Tubing is a
pipe or hollow cylinder for the conveyance of fluids (liquids or gases). The terms 'pipe' and 'tubing' are almost interchangeable, although minor distinctions exist (generally, "tubing" implies tighter engineering requirements than "pipe"). Both "pipe" and "tube" imply a level of rigidity and permanence, whereas a "hose" is usually portable and flexible. Tubing and pipe may be specified by standard pipe size designations, e.g. Nominal Pipe Size — or by
nominal outside or inside diameter and/or wall thickness. The
actual dimensions of pipe are usually
not the nominal dimensions (i.e., a "1-inch" pipe will not actually measure 1" in
either outside
or inside diameter) — whereas many types of tubing are specified by
actual I.D., O.D., and/or wall thickness. There are many industry and government standards for pipe and tubing.
There are three classes of manufactured tubing seamless, as-welded, and drawn-over-mandrel (DOM).
Many standards exist for tube manufacture. Some of the most common ones are as follows
ASTM material specifications generally cover a variety of grades or types that indicate a specific material composition. Some of the most commonly used are
