RU2777824C1 - Method for finding the number of additional anodic groundings required to provide protective difference of potentials "pipe-earth" in a pipeline section - Google Patents

Abstract

FIELD: anti-corrosion protection.

SUBSTANCE: invention relates to the field of anti-corrosion protection of underground pipelines and can be used when planning a major overhaul. The method consists in selecting a CPS, in which the cathodic protection station (CPS) operates in the maximum mode for the output voltage, measuring the resistance to current spreading of the EP, short-term measurement of the CPS operating modes and finding the coefficient of its influence on the value of the protective potential difference "pipe-to-ground" in drainage point and at the junctions of protection zones with neighboring stations, step-by-step measurement of the operating modes of adjacent CPS, preventing the transition of the protective potential difference "pipe-ground" at the drainage point of the adjacent CPS to the area of ​​unacceptable values, without changing the operating modes of the remaining stations. The protective potential difference “pipe-to-ground” is measured after its stabilization, the coefficients of influence of each station are determined under the current operating modes of the remaining CPS, the stationary potential at the drainage point of the studied CPS, the stationary potential at the left junction of the CPS protection zones, the required potential shift at the CPS drainage point is calculated and at the junctions of its protection zones, the necessary values ​​of the current strength of the CPS are determined to ensure the protective potential difference "pipe-to-ground" at the drainage point and at the junctions of the protection zones of the CPS, a larger value of the CPS current is selected and the required value of the spreading resistance of the core is calculated, the required resistance of the additional anodes is determined, based on the condition, that EP is connected in parallel. The current spreading resistance of one EP in a vertical arrangement, the number of additional EPs are calculated, the resulting number is rounded up and taken as the required number of additional anodes.

EFFECT: increasing the reliability of determining the number of additional EPs necessary to ensure the protective potential difference "pipe-to-ground" in the pipeline section for existing CPS.

1 cl, 1 ex, 1 dwg, 1 tbl

Description

The invention relates to the field of anti-corrosion protection of underground pipelines, namely, finding the number of anode ground electrodes as elements of cathodic protection installations (CCP) against corrosion of underground pipelines and can, in particular, be used when planning a major overhaul.

At present, upon reaching the maximum operating modes of the cathodic protection station (CPS), the operating organization is forced to carry out work on its reconstruction, associated either with an increase in its capacity or with the replacement of anode ground electrodes. In the absence of funds to carry out these works, the question arises of the need to take measures aimed at ensuring the security of the facility for the period until the overhaul. This can be done by reducing the spreading resistance of the anode grounding of this SKZ by installing additional anode grounding switches. At present, there is no tool that allows to determine the number of additional anode ground electrodes necessary to maintain the electrochemical corrosion protection system in working condition based on the current operating modes for the existing CPS.

A known method of restoring a deep anode ground electrode, including diagnosing rock formations with a minimum electrical resistivity by vertical electrical sounding, calculating the parameters of a deep anode ground electrode from prefabricated electrodes, flushing the ground electrode to the design depth, pumping out water, lowering prefabricated electrodes, backfilling with a coke-mineral activator , connection of ground electrodes to the cathodic protection station. Additionally, the ground electrode is diagnosed from the inside, corrosion deposits are destroyed and removed from the ground electrode, and the installation of prefabricated electrodes and backfilling with a coke-mineral activator is performed with simultaneous gradual build-up and compaction. At the same time, the destruction of corrosive deposits of the ground electrode is performed by an electro-hydraulic method, the compaction of the coke-mineral activator is carried out simultaneously by hydraulic and electro-hydraulic methods, and the diagnosis of the ground electrode from the inside is carried out by the ultrasonic immersion method (RF patent No. 2541247, class C23F 13/00, publ. 10.02.2015).

The disadvantages of this method are the high complexity of the process, the low efficiency of restoring the operability of the anode ground electrode.

There is a known method for assessing the technical condition of anode ground electrodes by measuring the resistance to current spreading of anode grounding, which consists in installing measuring and auxiliary ground electrodes in the ground, connecting ground electrodes and anode grounding according to a three-electrode circuit to a measuring device and measuring the resistance to spreading current of an anode ground electrode when alternating current flows through current electrodes (see Backman V., Shvenk V. Cathodic corrosion protection: Sprav, ed. translated from German. - M .: Metallurgy, 1984. - S. 118-119.). Over time, corrosion deposits form on the anode surface, increasing the resistance to current spreading.

