High Quality Content by WIKIPEDIA articles! A pipe is round tubular section or hollow cylinder used mainly to convey media. It can also be used for structural applications. In layman's terms the appellations pipe and tube are almost interchangeable, but in industry and engineering discipline the terms are uniquely defined. Depending on the applicable standard to which it is manufactured, pipe is specified by the internal diameter (ID) and a wall thickness, a nominal diameter and a wall thickness, or an outside diameter (OD) and a wall thickness. Tube is most often defined by the outside diameter (OD) and a wall thickness but may be specified by any combination of dimensions (OD, ID, wall thickness). Pipe is generally manufactured to several long-standing and broadly applicable industrial standards (such as ASME/ANSI B36.10/B36.19). While similar standards exist for specific industry application tubing, tube is often made to custom sizes and a broader range of diameters and tolerances.