CORTEN SQUARE TUBES 

ASTM A847 is a specification for cold-formed welded and seamless high-strength, low-alloy structural tubing with enhanced atmospheric corrosion resistance. It is commonly referred to as Corten tube due to its similarity to the weathering steel known as Corten steel. ASTM A847 Corten tube is designed for use in welded, bolted, or riveted construction of bridges and other carbon steel structural channels where high strength and enhanced corrosion resistance are required. It can be used bare (unpainted) for many applications when properly designed and exposed to the atmosphere.