PURPOSE: To make metal ring to be small and light, and at the same time, improve the workability, by reducing stress of metalic vessel, when the metalic vessel is shrinked and fixed to non-metalic rigid tube by shrinkage fit of metal ring of the metalic vessel.

CONSTITUTION: On a metalic vessel 21, a plurality number of kerves 23 whose widthes are slightly larger than that of metal ring 13 are provided toward the bottom part 25 from the rim 22. When the metalic vessel 21 is shrinkage-fitted by the metal ring 13, residual part of the kerf 24 is bent to inner direction toward the bottom part 25. At this time, since the force which is acted on the metal ring 21 is simple bending, stress in the circumference direction is seldom generated.