Abstract
Pipeline integrity is of crucial importance for reliable pipeline operations, and to avert expensive downtime and failures. To maintain integrity, pipelines are equipped with two primary layers of defence for preventing External Corrosion – Coating and Cathodic Protection (CP). Coating and CP go hand in hand and are complimentary to each other.
Periodic assessment of Coating and CP system is paramount to eliminate external corrosion issues which a pipeline may face during its lifetime. Numerous above ground surveys are presently available for inspection of Coating and CP. The survey technologies have been advancing gradually since the 1980s, both in equipment hardware and software capabilities, although the scientific principle behind all of them remains the same.
A major leap in the advancement of such surveys occurred when multiple inspection techniques were combined within the same survey for conducting up to ten (10) aboveground surveys in a single run over the pipeline categorized as Integrated Inspection Techniques (IIT’s). In addition, recording continuous encrypted raw waveforms (up to 35 times per second) and auto integrating the multiple survey data of Close Interval Potential Survey, Direct Current Voltage Gradient, Alternating Current Voltage Gradient, Current Attenuation Test, Alternating Current-Pipe to Soil Potential, Depth of Cover, Pipeline Elevation, Gas Leak Detection, AC Interference and DC Interference in a viewer and analysis software to avoid any manual intervention of survey data.
IITs have been a major proven breakthrough for assessing the external integrity of pipelines transparently and providing instant on-site verification and repair of geotechnical, CP and coating indications.