Prioritizing the Maintenance of Pipeline Based on Risk Analysis

There have been a number of incidences reported for pipeline failures at both onshore and offshore facilities. In order to minimize the failure causes, it is required to clearly understand the failure mechanism, probability and consequences of failure and also the methodology for data to be analyzed. This thesis was based on an Analytical Hierarchy Process (AHP) to determine the risk factors of pipeline failure. AHP provide a multiple criteria scoring results based on expert judgment for prioritizing the maintenance of the pipeline. To perform the AHP approach, two pipeline systems have been chosen for case studies was located in Kertih, Malaysia and Kutai Basin, Indonesia.

Analysis of the AHP process showed that the gas pipeline in Kertih involves greatest risk failure covers probabiliy and consequences. The highest probability is internal corrosion of 41.7% and the rest is caused by internal erosion of 19.1%, external impacts of 13.8 %, external corrosion of 10.7%, free span of 8.1%, and on bottom stability of 6.7%. The greatest consequences of pipeline failure would impact on the environment of 59.4%, and the others will be the impact on economic of 24.9% and safety of 15%. On the other hand the highest probability for oil pipeline at Kutai Basin is caused by system operation of 34.7% and the other factors are design index of 23.7%, maintenance of 23.7%, and third party index of 18%. The greatest consequences will be on business of 60%, the second impact is environment of 20% and the last impact is on population of 20%.

Based on these two pipelines systems then the moderation for probability and consequence of failure have been determined. The result of analysis shows in general the factor of probability and consequence of failure are similar in various pipeline areas. By clearly knowing and understanding the probability and consequences of pipeline failure, then the risk level and category can be determined. From this analysis the pipelines can be ranked according to risk will assists the prioritization of pipelines maintenance. The inspection and maintenance budgets would be more effectively plan by setting priorities based on these pipelines risk. Those pipelines with higher risk should be given more urgent attention for maintenance action while those with lower risk rank may be put on a waiting list.

The AHP method has been compared to the existing method in formulating the pipeline maintenance, from the analysis the detail and complete result for AHP has been showed. AHP can exactly show the factors that may cause the pipeline failure based on the structure of hierarchy of risk pipeline failure and categorize the risk into risk category so that proper maintenance can be determined. Where as in the existing method the maintenance plans only based on inspection and comparison of each factor has not been made. This practice will result in improper maintenance which may incur unnecessary cost.