| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a connection structure of a plug-in underground steel pipe, which has a packing with a proper connection force capable of promptly and reliably connecting steel pipes together, when connecting steel pipes except thin-walled steel pipes. <P>SOLUTION: In the connection structure, the inner surface of a socket part 1 is provided with an annular recess part 3, and an annular packing 2 is provided to be fitted into the annular recess part 3. One part of the cross section of the annular packing 2 has an almost rectangular shape, and an annular pleat part 2a is provided, which has a tongue-shaped cross section inclining from one inner surface to the other inner surface of the packing 2 and inclining in the direction of the central axis of the packing 2. When the annular packing 2 is fitted into the annular recess part 3, the tip edge of the pleat part 2a is placed in a manner that the pleat part 2a faces to the deep part of a steel pipe A, and projects out from the inner surface of the socket part 1. Thus when one end of a steel pipe B to be connected is inserted, the pleat part 2a is configured to be pressed to the inner surface of the annular pacing 2 by being pushed by the outer surface of the steel pipe B. <P>COPYRIGHT: (C)2012,JPO&INPIT |
