A physical object that is a long tube or hollow body intended for conduction of liquid, gaseous or finely divided solid materials, or used for structural purposes.

A fluid conductor that consists of pipe, possibly also including pumps, valves, and control devices, intended for conveying liquids, gases, or finely divided solids.

A physical object that is a vertical or near vertical pipe for the upward flow of liquid or gas.

A physical object that is intended to mix fluid by means of diverging the flow with static obstacles or by increasing locally the velocity.