The seawater intake system of a power plant has the function of delivering cooling water to condenser and auxiliaries. In fact, the HDPE pipeline in the marine environment has been used for seawater intake system due to its advantages, such as immunity to galvanic corrosion, light weight, and flexibility. Hence, it is indeed imminent to employ the HDPE pipeline safely sinking analysis and thus, rigorous study should be carried out. Moreover, the Daewoo Engineering and Construction Ltd. had installed the ultra-diameter of 2500mm HDPE pipeline successfully for Ras Djinet Combined Cycle Power Plant in Algeria. With that, this paper introduces the design and the analysis pertaining to installation of HDPE pipeline. © 2016 Taylor & Francis Group, London.