Risk based inspection analysis (RBIA) on offshore oil and gas (O&G) production systems optimize level of in-service inspection. The potential failure risk of a system, a sub-system or a thickness measurement location (TML) of O&G production systems comprise the consequence of failure (CoF) and probability of failure (PoF). A tailor-made risk matrix supports the estimation of maximum inspection intervals. When the inspection intervals are calculated using a risk matrix, suboptimal classification tends to occur as there are no means to incorporate actual circumstances at the boundary of the input ranges or at the levels of linguistic data and risk categories. This manuscript suggests a fuzzy inference system (FIS) to overcome the aforementioned. Membership functions and the rule base development have been carried out in alignment with a tailor-made risk matrix which has been utilized by a production plant owner operator organization. A rule view and a calculation result have been demonstrated to illustrate the methodology.