| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a trouble such as a disturbance of insertion of a plastic pipe even after a long lapse of time after joint molding by specifying a ratio of a coil diameter of a heating wire buried in the form of coil in a joint to a wire diameter of the heating wide. SOLUTION: In an electrofusion joint 1 provided with a heating wire 2, which is buried in the form of coil on the connection face with a plastic pipe, so as to be electrically fused with the plastic pipe in piping construction using a plastic pipe, a ratio D/d of a coil diameter D of the heating wire 2 buried in the form of coil in the joint 1 to a wire diameter (d) of the heating wire 2 is set to be 145 or less, desirably, 120 or less. When the heating wire 2 in which the ratio D/d is 145 or less is used, an insertion trouble due to shrinkage in a diameter of the plastic pipe can be solved. Although a lower extent of the ratio D/d is not limited, rigidity is increased more as the wire diameter (d) is increased and difficulty in wire winding and increase in costs are caused. In consideration of these points, the lower limit of the ratio D/d is 80 or more, desirably, 90 or more. |
