Construction defect analysis of insulation panels for cargo tanks on liquified natural gas carriers

Abstract

Detection and inspection of physical defects on newly installed insulation panels of liquefied natural gas (LNG) containment system on LNG ships is carried out in pursuance to the contractual conditions aims at achieving quality, reducing risk and ensuring safety. It is carried out throughout the installation process and the defect data are processed for the purpose of initiating the rectification process. Detection and inspection could be strategised to focus on the more serious defects, frequently occurring defects and areas which are defect prone. The research analyses four types of physical defects, namely, foam defect, plywood defect, rigid triplex defect and supple triplex defect and predicts the chances of occurrence at strategic locations. Physical defects data gathered during the installation of 2541 insulation panels on two LNG ships are analysed. Linear and polynomial prediction lines on chances of detecting the defects have been produced. The results indicate that supple triplex defect is most common (61.3%) and defect is likely to be found at the tank bottom (30.4%). The chance of discovering defect on the insulation panel inspected is 1%. While for supple triplex defect, the most common defect type is also 1%. There is an indication that the defects at the tank bottom will be found on certain area only.