Duplex steel welded tube is a type of steel tube that consists of two types of steel alloys. It is a combination of austenitic and ferritic steel alloys. The welded tube is made by welding two pieces of steel together using a welding process. The Duplex steel welded tube is widely used in many industries due to its excellent strength and corrosion-resistant properties. It is used in oil and gas pipelines, pressure vessels, petrochemical plants, and other industrial applications.