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PIPELINE PIGGING TECHNOLOGY- P16

PIPELINE PIGGING TECHNOLOGY- P16: Why pig a pipeline? This paper introduces a number of reasons for doing so, together with a discussion of the advantages and alternatives. In general terms, however, pigging is not an operation to be undertaken lightly. There are often technical problems to be resolved and the operation requires careful control and co-ordination. | Pipeline Pigging Technology LINE OF CONSTANT ECONOMIC RISK OUTAGE CONSEQUENCES ECONOMIC OUTAGE OUTAGE RISK PROBABILITY X CONSEQUENCES PIPELINE X OUTAGE PROBABILITY _Fig.6. Economic risk components. Economic risk outage probability x outage consequences One of the most significant components included in the estimate of outage consequences is the potential reduction in exported gas volumes caused by an outage. Although this is not a direct cost to NOVA and its estimated value is subject to some assumptions it is included to recognize the importance of each pipeline segment to the reliable performance of the Alberta gas industry. The other components of outage consequences are the value of lost gas and repair cost. The results of the economic risk assessment can be effectively illustrated using the diagram in Fig.6 which shows how the probability and consequences are contributing to the economic risk. In general pipeline segments with high outage probability are those with a history of known specific problems Points 1 2 and 5 for example in Fig.9 which require monitoring and maintenance on a periodic basis to prevent operating failures. Inspection and assessment projects for such lines have historically been the core of our pipeline integrity programme however in recent years projects have been planned and carried out on other pipeline segments based solely on the results of the economic risk assessment. These lines generally have only moderate outage probabilities no history of failures but high outage consequences Points 3 and 4 in Fig.7 for example . The effect of a pipeline integrity project is to reduce the outage probability for a pipeline segment shifting its position to the left as shown for several completed projects in Fig.8 to a lower value of economic risk. 432 Please purchase PDF Split-Merge on www.verypdf.com to remove this waterr Risk assessment and inspection for integrity PIPELINE 1.2 12- 10- 8- ECONOMIC RISK 500 000 5 6- 8 10 ANNUAL .