Coupling and focusing ultrasonic detection method and detection device for polyethylene pipe hot melt butt joint

Abstract

The invention relates to a method for detecting the welding quality of a hot-melt even joint of a polyethylene pipeline and a detection device thereof. The aim of the invention is that the provided detection method and the detection device have the characteristics of high sensitivity, high detection precision, high reliability, high detection efficiency and low misoperation rate. The technical proposal is a method for the coupling focusing ultrasonic detection of the hot-melt even joint of the polyethylene pipeline, which comprises the following steps: (1) a coupling agent liquid is positioned on the outer surface of a pipeline joint fusion region; (2) an ultrasonic probe adopting a spherical curved wafer is immersed into the coupling agent liquid in order that the focus is positioned in the centerline of the pipeline joint fusion region; and (3) the ultrasonic probe does linear scanning motion along the diameter direction of the pipeline and does uniform scanning motion along the circumferential direction of the pipeline; and obtained signal data is processed by a computer to form a C scanning picture. The ultrasonic detection device comprises a coupling receiving device, the ultrasonic probe adopting the spherical curved wafer, a mechanical scanning device, a signal processing and controlling system, and the computer.

Description

technical field [0001] The invention relates to a detection method and a device for a pressure pipeline, in particular to a detection method and a detection device for the welding quality of a hot-melt butt joint of a polyethylene pipeline. Background technique [0002] Polyethylene pipes are widely used in the transportation of dangerous media such as gas. The most commonly used connection method between polyethylene pipes is hot-melt butt joint. Hot-melt butt welding has strong applicability, simple operation and low cost. However, hot-melt welding has more process parameters and more complicated construction operations, so the welding quality is greatly affected by human factors. Since there may be various defects at the joints of polyethylene pipes, and most of the polyethylene pipe accidents are caused by joint defects, the joints become the weak link of the polyethylene pipe system. In order to improve the safety of polyethylene pipelines, in addition to improving th...

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Problems solved by technology

[0006] 2) During the docking process of polyethylene pipes, a part of the material is melted and extruded from the inner and outer surfaces under the action of operating pressure, forming curls on the inner and outer surfaces. The curls affect the flatness of the detection surface, which will affect the probe and the ultrasonic testing. The contact of the workpiece and the contour echo will affect the ultrasonic testing

[0007] 3) Among the defects caused by polyethylene pipe welding, the joint performance cannot meet the requirements due to the imperfect welding process (such as welding pressure is too high or too low, welding temperature is too high or too low, etc.), and such technological defects have not been found so far An effective detection method

But there are still some problems, mainly: 1) It is impossible to detect and evaluate the unfused defect of the hot-melt joint; 2) It is impossible to accurately determine the height of the defect itself; 3) It is impossible to perform real-time imaging during the detection process

The development of ultrasonic testing equipment is still blank in China

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