What is the term for a line joining the points of highest elevation of water in vertical open pipes connected to a pressurized pipeline?

The term that refers to the line joining the points of highest elevation of water in vertical open pipes connected to a pressurized pipeline is known as the hydraulic grade line. This line represents the potential energy available to the water at various points in the system, specifically indicating the height to which water will rise in piezometric tubes or open stands when connected to the pipeline.

The hydraulic grade line is crucial in understanding fluid mechanics within hydraulic systems, as it combines both the pressure head and elevation head. It essentially helps engineers predict how water behaves in different parts of a system, which is pivotal for the design and management of water distribution networks.

The term hydraulic gradient, while related to the hydraulic grade line, specifically refers to the slope of the hydraulic grade line over a certain distance, rather than a direct representation of the highest water elevation.

Options like pressure gauge line and elevation line do not accurately describe this concept. The pressure gauge line would imply a direct measurement of pressure rather than elevation points, and elevation line does not capture the idea of potential energy associated with water flow in the context of real-time hydraulics.