Japan's Largest Spherical Gas Tank Under Construction
NKK is building one of Japan's largest spherical gas tanks in the center of the Echigo Plain in northwestern Japan. The gas tank, located in the town of Kurosaki near Niigata City, is 40 meters tall, equivalent to a 10-story building.
The tank is in the shape of a sphere with a diameter of 34 meters, and will be the first of two tanks being planned by Hokuriku Gas Co. to store natural gas. The tank will have a maximum storage capacity of 200,000 Nm3. In the construction of the tank, a total of 126 high-tensile strength steel plates, each measuring 12 × 3 meters and 35mm in thickness, are being used. To make up a sphere, each of the plates is trapezoid-shaped and slightly curved. After being bent to the required curve at NKK's fabrication shop, the plates were transported to the site for assembly and welding. The spherical shape of the tank is ideally suited to the storage of high-pressure gas, as it ensures a uniform distribution of internal pressure. This is because the tank will optimally withstand the pressure from the compressed gas, which tries to expand, by being as close as possible a true sphere. The first of these spherical gas tanks is scheduled to go into service in the autumn of this year. NKK will build a second tank of a similar capacity on the same site. The second tank is expected to be completed in the autumn of 2000. |
