Vertical lengths of pipe are calculated using elevations, while horizontal lengths are caculated using north-south and east-west coordinates. Pipe lengths are determined through calculations using coordinates and elevations. Because iso's are not drawn to scale, dimensions are required to specify exact lengths of piping runs. The Iso, as isometric are commonly referred, is oriented on the grid relative to the north arrow found on plan drawings. Usually, piping isometrics are drawn on preprinted paper, with lines of equilateral triangles form of 60°.
The symbols that represent fittings, Valves and flanges are modified to adapt to the isometric grid. Isometrics are usually drawn from information found on a plan and elevation views. Unlike orthographics, piping isometrics allow the pipe to be drawn in a manner by which the length, width and depth are shown in a single view.
