RU98588U1 - DISCRETE INDICATOR OF LOCAL CORROSION OF METAL STRUCTURES - Google Patents

Abstract

The utility model relates to monitoring corrosion of underground metal structures in contact with electrically conductive media, for example, soil, in particular, to discrete indicators of local corrosion of metal structures and can be used to determine the danger of corrosion and the effectiveness of protection of underground metal structures.

The technical result that can be obtained using the proposed utility model is to obtain the full amount of data on the corrosion state of the underground structure, the ability to assess the depth and rate of corrosion, the dynamics of the development of the local corrosion process during the operation of the structure, from the moment the discrete indicator of local corrosion was installed. If a discrete indicator of local corrosion is installed simultaneously with the commissioning of an underground structure, then it can be used to identify the critical moment of operation, after which replacement or overhaul of the structure is required.

The discrete indicator of local corrosion, which is installed in the soil in the immediate vicinity of the structure or on its surface, shown in Fig., Consists of a housing 1 made of the same metal as the structure and having electrical contact with the structure to equalize the potentials, case 1 contains at least two cavities 2, in this example, five cavities 2 are filled with a high-resistance, dehydrated capillary-porous material into which metal electrodes 3 with zhnosti formation between the body 1 and the electrodes 3 the electrical contact with ground moisture penetration as a result of perforation through corrosion indicator working plane 4, having a normalized thickness between the lower forming cavities 2 and the work plane 4 δ1 ... δ5. The working plane 4 has direct contact with the soil (not shown in Fig.). All cavities 2 are identical in design, only the thickness δ varies, therefore, in FIG. the design is considered on the example of a cavity 2 having a thickness between the lower generatrix of the cavity 2 and the working plane 4 δ5. In the upper part of the cavities 2, glands 5 of elastic material are installed, which carry out the primary sealing of the cavity 2, through which the electrode 3 is passed. The electrode 3 is the exposed part of the metal core of the cable 6 located in the cavity. One of the cores of the cable 6 is connected to the housing 1 of the indicator. Cable 6 is brought to the surface for remote monitoring of the status of the indicator, each core of cable 6 has a marker 7 corresponding to its location in the housing 1 of the indicator. The space of the housing 1, where the cable entry 6 and the glands 5 are located, is filled with a non-conductive sealing mass 8. The outer surface of the indicator, with the exception of the working plane 4, is protected by an insulating coating 9. The core of cable 6, with a marker “K”, has an electrical contact 10 with housing 1. IL .1, 1 P. F.

Description

The technical field to which the utility model relates.

The utility model relates to monitoring corrosion of underground metal structures in contact with electrically conductive media, for example, soil, in particular, to discrete indicators of local corrosion of metal structures and can be used to determine the danger of corrosion and the effectiveness of protection of underground metal structures.

State of the art

A device is known that is used in the method for determining the places of corrosion of underground objects, consisting of copper-sulfate reference electrodes, an H 399 microvoltmeter, a structure, a polarization source, an anode ground electrode, and in a method that includes the cathodic polarization of a structure, measuring the EMF between points on the earth's surface immediately above the structure and at a distance of 2 to 10 meters from the structure after switching off the polarization source, determine the polarity of the EMF value for points located above the structure.

In the method of carbonate corrosion cracking is judged by the presence of positive polarity for points of the earth's surface above the structure after turning off the polarization source for 1 hour to 3 days (see US Pat. RU No. 1748496, IPC G01N 17/00, publ. 10.10. 1995).

The disadvantage of this device is the limited duration.

A known block of indicators of the rate of corrosion of underground metal structures containing at least three indicators of the rate of corrosion of various thicknesses and widths of not more than 2 mm, made of the same material as the underground metal structure, and attached at one end to a control plate that is made of the same of the material as the underground metal structure, at a distance of at least 3 mm from each other, control conductors are connected to the control plate and opposite ends of the indicators with a decree firs thickness of the corrosion rate indicators, the inner surface corrosion rate indicators isolated anti-corrosion coating, and the corrosion rate indicator unit and a control plate mounted in the dielectric housing. The moment of corrosion failure of the indicator is determined by periodically measuring the electrical conductivity of the circuit between the control conductors attached to the control plate and one of the indicators. The use of a block of indicators of the corrosion rate allows you to obtain data on the kinetics of the corrosion process in time and evaluate the effectiveness of anti-corrosion measures that are taken after the indicator is triggered. (see Pat. RU No. 2161789, IPC G01N 17/00, G01N 27/30, publ. 10.01.2001).

