Thereby, according to the invention, the heater section is provided with at least one distance control means arranged for being in {TAIL ~ contact} with the shell surface during the heating and for automatically regulating {HEAD ~ the second distance} by means of a self regulating mechanism 
Thereby , according to the invention , the heater section is provided with at least one distance control means arranged for being in { TAIL ~ contact } with the shell surface during the heating and for automatically regulating { HEAD ~ the second distance } by means of a self regulating mechanism
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH