A Case Study: Failure Analysis of Crude Oil Pipeline Rupture

Abstract

More than 80% of crude oil requirement in India is met through imports. Imported crude oil is delivered to the shore tanks through Single Point Mooring (SPM) system. Generally, SPM systems are installed in the sea where water depth is around 30m and more. Crude oil tankers discharge their cargo through these SPMs and off-shore pipelines to storage tanks located in the shore. Therefore, off-shore crude unloading pipelines are a vital link to in the energy supply chain in India. Management of these off-shore pipelines is a challenging task. This paper discusses a case of mechanical damage to an Indian off-shore pipeline and how the damage is being evaluated to ensure reliability and safety of this vital link to ensure sustained and safe operation of the line. The mechanical damage discussed in this paper is in a 48″ off-shore pipeline at a depth of nearly 30m and 24km away from the shore. Owners believe that the damage was caused due to anchor hit from a ship that was buffeted away from safe anchor zone to no anchor zone during a cyclonic storm. Owner had to face considerable challenge in locating and measuring the extent of damage and evaluating its severity and probable impact on the integrity of the pipeline. Owner had done multiple geometry inspection of the pipeline to measure the length of the damage and restriction introduced in the bore due to local reduction in diameter. Possibility of presence of a crack and its likelihood of growth in the near and distant future is also evaluated. The paper also discusses the possible remedial measures to ensure long term integrity of the pipeline.