Climate Tanks™

Weathered finish steel produced by Climate Tanks™, often referred to by the generalized trademark COR-TEN steel and sometimes written without the hyphen as corten steel, is a group of steel alloys which were developed to eliminate the need for painting and form a stable rust-like appearance if exposed to the weather for several years. No, COR-TEN is not available. What is available is steel in an ASTM A606-4, A588, and A847 finish. Weathering steels, such as ASTM A847, A588, A242, A606 and COR-TEN exhibit superior corrosion resistance over regular carbon steel as a result of the development of a protective oxide film on the metals surface which slows down future corrosion. A606-4 steel is available in metal roofing/siding panels, standing seam panels, flat sheets, and coil form. If you are looking for a panel that will give you a rustic look the two best options are bare cold rolled finish and A606. A606-4 will cost more, but it definitely will last longer. The original COR-TEN received the standard designation A242 (COR-TEN “A”) from the ASTM International Standards Group. Newer ASTM grades are A588 (COR-TEN “B”) which is normally heavier gauge plates and A606 for lighter gauge flat sheets. ASTM A847 is used for pipe and tube. All alloys are in common production and use. Weathered refers to the chemical composition of these steels, allowing them to exhibit increased resistance to atmospheric corrosion compared to other steels. This is because the steel forms a protective layer on its surface under the influence of the weather.

The protective patina layer cannot form, however, if the surface of the steel is continuously damp or dirty; keeping the surface clean will in fact improve the patina effect. The corrosion-retarding effect of the protective layer is produced by the distribution and concentration of alloying elements in it. The layer protecting the surface develops and regenerates continuously when subjected to the influence of the weather. In other words, the steel is allowed to rust in order to form the protective coating; all of these Climate products are delivered un-patinated. Weathering steel is popularly used in outdoor sculptures, such as in the large Chicago Picasso sculpture, which stands in the plaza of the Daley Center Courthouse in Chicago, which is also constructed of the same weathering steel and as exterior facades, for its rustic antique appearance. Examples include Barclays Center, Brooklyn, New York, The Angel of the North, Gateshead, UK and the Humanities and Arts complex at Leeds Metropolitan University – Broadcasting Place – Leeds, UK

It is also used in bridge and other large structural applications such as the New River Gorge Bridge, the second span of the Newburgh–Beacon Bridge (1980), and the creation of the Australian Centre for Contemporary Art (ACCA) and MONA. It is very widely used in marine transportation, in the construction of intermodal containers [10] as well as visible sheet piling along recently widened sections of London’s M25 motorway. The first use of weathering steel for architectural applications was the John Deere World Headquarters in Moline, Illinois. The building was designed by architect Eero Saarinen and completed in 1964. The main buildings of Odense University, designed by Knud Holscher and Jørgen Vesterholt and built 1971–1976, are clad in weathering steel, earning them the nickname Rustenborg. In 1977, Robert Indiana created a Hebrew version of the Love sculpture made from weathering steel using the four-letter word ahava (אהבה, “love” in Hebrew) for the Israel Museum Art Garden in Jerusalem, Israel. In Denmark, all masts for supporting the catenary on electrified railways are made of weathering steel for aesthetic reasons.

Weathering steel was used in 1971 for the Highliner electric cars built by the St. Louis Car Company for Illinois Central Railroad. The use of weathering steel was seen as a cost-cutting move in comparison with the contemporary railcar standard of stainless steel. A subsequent order in 1979 was built to similar specs, including weathering steel bodies, by Bombardier. The cars were painted, a standard practice for weathering steel railcars. The durability of weathering steel did not live up to expectations, with rust holes appearing in the railcars. Painting may have contributed to the problem, as painted weathering steel is no more corrosion-resistant than conventional steel, because the protective patina will not form in time to prevent corrosion over a localized area of attack such as a small paint failure. These cars have been retired by 2016. Weathering steel was used to build the exterior of Barclays Center, made up of 12,000 pre-weathered steel panels engineered by ASI Limited & SHoP Construction. The New York Times says of the material, “While it can look suspiciously unfinished to the casual observer, it has many fans in the world of art and architecture.”