PURPOSE: To make a stable operation possible so as to prevent a cracking and breakage of a fire resistant tube in vacuum pressure casting operation by making a fire resistant tube member of two divided parts at least assemble to one body through the improvement of structure.

CONSTITUTION: Joining of both members 2, 3 at the joining part 4 is composed of the tapered screw of the nipple 10, which has an angle of 2-15 degrees to its axis and a pitch of 10-85mm to make airtight possible. This greatly improves an usable life of the fire resistant tube for steel vacuum pressure casting and makes the improvement of casting efficiency and safety possible to significantly reduce casting cost.