Pipe can be represented on drawings as either single line or double line. Pipe 12'' and smaller is typically drawn single-line and pipe 14'' and larger is drawn double line. Single-line drawings are used to identify the center line of the pipe. Double lines are used to represent the pipe's nominal size diameter.
The standard scale used on piping drawings is 3/8'' = 1'-0''. Typically hand drawn, single-line lead holder. When drawing single-line pipe with AutoCAD, a PLINE having a width of approximately .56'' (9/16'') is used on full-scale drawings or. 0157'' when drawing to 3/8'' =1' -0'' . Double-line pipe uses standard line widths to draw the pipe's nominal size diameter. A centerline is used on all double pipe to allow for the placement of dimensions