Pipeline Integrity Assessment Applied to the Conversion of a Large Diameter Natural Gas Transmission Pipeline to Liquid Products Service

摘要

A major conversion project was undertaken in 2001 to convert a fifty-year-old natural gas transmission pipeline to refined petroleum products service. A joint venture Limited Liability Corporation (LLC) was formed to modify and convert the existing pipeline, as well as operate and maintain the system to transport refined liquid fuels from the Gulf Coast to the Midwestern United States. As part of the United States Federal Energy Regulatory Commission(1) (FERC) approval process, this partnership made a commitment to assure the mechanical integrity of the pipeline system prior to placing the converted line into service. The integrity of the pipeline was assessed and confirmed using several integrity assessment methods. This paper will outline the methods employed to detect and remove potentially hazardous defects prior to startup. It will discuss the metallurgical evaluation of the 1950's vintage pipe and known integrity concerns. It will discuss the use and objectives of In Line Inspection technology, and how this technology combined with a customized hydrostatic testing protocol produced a comprehensive evaluation of the system. It will discuss the USDOT Office of Pipeline Safety's (OPS) recently enacted Integrity Management Plan rule and how this rule affected the planning and execution of the project. Finally this paper will describe the extensive amount of planning, coordination, and communication required to execute the integrity assessment of approximately 700 miles (1126 km) of fifty year old pipeline which today serves the motor fuel deficient Midwest region.