BACKUP RING AND TANK WITH THE SAME

摘要

Provided are a backup ring for reinforcing a seal such as an O-ring, preventing the seal from protruding, suppressing opening of the seal into the circumferential direction, and increasing sealing ability of the seal, and a tank having the backup ring. The backup ring is an annular body where one cut surface (11A) and the other cut surface (11B) that are formed by cutting are made to be in contact with each other. An engagement ridge (12A) is formed on the one cut surface (11A), and an engagement groove (12B) separatably engaging with the engagement ridge (12A) is formed in the other cut surface (11B). When the ridge and groove are engaged with each other, the one cut surface (11A) is in contact with the other cut surface (11B) and the other cut surface (11B) prevents circumferential movement of the one cut surface (11A) relative to the other cut surface (11B).