An Ultrasonic Probe for Wall Thickness Thinning Measurement in Extreme Environments

Abstract

The invention relates to an ultrasonic probe for wall thickness reduction measurement under an extreme environment. A piezoelectric wafer is embedded in a circular upper damping block, and a positiveelectrode and a negative electrode located on the piezoelectric wafer are connected with a positive wire and a negative wire respectively, and the positive wire and the negative wire pass through theupper damping block to be connected with a threaded joint on a cover-shaped outer shell; the upper damping block and a lower damping block with the same size are closely fit and are closely fixed by an inner shell, and the inner shell is embedded in the cover-shaped outer shell and a cylindrical outer shell; the upper end surface of a guided wave plate passes through the back cover of the cylindrical outer shell and the lower damping block to be connected with the piezoelectric wafer, and the lower end surface of the guided wave plate is contacted with a tested piece; the thickness and the width of the guided wave plate have to enable single-mode zero-order horizontal shear waves to pass in a non frequency dispersion mode; and the piezoelectric wafer can excite and receive transverse wavesignals, and the cross section is matched with that of the guided wave plate. Long-term online monitoring or offline multi-point measurement on ultrasonic guided waves under extreme environments can become possible.

Description

technical field [0001] The invention discloses an ultrasonic probe for measuring wall thickness thinning in an extreme environment, and relates to the field of ultrasonic nondestructive testing. The device can conduct online long-term measurement and offline multi-point measurement of the wall thickness reduction of pipelines or containers working in extreme environments. Background technique [0002] High-temperature, low-temperature, high-pressure pipes or containers are widely used in nuclear power, ultra-supercritical power generation, petrochemical and other fields. Once they rupture, they will cause fatal injuries to on-site workers and nearby equipment. Some equipment can be stopped for maintenance regularly, while some equipment cannot be stopped for maintenance for a long time. On-line long-term monitoring of the "serious" components in these devices or multi-point measurement without dismantling the insulation is the best means to ensure their safety. [0003] In...

AI Technical Summary

Problems solved by technology

There are mainly piezoelectric ultrasonic transducers, laser ultrasonic transducers, electromagnetic ultrasonic transducers and magnetostrictive transducers that can generate ultrasonic guided waves, but these excitation methods are directly used for equipment in extreme environments There are certain difficulties in the on-line monitoring of the piezoelectric ultrasonic transducer. The corrosive environment will corrode the metal ultrasonic probe, thereby affecting its performance. In addition, (1) the operating temperature of the piezoelectric ultrasonic transducer exceeds the upper Curie point and the lower Curie point. The phenomenon of depolarization will reduce the piezoelectric effect of the piezoelectric material. The general operating temperature is between (0-200) ° C. It is difficult to directly install it in high and low temperature environments for off-line monitoring of structural damage. Cannot do real-time online monitoring

(2) The laser ultrasonic transducer can generate ultrasonic waves without contact with high temperature and low temperature equipment, and monitor the defects of the equipment. This indirect contact method determines that the laser ultrasonic transducer can be used in high and low temperature environments, but its price Relatively expensive and susceptible to external interference, it is difficult to widely promote and apply in engineering

(3) Electromagnetic ultrasonic transducers and magnetostrictive transducers are also favored devices in high and low temperature environments, but whether they are transducers based on the principle of Loren magnetic force or transducers based on the principle of magnetostriction device, the complexity of the structure and the constraints of its limited lift-off distance determine that they are not suitable for long-term on-line monitoring

US005159838A uses a metal wire wrapped in a metal shell to make a guided wave transducer. This method can effectively propagate guided waves in modes such as longitudinal waves and shear waves, but the signal is relatively weak

In order to overcome this shortcoming, US005962790A uses a metal wire bundle wrapped in a metal shell to make a guided wave transducer. Although this method has changed the above shortcoming, the production cost is too expensive because each wire has to be welded to the chassis separately.

CN202903149U etc. have announced the system that cylindrical probe transmits Lamb wave and measures pipeline wall thickness thinning, but this structure is often welded on the tested piece, easily introduces stress concentration, does not see popularization and application yet

CN 206223118U discloses a high-temperature component wall thickness monitoring device based on a rectangular cross-section probe. The device mechanically assembles a piezoelectric sensor on one end of a rectangular cross-section probe, and the loss of ultrasonic energy is serious. At the same time, the device uses two The parallel rectangular cross-section plates are probes, one for excitation and one for reception. Once the probe is bent, it will lead to failure of one-sided probe

The ultrasonic nondestructive testing equipment announced by CN200680050234.0 and US 2016 / 0109414 Al can excite both shear wave and compression wave by means of the coil of the electromagnetic ultrasonic transducer, and the overall structure of the equipment is relatively complicated

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