The disadvantage of this method is the ability to determine only the current value of the current spreading resistance of the anode ground. It should be taken into account that in a good condition of the insulating coating of the pipeline, small current values are required to maintain the protective potential difference "pipe-to-ground" at the facility. Exceeding the current spreading resistance values in this case leads to the need to increase the voltage at the output of the cathodic protection station, and when the cathodic protection station reaches its maximum operating modes, it is necessary to reduce the spreading resistance value of the anode grounding. This method does not show how much it is necessary to reduce the resistance to spreading of the anode grounding current, and, accordingly, how many anode ground electrodes must be added to the existing ones.

There is a known method for calculating the number of anode ground electrodes in subsurface grounding, depending on their location, at the stage of developing design documentation, which we took as a prototype (STO Gazprom 9.2-003-2009 Corrosion protection. Designing electrochemical protection of underground structures - M .: OAO "Gazprom" - VNIIGAZ LLC, 2009. - pp. 20-22).

With a vertical or horizontal arrangement of anode ground electrodes, the number of electrodes in the ground is calculated by the formula:

where R _p1 is the resistance to current spreading of one electrode, Ohm,

R _p is the resistance to spreading of the anode grounding current, consisting of N anode ground electrodes, Ohm.

The current spreading resistance of one subsurface ground electrode depends on its location and the presence of coke filling of the ground electrode.

With a vertical arrangement of the earth electrode, the calculation is made according to the following formula:

where p _g is the specific electrical resistance of the soil, Ohm m,

- длина электрода заземлителя, м,

- length of the grounding electrode, m,

d _e - diameter of the earth electrode, m,

h - depth (up to the middle of the earth electrode) of the earth electrode, m.

<h, то есть для короткого электрода, расчет производится по формуле (3):With a horizontal electrode of the ground electrode, when

<h, that is, for a short electrode, the calculation is made according to the formula (3):

The initial spreading resistance of the anode grounding current in various soils should not exceed the values \u200b\u200bspecified in table 1.

The disadvantage of this method is that the calculation of the number of anode ground electrodes is carried out for the initial period of operation and this calculation is not applicable to the current UKZ, since, as a result of the anode current draining and destruction of the anode electrodes, the spreading resistance of each anode electrode changes. Also, the requirements for the initial value of current spreading resistance for various conditions are not necessary during operation, and the calculation of satisfying values for current conditions using this method is impossible.

The technical problem solved by the invention is the creation of a reliable method for finding the number of additional anode ground electrodes necessary to provide a protective potential difference "pipe-to-ground" in the pipeline section for existing corrosion protection installations.

The technical result from the use of the invention is to increase the reliability of determining the number of additional anode ground electrodes necessary to provide a protective potential difference "pipe-to-ground" in the pipeline section for existing corrosion protection installations.

The technical result is achieved by the fact that in the method of finding the number of additional anode ground electrodes necessary to ensure the protective potential difference "pipe-to-ground" in the pipeline section, a cathodic protection installation is selected, in which the cathodic protection station operates in the maximum output voltage mode, the resistance is measured spreading of the anode grounding current, which is part of this cathodic protection installation, they briefly change the operating modes of the cathodic protection station and find the coefficient of its influence on the value of the protective potential difference "pipe-to-ground" at the drainage point and at the junctions of protection zones with neighboring stations, change the modes step by step operation of adjacent cathodic protection stations, preventing the transition of the protective potential difference "pipe-to-ground" at the drainage point of an adjacent cathodic protection station to the area of unacceptable values, without changing the operating modes of the remaining stations, measure the values of the protective potential difference "pipe-to-ground" after its stabilization ilization, determine the coefficients of influence of each station under the current operating modes of the remaining cathodic protection stations, the stationary potential at the drainage point of the studied cathodic protection station, the stationary potential at the left junction of the protection zones of the investigated cathodic protection station, calculate the required potential shift at the drainage point of the studied cathodic protection station and at the junctions of its protection zones, by excluding the stationary potential at the drainage point and at the junctions of the protection zones of the station under study from the required value of the protective potential difference "pipe-to-ground", the necessary values of the current strength of the cathodic protection station under study are determined to ensure the protective potential difference "pipe-to-ground" » at the drainage point and at the junctions of the protection zones of the studied station, choose a larger value of the current of the cathodic protection station from those found, determine the required value of the spreading resistance of the anode grounding, determine the required resistance of additional anodes, based on the condition h then the anode ground electrodes are connected in parallel, determine the resistance to current spreading of one anode ground electrode in a vertical arrangement, the number of additional anode ground electrodes, round the resulting number up and take it as the required number of additional anodes, as the ratio of the increment of the protective potential difference "pipe-ground" to the increment current of the cathodic protection station. The stationary potential at the drainage point of the investigated SCZ is determined by the formula (4):

where ϕ _TD - protective potential difference "pipe-ground" at the point under study,

