LNG Tank Post-tensioning
Sakhalin Investment Energy Co
Chicago Bridge & Iron Co
The Sakhalin LNG Plant is located on the Pacific coast of Sakhalin Island, Russia – a cold climate with daily temperatures at sub zero level from November to March, meaning the site can only operate from April to December.
The two tanks have a capacity of 130,000mÑ for the storage of liquefied natural gas, with a wall height of 39m and an internal diameter of 66m.
Freyssinet’s scope for the works included the design and detailing of the post-tensioning system, plus the supply of the PT materials, the hire of specialist PT plant and the supply of on site technical assistance for the duration of the installation works.
The post-tensioning system for each tank comprised of 70 No “hoops” with each hoop made up of two 19C15 tendons, installed in the form of horizontal tendons only stressed at buttresses located at 90 degrees apart.
Prior to the approval and supply of the Freyssinet C Range anchorage system, full scale Cryogenic testing of a complete anchorage and tendon was undertaken by Freyssinet Technical Department within PPC factory facility in May 2004.
Partial strand installation and stressing activities were undertaken in a joint venture with FIC.
Due to the cold climate conditions and constraints in the works programme, tendons could not be grouted following the completion of the first stage stressing activities. To overcome the problems of potential corrosion of the strand during the winter months, soluble oil (Shell Dromus B) was injected into the ducts periodically during this time to give a short-term, temporary corrosion protection and allowing the tendons to be grouted during the spring when warmer temperatures will be achieved.