ENGINEERING CRITICAL ASSESSMENT INSTALASI PIPA BAWAH AIR DENGAN METODE S-LAY
Santi Fresti Qauli 1), Prof.Dr.Ir. Ricky Lukman Tawekal 1), Ahmad Taufik, Ph.D 1)
1) Magister Teknik Kelautan Fakultas Teknik Sipil dan Lingkungan Institut Teknologi Bandung
Jalan Ganesha 10 Bandung 40132
email: santiq@xlfutureleaders.com
Abstract: Submarine pipe weld joints are an area that is likely to experience defects. This study was conducted to evaluate the mechanical integrity and thickness of welds that had weld defects using Engineering Critical Analysis (ECA) with the Failure Analysis (FAD) method. ECA is a fairly good method for evaluating the integrity of a pipe structure that is defect4e in the weld. FAD d4ides two areas, namely the safe area and the unsafe area which is created by two axes, namely the x-axis is stress ratio (Lr) and the y-axis is the stress intensity ratio (Kr). Stress ratio (Lr) is ratio between reference stress (σref) and material stress (σys), while stress intensity ratio (Kr) is ratio between stress intensity factor (KI) and material toughness (KIC). ECA is carried out in two conditions, firstly during installation with bending loading due to S-Lay notation and secondly during hydrotest. Based on analysis at installation conditions, it is found that crack dimensions with a: 4 mm, c: 100 mm are declared unsafe, whereas defect dimensions below 4 mm at the time of installation it is declared safe. Whereas in the hydrotest condition, the crack dimensions with dimensions greater than a: 3 mm, c: 12.5 mm were declared unsafe, while under these dimensions it was declared safe. In installation conditions, welded joint number 20 with depth defect 4 mm, width of 200 mm is unacceptable or unsafe. In hydrotest conditions, welded joints numbered 13 to 20, with a depth of defect (a) strating from 3 mm to 4 mm, are unacceptable or unsafe. Based on the analysis, the depth of the defect (a) are more influential to material toughness.
Keywords: Welding Defects, Submarine Pipes, Engineering Critical Assessment, Failure Analysis Diagram, S-Lay
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