Cased pipe segments could be less safe than uncased segments

摘要

A comparison of scheduled or immediate responses/mile vs number of repairs from an Interstate Natural Gas Association of America study and the US Pipeline and Hazardous Materials Safety Administration database suggests cased pipe segments could be less safe than uncased segments, although this result is not conclusive. Although peak anomalies tend to be located near the ends of the casing, the severity of the individual anomalies determined by the factor of safety does not depend on location. Anomalies were found on 47.7% of the nonshorted cased pipe segments and 53.3% of shorted cased pipe segments. The higher susceptibility of shorted cased pipe segments to corrosion suggests metallic shorts increase the chance of external pipe corrosion and thus shorted casings should be given higher priority when conducting integrity assessment. Nonshorted casings (a subtotal of 157) are four times more prevalent than shorted casings (28).