anchor chain used to anchor the Gamkonora FSO to the seabed. This analysis was conducted to determine the operating life of the anchor chain by considering the fatigue life. The study was started by conducting an analysis of the movement of amconoric FSOG due to environmental loads in free floating and moored conditions to obtain the amount of tension in each anchor chain. Next, calculate the tension anchor chain for all corrosion variations, namely 0%, 5%, 10% and 15%. After that, the tension range is calculated and the cumulative damage value is calculated using the TNCurve method based on Palmgren Miner's failure law by estimating failure using the rainflow counting method. From the results of numerical modeling, it was found that the largest translational motion behavior in the FSO is 1,409 m/m for the heave motion and the largest rotational motion is 3,463 deg/m for the roll motion when the FSO is full load. For the largest tension results on the anchor chain, namely 1695.14 kN at heading 90 when conditions are 0% corroded with a safety factor of 4.53. After that, the cumulative damage value from the T-N Curve is obtained with the largest value of 0.0702. Based on the cumulative damage, the fatigue life of the anchor chain is 14.25 years during its operating lif