To maintain pipe line integrity, corrosion usually is characterized as significant based on the maximum corrosion depth and the ratio of predicted burst pressure to maximum operating pressure. Statistical methods using these anomaly assessment are referred to as POE (probability-of-exeedance) analyses. The POE method can help to efficiently prioritize corrosion data received from in-line inspection. The advantages of the approach include the consideration of tool inaccuracy effects. Numerical failure probability can be attached to any unexcavated anomaly. The value of further excavations in succeeding years as well as re-inspection intervals can be assessed, and corrosion anomalies can be ranked by pipe joints, milepost, incremental distance, or by the entire pipe line system. Corrosion rate effects on anomaly growth over any chossentime period can be examined. The POE analysis methods evaluate the probability that out of corrosion depth is greater than 80 % wall thickness, predicted burst pressure is less than abnormal operating pressure and calculated anomaly operating pressure is less than the maximum operating pressure one of the three aforementioned conditions will exist. By measuring maximum probability against time, operators can select a suitable POE level, and determine the number of excavations needed to maintain this level. The resources can be allocated to systems with the highest release probabilities by comparing segment probabilities.
Probability approach promises enhanced maintenance program
Pipe Line and Gas Industry ; 84 , 1 ; 69-73
2001
5 Seiten, 8 Bilder
Article (Journal)
English
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