| 摘要 |
PROBLEM TO BE SOLVED: To provide a connection structure having a loosening prevention mechanism by which connection of a piping member by screwing is not easily loosened due to temperature variation or the like, and improving workability.SOLUTION: A cleaning port 12 of a piping member 2 is provided with engaging parts 15 engaging with engaged parts 23 of a box nut 20. Although the engaging parts 15 are provided at two places, they are not provided at the two places opposing by 180° and arranged in a positional relationship which is not n times as large as a repeated pitch of the engaged parts 23. Therefore, any one of the engaging parts 15 provided at two places never engages with the engaged part 23, while the other surely engages with the engaged part 23 to surely function as loosening prevention means. |
