Abstract: A cylindrical metal container with a relatively large holding capacity has triple seams having a vertically long, generally elongate rectangular cross section, the top and bottom parts of the seam having a convex substantially semi-elliptical or semi-circular profile. The outer face of the seam bulges outward adjacent its top, or its top and bottom, and the middle part between the top and bottom constitutes a pressed groove between the top and bottom and substantially parallel to the axis of the container. The body and end plate flanges are held in strong and direct contact with each other, overlapping each other in the center of the seam. A sealing compound is sealed in a void left between the edge of one flange and the curved portion of the other flange.

Abstract: A microwave heating apparatus having a door equipped with a microwave attenuating cavity constituted by a fundamental wave choke channel and a second higher harmonic choke channel opposing thereto back to back. A wall surface defining the second higher harmonic choke channel has a periodic structure provided with a plurality of trapezoidal metal pieces a tip of each of which is bent inwards. The periodic structure efficiently guides leakage microwave energy into the microwave attenuating cavity and promotes microwave energy leakage preventive effect. The door is suitable for reduction in size and thickness and permits a microwave heating apparatus of improved space factor to be provided.