Structural Integrity Assessment on the Sustainability of an LNG Export Terminal

Abstract

Natural gas reserves were discovered at offshore of Bintulu, Sarawak in late 1960s.  First Liquefied Natural Gas (LNG) project begin operation since 1983. Currently there are nine (9) LNG production trains with an export terminal of three (3) berths in operation. This paper presents structural integrity assessment of an LNG export terminal to ensure sustainability and continuous safe cargo delivery, which was originally intended to operate up to 2021.  Extension of service life avoid demolition of existing jetty, minimise construction activities and material used thus reduce CO2 and waste generation. Various inspection techniques such as visual inspection, underwater inspection, detail inspection with destructive test (DT) and non-destructive test (NDT) were conducted.  Detail analysis with StaadPro V8i software was performed to assess the jetty structure integrity at current stage and prediction on safe operation in future. The field inspection results show that 62% of concrete pile jackets experienced moderate to severe defects. Generally, the jetty concrete structure was found to be still in good condition with minor defects.  DT and NDT on the concrete structure indicated that the test results are within acceptable limits.  Surface corrosions were observed on miscellaneous steel structure. Structural analysis result indicates that the berthing velocity need to be reduced from 115 mm/s to 100 mm/s for safe berthing of 80,000 DWT vessel unless the piles capacity is reinstated. The study concluded that through proper repair and rehabilitation of existing piles and structures, jetty service life can be further extended for 20 years.