RELIABILITY ANALYSIS OF API X65 GAS PIPELINES USING PROBABILISTIC FRACTURE MECHANICS METHOD FROM INSPECTION RESULT OF PHASED ARRAY ULTRASONIC TESTING (PAUT)

• Main Author: ANGGAKUSUMA (NIM : 12514023), JEREMY
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/28255
• Institution: Institut Teknologi Bandung

Pipelines are equipment used to distribute various types of fuel used for energy fulfillment. To determine safety of the pipeline, the exact values are needed for decision making. In this research, Probability Fracture Mechanics method will be used. This research will study how the differences in pipe constituent materials, operating pressures and crack propagation methods affect the size of the critical crack and the age of a pipelines. Data in the form of length, width, and crack position were taken using the Phased Array Ultrasonic Testing (PAUT) method. For the determination of critical cracks, FAD diagram is used with API 579 section 9 standard. A series of simulations with the failure limit are conducted to study the difference in pipeline age using Crystal Ball application. Three crack propagation methods are used to determine the age of the pipe network. The three methods are Stress Corrosion Cracking with the assumption that the pipeline environment has the same content as NS4 Synthetic Water, Stress Corrosion Cracking with the assumption that the gas contains CO2, and Fatigue Crack Growth. There are variations of pipe constituent materials, namely API X65 (field data), API X65 (API standard), and API X70. Simulations were carried out at operating pressure with variations of 2.2 MPa, 4.2 MPa, 6.2 MPa, 8.2 MPa 10.2 MPa, and 12.2 MPa. The results of the determination of critical cracks indicate that there is an increase in the size of the critical crack along with the increase in the value of the fracture toughness of the material used to construct the pipeline. The results of the determination of pipeline age show that there is a decrease in pipeline age along with the increase in operating pressure on the three assumptions of the crack propagation method. In crack propagation using Stress Corrosion Cracking method, it is known that the partial pressure of CO2 gas significantly decreases the life of the pipeline. In crack propagation method with Fatigue Crack Growth, it is found that the age of the pipeline is very high, ie> 100 years of pressure low operation. While at high pressures, the age of the pipeline network decreases significantly in all pipelines.