RELIABILITY ANALYSIS FOR PIPELINE SHIFTING USING DAVIT LIFT AT NORTHERN PATIMBAN SEA, WEST JAVA

• Main Author: Hasan Taherdito, Achmad
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/80208
• Institution: Institut Teknologi Bandung

The subsea pipe installation process is a highly dynamic activity, and at the times, it may not align with the design. In such cases, the final part of the pipe deployment process, known as the laydown process, may fall outside the target box and require adjustments to reach the planned location. Therefore, it needs to be shifted and moved to the actual location. By referring to DNVGL-ST-F101 as a basis for ssubsea pipe installations, a case study was conducted on shifting pipes using a davit lift, and the reliability of this activity was assessed. In this research, the reviewed structure is a 16-inch NPS pipe, 2.1 km in length, running along the seabed at northern sea of Patimban. The pipe will be moved using a davit crane, advancing up to 10 meters towards the target box. The pipe is already filled with water due to post-activity from pre-commissioning. Numerical modeling using Offpipe indicates that the most optimal configuration for davit lifting involves 5 davit cranes. The pipe can be lifted safely to a height of 16 meters from the seabed, with a free span of 144 meters. The maximum stress at the sagbend section is 77.55% of SMYS. Reliability analysis is performed after the numerical modeling process. The data that is random in the analysis is wave height data, while other values are deterministic. However, for the allowable stress limit, it will be divided into two conditions: constant and random. The probability of failure in the pipe-shifting activity is 6.52?????18 for the constant condition and 0.0329 for the random condition. From these probability values, the reliability index calculations can be performed, resulting in values of 7.906 for the constant condition and 2.839 for the random condition. The reliability index value is exceptionally high, indicating that the pipe-shifting activity remains feasible and safe. The chance of structural failure in this activity is relatively low, given the minimal possibility of wave height causing overstress in the pipe.