RU2065147C1 - Method of inspection of rate of corrosion destruction of pipe line - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: warning samples in the form of cubes are put into pipe-line inside which there is built warning device made by alternation of conductive and nonconductive layers manufactured from same material as walls of pipe-line or its lining. Summary thickness h of warning device is determined by formula h= h₀/k_s, where h₀ is thickness of wall of pipe-line or of its lining; k_s is factor of safety. Corresponding shortest distances l_m of each of conductive layers both from base and to its side walls are equal and are determined by formula

Description

 The invention relates to the field of continuous monitoring of the rate of corrosion of pipelines and can be used for continuous monitoring of the rate of internal gas corrosion of underground sewer collectors from reinforced concrete pipes.

 A known method of controlling the rate of corrosion destruction of pipelines is that an annular sample is cut out of the material of the controlled pipeline, put it on the ring, create tensile stress in the sample, place the assembly assembled with the ring in the medium, and the degree of corrosion cracking is judged by the destruction of the sample ( 1).

 The disadvantage of this method is the low reliability and use of harmful radioactive substances.

 Also known is the prototype method of controlling the rate of corrosion of pipeline destruction, which consists in placing alarm samples in the pipeline, keeping them in the flow of aggressive media flowing through them, and evaluating the corrosion losses of the alarm samples, which are used to judge the internal corrosion of the pipeline (2 )

 The disadvantage of this method is that in order to control the rate of corrosion damage, signaling samples must be removed from the pipeline and their corrosion losses should be estimated by changing their thickness. This method does not allow you to receive multiple signals for many years of operation of the sample signaling device in the pipeline, which does not provide sufficient accuracy for determining the internal corrosion of the pipeline in its dynamics.

 The technical result of the invention is to increase the accuracy of determining the corrosion rate of the pipeline by remote continuous measurement of quantitative and qualitative indicators of the corrosion rate simultaneously over the entire thickness of the pipeline.

где h суммарная высота сигнализатора
h₀ толщина стенки трубопровода или его отделки
K_з.п. запас прочности трубопровода,
а соответствующие кратчайшие расстояния каждого из токопроводящих слоев как от основания куба, так и до его боковых сторон равны и определяются по формуле

где l_m толщина стенки трубопровода или его отделки
m порядковый номер токопроводящего слоя сигнализатора от основания образца
n общее количество слоев сигнализатора.The specified technical result is achieved by the fact that in the method of controlling the rate of corrosion destruction of pipelines, which consists in the fact that signaling specimens are placed in the pipeline, they are held in a flow of aggressive medium flowing through it, and the corrosion losses of the specimen-signaling apparatus are evaluated by which internal corrosion is judged the pipeline, inside the cube-shaped sample, a signaling device is placed coaxially with it, which is performed by alternating layers of conductive material and non-conductive layers made of the same material as the walls of the pipeline or its finish, the length of the face of the cubic sample is taken equal to twice the total height of the signaling device, and the total height of the signaling device is determined by the formula

where h is the total height of the detector
h ₀ wall thickness of the pipeline or its finish
K _s.p. margin of safety of the pipeline,
and the corresponding shortest distances of each of the conductive layers both from the base of the cube and to its lateral sides are equal and are determined by the formula

where l _{m the} thickness of the pipe wall or its finish
m serial number of the conductive layer of the detector from the base of the sample
n total number of layers of the detector.

 The invention is illustrated by drawings, where figure 1 shows a vertical section of a pipeline with samples of signaling devices, figure 2 - sample signaling device, figure 3 a horizontal section of a sample signaling device.

 The method is as follows.

где h суммарная высота сигнализатора
h₀ толщина стенки трубопровода или его отделки
K_з.п. запас прочности трубопровода.Signal samples 2 are placed in the pipeline 1, and inside the cube-shaped sample, a signaling device is placed coaxially with it, which is performed by alternating layers of conductive material 3 and non-conductive layers 4 made of the same material as the walls of pipe 1 or its finish, the length of the face of the cubic sample is taken equal to twice the total height of the signaling device, and the total height of the signaling device is determined by the formula

where h is the total height of the detector
h ₀ wall thickness of the pipeline or its finish
K _s.p. margin of safety of the pipeline.

