To longitudinally expand and contract a tube without damaging the mechanical sealing state between a tube and a tube sheet exposed to a high temperature by a simple constitution.
This mechanical seal device is provided with a first outer sleeve 40 having a wall part 42 terminating in the upper face, and an annular space is formed between its lower end and a heat tube 14 and a tube sheet 16. A high nickel metal inner ring 60 is arranged in the annular space 47. The inner ring 60 is partially stored in a casing 66, when a downward force is applied to the first outer sleeve 40, the annular space is reduced to force the inner ring 60 and the casing 66 into the sealing relation between the heat tube 14 and the tube sheet 16, while allowing for vertical expansion of the heat tube 14. A means 48 preventing the inner ring from being damaged when the downward force is applied to the outer sleeve is further provided. A filling material 52 is arranged between the first outer ring 40 and the wall of the heat tube 14 to form a second seal.
WARESU JII MAREI