As a result of multiple incidents in the pipeline industry that occurred in the last 25 years and the need to address pipelines that could not be inspected i.e. upiggable using In-Line Inspection (ILI) or could not be taken out of service to be hydro tested due to high security concerns, a team was formed of pipeline operators, researchers, and vendors to start putting together the first direct assessment process in 1998. This team was formed for the purpose of coming up with an
using proven monitoring technologies which consisted primarily of above ground (external) techniques which we all know as close interval survey (CIS), direct or alternating current voltage gradient and current attenuation techniques which later became NACE SP0502 External Corrosion Direct Assessment (ECDA). The key word is ?process? using existing or proven above ground i.e. techniques and tools. More than a decade has gone by and newer technologies have been developed and proven; however, NACE and PHMSA1 have been cautious in giving approval for newer techniques/tools for both internal and external threat applications. This paper will discuss these new technologies and tools that have been developed in the last 10 years. The Direct Assessment process is still valid even though the tools change; however, the question should always be asked ?Are these the right tools to address threat or threats adequately.
Most external corrosion assessments have been performed by NACE certified technicians who are operator qualified to conduct above ground or external surveys such as CIS, DC/ACVG, and current attenuation surveys on upiggable lines. However, as with any tool or technology, each tool has limitations which also include ILI and related tools. There are many instances that both external and internal tools must be run consecutively to truly assess all the threats adequately.
