SEALING STRUCTURE

PROBLEM TO BE SOLVED: To provide a sealing structure with a seal ring and a backup ring independently exchangeable, for preventing the backup ring from being largely protruded from an annular groove with thermal expansion. SOLUTION: The sealing structure comprises: the annular groove 9 formed on the outer peripheral face of a fitting portion 8 to be detachably fitted into a cylindrical portion of a high-temperature and high-pressure treatment device; the seal ring 1 mounted in opposition to a first side wall face 13 on the high pressure side of the annular groove 9 for sealing; and the resin backup ring 3 mounted in opposition to a second side wall face 14 on the low pressure side of the annular groove 9 for supporting a back face 4 of the seal ring 1. On a supporting face 5 of the backup ring 3 in contact with the back face 4, an annular uprising portion 6 is formed to be swollen to the side of the seal ring 1. Besides, a stepped face 11 is formed on the back face 4 in a mounted and non-compressed condition for engaging with an outer diameter peripheral face 10 of the annular uprising portion 6. COPYRIGHT: (C)2008,JPO&INPIT