Integrity Validation of Non-Piggable Pipelines Through Turnkey ECDA, ICDA and SCCDA

Abstract The demand for pipeline integrity assessment is ever-increasing due to an ageing pipeline network, a need for maintaining safe pipelines along with a stringent industry regulation environment. Not all pipelines are piggable and the non-piggable pipelines are considered more challenging due to their limitations for assessment. Fortunately, the industry has provided with standards and codes related to Direct Assessment (DA) program, as an integrity validation tool, which is especially applicable for non-piggable pipelines. DA is a process driven approach that involves understanding the history of each of the pipelines, conducting multiple aboveground surveys, performing software simulations related to liquid and solid hold up resulting in prediction of corrosion rates and eventually directly inspecting the pipelines to determine the extent of actual corrosion along with condition of the pipeline. These results are utilized for predicting the remaining life and providing a root cause analysis along with mitigation strategies for each pipeline. Pipeline owner, Pipeline Infrastructure Limited (PIL) operates India’s single largest natural gas mainline of 48″ originating from Kakinada and terminating in Bharuch, covering a span of 1,375 km passing through five (5) states and known as the East West India pipeline. The mainline also comprises of various spurs and interconnections along its route which are considered non-piggable. Ten (10) of these non-piggable lines were proposed for code-compliant DA integrity assessment program as part of pipeline owner’s corporate mandate, keeping in mind the greater good of maintaining utmost safety at all times. The DA methodology was applied for evaluating External Corrosion (ECDA), Internal Corrosion (ICDA) and Stress Corrosion Cracking (SCCDA). These lines were commissioned in year 2009 to 2013 were located in the states of Andhra Pradesh (2 pipelines), Maharashtra (1 pipeline) and Gujarat (7 pipelines) and ranged in diameter from 10″ to 30″ with a length of 300 m to 28 kms. This paper will discuss the findings and learnings of the turnkey DA program related to all the three (3) threats and results of the four (4) steps i.e., Pre-Assessment, Indirect Inspection, Direct Examination and Post Assessment. The pipeline owner was not only able to perform a code compliant integrity validation program for these non-piggable lines, but also customize a go forward action plan as applicable to each pipeline.