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Innovation in Using Precast, Prestressed Concrete for Liquefied Natural Gas Storage Tanks

Cutaway section at the base of a composite concrete cryogenic LNG storage system. Precast concrete walls are used for both the primary and secondary containment. The annular space between the primary and secondary containment walls is filled with loose perlite insulation. Note: LNG = liquefied natural gas. 1 mm = 0.0394 in.

As the world’s energy consumption moves toward the use of natural gas rather than coal and oil, transporting large amounts of natural gas is increasingly important because of the increased demand for this type of fuel. An efficient way of transporting large quantities of natural gas, if pipeline is not available, is to transform it into a liquid for storage and shipment to various destination around the world.

One of the difficulties of transporting natural gas is precisely because it is a gas or “vapor.” Because gasses are less dense than liquids or solids, they occupy more volume than either of the other two substance phases. For instance, a quart of steam (water vapor) will transition into a much smaller amount of water once cooled into a liquid. Liquefied natural gas (LNG) also takes up less room than vapor natural gas—1/600ths of the volume of the vapor. By cooling to cryogenic temperatures about -260 degrees Fahrenheit at ambient pressure, the now liquefied gas can be stored in large tanks as much as 190,000 cubic meters (6,700,000 cubic feet). From there, the fuel is transported to its destination, then warmed back to a gaseous state for general use.

Storing LNG is expensive, as the tank has to be able to operate at cryogenic temperatures and provide enough insulation to maintain the low temperature. Currently, conventional storage technology uses a 9 percent nickel steel construction for the inner storage tanks with a prestressed concrete outer wall. Unfortunately, this type of steel is expensive to produce and supply, and is available from only a few mills in the world. In addition, the number of contractors able to build these steel tanks have not kept pace with the increase in demand.

A team of BergerABAM engineers has analyzed the current state of design and construction challenges and has developed an all-concrete LNG storage tank solution that has the potential to address these challenges. The concept has been recently published as a paper in the Precast Concrete Institute (PCI) Journal and discusses the work done to develop and qualify the composite cryogenic LNG storage tank technology, showing that a composite concrete cryogenic LNG storage tank offers a more cost-effective, high-quality, and reliable alternative than the current steel and concrete tanks currently used.

The article researched and written by Kåre Hjorteset, PE, SE; Markus Wernli, PhD, PE; Michael W. LaNier, PE; Kimberly A. Hoyle; and William H. Oliver, PE, is available for review in PCI Journal’s Fall 2013 issue.