FI99163B - Method for measuring of defects in pipes - Google Patents

Description

99163

METHOD OF MEASURING PIPE DEFECTS

The invention relates to a method for measuring defects in a pipe and for detecting foreign objects present in the pipe.

5 Today, in various process industries, power plants and the like, monitoring the condition of pipelines poses problems in maintenance. Usually, damage to pipelines is not noticed until after the leak has occurred, in which case the resulting damage can be significant.

The object of the invention is to eliminate the above-mentioned drawbacks. In particular, the object of the invention is to provide a measuring method by means of which the condition of the pipelines can be monitored whenever desired without interfering with their use in various processes and by means of which the errors of the pipelines can be accurately located.

The method according to the invention is characterized by what is set forth in the characterizing part of claim 1.

In the method according to the invention, two transmissive radii of the tube are directed through the walls of the tube, the rays are moved successively in the measuring direction with respect to the tube, the intensities of the radii passing through the tube walls are measured and the defects of the tube are determined by comparing the angles; the distance between the signals given by the roads in the measuring direction and the distance between the beams at both transmission points.

The measuring device 30 used in the method for measuring tube defects comprises, on one side of the tube, a gamma or X-ray source and on the other side: two detectors located in the direction of the \ -m axis of the tube spaced apart and directed to the radiation source, and * * ; * 35 the radiation source is arranged to direct the measuring beams j '·· through the walls of the tube to be measured at an angle to each other: ***:, the detectors are arranged to detect beams passing through the walls of the tube 99163 2 and the printing device is arranged to output a signal characterizing the tube wall thickness.

The measuring device and the measuring method according to the invention are based on the fact that two collimated radiation moving in succession in the measuring direction pass through the walls of the tube at different distances from each other. That is, the rays pass through the wall of the tube at a certain distance from each other as they enter the tube and when they come out through the sheath on the other side of the tube the distance between them is differently large, preferably greater. In this way, by comparing the measurement results given by the different radii, it can be deduced on which side of the tube and at which point the measured observation point, e.g.

15 thinning, is.

The measuring device and method are based on the fact that the thicker the penetration point, the more radiation is absorbed into the pipe jacket. Thus, the method according to the invention can also be used to measure pipe blockages in addition to various corrosion damages and the like.

The pipes to be measured can be made of reinforced plastic, ·· .. steel, aluminum, copper, etc. and can also m · • ·; ·, ·. be insulated with different insulation materials.

• · 25 The radiation used in the invention is gamma- *. . or X-rays. The wavelength of the radiation is on the order of 10 · 3 cm, gamma radiation, and 10 ~ 3 - 10 "J cm, X-ray radiation. It is particularly suitable as a radiation source • · m: for measuring Cs 137.

30 Radiation detected through the walls of the tube. with detectors on the opposite side of the tube. Any of the conventional radiation detectors suitable for detecting the gamma and X-ray radiation in question can be used as detectors. The signals from the detectors can be amplified and the signals can be printed by conventional methods known in the art on a plotter, film, magnetic tape or the like.

Preferably, the radiation emanating from the radiation source is directed by the collimator precisely before and / or after the tube to be measured so as to obtain an accurate limitation of the radiation.

Although it is possible that one of the radiations is perpendicular to the tube and the other at an angle, it is preferred that the angle between the radiation detected by the detectors and the normal of the tube is 1 to 60 °, suitably 1 to 15 °, preferably 1 to 5 °, at equal and opposite angles to normal. Thus, the measurement conditions are exactly the same for both radiations and any differences observed in the radiations indicate deviations in the tube structure 15 or blockages in the tube.

Preferably the distance between the detectors is of the order of 10 to 100 mm, suitably 10 to 60 mm, for example 10 to 20 mm.

The beams entering the detectors can be attenuated to suit the detectors with filter plates. The filter plates can be placed either after the radiation source before the tube or after the tube before the detectors. The material of the filter plates is a conventional radiation attenuation material.

25 Detector signals can be amplified. · · *. electronically as needed to fit the recorder, • both channels separately so that the thickness is readable when the instrument is first calibrated.

··:: The measurement according to the invention is performed by moving the measuring device and the pipe to be measured relative to each other. This can be done either by moving the measuring device relative to the fixed tube or by moving the club relative to the fixed measuring device.

The measurement according to the invention is preferably performed as an equilibrium measurement, so that the radiations to be measured are continuously compared with each other and only when the intensities of the radiations differ, the magnitude and location of the difference in the piping are recorded in a suitable manner.

An advantage of the invention compared to the prior art is the possibility of quickly, accurately and simply measuring the condition of the pipelines 5 without disturbances caused by the use of the pipelines.

