Process of operating a bell-type convection annealing furnace

Abstract From the Canadian patent

In a process of operating a bell-type convection annealing process, annealing and the subsequent cooling are performed under a combustible protective gas. In order to ensure that the safety risk will be negligible in spite of the use of that protective gas, the gas pressure under the protective bell is increased above the operating pressure before the beginning of the annealing treatment and/or before the beginning of the cooling treatment, the gas pressure under the protecting bell is subsequently intentionally decreased to a testing pressure which, also exceeds the operating pressure and the pressure drop taking, place during a predetermined period of time is monitored.