Gas transmission lines, especially those which were built from mid-20th century to the early 1980s are often affected by external stress corrosion cracking (SCC). A common methodology to address this threat is to utilize EMAT based inline inspection tools to collect data to characterize the asset and flaws. As the EMAT technology is not only sensitive towards SCC or cracking, operators are also often challenged by a significantly high number of reported features, which afterwards turn out to be partly false calls.

Alternatively to EMAT, NDT Global has recently developed a new technology which is based on directional gas coupled guided wave generation in the pipe wall. The small size (compared to EMAT) of the sensors allows for a high sensor density and subsequently a dense measurement grid. This directly translates into high resolution and highly accurate data which enables detection, identification and sizing of SCCs and other linear imperfections. Development efforts over the last few months focused on increasing robustness of the entire inspection system and the underlying analysis approach. To do this, the team addressed the sensing technology, in particular the transducers, as their performance is fundamentally connected to the system robustness.

Within this paper, iterations of transducer enhancements, their testing program and performance criteria are discussed together with their capabilities and benefits in the process chain with regards to automation, robustness and quality. It will be shown how the enhancement in data quality will facilitate to move from traditional manual analysis methodologies towards new approaches, again increasing quality and repeatability of reported results. Finally, a general status update of the new gas crack service will be provided.