A straight, hollow product, welded or seamless, of round, square, or any other cross section and continuous periphery, which does not conform in cross sectional dimensions to recognized pipe standards, or those in tables 1 through 10, appendix c, fiig a004a. it is designed to convey fluids, gasses, and/or semisolids. it may be rolled into coils for ease in handling. for items designed to join a tube or tube fitting to another tube, pipe, or hose or fitting, see adapter (as modified); coupling (as modified); or nipple (as modified). excludes tube, bent (as modified); pipe, metallic; spacer, sleeve; metal bar (hollow); and items with fittings, except end protectors.