During the mechanical cycles, the packing temperature was subjected to varying thermal cycles repetitively between {HEAD ~ the ambient temperature} and {TAIL ~ 450° F.}  
During the mechanical cycles , the packing temperature was subjected to varying thermal cycles repetitively between { HEAD ~ the ambient temperature } and { TAIL ~ 450 ° F. }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH