The first step in the development of any pipe rack is the generation of a linerouting diagram, shown in following figure.

A line-routing diagram is a schematic representation of all process piping systems drawn on a copy of the plot plan.

Although it disregards exact locations, elevations, or interferences, it locates the most congested piping bent in the pipe rack.

Usually, the information available on early piping and instrumentation diagram issues covers only commodity, line number, and preliminary sizes.

Process flow diagrams provide insight to operating temperatures and identify the need for insulation.

Once the routing diagram is complete, the development of rack width, bent spacing, and numbers of levels and elevations may proceed.