I _BC - current strength of the studied cathodic protection station,

A _GDVS is the coefficient of influence of the studied cathodic protection station on the magnitude of the protective potential at its drainage point,

I _LS - current strength of the adjacent cathodic protection station, located to the left of the studied cathodic protection station along the pipeline route,

A _GDLS is the coefficient of influence of an adjacent cathodic protection station located to the left along the pipeline route from the cathodic protection station under study, on the magnitude of the protective potential at the drainage point of the station under study,

I _PS - current strength of the adjacent cathodic protection station, located to the right of the cathodic protection station under study along the pipeline route,

And _HDPS is the coefficient of influence of the adjacent cathodic protection station, located to the right along the pipeline route from the cathodic protection station under study, on the value of the protective potential at the drainage point of the station under study.

The stationary potential at the left junction of the protection zones of the studied cathodic protection station (ϕ _SttsLSt ) is determined by the formula (5):

where ϕ _SttsLSt - protective potential difference "pipe-ground" at the left junction of the protection zones of the studied station,

I _LS - current strength of the adjacent cathodic protection station, located to the left of the studied cathodic protection station along the pipeline route,

A _LStLS is the coefficient of influence of the adjacent cathodic protection station, located to the left along the pipeline route from the cathodic protection station under study, on the value of the protective potential at the left junction of the protection zones of the studied station,

I _BC - current strength of the studied cathodic protection station,

A _LSTS is the coefficient of influence of the studied cathodic protection station on the value of the protective potential at its left junction of protection zones,

I _PS - current strength of the adjacent cathodic protection station, located to the left of the studied cathodic protection station along the pipeline route,

A _LSTP is the coefficient of influence of the adjacent cathodic protection station, located to the right along the pipeline route from the cathodic protection station under study, on the value of the protective potential at the left junction of the protection zones of the studied station.

The required potential shift (Δϕ _NZi ) is determined by formula (6):

where Δϕ _NZi - the required value of the potential difference "pipe-to-ground", corresponding to the pipeline protection condition according to clause 5.1 of GOST R 51164-98,

ϕ _Stci - stationary potential in the i-th (i=LSt, TD or PSt) control point.

The required values of the current strength of the studied station of cathodic protection (I _IZVS ) to ensure the protective potential difference "pipe-ground" at the drainage point and at the junctions of the protection zones of the studied station are determined by the formula (7):

where Δϕ _H3i is the required potential shift,

A _iVS - coefficient of influence of the studied cathodic protection station of the i-th (i=LSt, TD or PSt) control point.

The spreading resistance value of anode grounding (R _A3H ) is determined by formula (8):

where U _BCmax is the rated voltage of the investigated cathodic protection station,

I _BC - current strength at the output of the studied RMS.

The required resistance of additional anodes ( _RAZD ), based on the condition that the anode ground electrodes are connected in parallel, is determined by the formula (9):

where _RAZN - the required value of the spreading resistance of the anode ground,

R _AZS - the spreading resistance value of the existing anode grounding.

The current spreading resistance of one anode ground electrode in a vertical arrangement (R _pl ) is determined by the formula (10):

where ρ _g - electrical resistivity of the soil,

- длина электрода заземлителя,

- the length of the earth electrode,

d _e - diameter of the earth electrode,

h - depth (up to the middle of the earth electrode) of the earth electrode.

The number of additional anode ground electrodes is determined by the formula (11):

where R _p1 is the resistance to current spreading of one anode ground electrode,

R _AZD - resistance to current spreading of additional anode grounding.

Implementation of the method.

The present invention is illustrated below by the following examples and FIGS.

In FIG. 1 shows a diagram of a pipeline section (1) with three cathodic protection units (CCP) (2, 3, 4) located at a distance of 30 km from each other. Each of the three VCSs contains the VCS: the investigated VCS (5), the left VCS (6), the right VCS (7).

Investigated RMS (5). Each SKZ contains: anode grounds (8, 9, 10), drainage points (11, 14, 15). Between the UKZ there are joints of the SKZ (12.13). The method is carried out as follows.

