Pipeline in-line inspection (ILI) is a reliable technique to evaluate and assess the integrity of pipelines. Multiple technologies are currently deployed for ILI. The most widely used include; Magnetic Flux leakage (MFL), Ultrasonic (UT), Electromagnetic Acoustic Transducer (EMAT) and Eddy Current (EC). ILI is used to identify different anomalies and defects, to prevent pipeline leaks or ruptures that will result in production loss and/or adverse environmental impact. Extensive planning is required before running an ILI tool in a pipeline. Even with extensive and rigorous planning between pipeline owners/operators and the ILI vendors, some ILI runs fail. This paper will discuss field experience as to why some pipeline ILI runs fail. It will also discuss key factors to consider during pre-planning and preparation, to minimize the potential for ILI failure. Several of these factors include understanding all pipeline physical parameters, compliance with ILI vendor tool operational limits; such as magnetization capability, velocity, differential pressure and temperature requirements, and compliance with sound operational practices for launching and receiving of ILI tools. It is essential to identify the root cause(s) of an ILI failure to avoid reoccurrence.
Since the first pipelines began to fail, operators have wanted to find out why; what condition the remainder of the pipeline might be in, and was the problem going to occur in other pipelines? Initially, there were very few methods available to assess the integrity of an in-service pipeline. Basically, the only option was to fill the line with water and pressurized it, to see if the line would "hold" the pressure, as an indication of presumed integrity. This often proved unsatisfactory, as the line would be pressurized shown not to leak while under pressure, and then would leak again several days, weeks, or months later. The actual condition of the pipeline or extent of the original problem; were not effectively determined.
