The Disadvantages of Corrosion resistant steel
Using Corrosion resistant steel in construction presents several challenges. Ensuring that weld-points weather at the same rate as the other materials may require special welding techniques or material. Corrosion resistant steel is not rustproof in itself. If water is allowed to accumulate in pockets, those areas will experience higher corrosion rates, so provision for drainage must be made. Corrosion resistant steel is sensitive to salt-laden air environments. In such environments, it is possible that the protective patina may not stabilize but instead continue to corrode. Hawaii'sAloha Stadium, built in 1975, is one example of this. The former Omni Coliseum, built in 1972 in Atlanta, Georgia, never stopped rusting, and eventually large holes appeared in the structure. This was a major factor in the decision to demolish it just 25 years after construction. Corrosion resistant steel's normal surface weathering can also lead to rust stains on nearby surfaces.
The U.S. Steel Tower in Pittsburgh, Pennsylvania was constructed by U.S. Steel in part to showcase COR-TEN steel. The initial weathering of the material resulted in a discoloration of the surrounding city sidewalks, as well as other nearby buildings. A cleanup effort was orchestrated by the corporation once weathering was complete to clean the markings. A few of the nearby sidewalks were left uncleaned, and remain a rust color. This problem has been reduced in newer formulations of weathering steel. Staining can be prevented if the structure can be designed so that water does not drain from the steel onto concrete where stains would be visible.