Microwave scanning detection method of polyethylene pipeline electric smelting joint

Abstract

The invention relates to the field of detection of a pressure pipeline, in particular to a microwave scanning method of a polyethylene pipeline electric smelting joint, which comprises the steps of: detecting the polyethylene pipeline electric smelting joint by using a microwave scanning device, emitting microwaves to the joint to be detected by an emitter in a microwave probe, recording base line amplitudes by the microwaves through two receiving sensors, then penetrating through the surface of the joint to enter the inner part of the joint, when the travelling microwaves meet the defect, enabling the microwaves to generate reflection by the change of a dielectric constant; and generating interference by the reflected microwave signals and the emitted microwave signals, receiving by the receiving sensor and converting into a voltage signal, inputting to a computer after the voltage signal and scanning position information pass through a signal conversion system to obtain a scanning image, and obtaining relevant information of the defect in the electric smelting joint according to the scanning image. The detection method has the advantages of capability of detecting multiple types of defects, high detection sensitivity and precision, good reliability and the like, and can be especially used for effectively detecting process defects such as cold welding and the like, is convenient for operation, and has lower cost.

Description

technical field [0001] The invention relates to the detection field of pressure pipelines, in particular to a microwave scanning detection method for welding quality of polyethylene pipeline electrofusion joints. Background technique [0002] Polyethylene (PE) pipe has many excellent properties, such as low temperature resistance, corrosion resistance, good toughness, crack resistance, convenient connection, good scratch resistance, good resistance to rapid crack transfer, etc. 4 times. Therefore, polyethylene pipe has become the best choice for urban gas transmission network and medium and low pressure water supply network. The connection methods between polyethylene pipes mainly include hot-melt welding and electric fusion welding. There is a big difference in process. The hot melt welding technology is mature, and the connection cost is relatively low. In the case of using large nominal diameter pipes, hot melt welding is more common. The main process of electrofusion ...

AI Technical Summary

Problems solved by technology

Among them, the detection of technological defects such as cold welding defects is the most difficult, because such defects generally do not appear as changes in the macrostructure of the joint, but will have a great impact on the quality and performance of the joint

Visual inspection has not yet formed a national or industry standard. The inspection method is mainly formed based on engineering experience. During inspection, the quality is judged only by visual appearance and size, and the internal defects of welding cannot be observed, and the reliability is lacking.

Ultrasonic testing can directly obtain the state information inside the material, and can identify some macroscopic defects, but it is difficult to detect process defects (such as cold welding)

Polyethylene is a polymer material that absorbs and loses more sound wave energy than metal materials, and because its structure is more complex than metal materials, it is easy to increase the scattering of sound waves, which increases the difficulty of ultrasonic testing of polyethylene pipe joints

More importantly, the ultrasonic method is very difficult to detect process defects, and no effective detection method for process defects has been found so far

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