When a single source based crude oil feeder ‘difficult-to-pig’ pipeline runs through a highly sensitive marine national park, the Operator is challenged with the dilemma of how to assure the integrity of the pipeline with the limited options that are available.

After ten (10) years of service, in 2015, an Indian Operator chose to assess the time dependent threat of internal corrosion on their difficult-to-pig offshore (SPM) to onshore (Tank Farm) crude oil pipeline by utilizing the NACE SP0208-2008 Standard for Liquid-Petroleum Internal Corrosion Direct Assessment (ICDA). This methodology was already recommended by ASME B31.8S as one (1) of the three (3) options for assessing integrity of a pipeline. Only a year earlier, in 2014 – the Indian regulators, Oil Industry Safety Directorate (OISD) had also brought the technique of ICDA within its regulatory framework for Operators as a credible option to assess integrity of pipelines that are difficult to pig and/or un-piggable.

This paper discusses on the findings of the ICDA program that forced the Operator to accelerate their integrity program for the subject pipeline and perform specialised In-line Inspection (ILI) in 2018. The paper also compares the results obtained from the non-intrusive predictive based ICDA program Vs. the ILI measured data.

This paper will be useful for Operators to understand the complementary nature of ICDA with ILI and provide guidance on how combination of these two (2) pipeline integrity tools not only identify the locations at which internal corrosion activity has already occurred but also answers the questions on why it occurred and how would it be mitigated?

The Operator managed to assure the integrity of their “difficult-to-pig” pipeline by timely utilisation of the integrity validation tools of ICDA and ILI. By doing this they were able to prevent the occurrence of any catastrophe that may result in an environmental, and subsequently an economic disaster.

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