The disadvantage of this block of indicators is its low information content, the inability to determine the degree of local corrosion and a limited duration.

The closest in technical essence and the achieved positive effect and adopted by the authors for the prototype is a device for controlling the degree of local corrosion of metal structures in conductive media, consisting of an enclosure electrically closed to the structure made of the same material as the structure, while the entire body or its part in contact with the medium is smaller than the wall of the structure, a predetermined thickness, the body cavity is filled with non-conductive inert capillary-porous material ohm, into which the metal electrode so as to form between the housing and the electrode in electrical contact with a local corrosion perforation body or its parts and thinner absorption medium inside, while between the body and the electrode is enabled recording device.

In the device in contact with the medium, the part of the building serves as a section of the wall of the structure (see US Pat. RU No. 2143107, IPC G01N 17/00, G01N 17/02, publ. 12/20/1999).

The main disadvantage of the device for monitoring the degree of local corrosion of metal structures is the lack of data on the kinetics of the corrosion process over time, which excludes the assessment of the effectiveness of anti-corrosion measures performed after the moment of detection of corrosion perforation of a thin wall of the device body.

The use of a block of indicators of the rate of corrosion of underground metal structures does not allow us to assess the degree of danger of local corrosion.

A common disadvantage of these devices is their low information content and a limited duration.

Utility Model Disclosure

The objective of the proposed utility model is to develop a discrete indicator of local corrosion, with which you can get the most complete amount of data on the corrosion state of an underground structure, the ability to assess the depth and rate of corrosion, the dynamics of the development of local corrosion during the operation of the structure, from the moment the discrete indicator of local corrosion is installed . If a discrete indicator of local corrosion is installed simultaneously with the commissioning of an underground structure, then it can be used to identify the critical moment of operation, after which replacement or overhaul of the structure is required.

The technical result that can be obtained using the proposed utility model is to obtain the full amount of data on the corrosion state of the underground structure, the ability to assess the depth and rate of corrosion, the dynamics of the development of the local corrosion process during the operation of the structure, from the moment the discrete indicator of local corrosion was installed. If a discrete indicator of local corrosion is installed simultaneously with the commissioning of an underground structure, then it can be used to identify the critical moment of operation, after which replacement or overhaul of the structure is required.

The technical result is achieved using a discrete indicator of local corrosion of metal structures, consisting of a building electrically closed to the structure, made of the same material as the structure and the part of the housing in contact with the medium contains cavities having a thickness less than the wall of the structure, filled with non-conductive capillary-porous material into which metal electrodes are inserted with the possibility of electrolytic formation between the body and electrodes contact during local corrosion perforation of the thinner part of the casing and the absorption of the medium inward, while the casing is equipped with at least two cavities in the upper part of which seals of elastic material are installed, made with the possibility of primary sealing, through which an electrode is passed, as which use the bare part of the metal core of the cable located in the cavity, which is exposed to insulation, one of the core of the cable is connected to the indicator housing, and each core of the cable has a marker corresponding to location in the display housing, wherein the housing space, wherein the cable entry is located and seals filled nonconductive sealing mass.

Brief Description of the Drawings

In FIG. A discrete indicator of local corrosion of metal structures, a general view.

