Abstract

There is an old adage “if it is not broken, do not fix it” and this could be applicable for our day-to-day menial activities, but could prove fatally disastrous if followed by any pipeline owners globally. Although, pipelines are statistically the safest means of transporting hydrocarbon — the consequence to an event could be exponential, even if the probability of the event to occur is low. The magnitude of consequence only goes higher with the ever-burgeoning population.

To this effect, Oil India Limited (OIL) owns an intensive network of spider-webbed carbon steel pipelines in Upper Assam, India geographical area with varying vintage.

Understanding the associated risks of operating such critical pipeline systems, it was decided for the pipelines to undergo code-compliant integrity assessment.

It is well known that non-CP protected pipelines are electrically continuous conductors without any insulation (isolation) joints to separate the above-ground station piping to the cross-country underground pipeline sections. With respect to this, OIL deployed a state-of-the-art integrated indirect inspection survey tool to assist in conducting Direct Assessment based integrity assessment. This paper provides an insight into such a scenario where the operator proactively employed the use of advanced high-resolution integrated survey technology to their non-cathodically protected, but coated pipeline assets.

Due to the age and design of these “temporary” pipeline systems, there were no prior readily available records in terms of construction, drawings, maps, alignment sheets, operational or historical maintenance data for these pipelines.

The advanced Integrated survey played a vital role in decluttering these extensively jumbled network of non-CP pipelines. Firstly, by actually locating the pipeline based on sub meter accuracy and secondly performing simultaneous above ground survey for coating assessment and susceptibility for corrosion. The adaptability of integrated survey as per given situation helped overcome the difficult pipeline route conditions and customize the assessment for these highly challenging pipelines and make ECDA feasible as per NACE SP0502 Standard Practice for this very complex spider web network of pipelines.

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