RU2199735C2 - Method of detection of through defects in walls of reservoirs filled with liquid - Google Patents

Abstract

FIELD: detection of defects by means of ultrasonic waves. SUBSTANCE: proposed method consists in radiation of ultrasonic pulses into liquid by means of two transducers located near reservoir wall in opposite directions coaxially relative to reservoir, followed by reception of pulses and determination of velocity v_x of liquid in radiation-reception direction. Second pair of transducers is arranged oppositely and coaxially; transducers of each pair are located at similar distance and directions of their radiation and reception are mutually perpendicular. Ultrasonic pulses are radiated and received by second pair of transducers in opposite directions; on basis of measured information velocity v_y is determined in of radiation-reception directions; then, velocity modulus V is determined from formula

and its direction φ relative to direction of sonic test of first pair of transducers is determined by formula tgφ = v_y/v_x, after which transducers are moved along direction φ and velocity modulus is determined successively and position of transducers at which velocity modulus is maximum is found. Velocities v_x, v_y of liquid are determined on basis of measurements of difference in time of passage of ultrasonic pulses in opposite directions for each pair of transducers. EFFECT: enhanced reliability of defect detection. 2 cl, 1 dwg

Description

 The present invention relates to methods for detecting defects in an article using ultrasonic waves. It can mainly be used to detect through defects in the walls of metal containers filled with liquid, on the outside of which there is concrete cladding or other insulation (for example, earth).

 In industry, leak detection methods are widely used to detect end-to-end defects in product walls [1], the essence of which is to measure the flow of test substances (gases) through the product walls. The disadvantage of these methods is their suitability for monitoring closed vessels not filled with liquid of relatively small overall dimensions.

 A known method for detecting end-to-end defects in the walls of containers filled with liquid by visual inspection of their surfaces and the determination of fluid smudges on them. The smudge location corresponds to the coordinate of the through defect. This simplest method is not suitable for detecting leaks in containers lined with concrete or buried in the ground.

 The closest in technical essence and the achieved result is a method for detecting through defects in containers with liquid by measuring the flow rate of a liquid near a through defect, implemented in ultrasonic flow meters [2, 3].

To implement the method of measuring the fluid flow rate in pipelines, two oppositely aligned piezoelectric transducers can be used, with the help of which the fluid is alternately sounded in opposite directions - “upstream” and “upstream”. In the first case, the signal transit time is determined by the relation t ₁ = l / c + v _x , and in the second, t ₂ = l / s-v _x , where l is the base between the transducers, c is the ultrasound velocity in the liquid, v _x is the projection fluid flow rates in the direction of sounding. By measuring the time interval Δt = t ₂ -t ₁ between the delays of the signals passed upstream and downstream, it is possible to determine the projection of the fluid velocity v _x = Δt • c ² / 2l. This method of measuring speed is called temporary. There are other measurement methods — phase, frequency, or combined [2], which allow for higher measurement accuracy.

 The known method allows you to measure the speed of movement of the liquid in the tank, but does not allow to determine the location of the through defect.

 The technical problem solved by the invention is to develop a method for detecting the location of a through defect in the wall of a liquid-filled container, lined with concrete on the outside or buried in the ground.

и его направление φ относительно направления прозвучивания первой пары преобразователей по формуле tgφ= v_y/v_x, затем преобразователи перемещают вдоль направления φ, последовательно определят модуль скорости и находят то положение преобразователей, при котором модуль скорости будет максимальным.The problem is solved in that, as in the known method, the fluid flow rate through the hole in the vessel wall is measured. For this, pulses of ultrasonic waves are emitted into the liquid by a pair of oppositely aligned transducers sequentially in opposite directions, the pulses transmitted in opposite directions are received, and the velocity v _{x of the} liquid in the radiation-reception direction is determined based on the measured information. But unlike the known method, a second pair of transducers is located opposite and coaxial, and the transducers of each pair are located at the same distance towards each other and their radiation directions - the reception is mutually perpendicular, emit and receive ultrasonic pulses of the second pair of transducers in opposite directions, based on the measured information _in determining the velocity v in the direction of emission - receiving a second pair of transducers, the velocity v is calculated by module pho mule

and its direction φ relative to the direction of sounding of the first pair of transducers according to the formula tgφ = v _y / v _x , then the transducers move along the direction φ, sequentially determine the speed modulus and find the position of the transducers at which the speed modulus will be maximum.

