RU2262688C2 - Method and device for acoustic inspection of pipes - Google Patents

Abstract

FIELD: crack detection.

SUBSTANCE: device has control unit and three active supports into one of which detector with spectrum analyzer is built in and into three other ones - piezoelectric plungers with power supplies. Supports representing piezoelectric plungers with power supplies are disposed at ends of pipe in symmetry to support, which has detector with spectrum analyzer. Oscillations are excited in pipe mounted on supports by simultaneous shocks at two symmetrical points of pipe. Quality of pipe is judged from data parameters of spectrum of oscillations generated.

EFFECT: improved truth of crack detection data.

4 cl, 3 dwg

Description

The invention relates to the field of non-destructive testing of products by acoustic methods and can find application for pipe quality control, for example tubing (input control, planned inspection in the field).

A known monitoring system of tubing and couplings "Uran-2000M" [1].

The system includes:

- measuring controller;

- a sensor for monitoring the pipe strength group;

- sensor control group strength couplings;

- a set of flaw detection sensors;

- gauge thickness gauge;

- signal processing unit;

- display device controller;

- the desktop of the controller with a built-in control panel and indication (monitor);

- monitor display device;

- software;

- a set of working samples;

- instrument "Spectrotest F".

The system determines the mechanical properties, thickness, chemical composition and defectiveness of the pipes.

The defects are checked in a constant magnetic field, and the mechanical properties and thickness are checked in an alternating magnetic field. During monitoring, the pipe is moved using a transport device through 32 sensors.

The disadvantage of the known system [1] in its complexity and ability to work only in stationary conditions.

A device for controlling long products [2]. The device contains a mechanism for creating a single shock pulse in a controlled product, series-connected acceleration sensor, amplifier and spectrum analyzer.

A shock pulse in the form of a voltage wave propagates through the product, repeatedly reflected from the free edges of the product. The voltage waves passing through the product are received by an acceleration sensor, the signals from the output of which are amplified by an amplifier and fed to the input of the spectrum analyzer, at the output of which an impact spectrum is obtained in the form of a normalized time function.

The device [2] provides for the detection of structural heterogeneities in the material of long products by determining the spectrum of the first wave that has arisen in the product as a result of a shock pulse, determining its integral estimate and dividing by it the integral estimates of the spectrum of subsequent waves resulting from multiple reflection in the product.

The device [2] is the closest to the proposed and therefore we have chosen for the prototype.

Unfortunately, the device [2] gives insufficiently reliable results.

In order to increase the reliability of pipe inspection, we propose an acoustic pipe inspection device and a method for its use. The device contains two strikers, a sensor and a spectrum analyzer, different from the known one in that it additionally contains a control unit and three active supports, one of which has a sensor with a spectrum analyzer and a power supply, and the other two have piezoelectric strikers with power supplies, in this case, the supports representing the drums with power supplies are located at the ends of the pipe symmetrically relative to the support containing the sensor with a spectrum analyzer.

Figure 1 presents the structural diagram of the device, figure 2 and 3 are the frequency spectra of the natural oscillations of the tubing without defects and with cracks, respectively.

The device for acoustic control of pipes contains three active supports 2, 3, 4 and a control unit 5 (see figure 1). An acoustic vibration detector with a spectrum analyzer is mounted in the support 2, and piezoelectric drums in the supports 3, 4. The supports 3 and 4 are located at the ends of the pipe symmetrically with respect to the support 2. The acoustic vibration receiver 2, the piezoelectric drums 3, 4 and the control unit 5 can be interconnected by radio.

The device operates as follows. The pipe 1 is placed on the active supports so that the sensor 2 is symmetrical with respect to the impactors 3 and 4 located at the ends of the pipe. Using the control unit 5, pipe vibrations are excited by a simultaneous shock at two points 3 and 4 symmetrically located relative to the sensor 2, and the quality of the pipe is judged by the nature of the informative spectrum parameters of the resulting free damped vibrations.

The presence of two sources of waves and interference of the latter enhances the effect and increases the reliability of defect detection.

The advantage of the device is the possibility of its use not only in stationary conditions at repair bases, but also in the field directly in the field.

Example.

The proposed device for acoustic control of pipes and the method of its use were tested on two tubing made of steel 14 × 3 GML with a diameter of 73 mm, a length of 5.5 m. One pipe was defect-free, and the second had two visually visible cracks.

Figure 2 shows a view of the acoustic spectrum obtained on a pipe without defects, and figure 3 is a spectrum obtained on a pipe with cracks. The frequencies in Hz are plotted along the abscissa in FIGS. 2 and 3, and the relative amplitudes of the spectrum components are plotted along the ordinates.

In the spectrum of the defective pipe, a shift in the fundamental frequency and the appearance of additional harmonics with a higher frequency that are absent in the defective pipe are observed.

Thus, this example shows the possibility of rejecting defective pipes according to their acoustic characteristics.

Literature

1. The control system of tubing and couplings "Uranus 2000-M". Leaflet of the Ural Scientific Research Technological Institute. E-mail-uran@uralniti.ru. Contact phone number 56-14-49.

2. Device for monitoring long products. G 01 N 29/04 No. 1208509, publ. 01/30/86. Bull. Number 4.

Claims (3)

1. An acoustic pipe control device comprising a hammer, a sensor and a spectrum analyzer, characterized in that it further comprises a control unit and three active supports, one of which has a sensor with a spectrum analyzer and a power supply, and the other two have piezoelectric drums with power supplies, while the supports representing the piezoelectric shock with the power supply are located at the ends of the pipe symmetrically relative to the support containing the sensor with a spectrum analyzer. 2. The device according to claim 1, in which the sensor, shock and the control unit are interconnected by radio. 3. A method of acoustic pipe monitoring, including impact on a controlled object with a shock and registration of mechanical vibrations of the object, characterized in that the pipe vibrates by simultaneous impacts at two points symmetrically located relative to the sensor at the ends of the pipe, and the quality of the pipe is judged by the informative parameters of the spectrum arising from this vibrations.

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