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Conclusions on Scalable Accuracy

By Greg Alvarado at Inspectioneering Journal. September 9, 2013

We’ve been discussing Scalable Accuracy and its use related to Lifecycle Management technologies available to owner/operators. The last few topics have included Risk Based InspectionFitness for Service using Accuracy, the approach for Equipment Lifecycle Management and, to lay the foundation for proper thinking, making the case for Scalable Accuracy. You can view the last few blogs on this topic.

In this week’s blog, we will wrap up our discussion of Scalable Accuracy.

I want to discuss certainty and uncertainty. The model below illustrates what happens when we have scatter in data and ensuing output results. The intent with qualitative RBI or more conservative FFS is that we err to the conservative. In this case our scatter is above the Absolute Certainty line. 

If we err to the non-conservative side of the model, or below the Absolute Certainty line, we may be in no-man’s land. Examples of when this happens are when we use inexperienced or unqualified people for the damage mechanisms assignment or to make reasonably conservative assumptions in RBI or FFS, when we have erroneous data, when conditions driving the damage change and we don’t know it, etc.

Using this scalable accuracy approach one can optimize the use of resources and money.

Hopefully you can see how the latest API RP 581 technology is a fully calibrated risk model, able to be used qualitatively to semi-quantitatively and augmented with a scalable way to get an adjusted, more accurate t-min and PoF. These technologies also are very powerful and provide answers to dilemmas and challenges of inspection and engineering professionals managing fixed equipment.

Consistency, systematic work processes, documentation of assumptions and engaging qualified analysts and team members is certainly important. Regarding the Certainty Uncertainty Model, as equipment gets older or more damaged, if risk justifies, we will get more data to tell us more about the condition of the equipment and we will grow closer and closer to the absolute certainty line about the true damage state or condition of the equipment. At the right time we will either repair or replace the equipment. We may, during the course of the equipment lifecycle, decide to mitigate or slow the amount of damage to prolong equipment life by introducing a lining, injecting a chemical to slow corrosion, etc.

Finally, the risk analysis provides information needed to convince management. The process may also remove some items from that list as tool like RBI help identify non-value adding practices through a systematic, consistent, technically sound approach.

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