The invention will now be described in detail by way of example with reference to the accompanying drawings, in which Figure 1 shows a schematic diagram of an apparatus used in the invention, Figure 2 shows an arrangement according to the invention, Figure 3 shows an example of Figure 2 from another angle and Figure 4 shows radiation intensities measured by detectors.

According to Figure 1, a gamma or X-ray source 2 and two detectors 3.31 are placed on opposite sides of the walls of the tube 1 to be measured. The detectors of the Detek-20 are arranged in succession in the axial direction of the tube to be measured and oriented relative to each other so that the radii impinging on the detectors are equal ·. at an angle α to the normal of the tube under consideration.

I The radiation from the radiation source 2 is collimated by means of collectors *, 25, 5 :, 53 before the tube 1 and • · [after the tube into two precise beams which are * precisely directed to the detectors 3.3 *. In order to adjust the radiation from the radiation source 2 ·· to the detectors 3.31, the radiation can be attenuated by filter plates 7.

30 The measuring device according to Figure 1 is used as follows. The measuring device is moved to the axis of the tube 1; In the direction in which the radiation p from the radiation source 2 passes through both walls of the tube.

:: If the tubes are of uniform thickness and error-free, the signals to the output device 4 are similar and • in the balance measurement, the output device does not output a signal.

• P

signals.

p • · 5 99163

In Figure 4, the radiation intensity I is on the y-axis and the length of the tube 1 in the direction of movement is on the x-axis. Curve 9 shows the signal of detector 3 and curve 10 shows the signal of detector 3 'when the tube is moved relative to the measuring device. When the tube or measuring device is moved relative to each other, the intensity of the radiation changes if there are defects or other changes in the walls of the tube. An increase or decrease in intensity, i.e., an increase or decrease in the radiation passing through the tube, indicates the strength of the tube wall. The measuring range is linear in the measuring direction in the direction of the pipe axis. The measurement speed when moving the measuring device depends on the detectors, and can be such that the measurement can be performed even at a walking speed.

Referring to Fig. 4, if there is, for example, thinning in one of the two walls of the pipe, the first sign of the error is obtained from the first radius, which is absorbed differently into the structure of the pipe at the error than at the error-free point. The x-axis representing the length 20 of the pipe provides information on the location of the error in the pipe. When the measuring device is moved further, a corresponding error signal is obtained from another radius, whereby, from the distance between the error signals in the x-axis direction, it is seen which wall of the pipe has the error.

25 This observation is based on the fact that the rays pass through the '* * tube at an angle to each other, so that they pass through the different walls of the tube at different distances from each other.

:! In the embodiment of Figure 2, the radiation source 2 and the detectors 3,3 'are placed in a transmission device 6, which. allows the device to be moved relative to tube 1; in the axial direction of the pipe at the time of measurement.

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As shown in Figure 3, the tube is surrounded by a transfer device 6 consisting of an arc 3/4 of the circumference of the tube 35 and resting centrally on the tube with three support legs with wheels 8. The arc comprises a radiation source on the opposite sides of the tube and two detectors. - • · 6 99163 ria in the axial direction of the pipe in succession. The detectors are oriented, for example, at an angle of about 3 ° to the normal of the tube and 10 to 20 mm apart. The radiation is directed precisely from the openings 5 of the collimators in front of the tube to the openings of the two collimators connected to the detectors on the other side of the tube and further to the detectors, each with its own radius. If necessary, the radiation is attenuated by filter plates to ensure the wall thickness and the operation of the detectors.

The signals of the detectors are electronically amplified by methods known in the art, if necessary to suit the plotter, both channels separately, whereby the thickness can be read when the device is first calibrated.

The method according to the invention can be used to measure the defects of various pipelines, such as defects in the walls of the pipe, foreign objects present in the pipes and blockages. The defects in the pipe walls can also be measured without removing the insulation, through the insulation 20.

The invention is not limited to the above examples, but its applications may vary according to the appended claims. requirements.

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Claims (2)

A method for measuring and locating errors in pipes, in which method - through the walls of the tube (1) is directed relative to each other at an angle standing through the tube passing beams and - the intensity of the beams passing through the walls of the tube is measured. , characterized in that 10 two collimated beams are used in the measurement, which are subsequently moved in the axial direction of the tube (1), the locations of the errors in the tube being determined by atc in the measuring direction comparing from the distal position of the signals given by the beams with the distance given by the beams from each other in the passage points in the bed walls of the pipe. 2. A method according to claim 1, characterized in that the measurement is carried out as an equilibrium measurement, such that the measuring device gives a measurement signal only there when the intensity of the jets deviate from each other. * * * • · m m • · »• ·» · · · · · · · · · · · · · · · · · 1 ·· · • m · ♦ · m *