Detailed design of pipe connections in AutoCAD 2D drawing. Pipe fittings, sometimes referred to as pipe connectors, join two pipes together to extend the run or switch the flow in a plumbing system. These come in a range of sizes to fit the pipe they will attach to and are used to combine, divert, or lessen the flow of the water supply. For more knowledge and detailed information download the AutoCAD 2D dwg file.