| Following the successful completion in 2000 of two Ethylene Tanks in Ruwais, Abu Dhabi for Chicago Bridge & Iron, NASA Structural Systems LLC (NSSL) have recently been appointed by CB&I for the post-tensioning works associated with 4 Full Containment LPG Tanks for GASCO. |
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| NSSL’s scope for this project, also located in Ruwais, Abu Dhabi consists of the detailing, installation, stressing and grouting of approx. 820MT of PC strand within the walls of 2 Propane and 2 Butane Tanks, each 86,300m3 in volume, 34m high and 62.8m internal diameter. The width of the tank walls is generally 500mm, tapering over the lowest 6.8m of walls to a width of 800mm at their base. |
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| Horizontal tendons typically comprised of 19 x 15.7mm diameter, 1860MPa UTS, low relaxation, Euronorm 7 wire PC Strands housed, stressed and grouted within galvanised iron ducting of 105mm ID have been detailed to satisfy the Effective Force Profile nominated by our Client. Each tendon is approximately 105m length and is to be stressed from both ends to a load of near 420T. |
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| BBR Cona Compact M3 Multi-Strand Anchorages, positioned at the buttresses, were chosen to anchor these tendons due to the specification requirement for the pre-stressing system to be workable at cryogenic temperatures. |
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| The tank walls are being constructed with a permanent steel liner positioned on the inside wall face prior to casting of concrete, leaving only the outer face to be formed, and the walls are being cast in 3.4m lifts. |
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| Construction of the walls commenced in July 2006, with the anchorage castings and ducting already cast into the concrete of the first 2 lifts, and is expected to be completed mid 2007. |
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