Process Safety and Environmental Protection 1 0 2 ( 2 0 1 6 ) 71–84 Contents lists available at ScienceDirect Process Safety and Environmental Protection journal h om ep age: www.elsevier.com/locate/ps ep Enhancing offshore process safety by selecting fatigue critical piping locations for inspection using Fuzzy-AHP based approach Arvind Keprate * , R.M. Chandima Ratnayake Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger, Norway a r t i c l e i n f o Article history: Received 17 December 2015 Received in revised form 19 February 2016 Accepted 20 February 2016 Available online 28 February 2016 Keywords: Hydrocarbon release Process safety Offshore topside piping Vibration induced fatigue Fuzzy-AHP PFCL a b s t r a c t Topside piping is the single largest source of the hydrocarbon releases (HCRs) on the offshore oil and gas (OOG) platforms in the North Sea region. Consequently, if the leaked hydrocar- bons from the process pipework are ignited, it may lead to a catastrophic event, thereby causing significant economic losses, environmental damage, and posing serious threat to the safety of the onboard personnel. In order to avert such a fateful event and to enhance process safety, it is vital to maintain the technical integrity of the topside piping. In regard to this, risk based inspection (RBI) plays a vital role, as the inspection locations and fre- quency are decided based on the risk of potential failure. However, international standards such as API 570, API 581 and DNV RP-G101 provide limited guidance in regard to inspec- tion of the fatigue degradation of the offshore topside piping. Due to the aforementioned, selection of the fatigue critical piping locations for inspection, is currently done either on the ad-hoc basis or using the three staged Risk Assessment Process (RAP) mentioned in the Energy Institute (EI) guidelines. Nevertheless, it has been revealed that the methodology for stage 1 of the RAP is laborious and time consuming. Thus, to reduce the toil of the prac- ticing inspection engineer and with the aim of mitigating the dearth of RBI methodologies for topside piping fatigue, this manuscript proposes a Fuzzy-Analytical Hierarchy Process (FAHP) centered approach for selecting the fatigue critical piping locations for inspec- tion and repair. The usability of the proposed approach is demonstrated by an illustrative case study. © 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction 1.1. Background Throughout the offshore oil and gas (OOG) industry, consid- erably effort is being laid on enhancing the process safety, in order to prevent hydrocarbon releases (HCRs) from the off- shore production facilities (OGP, 2011). The reason for the aforementioned is that, if the leaked hydrocarbons are ignited, it may lead to a catastrophic event, thereby causing significant ∗ Corresponding author. Tel.: +47 40386776. E-mail addresses: arvind.keprate@uis.no, arvindkeprate@gmail.com (A. Keprate) . economic losses, environmental damage; and posing serious threat to the safety of the onboard personnel. During the period between 1996 and 2011, an average of 23.3 hydrocarbon leaks above 0.1 kg/s were registered on the offshore platforms in the Norwegian Continental Shelf (NCS) (Bergh et al., 2014; PSA, 2012). Statistics indicate that the single largest contribu- tor of the HCRs on the OOG platforms in the North Sea region is the topside piping (as pipework contributed to 56% of failures on OOG platforms in the UK sector of the North Sea), followed by valves, flanges and other pressure equipments (HSE RR672, http://dx.doi.org/10.1016/j.psep.2016.02.013 0957-5820/© 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.