Using a multimeter, the current values of the current and voltage at the output of the RMS in the selected section of the pipeline (1) (Fig. 1) are measured. Select the UKZ (2), in which the SKZ (5) operates in the maximum or close to the maximum mode equal to 70% of the rated output voltage or more, according to the declared characteristics of the station.

Measure the spreading resistance of the anode ground (8), which is part of the UKZ (2) according to a three-electrode circuit (Manual for the operation of anti-corrosion protection systems for pipelines. - M .: OAO Gazprom - OOO VNIIGAZ, 2004. - 300 p.).

Short-term change the operating mode of the CPS (5) and manually or remotely, using remote corrosion monitoring equipment, measure the values of the protective potential difference "pipe-ground" at the drainage point (11) and at the junctions of protection zones with neighboring stations (12) and (13 ). The coefficient of influence of the RMS (5) on the value of the protective potential difference "pipe-to-ground" at the drainage point (11) and at the junctions of the protection zones with neighboring stations (12, 13) is found using the formula:

where A _iBC is the coefficient of influence of the investigated VCS,

Δϕ _i - protective potential difference "pipe-ground",

ΔI _BC - increment of the current strength of the RMS under investigation.

Step by step change the operating modes of the adjacent VPS (6) and (7), without changing the operating modes of the remaining stations of the pipeline and preventing the transition of the protective potential difference "pipe-to-ground" at the drainage points (14) and (15) of the adjacent VPS (6) and ( 7) into the area of invalid values. Manually or remotely, using remote corrosion monitoring equipment, the values of the protective potential difference "pipe-to-ground" are measured, after its stabilization, at the drainage point (11) and at the junctions of the protection zones (12) and (13) investigated by the VCS (5) . Return the initial operating modes of adjacent RPS (6) and (7), the coefficients of influence of adjacent RPS (6) and (7) on the value of the protective potential difference "pipe-to-ground" at the drainage point (11) of the investigated RPS (5) at the junctions of its zones protection is determined by the formulas:

where A _iLS - coefficient of influence of adjacent RMS,

ΔI _{LS (PS)} - increment of the current strength of adjacent RMS (6.7).

The stationary potential at the drainage point (11) of the studied SKZ (5) and at the junctions of its protection zones (12) and (13) is determined by formula (4).

The required potential shift is determined, which must be maintained, taking into account the stationary potential at the drainage point (11) and at the junctions of the protection zones (12) and (13) of the investigated RMS according to the formula (6).

The required values of the current strength of the investigated RMS (5) are determined to ensure the protective potential difference "pipe-ground" at the drainage point (11) and at the junctions of the protection zones (12) and (13) according to the formula (7).

The obtained values are compared and a larger RMS current value is selected from the calculated ones.

The required value of the current spreading resistance of the anode grounding (8) is determined as the ratio of the maximum voltage at the RMS output to the greater value of the RMS current required to ensure the protective potential difference "pipe-to-ground" and based on the condition that the value of the resistance of the connecting wires and the input resistance of the pipe is extremely small and can be neglected, according to formula (8).

Determine the required resistance of additional anodes, based on the condition that the anode ground electrodes are connected in parallel, according to the formula (9).

Spreading resistance is determined in accordance with STO Gazprom 9.2-003-2009 “Corrosion protection. Design of electrochemical protection of underground structures" of one anode grounding switch when it is vertically installed in the ground according to the formula (10).

Find the number of additional anode ground electrodes according to the formula (11). The resulting number is rounded up and taken as the required number of additional anodes.

Example.

UKZ No. 26 with a power of 1 kW with a nominal current of 21A, a voltage of 48 V, is located at km 240 and provides electrochemical protection against corrosion at the section of the main gas pipeline km 225 - km 255 as of 01/01/2019 Based on the results of seasonal measurements specialists of the corrosion protection service of the operating organization found that the protective potential difference "pipe-ground" is within the range regulated by GOST R 51164-98 and is equal to minus 1 V at the drainage point, at the left junction of protection zones from UKZ No. 26-minus 0 .95 V, and at the right junction of the protection zones of UKZ No. 26 - minus 0.92 V. At the same time, the specialists of the corrosion protection service of the operating organization measured the current and voltage at the output of the CPS, which is part of this UKZ No. 26. The current values are 5.8A, the voltages are 36 V. It is noted that the voltage value exceeds 70% of the nominal value of this RMS (33.6 V), respectively, this RMS operates in the maximum mode. To reduce the voltage at the output of this SKZ, it is necessary to reduce the resistance to the spreading of the current of the anode grounding of this SKZ, in tandem with which this station operates. To do this, it is necessary to install and connect to existing, additional anode ground electrodes. The existing anode grounding is made in a subsurface design and consists of 20 anode ground electrodes installed vertically. The specific electrical resistance of the soil in the area of the existing anode grounding is 300 mm.

