Determining the degree of fuzziness for Fuzzy-AHP methodology used for identifying fatigue critical piping locations for inspection

Abstract

This paper acts as a supplement to the Fuzzy Analytical Hierarchy Process (FAHP) based methodology proposed by the authors to prioritize inspection of Potential Fatigue Critical Locations (PFCLs) on topside piping. In order to account for the uncertainties in the AHP based approach (proposed by the authors), arising from the crisp scale, authors have proposed an FAHP based methodology. The aforementioned approach uses a pre-defined fuzzy set scale and a certain degree of fuzziness (δ). Generally, the degree of fuzziness is determined by the sensitivity analysis. However, such an approach is not suitable for the FAHP methodology proposed by the authors. Hence, in this manuscript the authors have proposed an alternative approach to select the value of δ based on the experts' background knowledge regarding the technical reality of the piping system. In real-world situations the aforementioned depends upon his/her past on-site experience, accessibility to the technical reports and other technical documents. Thus, the value of δ based on the expert's background knowledge reflects his/her confidence regarding the technical reality/condition of the system. A case study is performed to illustrate the applicability of the proposed approach.