Follow these steps to unhook a pipe and reconnect it to a different end node:

1. First, select the Pipe Drawing tool in the tool menu above the drawing
2. Now click on the pipe which highlights the pipe in yellow
3. Click on the pipe again and it will unhook from the end node
4. The pipe will now be rubber banding and you can move the mouse to hover over a new end node
5. Left click on the mouse to drop the pipe and connect it to the new end node.

Follow these steps to unhook a pipe and reconnect it to a different start node:

1. First, select the Pipe Drawing tool in the tool menu above the drawing
2. Now click on the pipe which highlights the pipe in yellow
3. Now Right click on the mouse while hovering the cursor over the pipe
4. Select 'Reverse Pipe Direction' from the popup menu
5. Click on the pipe again and it will unhook from the new end node (the original start node)
6. The pipe will now be rubber banding. Move the mouse to hover over a new end node
7. Left click on the mouse to drop the pipe and connect it to the new end node
8. Now Right click on the mouse while hovering over the pipe
9. Select 'Reverse Pipe Direction' from the popup menu

The pipe is now connected to a new start node and the original end node.

Follow these steps to remove a pipe and copy it to connect two different nodes:

1. First, select the Pipe Drawing tool in the tool menu above the drawing
2. Now click on the pipe which highlights the pipe in yellow
3. Now Right click on the mouse while hovering the cursor over the pipe
4. Select 'Set as Default Pipe for Drawing' from the popup menu
5. Now click on the 'Delete' tool button in the toolbar above the drawing
6. The current pipe will now be deleted and removed from the drawing
7. Left click on the start node where you want the new pipe to be added
8. A new pipe start rubber banding.
9. Now click on the end node to connect the pipe

The new pipe will have exactly the same details as the previous pipe.