Nourai - Rastar Farayand Consulting Enginers
Hashemi - Rastar Farayand Consulting Enginers
Ghalajkhani - Rastar Farayand Consulting Enginers

For the first time in Iran, a Pipeline Integrity Management (PIM) Program was developed for a set of cross-lake pipelines in Khuzistan province, south of Iran. The pipelines were being designed to carry oil, gas and condensate that contain up to 9,500 ppm of H2S. Since the design was still is in its basic stage, it was the main objective of the study to determine the least risky way of crossing the lake through a traffic bridge. There were 3 main alternatives for each pipeline to study. In order to do so, a formal risk assessment of pipeline threats was performed using first a preliminary hazard analysis technique to identify hazardous situations. Next, the project team performed quantitative modeling of hazardous scenarios that lead to better understanding of the dimensions of fire and explosion threat to people, passing vehicles and the bridge itself. The tools used for this step were a professional modeling software and computational fluid dynamics (CFD). A comprehensive survey of pipeline accident statistics in USA, Europe, UK, and the former Soviet Union was made in order to relate the identified hazards to world statistical data headings. Then, the team derived typical failure rates from various scientific sources and assigned them to each failure scenario as a function of leak size. Subsequently, combining the above statistics with these data, allowed the team to establish a representative set of failure frequencies to each scenario as a function of failure type. A final risk ranking step that incorporated other important aspects like pollution potential, ease of maintenance, complexity of protective systems as well, allowed comparison of the three main alternatives in mitigated and non-mitigated states and determination of the best alternative. Based on the findings, and taking into consideration the specific characteristics of the pipelines under study, an integrity management program was developed. Although the current pipeline integrity management practices are used mainly for very long pipelines, their guidelines are very useful in preparation of PIM’s. The prepared PIM program was developed into a comprehensive framework incorporating instructions for pipeline data management, operational risk assessment methodology, typical defects of the pipelines, suitable testing and inspection techniques and tools, inspection schedule, in-line inspection data analysis and action-taking, corrosion control and monitoring, leak detection and remedial actions, accident prevention and mitigation methods, and applicable maintenance and repair methods.

Pipeline Integrity Management (PIM), Pipeline Risk Assessment, Pipeline Risk Management, Fire and Explosion, Accident Simulation, Pipeline Inspection and Maintenance