Utility Model Implementation

The discrete indicator of local corrosion, which is installed in the soil in the immediate vicinity of the structure or on its surface, shown in Fig., Consists of a housing 1 made of the same metal as the structure and having electrical contact with the structure to equalize the potentials, case 1 contains at least two cavities 2, in this example, five cavities 2 are filled with a high-resistance, dehydrated capillary-porous material into which metal electrodes 3 with zhnosti formation between the body 1 and the electrodes 3 the electrical contact with ground moisture penetration as a result of perforation through corrosion indicator working plane 4, having a normalized thickness between the lower forming cavities 2 and the work plane 4 δ1 ... δ5. The working plane 4 has direct contact with the soil (not shown in Fig.). All cavities 2 are identical in design, only the thickness δ varies, therefore, in FIG. the design is considered on the example of a cavity 2 having a thickness between the lower generatrix of the cavity 2 and the working plane 4 δ5. In the upper part of the cavities 2, glands 5 of elastic material are installed, which carry out the primary sealing of the cavity 2, through which the electrode 3 is passed. The electrode 3 is the exposed part of the metal core of the cable 6 located in the cavity. One of the cores of the cable 6 is connected to the housing 1 of the indicator. Cable 6 is brought to the surface for remote monitoring of the status of the indicator, each core of cable 6 has a marker 7 corresponding to its location in the housing 1 of the indicator. The space of the housing 1, where the cable entry 6 and the glands 5 are located, is filled with a non-conductive sealing mass 8. The outer surface of the indicator, with the exception of the working plane 4, is protected by an insulating coating 9. The core of cable 6, with a marker “K”, has an electrical contact 10 with housing 1.

The discrete indicator of local corrosion is operated as follows.

A discrete indicator of local corrosion, consisting of a sealed metal housing 1 made of the same metal as the structure, is installed in the ground in the immediate vicinity of the structure or on its surface is in electrical contact with the structure to equalize potentials. Thus, the indicator is in the same environment, under the same conditions as the structure, and is subject to corrosion to the same extent. In the indicator housing 1 there are cavities 2 filled with a dry capillary-porous, non-conductive electric current material into which metal electrodes 3 are inserted. The metal of housing 1 between the lower generators of each cavity and the working plane has a different normalized thickness δ1 ... δ5, which in the future will be called the “Caliber” δ1 ... δ5. The resolution and resolution of the indicator depend on the caliber. So with calibers δ1 = 0.1 mm, δ2 = 0.2 mm, δ3 = 0.3 mm, δ = 0.4 mm, and δ5 = 0.5 mm, the resolution of the indicator is 0.1 mm, with discreteness 0.1 mm Depending on the corrosive activity of soils, the wall thickness of an underground structure, the resolution and resolution of the indicator can be different, but equal. For example, with a resolution of 0.5 mm, the resolution should also be equal to 0.5 mm, this is justified from the point of view of further interpretation of the data. The shape of the indicator housing 1 can be either rectangular or cylindrical, the number of cavities 2 can also be different, provided that each cavity 2 is equipped with an electrode 3. The cable 6, which is part of the indicator, allows you to control the corrosion state of the indicator on the ground surface, for these purposes each of the cores of cable 6 located on the surface has a marking corresponding to the location of the cores in the cavities 2 of the indicator and the cores connected to the housing 1 of the indicator. The cable core 6 connected to the housing 1 must be connected to the structure. After placement in the ground, the working plane 4 of the indicator is exposed to corrosion, during which there is a through corrosion perforation of the caliber. It is most likely that the thinnest gauge δ1 will undergo the first through perforation. Under the action of capillary forces inherent in the filler, the penetration of soil moisture into the cavity 2 occurs, creating a medium that provides ionic conductivity between the indicator housing 1 and the output of the electrode 3 located in this cavity 2, which is remotely recorded by an external measuring device (not shown in Fig.) . As a capillary-porous material, synthetic cotton wool is used, impregnated with a saturated solution of sodium chloride (NaCl), subsequently subjected to drying at elevated temperature. The use of this material as a capillary-porous material is due to its properties. So 1 mm of the surface of the dry material has a resistance of more than 20 MΩ, and the introduction of 2% moisture reduces the resistance to 20 kΩ or less, which provides a quick and unambiguous response to through corrosion perforation of the indicator cavity 2. The fact of corrosion perforation is recorded by a resistance meter, at a limit of 20 megohms. In this case, resistance measurements are made between the lead of the cable 6 connected to the indicator housing 1 and one of the wires located in the cavities 2 as electrodes 3. If the resistance is more than 2 MΩ, the controlled cavity 2 maintains integrity since the capillary-porous material remains dry and there are no prerequisites for creating an electrolytic contact, if less than 2 MΩ, through perforation takes place due to the penetration of soil moisture into cavity 2 and the formation of an electrolytic medium that provides ionic conductivity. Knowing the value of δ, one can determine the depth of corrosion. If several cavities 2 have undergone through corrosion perforation, the maximum value δ is selected as the final value when determining the depth of corrosion. For example, if, when measuring the resistance between the core cable 6 connected to the indicator housing 1 and the core wires 6, which are electrodes 3, located in cavities 2, having a caliber δ1, δ2, and δ3, the measured resistance value is less than 2 MΩ, and δ4 and δ5 - more than 2 megohms, the final value of the depth of corrosion is δ3, the depth of corrosion = δ3. Knowing the date of installation of the indicator and the date of detection of through corrosion perforation of the cavities, you can determine the corrosion rate by the formula:

