My Turn,
Pipe, as in round iron pipe, schedule thickness pipe, plastic pipe, steel brake line pipe.
Tube, as in square tube, rect. tube, column tube.
Flowline, left to right product line, float glass line, assembly line.
String, flow line of assembly, bob line of squareness, elevation of pipe, ground, platform, concrete, block. Flow line of liquid flow.
Luck
The rentapen