 A layer of the conductive layer 3, which can be used is a thin constantan wire, which is easily destroyed by corrosion and has stable electrical parameters, is connected to the cable 5.

где l_m толщина стенки трубопровода или его отделки
m порядковый номер токопроводящего слоя сигнализатора от основания образца
n общее количество слоев сигнализатора.Moreover, the corresponding shortest distances of each of the conductive layers 3 both from the base of the cube and to its lateral sides are equal and are determined by the formula

where l _{m the} thickness of the pipe wall or its finish
m serial number of the conductive layer of the detector from the base of the sample
n total number of layers of the detector.

 Then, the signaling samples 2 are kept in the flow of aggressive medium 6 flowing through them and the corrosion losses of the signaling samples are evaluated by the signals received from them as the next layer is destroyed on the control and measuring equipment, which can be used as any standard meter, for example ohmmeter; the signals received from the instrumentation, judge the internal corrosion of the pipeline at a given time.

 Samples are suspended in the pipeline on the hook 7.

 An example of a method for controlling the rate of corrosion failure of a pipeline.

The corrosion rate of the sewer collector with a diameter of 2000 mm, a finishing thickness of 300 mm and a coefficient is monitored. margin of safety To _z.p. 3.0.

 By formulas (1), (2), (3) determine the geometric parameters of the sample.

, H 200 мм
Количество слоев принимают равным n 10.

H 200 mm
The number of layers is taken equal to n 10.

 The distances from the conductive layers 3 to the horizontal edges of the sample-signaling device 2 are calculated by the formula (2).

 Concreting of the sample signaling device is carried out in standard cubic form with dimensions of 200 x 200 x 200 mm. The concrete grade must match the concrete grade of the collector finish.

 Laying concrete in a cubic form is done manually.

 After concreting the first layer with a thickness of 10 mm and a 3-4-hour pause, a conductive material that is easily destroyed by corrosion and has stable electrical parameters, for example, constantan thin wire, is laid on the first concrete layer, it is connected to a multicore cable in a concrete space. After that, the second layer of concrete is laid and the whole cycle is repeated until all layers are completely concreted, then concrete is laid down in the form and a short hook is inserted from above for hanging on the walls of the collector.

 After 28-day hardening of the sample-detector, the electrical parameters are removed from all conductive layers. A sample signaling device is installed in the collector at the test site. The cable is output to the measuring console. Simultaneous registration of electrical parameters from all conductive layers of the sample-detector.

 An increase in the electrical resistance of the conductive layer indicates the presence of an active corrosion phenomenon in the concrete layer and the beginning of the destruction of the conductive layer itself.

 A sharp increase in the electrical resistance of the electrically conductive layer will lead to the termination of the signal, which indicates the complete destruction of 10 mm of the concrete layer of the specimen-signaling device and, therefore, the collector finish.

 Using the proposed method for controlling the rate of corrosion destruction of pipelines will improve the accuracy of determining the rate of corrosion of the pipeline by continuous remote measurement of quantitative and qualitative indicators of the corrosion rate simultaneously over the entire thickness of the pipeline.

 The systematic registration of readings from signaling devices installed in areas potentially hazardous from the point of view of gas corrosion will help to determine the onset of corrosion processes, their development dynamics over the entire thickness of the finish and take measures to eliminate them.

Claims (1)

A method for controlling the rate of corrosion destruction of a pipeline, which consists in placing signaling samples in the pipeline, keeping them in a flowing stream of aggressive medium, and assessing the rate of corrosion failure of the pipeline, characterized in that it is placed coaxially inside the cube-shaped sample with it, an indicator made by alternating layers of conductive material and non-conductive layers of the same material as the walls of the pipeline or its lining, the length of the face of the cubic sam ples taken equal to twice the thickness of the indicator, the total thickness h is determined by the formula alerter

where h _{o the} thickness of the wall of the pipeline or its lining;
To _zp safety factor,
and the corresponding shortest distances l _{m of} each of the conductive layers both from the base of the cube and to its lateral sides are determined by the formula

where m is the serial number of the conductive layer from the base of the sample;
n total number of layers of the detector.

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