Pipelines are energy lifelines, networks that deliver the nation's petroleum products within the country and across the borders. However, pipelines do deteriorate over the time. Detailed Integrity Assessment of one such veteran pipeline is carried out, having passed seven decades in operation while commissioned in 1945. This paper discusses the assessment challenges, inspection findings and recommendations given to keep this old offshore/onshore unpigable giant in service.

Using the complex geometry of the different pipeline sections (pigable and unpigable); Hazard Identification studies (HAZID), Internal Corrosion Direct Assessment (ICDA) and External Corrosion Direct Assessment (ECDA) have been modified for both offshore and onshore unpigable sections. ICDA methodology has been modified in view of environmental, operational and inspection data along with flow modeling study. The ECDA approach is modified for offshore sections by managing risk of the pipeline corrosion failures while minimizing the cost required for verifications and repairs. Direct examination of these locations has been carried out followed by statistical evaluation of results. The offshore pipeline section stability has been ensured in view of free span analysis. Recommendations pertaining to internal and external corrosion control have been given for the safe operation of the pipeline along with remnant life.

Subject
External corrosion direct assessment, Water, Corrosion rate, Pipeline sections, Pipelines, Inspection, Mechanical failure, Internal corrosion, Wall thickness, Internal corrosion direct assessment, External corrosion, Surveys, Microbiologically influenced corrosion
Keywords:
HAZID, ICDA, ECDA
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2017
Association for Materials Protection and Performance (AMPP)
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