Select the correct term for a vertical steam supply line.

The term for a vertical steam supply line is known as a steam riser. A steam riser is an upward vertical section of pipe that carries steam from a lower level, such as a boiler room, to higher levels to distribute steam for heating or other processes. This terminology is standard in plumbing and steam distribution systems, where it is important to differentiate between horizontal and vertical piping configurations.

Understanding the role of a steam riser is crucial since it is designed to facilitate the movement of steam throughout a building while handling the pressure and thermal dynamics involved in steam systems. System efficiency and safety often depend on proper installation and maintenance of these risers to avoid issues such as condensation or pressure loss.

In contrast, a steam header refers to a main collection point for steam from multiple risers, acting as a distribution hub. A steam line can describe any type of piping carrying steam, regardless of orientation. A steam duct specifically tends to refer to enclosed channels for transporting steam or air, typically in heating, ventilation, and air conditioning systems, and does not specifically imply the vertical nature that defines a riser.