Method for detecting welding seam of resistance weld pipe through creeping wave and creeping wave probe for method

Abstract

The invention discloses a method for detecting a welding seam of a resistance weld pipe through a creeping wave and a creeping wave probe for the method. The method comprises the following steps of: S100, selecting the specification of the creeping wave probe according to the curvature of the resistance weld pipe; S200, regulating the ratio of the sound path and depth of a reflected wave to 2:1; S300, selecting a reference point as the first point of a DAC curve, sequentially determining points at an interval of 5mm to the first point, measuring the amplitude of the reflected wave, drawing a distance-wave amplitude curve according to a measurement result, and attenuating the DAC curve by 10 dB as an evaluation line; S400, placing the sound beam center line of the creeping wave probe on a detection surface in such a way that the sound beam center line of the creeping wave probe is perpendicular to the center of the welding seam, and scanning the part, which is 20-25 mm far away from the center of the welding seam, of one side of the welding seam, wherein the scanning speed of the creeping wave probe is not more than 50mm / s; and S500, comparing a detection result obtained from the step S400 with the evaluation line. The creeping wave probe is a twin-lamella parallel creeping wave probe. The method disclosed by the invention can be used for accurately detecting the defects of the welding seam.

Description

technical field [0001] The invention relates to a welding seam detection method and a special probe thereof. Background technique [0002] The Huainan-Shanghai 1000kV transmission line, namely the "Anhui-East Power Transmission Project", is my country's first double-circuit UHV transmission line with steel pipe towers on the same tower. The steel pipe tower has the advantages of clear structural force transmission, less steel consumption, small footprint, beautiful tower shape and small additional load, which is conducive to giving full play to the bearing capacity of materials and improving the construction level of transmission lines. The steel pipe tower adopts the form of butt welding connection between the straight seam welded pipe and the neck flange, and the used straight seam welded pipe requires a diameter of less than 426mm to be produced by high frequency welding technology. Therefore, there are a large number of thin steel pipes with a thickness between 4mm and ...

AI Technical Summary

Problems solved by technology

For welds with a wall thickness greater than or equal to 8mm, ultrasonic testing can be carried out in accordance with GB / T11345 standards, but there is currently no suitable method for ultrasonic testing of welded seams of thin-walled welded pipes with a thickness less than 8mm

When using conventional shear wave detection, because the pipe diameter is small and the curvature is large, the probe is in line contact with the steel pipe surface, and the coupling effect is poor. If the probe is processed into a curved surface, the reflection clutter will increase, which will also affect the defect detection effect; the probe The combination with the ultrasonic instrument determines that the initial pulse width is relatively large, resulting in part of the wall thickness being included in the clutter, which makes it difficult to identify when judging; because the thin-wall generally uses a larger K-value probe (K3 is generally selected), to Avoid detection in the near-field area, but the waves generated by the couplant that exist at any time and the surface waves that cannot be eliminated by the K3 probe will fall near the position of the defect wave that needs to be judged, and there is no effective way to remove it, so it affects the damage judgment

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