Keystone Tube Company, LLC is a subsidiary of A.M. Castle & Co., a publicly traded (OTCQB: CASL) specialty metals distribution company headquartered in Oak Brook, Illinois. The company provides a range of metal products, including alloy, aluminum, nickel, stainless steel, carbon, and titanium, alongside value-added processing and supply chain services. As of mid-2017, the firm operated 21 service centers across North America, Europe, and Asia, employing 619 people to serve the aerospace, defense, and industrial sectors.
