| 摘要 |
PROBLEM TO BE SOLVED: To ensure sealing properties of a resin-made branch joint configured to be adapted to the case where fluid circulating in a main pipe is not only a low-pressure gas but also a high-pressure fluid such as water. SOLUTION: A predetermined range of a peripheral surface of a seal plug 20 from an end surface on the main pipe 100 side is formed into a straight surface 23, a peripheral groove 24 is formed in the straight surface 23, and an O-ring 25 is mounted in the peripheral groove 24. The seal plug 20 is moved to the main pipe 100 side, thereby the O-ring 25 is tightly stuck to an inner peripheral surface of an opening 8 communicating with the main pipe 100. The O-ring 25 has a small seal area. Under high pressure, the O-ring is greatly deformed by high pressure to thereby perform watertight sealing. Since the O-ring 25 has the small seal area, this requires little force to generate initial surface pressure and requires little screwing torque for the seal plug 20. Therefore, when screwing the seal plug 20, screw threads of screws 22, 7 formed on the seal plug 20 and a branch cylinder part are prevented from being crushed. COPYRIGHT: (C)2008,JPO&INPIT
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