What fitting or piping arrangement is required when the size of a pipeline conveying condensable vapours is reduced?

In the context of reducing the size of a pipeline that carries condensable vapours, the use of an eccentric reducer is essential. Unlike a concentric reducer, an eccentric reducer maintains a consistent horizontal or vertical position of the pipe, preventing the formation of vapor pockets that can occur with condensable vapours. This is critical because condensable vapours can condense into liquid, creating a risk of blockage or uneven flow if proper venting and drainage path are not maintained.

The design of an eccentric reducer allows for more effective drainage of any potential condensate since it provides a flat side that can facilitate the exit of liquid from the bottom side of the pipe. This helps to keep the line clear and ensures a more reliable flow of the vapours, reducing the chances of operational issues caused by condensate buildup.

In summary, when conveying condensable vapours, an eccentric reducer is the appropriate choice due to its ability to manage condensate and maintain effective flow characteristics.