Age-reliability characteristics

TABLE 5.11 Summary of Corrosion-Related Accidents in Pipelines  

In a summary report for incidents between 1985 and 1994, corrosion accounted for 28.5% of pipeline incidents on natural gas gathering and transmission pipelines. For incidents between 1986 and 1996 corrosion accounted for 25.1% of pipeline incidents on hazardous liquid pipelines. 

In addition to the reported accidents, an average of 8000 leaks per year are repaired on natural gas transmission pipelines, and 1600 spills per year are repaired and cleaned up for liquid product lines. 

Extensive studies on failure patterns to improve maintenance strategies and operational procedures identified six basic patterns. 

Pattern A. Referred to as a bathtub curve with three identifiable regions, namely (i) the initial period of high probability of failure (ii) region of constant and low probability of failure (iii) a wear-out region of high probability of failure. 

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