User may define a line name for any pipe element in the model. It allows to:
To hide the lines deselect the check box in the "visible" column. To invert visibility click "Inv". For other actions with visibility click "Res".
To add any part of the piping to a specific line, just select that part and click "Add" in Lines window. or open the pipe properties and select the required line number. Also the same functions are available in the Project Tree and properties Window.
To display this view, check the option View > Floating Windows > Line List