Theoretical stress analysis on the container flange - bolted cover lid flange

A three-dimensional, linear-elastic R and D analysis was carried out to investigate the stress and deformation behaviour of the flange joint, including the screws of the reactor pressure vessel (High Pressure Reactor - Grosswelzheim) in load cases such as prestressing (tightening force per screw 2.7 MN), stressing finished, internal pressure (100 bar), temperature load, and their overlapping. A 9deg-segment from the flange joint, including a screw, was idealized for calculations, which revealed that the packing surface gape reaches its maximum in the load case of internal pressure. This opening, however, can be by-passed by enlarging the internal metal-O-ring packing due to internal pressure in order to avoid a leak gap even at 100 bar. A comparison of the calculated strains with those measured during the 'cold' and 'warm' pressure tests showed very good agreement in the load cases without the temperature component. The reason for greater deviations in the case of heat stresses is presumably due to the lack of input and material data. (orig./HP)