Application of probabilistic methods for predicting the remaining life of offshore pipelines

When offshore pipelines are approaching the end of their design life or have gone beyond their design life, their condition could possibly threaten oil flow continuity (through leak or rupture) as well as become a potential safety or environmental hazard. Some of the pipelines may show signs of deterioration and ageing due to corrosion, cracking or other damage mechanisms. Any assets, such as the pipeline, may be desired to continue transporting hydrocarbons beyond its design life due to increased oil and gas demand, due to unforeseen increased oil and gas reserves, or due to upgrade where additional assets are tied-into the existing pipeline system. Other situations may force operators to maintain the pipeline's design life in spite of premature ageing of the pipe wall caused by the increased corrosion growth or other anomalies. Hence, there may be a need to assess the remaining life of pipeline in order to determine if it is capable of coping with current and future operational demand. The first task in the assessment process is to identify degradation mechanisms and their rate of growth, then estimate uncertainties in the collected data concerning pipeline flaw geometry, pipeline mechanical properties and operating characteristics. Based on the collected data and the assessment, the probability and consequence of failure can be determined. The remaining life of a pipeline is the time it takes the pipeline to fail or exceed the target failure probability. This paper presents a methodology for assessing the condition of ageing pipelines and determining the remaining life that supports extended operation without compromising safety and reliability. Applying this methodology would facilitate a well-informed decision that enables decision makers to determine the best strategy or adequate course of action for assessing and maintaining the integrity of ageing pipelines. Copyright © 2014 by ASME.