| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for simply detecting a joint failure in piping for ultrapure water. SOLUTION: A method for inspecting a joint portion comprises steps of butt contacting end faces of pipe bodies 10, 11 to be connected which are made from a thermoplastic resin, placing a conductor 12 on the outer circumference of the butt contacted portion and generating resistance heat by energizing the conductor for thermowelding the pipe bodies. The method further comprises steps of (a) inserting an electrode 14 in the joint portion in such a manner that it is brought into contact with or close to the inner surface thereof before or after the pipe bodies 10, 11 are thermowelded, (b) impressing a high voltage between the contractor 12 and the electrode 14, (c) detecting the generation of electric discharge between the conductor 12 and the electrode 14, and (d) withdrawing the electrode 14 from the pipe bodies. When there is found any minute joint failure in the joint portion such as one in which the inner surface of the pipe bodies and the conductor 12 get continuous, it can be detected by existence of an electric discharge when a high voltage is impressed. |
