Schedule 40 pipe is available in a wide selection of thicknesses, ranging from 0.068 inches (1.727 millimeters) to 0.688 inches (17.475 millimeters). It is also available in respective widths ranging from 1/8 inch up to 34 inches, according to nominal pipe sizing.
For every level of increase in the trade size or diameter of the pipe, the pipe thickness increases accordingly. Schedule 40 pipe is made to withstand the pressures exuded on the piping system. In general, the wider the pipe necessary for the task at hand, the thicker that pipe has to be to handle the expected work load.