Airgas Inc. signed a long-term agreement to build an air-separation unit (ASU) to supply tonnage oxygen, nitrogen and argon via pipeline to Nucor Steel Tuscaloosa Inc., a subsidiary of Nucor Corp., at its steel manufacturing plant in Tuscaloosa, Ala. The large-scale ASU will be constructed adjacent to the existing Nucor facility and is expected to be on-stream in the spring of 2017. It will also produce oxygen, nitrogen, and argon to support the region’s merchant bulk gas market. Airgas currently owns and operates 16 ASUs and is the fifth-largest producer of atmospheric gases in the U.S.