Shirashima Oil storage base consists of 8 large oil storage barges. The barges are one of the largest floating structures in the world. The oil barges are being surveyed and repaired at mooring site from June 1999 to September 2000. The barges were supposed to be surveyed in detail at dry dock every 12 years. The dry-docking survey required transporting a barge from mooring site to the dry dock through the open sea and removing breakwaters at frequent intervals. In order to reduce the risks and cost of this work, the inspection and maintenance system at mooring site was examined and a new survey plan for the inspection and maintenance at mooring site was developed. This paper describes the summary of the new survey program and maintenance work at Shirashima base. The survey program can be applied not only to oil storage ships but also to all kinds of very large floating structures such as floating airports and floating container terminals in principle.
Japan National Oil Corporation (JNOC) began conducting national petroleum stockpiling activities in Japan in 1978 and completed stockpiling 50 million kiloliters of petroleum, which is a national petroleum target, in 1998. Fifty million kiloliters are stockpiled in 10 oil storage bases which are operated by 8 National Petroleum Stockpiling Companies established by JNOC and private companies. The oil storage bases are divided in four different systems, such as On ground tank system. In-ground tank system, Underground cavern tank system and Floating tank system. There are two bases of the floating tank system in Japan. One is Kamigoto oil storage base, which was entered into service in 1978 and is the first base in the world to use such system.