 The essence of the invention is illustrated in the drawing, which schematically shows an example of an acoustic system with which a method for detecting the location of through defects in the wall of a container filled with liquid is implemented. The proposed method is as follows. The measuring acoustic system is a rigid metal plate of square shape with a square hole, on which two pairs of I and II ultrasonic transducers are mounted diagonally. The directions of radiation - reception of each pair are mutually perpendicular. The transducers of each pair 1 'and 1 ", 2' and 2" are located coaxially towards each other and at the same distance from each other.

 The speaker system is suspended on a cable in a vertical position near the wall of the tank and with the help of a scanning system can move along a predetermined path relative to the wall.

и его направление φ относительно направления прозвучивания первой пары преобразователей по формуле tgφ=v_y/v_x. Затем акустическую систему с помощью сканирующего устройства перемещают вдоль направления φ, последовательно определяют модуль скорости и находят то положение, при котором скорость потока v будет максимальна. Положение акустической системы относительно стенки емкости определяет место расположение в ней сквозного дефекта.Using electronic equipment at the first time, the transducers 1 'and 2' are excited, and the transducers 1 "and 2" are receivers. In the presence of a fluid flow near the wall of the container through the holes, the time of arrival of the signals at the receivers will be different and equal to t ' ₁ = l / c + v _x and t' ₂ = l / c + v _y . Then, the converters 1 "and 2" are excited using the switch, and the converters 1 'and 2' are receivers. Based on the difference in time intervals Δt ₁ = t " ₁ -t ' ₁ and Δt ₂ = t" ₂ -t' ₂ , the projections of the flow rates v _x and v _y on the sounding directions are determined, the modulus of the flow velocity v according to the formula

and its direction φ relative to the direction of sounding of the first pair of transducers according to the formula tgφ = v _y / v _x . Then, using the scanning device, the speaker system is moved along the φ direction, the velocity modulus is determined sequentially, and the position is found at which the flow velocity v will be maximum. The position of the speaker system relative to the wall of the tank determines the location of the through defect in it.

 Consideration of the proposed method shows that its implementation allows you to determine the location of the through defect in the wall of the tank, lined with concrete or buried in the ground and filled with liquid.

LITERATURE
1. Gurvich A.K., Ermolov I.N., Sazhin S.G. Unbrakable control. Book 1 "General issues. Control of penetrating substances", M .: Higher school, 1992.

 2. Kiyasbeyli A.Sh., Gumailov A.M., Gurevich V.M. Time-frequency ultrasonic flow meters and counters. M .: Engineering, 1984.

 3. Khamidulin V.K. Ultrasonic measuring devices and systems. L .: Leningrad State University, 1989.

Claims (2)

1. A method for detecting through defects in the walls of containers filled with liquid, which consists in emitting ultrasonic pulses into a liquid by a first pair of transducers oppositely coaxially located near the vessel wall in series in opposite directions, receiving pulses transmitted in opposite directions, determining, based on the measured information, the speed v _{x of} movement liquid in the direction of radiation - the method, characterized in that it further place a second pair of transducers located opposite and coaxial, and the transducers of each pair are located at the same distance towards each other and their radiation directions - the reception is mutually perpendicular, emit and receive ultrasonic pulses by the second pair of transducers in opposite directions, based on the measured information determine the speed v _y in the radiation directions - receiving the second pairs of transducers, calculate the module v of the fluid velocity according to the formula

and its direction φ relative to the direction of sounding of the first pair of transducers according to the formula tg φ = v _y / v _x , then the transducers move along the direction φ, sequentially determine the speed modulus and find the position of the transducers at which the speed modulus will be maximum. 2. A method according to claim 1, characterized in that the velocity v _x, v _y motion of the liquid is determined by measuring the time difference of ultrasonic pulses in opposite directions for each pair of transducers.