SENSITIVITY ANALYSIS, INFLUENCE OF WALL PIPE THICKNESS AND OPERATING TEMPERATURE ON PIPELINE GAS RELIABILITY USING PROBABILISTIC FRACTURE MECHANICS METHOD

• Main Author: Habibie, Fithratullah
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40297
• Institution: Institut Teknologi Bandung

Natural gas is the third most consumed energy in the world with the fastest growing consumption 1.4% a year compared by liquid merely 0.7% a year. Growing consumption trend of natural gas is supported by Indonesia government by structuring National Subholding gas. Subholding gas will focus on developing pipeline infrastructure along 10.547 km until end of 2019. Author is encouraged to study more about correlation of intrinsic variable and operation of gas pipeline with pipe failure. This study used probabilistic fracture mechanics (PFM) through Monte Carlo simulation to assess pipeline reliability. This study used data from Sumatra gas pipeline on kilometer 18, 77, and 122. Study is conducted to analyze sensitivity of variable leading failure probability and influence of thickness and operating temperature towards pipe reliability. This study conducts simulation based on API FFS 579 document section 9 which is crack like flaw. This simulation is done consecutively started by making work sheet of API 579 section 9 on Microsoft Excel. Value of fracture toughness used in work sheet is determined by API 579 annex procedure then weakest link size effect statitistics theory. Then crack propagation used in simulation is superposition crack propagation. Wall thickness and operating temperating variable are input in simulation. Wall thickness being used are 15, 18, 21, and 24 mm. Operating temperature being used are 77, 92, 107, and 122 °F. After that remaining pipeline life is determined by Monte Carlo simulation through Crystal Ball Application attached on Microsoft Excel. Based on results of simulation, increasing wall thickness from 15 mm till 24 mm will increase remaining life years. It is because decreasing of stress reference and stress intensity factor are larger than fracture toughness. Beside that, results show that increasing operating temperature from 77 till 122 °F will increase remaining life years. Increasing operating temperature will increase fracture toughness because material absorbs more energy. Sensitivity analysis shows that speed of crack propagation is the most influential on pipe failure, then followed sequentially by operating pressure, wall thickness, operating temperature, initial size crack, and pipe yield strength.