J.D. Henman is back with another nice routine; he has supplied the LISP code and a menu file for drawing pipe in AutoCAD of various schedules and diameters. Load the LISP file, then either start the command by entering DP at the Command prompt, or load the supplied menu and select an option from it. Both methods require you to select a line representing the centerline of the pipe.
If you run DP at the Command prompt, you can enter the inner and outer diameters of the pipe. If you run this command from the menu, the diameter values are supplied for you. The routine creates some default layers and colors that you can easily modify for your needs.