Setup of a reactor DN200

During the fabrication at the glassblowing lathes of a reactor made of borosilicate glass 3.3 (type DURAN, PYREX, etc.) with an internal diameter of 200 mm, we fuse a lateral tubing with screwthread GL18 to supply the double wall with cooling or warming water.
During this procedure, the temperature needs to be constantly at 500°C, in order to avoid tension, which can break the glass.