| 摘要 |
PROBLEM TO BE SOLVED: To correctly insert a horizontal plug used for an inner sub-pipe for a manhole made of concrete. SOLUTION: A joint 1 connecting a horizontal inflow pipe and the vertical inner sub-pipe is composed of a joint with a 90 deg. largely-bent elbow pipe line, the external curved wall 6 of the 90 deg. largely-bent elbow is formed of the front end face 8 of the horizontal plug 7, and a pin 20 is inserted to the outer end section of an inserting port 9, into which the plug 7 is inserted, and the slipping- off of the plug 7 is prevented. Since the pin 20 and the plug 7 are connected by a chain 22 and the length of the chain 22 is formed in length, in which the pin 20 is inserted from an upper section only when the front end face 8 of the plug 7 can be inserted correctly, the plug 7 can be inserted correctly.
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