| 摘要 |
PROBLEM TO BE SOLVED: To tighten a nut with proper torque and prevent generation of rust on the inside surface of the nut by performing fluorine-contained resin coating for the inside surface of the nut which is screwed into a fitting body and connects a pipe. SOLUTION: A double ferrule type fitting is constituted of four parts of a coupling body 1, a nut 2, a front ferrule 3 and a back ferrule 4. By inserting a pipe 6 into the coupling body 1 and screwing the nut 2 into the coupling body 1, the front ferrule 3 of the two ferrules 3, 4 between the coupling body 1 and the nut 2 is restricted along a tapered surface of the coupling body 1 and is curved or rolled, and the tip is press-fixed to the pipe 6. The back ferrule 4 is rolled along a tapered surface of the front ferrule 3, the tip part 5 is bitten into the pipe 6, and the connection of the pipe 6 and the fitting and sealing of internal fluid are performed. In this case, fluororesin coating is performed for the inside surface of the nut 2. |
