| 摘要 |
PURPOSE:To prepare easily and inexpensively a corrosion proof resin layer with a sleeve having a clearance between a screw part and the sleeve by inserting mask sockets into each joint part of a T-joint and blowmolding a specified parison. CONSTITUTION:Parison 30 having a thick-wall part 30a is set to the forming jig 21 having the nozzle opening 29 to open a valve by compressed air and a cavity 23. Mask sockets 31a, 31b are inserted into the side end parts directly connected to a T-joint 4 and the mask socket 31c having a concave hole part 32c is inserted into a branched side end part. The forming jig 21 to which the parison 30 is set is inserted into a tube and compressed air is introduced from an introducing passage 28 to carry out blow molding and then to remove each socket and the jig. Clearances lie between a sleeve 34 and each screw 5a, 5b, 5c and even when this joint is connected to the piping 1 this joint is excellent in corrosion resistance.
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