LNG liquid gas tanks, Cameron, USA

80-metre diameter climbed in 2-week cycles / Liquid gas tanks with PERI VARIO and CB climbing scaffold

In the US Federal State of Louisiana, three enormous circular containers - each with a 77.50 m internal diameter and a 43.80 m high wall - are currently being constructed simultaneously. These so-called LNG tanks will eventually be used for the storage of liquid gas. In the bottom third, the wall cross-section tapers externally from 90 cm at the base to 75 cm. The reinforced concrete wall then runs vertically up to the top with a constant thickness of 75 cm on both sides. Four buttresses, each 1.70 m thick and 4.50 m long, have been integrated into the ring wall to act as vertical bracing elements.

Engineers from the Fort Worth office of formwork and scaffolding manufacturer, PERI, provided the contractors with a cost-effective climbing formwork solution using the VARIO GT 24 girder wall formwork system together with CB climbing scaffold. Compared to conventional circular formwork, cost-intensive anchor points can be saved to a very large extent using the VARIO system. With a permissible fresh concrete pressure of 45 kN/m², only two DW 20 tie points are required with a concreting height of 4.65 m. However, numerous steel installation elements in the shear walls have had to be taken into consideration when determining the tie positions.

PERI supplied the 3.20 m wide and 4.90 m high pre-assembled VARIO panels directly to the construction site. Specially-constructed additional infill spaces between the GT 24 formwork girders and the SRU 140 universal steel walers ensure a very accurate plywood formlining curvature. Friction-locked connections between the steel waling are carried out by means of VARIO articulated couplings.

Together with the type-tested CB climbing scaffold system, the formwork and climbing scaffold can be moved in only one crane lift from cycle to cycle. In each case, two VARIO elements together with a CB platform form one individual climbing unit. The roller bearings on the CB 240 carriages enable the formwork elements on the climbing scaffold to be easily retracted for striking and cleaning to take place by up to 75 cm without the need of a crane.

With the PERI solution, the contractors are in the position is to climb the circular-shaped containers in two-week cycles. For each container, 80 climbing units are in use: 78 VARIO internal elements as well as 78 VARIO external elements on 40 CB platforms in each case. Due to the fact that all three structures are being built at the same time, site crews are working with a total of 468 VARIO dimensional elements in order to ensure that the concrete frame for the liquid gas storage tanks is completed on schedule. The tanks will be fully operational in 2008. Two additional containers are already being planned.

LNG stands for liquefied natural gas that has been processed to remove either valuable components e.g. helium, or those impurities that could cause difficulty downstream, e.g. water. The volume of the natural gas can be reduced through liquefaction to approximately two parts per thousand of the original state. Thus storage and transportation over long distances where pipelines do not exist is much more cost-efficient.

Project Details
Client: Baker Concrete Constr., Houston
Field Service: PERI Fort Worth, USA - www.peri-usa.com

PERI was founded in 1969 and is today one of the leading providers of formwork and scaffolding systems. Along with the headquarters in Weißenhorn, Germany, the company has 45 international subsidiaries and 70 stock yards around the world. The company has over 4.000 employees of which 700 are engineers. 2006 revenues will be around 900 million Euros.

PERI GmbH
Formwork and Shoring
P.O. Box 1264
89259 Weissenhorn
Tel.: 49/ 73 09/ 9 50-0
Fax: 49/ 73 09/ 9 51-0
info@peri.de
www.peri.de

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