A single dashed line in piping drawings is primarily used to represent what?

In piping drawings, a single dashed line is primarily used to represent pipe sizes and fittings. This visual representation helps to indicate the layout and configuration of the piping system, making it easier for engineers and technicians to understand the dimensions and relationships between different components. The dashed line signifies specific elements that may not be visible or are located behind other components, ensuring clarity in the drawing without cluttering the visual representation.

The other options fit different roles in piping drawings: hidden components are typically indicated with a dashed line but often involve more complex line styles. Flow direction is usually represented with arrows rather than dashed lines. Support structures are generally depicted using solid lines to indicate that they are essential components of the infrastructure and must be clearly defined in construction plans.