Oil & Gas Innovation OGI Winter 2018 Digital Version - Page 55

“In the world of metering Murphy’s Law is well known.” will be fit for purpose. Moreover, this can be checked independently, using the functional specifications as the requirements to verify against. On a more technical note, if for instance, it turns out that the received / delivered amount of energy contained in natural gas must be determined, the accuracy of said determination is dependent on more factors than just the flow meter. Here, the influence of gas composition is just as critical as the influence of the number of cubic metres or feet of gas. This is why a measuring system approach, instead of separate instrument focus, is key in ISO 10012. Phase 2, how do we use and maintain? Because of the variation in measurement applications, measurement systems too occur in many variations. This in turn makes that not every member of staff has the knowhow to properly use and/or maintain a particular system. Most commonly, a Quality Assurance system dealing with staff competence on the one hand and operating procedures on the other is applied to ensure systems being used and maintained as intended. Typically, regular internal and external audits are then performed to detect potential shortcomings. In real life, audits are often perceived as exams and non- conformities as mistakes, but the underlying goal of fit-for-purpose measurement is actually a positive and constructive one. Moreover, improving procedures and/or staff knowhow will have only positive spin-off. Two ISO 10012 pillars worth mentioning in this respect are re-calibration frequencies and staff access to instrument configuration. If all is well, back in phase 1 thought was given to (metrological) maintenance, including re-calibration. Fundamentally, the need for re-calibration is determined by the application itself. Is it a high risk or high value measurement; do legal prescriptions apply; is the applied technology sensitive to wear and tear; is the process abrasive, corrosive or otherwise likely to worsen metering performance? The combination of such and other arguments will result in a pre-determined re-calibration regime that needs to be upheld over the lifetime of the measuring system. definitely not as they should be. Potential problems arising in this case can only be pinpointed when performing site visits. And, during site visits please do perform spot checks on critical configuration parameters. Again, auditing may be linked to a perception of fault finding and blaming, but without it, fit-for-purpose measurements are a long way away. When dealing with newly built systems, activities providing similar insights are FAT’s and SAT’s