Been searching for awhile and have not found an answer, apologies if there is another forum on this.
I recently changed my EGR valve and when I was taking off/on the EGR tube I noticed there was no original gasket connecting the tube back to the valve. it is a metal to metal connection from the tube to the valve and secured by a nut. Is this sufficient enough to make it air tight? I do not have any symptoms of an air leak, but intuition tells me it needs an o ring gasket or some type of sealant?
Just to clarify, there is a gasket sealing the EGR valve back in place, my concern is the connection from the valve to the EGR pipe/tube. I see "EGR tube seals" for my make and model, makes me think I need a gasket to seal both ends of the tube; even though I only needed to disconnect the top part to change the valve, it is unknown if the lower tube connection has a gasket.

 

That tube gets pretty hot with exhaust gasses and if there was no gasket there when you separated the pieces, you shouldn't require one on reassembly..

 

Thank you for the input.