Ravva cathodic protection

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Ravva - Cairn’s first development success story has been the bedrock of innovation, and the foundation of our success story in the country and the region. Ravva, which in Sanskrit and Telegu means “diamond” showcases the journey of growth that Cairn has been able to achieve in its business. Incidentally, Ravva is the only field in India to get such a unique name indicating the belief of the nation in it.

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Ravva cathodic protection

  1. 1.               RAVVA Celebrating 16 Years of Technical Excellence HSE | Cathodic Protection
  2. 2. Ravva | HSECathodic ProtectionOne of the major causes of concern for an installation, like Ravva is the corrosion of underground metalstructures. All metals are naturally prone to corrosion, depending on the severity of the environment.Corrosion is the disintegration of material into its constituent atoms due to chemical reactions with itssurroundings.The principal methods for mitigatingcorrosion of underground pipelines areCoatings and Cathodic Protection (CP).The primary function of a coating on acathodically protected structure is toreduce the surface area of exposedmetal on the pipeline, thereby reducingthe necessity to cathodically protect themetal.CP is defined as ‘a reduction of the corrosion rate by shifting the potential of the structure toward a lessoxidising potential by applying an external current’.During the design/construction phase at the Ravva plant all the possible protections were provided.However, due to the ageing and environmental effects, regular monitoring for various degradationprocesses has become necessary.Monthly monitoring schedules are followed at Ravva to check health of the pipelines through the teststations provided in the pipeline corridor for all 13 lines (including newly laid pipelines as part of the RavvaPipeline Project).Cairn initiated Closed Interval Potential Survey (CIPS) for the onshore pipelines ( i.e Plant to Land Fallpoint) to check the potentials at very close intervals (at every 5 m).Over-the-line potential surveys provide measurement of potentials to a reference electrode directly abovethe pipe, and at frequent intervals along the pipe; survey results can be used to locate the more activelycorroding areas (hotspots) on a pipeline not under CP or areas of depressed potentials on cathodicallyprotected pipelines.Highlights of CIPS are:  Monitoring the potential of the pipelines from plant to land fall point.  Potential measurement at an interval of 5 metres  Survey awarded to reputed organisations – for about 3 weeks, surveying through the marshy pipeline tracks  Results proved that all pipelines are in the protection range (0.85-1.2 V)

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