The primary focus of a pressurized piping systems integrity management program (IMP) is to provide safe, reliable operation. One of the preferred tools leveraged by operators is the use of in-line inspection (ILI) technologies to assess the integrity of their assets. A comprehensive inspection program using ILI systems to detect, quantify and accurately classify anomalies is a mitigation strategy for pipeline threats thus reducing risk to the environment.

Magnetic flux leakage (MFL) is the most commonly used ILI technology for pipeline metal loss assessment. However, despite segments having been inspected multiple times with MFL systems, inservice
incidents still continue to occur. Some in-service failures have been associated with stress corrosion cracking (SCC) or other cracking related threats. Due to the size and geometry of tight cracks and the limitations of MFL based technologies, they can go undetected.

Electromagnetic acoustic transducer (EMAT) technology generates an acoustic wave in the pipe material.
The wave propagates around the pipe and is reflected back to receiver sensors when the acoustic wave
encounters a crack. While EMAT development for ILI systems began in the 1980s, significant
advancements in performance over the last decade have resulted in greater adoption and has recently
been included in some regulation.

This apper will outline TDW's experience validating EMAT performance with Williams, a gas pipeline
operator. A review of the added benefit EMAT technology provides to augment more traditional ILI
technologies, such as MFL and geometry, will be explained. An outline of the combined effect of multiple
technologies to produce the most comprehensive ILI system solution for accurately detecting and
characterizing crack anomalies that may otherwise go undetected will be presented.