Installing Parker air brake hose

[bevans6]

so I am getting ready to install my new DD3 chambers.  The hose from the chassis to the axle is a rubber line with a brass compression fitting, with springs, and with pipe thread fittings on both ends.  When I took the hose off I loosened the clamping nut so the hose would swivel inside the fitting, and undid the pipe thread connection.  I am not sure that is the correct way to do this, since it loosens the compression fit seal that the hose gets when everything is tightened down.  I'm going to ask about this at the hose store when I go to buy new hose, but I thought I would ask here too.

This is what the fitting looks like:  http://www.fastenal.com/web/products/detail.ex?sku=410736-131280&ucst=t

Brian