| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a butt-welding method for polyethylene tube, which is excellent in the long-term performance of the bonded part when polyethylene tubes of which the thickness is less than 20 mm, and of which the diameter is less than 250 mm are bonded to each other. SOLUTION: For this butt-welding method for polyethylene tubes of which the thickness is less than 20 mm, and of which the diameter is less than 250 mm, tube end surfaces of polyethylene tubes being heated to 160-240 deg.C are butted for 1.5-8 sec (T5) by a pressure (P5) of 0.06-0.4 Mpa in a first process, and following to the first process, the pressure is made a pressure (P6) which is 0.1-0.75 times (P6/P5) of the pressure (P5) of the first process, and the tubes are held until the surface temperature of the bonded part becomes 100 deg.C or lower in a second process, and this butt-welding method comprises the first process and the second process.</p> |
