Use the Insert Wire tool to insert lines that represent pipes on a P&ID diagram.
In AutoCAD Electrical toolset, different types of wires represent the type of running pipes that allow water or oil flows from one instrument to another.
Insert wires as pipes

.  Find 
  Specify wire start or [wireType/X=show connections]:
Enter T, pressENTER
Select the wire layer RED_25. Click OK.


.  Find 
  Specify wire start or [wireType/X=show connections]:
Enter T, pressENTER
Select the wire layer RED_10. Click OK.
Select the bottom of the discrete instrument
Specify wire end or [Continue]:
Drag the wire down a few spaces, press ENTER



.  Find 
  
 
  
 
  Specify insertion point:
Select to place the flow arrow at the bottom of the new wire

The P&ID diagram is complete.
If you want to see how to expand the P&ID drawing, refer to the P&ID demo drawing file (Demo01.dwg) in the Extra Library Demo project.