The measuring and auxiliary ground electrodes are installed in the ground, they and the anode grounding of the UKZ No. 26 are connected according to the three-electrode circuit to the measuring device and the resistance to current spreading of the anode ground electrode of the UKZ No. 26 is measured when alternating current flows through the current electrodes. The measured value of the current spreading resistance of the anode ground is 6 ohms.

The operating modes of the CCZ UKZ No. 26 are briefly changed and the values of the protective potential difference “pipe-to-ground” are measured at the drainage point of the UKZ No. 26 and at the junctions of the protection zones with the neighboring left UKZ No. 25 at km 210 and the right UKZ No. 27 at km 270. The value of the force current RMS UKZ No. 26 after the change is 10.8A, and the value of the protective potential difference "pipe-ground" at the drainage point of this RMS is minus 1.3 V, at the junction of the protection zones with the left UKZ No. 25 - minus 0.96 V, at the junction of the protection zones of the right UKZ No. 27 - minus 0.925 V.

Find the coefficient of influence of the studied RPS UKZ No. 26 on the value of the protective potential difference "pipe-to-ground" at the point of its drainage and at the junctions of the protection zones with neighboring stations, as the ratio of the increment of the protective potential difference "pipe-to-earth" to the increment of the current strength of the RMS according to the formula ( four):

for drainage point A _TDVS \u003d (minus 0.3) / 5 \u003d minus 0.06,

for the left junction of protection zones A _LSTS = (minus 0.1) / 5 = minus 0.02,

for the right junction of protection zones A _FSTS = (minus 0.05) / 5 = minus 0.01.

The operating modes of adjacent UKZ No. 25 and UKZ No. 27 are changed step by step. Increase the current strength at the output of UKZ No. 25 from 6A to 16A, control the protective potential difference "pipe-ground" at the drainage point of UKZ No. 26 and note that its value equal to minus 1.9 V does not go into the region of unacceptable values. Without changing the operating modes of the remaining SKZ UKZ No. 25 and No. 26, the value of the protective potential difference "pipe-to-ground" is measured at the drainage point of the investigated SKZ UKZ No. 26. The change in the protective potential difference "pipe-to-ground" at the drainage point of the UKZ No. 26 is minus 1.1 V, at the junction with the left UKZ No. 25 of the protection zones - minus 0.98 V, at the junction with the right UKZ No. 27 of the protection zones - minus 0, 92 V.

The initial mode of operation of the adjacent UKZ No. 25 is returned. Repeat these procedures with the adjacent UKZ No. 27 and increase the current strength at the output of the RMS from 7A to 17A, fix the change in the protective potential difference "pipe-to-ground" at the drainage point of the studied RPS UKZ No. 26 minus 1.05 V, at the junction of the protection zones on the left UKZ No. 25 - minus 0.95 V, at the junction of protection zones with the right UKZ No. 27 - minus 0.94 V.

Influence coefficients of the RMS of the adjacent UKZ No. 25, located to the left along the pipeline route from the VPS of the investigated UKZ No. 26, on the value of the protective potential difference "pipe-to-ground" at the drainage point of the RMS of UKZ No. 26 and at the junctions of its protection zones with neighboring UKZ No. 25 and No. 27, is found as the ratio of the increment of the protective potential difference "pipe-ground" to the increment of the RMS current according to the formula (13):

for drainage point A _TDLS \u003d (minus 0.1) / 10 \u003d minus 0.01,

for the left junction of protection zones A _LStLS = (minus 0.3) / 10 = minus 0.03,

for the right junction of protection zones A _PSTLS =0.

Influence coefficients of the RMS of the adjacent UKZ No. 27, located to the right along the pipeline route from the VPS of the studied UKZ No. 26, on the value of the protective potential difference "pipe-to-ground" at the point of drainage of the RMS of the investigated UKZ No. 26 and at the junctions of its protection zones with neighboring UKZ No. 25 and No. 27, is found as the ratio of the increment of the protective potential difference "pipe-ground" to the increment of the RMS current according to the formula (14):

for drainage point A TDPS \ _u003d (minus 0.05) / 10 \u003d minus 0.005,

for the left junction of protection zones A _LStPS = 0,

for the right junction of protection zones A _PSTPS - (minus 0.2) / 10 = minus 0.02.

