Dryer chocking problem

hi--- i want to know about the root causes of dryer choking problem in deep freezer. what are root causes----either it may problem of vacuuming, gas charging or it may be due to other problem please give me fully details and specify with standards.

coiling we use 8*0.9mm thinkness and matrerial is Aluminium

beside this we are facing internal leakage problems----

i hope a positive response

thanks