Use of a fuzzy inference system for criticality rank computation in NORSOK standard Z-008: maintenance of rotating equipment and instrumentation

摘要

The NOSOK standard Z-008 suggests a matrix to perform criticality assessment for categorising the rotating equipment and instrumentation connected to them. The categorisation of aforementioned has been utilised for maintenance planning, inspection planning and for prioritising work orders. When the criticality assessments has been carried out using a criticality matrix, suboptimal classification tends to occur as no means to incorporate actual circumstances at the boundary of the input (such as mean time between failure, down time cost, etc.) ranges or at the levels of linguistic data and risk categories. This manuscript suggests a fuzzy inference system (FIS) to overcome the aforementioned challenge whilst minimising the variation that may occur during the criticality assessment. Membership functions and a rule base were developed aligning with the Z-008 standard recommended guidelines as well as utilising data, experience, intuition and intensions of maintenance engineers. An illustration of rule view and a calculation result has been demonstrated to illustrate the methodology.