Every scientific or engineering assessment made in today’s life is with respect to a specific approach — prescriptive or performance-based. In India for a newly laid pipeline (approx. 443 Km) — there are various prescriptive regulations ascertained by OISD and PNGRB for the pipelines’ safe routine operations. In a prescriptive system, it becomes mandatory for a pipeline owner to have the most accurate coatings and Cathodic Protection (CP) data irrespective of the external soil environmental conditions. This will also require the other external aggravators such as AC interference, Railway Crossings, Temporal phenomena etc. to be taken into consideration while the survey data is being collected. Only then sufficient data is available for the Owner to make correct integrity-based decisions and step forward towards a performance-based integrity management program.
Hindustan Petroleum Corporation Limited (HPCL)-Rewari Kanpur Pipeline (RKPL) started the external line inspection (XLI) program as a prescriptive procedure for ascertaining the health of the in-place CP system and assess the integrity of the coating.This pipeline with length of approx. 443 Kms stretching across three (3) states of Haryana, Rajasthan, and Uttar Pradesh traverses through a truly varying surrounding soil and ambient environmental conditions. As per NACE Standard Practice SP0502, it is known that different aboveground survey tools are to be utilized by the pipeline owner for varying soil conditions. To overcome the complexity of dealing with varying environments, weather conditions (resulting in varying soil resistivity) for specific pipeline lengths to be surveyed by the various different technologies that may be applicable, HPCL-RKPL opted to deploy an integrated indirect inspection system which allows to perform the following aboveground surveys simultaneously, at the same time: DCVG, ACVG, ACCA (CAT), CIPS – AC & DC with all recorded raw logs for authenticity.
Using these raw logs, HPCL-RKPL were able to ascertain few intricate concerns with the in-place CP system which would have otherwise been veiled. This was possible due to the extremely high frequency of data capture on several times per second basis. The integrated CP and Coating Integrity data also aligned and correlated very well with the historically conducted in-line inspection information. This paper shall discuss the unique findings obtained during the survey.