Determination a risk-based approach to specify the inspection interval in a part of the East Azerbaijan Gas company's facilities

Abstract

Introduction: The use of pipelines for the transmission and distribution of natural gas, due to the high risk of the transported material can cause catastrophic accidents. Leakage means failure of safety measures in pipelines, so risk assessment and inspection are very important in the operation of these pipelines. Risk-based inspection uses the results of risk assessment to determine the optimal inspection time and, while avoiding repeated inspections, focuses the inspection process on higher risk sections. This reduces the cost of inspection and maintenance operations. Methods: This study was conducted in two parts and in a part of 19 km urban gas distribution pipelines in East Azerbaijan Gas Company. Kent Muhlbauer risk assessment method was used in the framework of the risk-based inspection process. The pipeline was divided into 94 separate sections. A Kent Muhlbauer evaluation checklist was developed, and for each section, a scenario related to the pipeline conditions was written. Risk assessment was performed in all sections and the most important indicators affecting the risk were determined. In the second part, acceptable risk values and inspection standard number were determined and used along with Kent Muhlbauer results to calculate the number and time of inspection in each part. Results: Scores from the evaluation ranged from 0 to 5. A score of 0 means the highest and a score of 5 means the minimum risk. 58.5% of the total pipeline had a medium level of risk, corrosion indices and damage caused by the third sector also had the lowest average score. The average inspection time is 166.48 days and their standard deviation is 39.291. The minimum time required for inspection and leak detection in 73% of pipeline sections was 6 months. Discussion: Focusing on effective indicators to increase the risk of pipelines can improve inspection processes and maintenance operations by reducing costs. Determining the optimal time intervals in the inspection of pipelines will ultimately increase the safety factor of the pipeline and reduce the risk of accidents. Therefore, using Kent Muhlbauer evaluation in the framework of risk-based inspection can be effective in risk reduction processes, increasing reliability and optimizing inspection programs in pipelines by determining the appropriate number and times for inspection