Plastic pipe and tubing are defined by their hollow, round cross-section intended for fluid or gas conveyance. Profile shapes are extruded plastic articles with non-circular or complex cross-sections — such as window glazing channels or structural trim — and are classified separately even when produced on similar extrusion equipment.

Antidumping and countervailing duty orders have been issued against certain plastic pipe and fitting products from specific countries. Importers should conduct a scope review against active orders, paying close attention to resin type, wall thickness, and pressure rating, as these specifications often define the scope boundaries.