Stainless Steel Round Tube offers high heat, corrosion and chemical resistance, and can be readily formed and welded. It is available in welded (WLD) and seamless (SMLS), in 304, 316 and 321 alloys and in mill (bright cold drawn) or 180 grit (satin brushed). What is the difference in "Pipe" and "Tube"? Tube is produced where the size matches the actual OD of the tube. (i.e. 2 inch tube is actually 2 inches, where as with 2" pipe the actual OD is larger than 2 inches and the ID will be relatively close to the nominal size.