where δ is the gauge subjected to through corrosion perforation. When several cavities are destroyed, the caliber δ of a cavity having a large thickness is taken into account.

τ is the number of days from the moment of installation of the indicator to the fixation of through corrosion perforation of the cavity, having the largest caliber of subjected to through corrosion perforation.

Thus, a discrete indicator of local corrosion sets the soil in the immediate vicinity of the structure or on the surface of the structure. The indicator cable 6 is brought to the surface of the earth. The cable core 6 connected to the indicator housing 1, equipped with a marker “K”, is connected to the output from the controlled structure on the ground surface to equalize the potentials of the indicator housing 1 and the structure. Thus, the working plane 2 of the indicator simulates the condition of a section of a structure that has insulation damage and is susceptible to the corrosion process to the same extent as a structure in the most critical section with damage to the outer insulation. The date of installation of the indicator is fixed in the operational documentation.

During operation, after certain periods of time, the duration of which depends on the degree of corrosion hazard and is established by the organization operating the underground structure, but not less than 3 months later, the indicator is monitored. To do this, a resistance meter at a limit of 20 megohms measures the resistance between the core of cable 6, equipped with a marker “K”, and sequentially with each of the core of the cable having markers δ1 ... δ5. If the resistance is more than 2 megohms - the controlled caliber has maintained integrity, there is no through corrosion perforation. The situation when the controlled resistance is less than 2 MΩ indicates a through corrosion perforation having a depth δ indicated on the corresponding marker. For the total depth of corrosion take the maximum value of the caliber δ from subjected to through perforation. The corrosion rate is calculated by the formula (1).

The proposed utility model in comparison with the prototype and other well-known technical solutions has the following advantages:

- obtaining the full amount of data on the corrosion state of an underground structure;

- the ability to assess the depth and speed of corrosion;

- the ability to assess the dynamics of the development of the local corrosion process during the operation of the structure, from the moment the discrete indicator of local corrosion was installed;

- the ability to identify the critical moment of operation, if a discrete indicator of local corrosion is installed simultaneously with the commissioning of the underground structure.

Claims (1)

Discrete indicator of local corrosion of metal structures, consisting of a body electrically closed to the structure made of the same material as the structure, while the body part in contact with the medium contains cavities having a predetermined thickness smaller than the structure wall, filled with a non-conductive inert capillary-porous material into which metal electrodes are inserted with the possibility of formation between the body and electrodes of electrolytic contact with local corrosion perforation of the thinner part of the casing and the suction of the medium inward, while the casing is provided with at least two cavities, in the upper part of which are seals made of elastic material made with the possibility of primary sealing, through which an electrode is passed, which is used bare from insulation part of the metal core of the cable located in the cavity, one of the core of the cable is connected to the indicator housing, and each cable core has a marker corresponding to its location in the indicator housing, This space of the housing, wherein the cable entry is located and seals is filled with a nonconductive sealant mass.