Heat cycle test of improved knife-edge type metallic sealing flange

High in reliability, the knife-edge type metallic sealing flange has been widely used in vacuum equipment, though it has some problems. To solve them, an improved flange (called IPD flange) is developed which is 1/2 to 1/3 in the number of bolts, about 3/5 in torque and about 7/10 in thickness as compared to conventional flanges. The present report focuses on a heat cycle test of the improved flange. The test covers two types of the improved flange with a diameter of 70mm and 152mm, which are referred to as IPD70 and IPD152, respectively. The maximum baking temperatures used were 500degC and 400degC. Both IPD70 and IPD152 showed a satisfactory sealing performance under high-humidity conditions at 400degC and 500degC. IPD70 was subjected to 60 heat cycles in the temperature range from 100degC to 400degC. Results show that the flange is satisfactory in sealing performance and integrity. At temperatures exceeding 300degC, the torque for IPD70 and IPD152 should be in the range of 80-100kg·cm and 100-125kg·cm, respectively, to ensure a high reliability for sealing. The improved flange is higher in performance than conventional flanges. (N.K.)