Oil and gas companies are expanding their operations in the remote Arctic offshore with harsh weather conditions such as the Barents Sea. One of the major challenges in reliability assessment of production plants operating in such areas is lack of life data accounting for the adverse effects of harsh operating conditions. The aim of this study is to develop an expert-based model to assess the reliability of oil and gas exploration and production plants operating in Arctic regions. Expert opinions are used to modify the life data available in normal-climate locations, which are considered as the base area, to account for the effects of operating conditions. The proposed model is illustrated by assessing the reliability of an oil processing train in the Western Barents Sea. Additionally, based on a criticality analysis, some design modifications are suggested to improve the reliability of the processing train.