The stationary potential at the drainage point, for the left junction of the protection zones and for the right junction of the protection zones of the RMS of the _{investigated UKZ} No. 26, is determined by the formula (4) _: .

The required shift of the protective potential difference "pipe-to-ground", taking into account the stationary potential at the drainage point, for the left junction of the protection zones and for the right junction of the protection zones of the RMS of the investigated _UKZ No. 26 is determined by the formula (6) _: \u003d minus 0.296 V, Δϕ _NZPSt \u003d minus 0.198 V.

The required value of the RMS current strength of the investigated UKZ No. 26 to provide a protective potential difference "pipe-ground" at the drainage point, for the left junction of the protection zones and for the right junction of the protection zones is determined by the formula (7): I _NZTDVS \u003d 7.3 8A, I _NZLStVS = 14.8 A, I _NZPStVS = 19.8 A.

The obtained values are compared and a larger RMS current value is selected from those found. In this case, the greater value of the current strength is 19.8 A.

The required value of resistance to current spreading of the anode grounding UKZ No. 26 is calculated as the ratio of the maximum allowable voltage at the output of the RMS to the value of the RMS current at which protection is provided at the right junction of the protection zones according to the formula (10): R _ADS = 1.7 Ohm.

Calculate the required resistance of additional anodes, based on the condition that the anode ground electrodes are connected in parallel, according to the formula (9): _RAZD = 2.37 Ohm.

They choose as additional anode ground electrodes, subsurface ground electrodes manufactured by Khimservice CJSC. Choose earthing switches of the brand "Mendeleevets-MK" with overall dimensions:

- длина электрода - 2 м,

- electrode length - 2 m,

d _e - electrode diameter - 0.04 m.

Calculate the current spreading resistance of one anode ground electrode when it is vertically installed in the ground according to the formula (10): R _P1 = 11 Ohm.

The number of additional anode groundings is calculated using the formula (11) and the resulting number is rounded up, taking it as the required number of additional anodes: N ₃ = 6.63≅7 pcs.

Thus, the proposed invention makes it possible to find the exact number of additional anode ground electrodes for the operating UKZ, necessary to ensure the protective potential difference "pipe-to-ground" in the pipeline section due to the fact that the method takes into account the degree of influence not only of the RMS of the studied UKZ, but also adjacent to it stations.

Claims (1)

A method for finding the number of additional anode grounding switches necessary to provide a protective potential difference "pipe-to-ground" in a pipeline section, including the selection of a cathodic protection installation, in which the cathodic protection station operates in the maximum output voltage mode, measuring the resistance to spreading of the anode grounding current, which is included into the composition of this cathodic protection installation, characterized in that they change the operating modes of the cathodic protection station and find the coefficient of its influence on the value of the protective potential difference "pipe-ground" at the drainage point and at the junctions of protection zones with neighboring stations, step by step change the operating modes of adjacent stations cathodic protection, preventing the transition of the protective potential difference "pipe-to-ground" at the drainage point of an adjacent cathodic protection station to the area of unacceptable values, without changing the operating modes of the remaining stations, measure the values of the protective potential difference "pipe-to-ground" after its stabilization, determine the coefficient The influence coefficients of each station under the current operating modes of the remaining cathodic protection stations, the stationary potential at the drainage point of the cathodic protection station under study, the stationary potential at the left junction of the protection zones of the cathodic protection station under study, calculate the required potential shift at the drainage point of the cathodic protection station under study and at the junctions of the zones protection, by excluding the stationary potential at the drainage point and at the junctions of the protection zones of the station under study from the required value of the protective potential difference "pipe-to-ground", determine the necessary values of the current strength of the cathodic protection station under study to ensure the protective potential difference "pipe-to-ground" at the point drainage and at the junctions of the protection zones of the investigated station, choose a larger value of the current strength of the cathodic protection station from those found and determine the required value of the spreading resistance of the anode grounding, determine the required resistance of additional anodes, based on the condition that the anode grounding conductors are connected are measured in parallel, determine the resistance to current spreading of one anode grounding conductor in a vertical arrangement, the number of additional anode grounding conductors, round the resulting number up and take it as the required number of additional anodes as the ratio of the increment in the protective potential difference "pipe-to-ground" to the increment in the current strength of the cathode station protection.

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