Anode ground electrode, what is it, purpose, classification, principle of operation, design and installation, manufacturers and popular models, what is KMA – ElektrikExpert.ru

Anode grounding is a device designed to create a positive potential in order to protect underground metal communications from corrosion.

Below we consider what are the design features, where it is used and what types there are. We will separately talk about the principles of design and installation, highlight popular models and their features.

What is an anode ground electrode, where is it used

Anode ground electrode is a working element of anode electrodes located in an electrolytic environment, characterized by a high probability of corrosion.

The purpose of the application is to protect metal underground structures from the appearance of rust on the surface of the material. Installation of anode ground electrodes helps to extend the service life of the metal, and in the future to reduce the cost of their replacement.

The device and the principle of operation

The anode earth electrode is usually installed vertically to a depth of more than 15 meters. Thanks to this mounting method, the resistance level is maintained at a level of no more than 4 ohms.

It should be noted that cast iron rails or pipes were used as the first grounding devices. But such a metal is quickly destroyed by corrosion and loses its effectiveness. Today, preference is given to other materials, which we will discuss below.

The anode ground electrode consists of the following components:

• electrode is the main element;
• connecting cable (conducts current);
• contact node;
• tube for gas outlet (for deep device);
• a fastener for collecting in the form of a garland (for a deep version).

To extend the service life, the product is covered with a galvanized casing, and the cavity between the outer part and the core is filled with a graphite or coke composition. The purpose of the latter is to protect the electrode from damage and extend its life.

The principle of operation of the anode earth electrode is aimed at compensating the negative charge of the soil with positive ions.

The reason for the corrosion of the metal in the ground is a high level of moisture, a heterogeneous structure and high acidity. As a result, different potentials appear on the surface of a metal product, provoking the appearance of rust.

An additional negative factor that accelerates the destruction of the metal is stray currents that appear due to the movement of electric vehicles, power stations, towers of mobile operators and other equipment on the surface.

The installation of an anode ground electrode guarantees the compensation of the negative charge and thereby prolongs the service life of metal products. One grounding can protect any metal located underground – pipes, containers, flat surfaces, etc.

History of creation

Before the advent of modern anode ground electrodes, old-style “sacrificial electrodes” or cathodic protection installations were used. The protected object played the role of the cathode, and the grounding – the anode. As a result, metal structures served longer, but the anode ground electrode was quickly damaged and required replacement.

Previously, such anodes were located horizontally, but in urban conditions such an approach is difficult to implement.

The solution to the problem was invented by Robert Kuhn, who proposed to install the grounding conductor to a great depth and vertically. At the first check in 1952, it was possible to install the anode at 90 meters.

Over time, experts came to the conclusion that this method of protecting metal structures is better suited for city conditions.

Classification

When studying the topic of anode ground electrodes, it is important to understand their features and classification. Conventionally, products are divided according to several criteria.

By location

Anode ground electrodes differ in position relative to the protected object or work item.

By location relative to the protected object, they are:

1. Deep – several electrodes combined with cables. They are located at a depth of about 40 m, covered with a coke-mineral composition, which significantly increases the weight of the product. For installation, drilling rigs are involved, which makes the work more expensive. Despite the high costs, deep anode ground electrodes have an increased range, and their resistance does not depend on the season. The average service life is about 30 years.
2. Surface – perform the same functions, but are installed on the same level with the protected products. Differ in compactness and rather small radius of action. It has the form of an electrode made of zinc, magnesium or iron-silicon alloy. The latter option is used most often, due to its more affordable price and high efficiency. They have the form of a round rod with points for connection with cable products.
3. Extended – anode ground electrodes, made in the form of a current-carrying cable with a wire electrode located around it. On the surface of the latter, a coating from the group of metal oxides is applied. The structure is packed in coke breeze used as a ground electrode. Extended ground electrodes are used in any type of soil, they are laid in the same pit with the protected metal object.
4. Internal – anode ground electrodes used to protect metal containers, pipes and other products. Their peculiarity lies in the installation inside the protected object vertically or horizontally. Structurally, they have the form of an electrode equipped with a cable that is resistant to corrosion and placed in a special dielectric cylindrical screen. Installation of ground electrodes is carried out manually without the use of additional devices and equipment.

By location relative to the working element, anode ground electrodes can be placed:

• vertically;
• horizontally;
• inclined;
• in the combined version – a combination of all the types discussed above.

By material

When choosing anode ground electrodes, it is necessary to take into account the material from which the working element is made.

There are several solutions available here:

• cast iron;
• steel;
• graphite and plastic;
• iron and silicon;
• composite polymer;
• conductive elastomer;
• combined valve metal, etc.

Conventionally, materials are metallic and non-metallic, but we will dwell on this issue below.

According to the shape of the cross section

In the manufacture of the anode ground electrode, different forms of electrodes can be used.

Available options:

• rectangle;
• cylinder;
• sphere;
• screw;
• corner;
• flat panel;
• hollow tube;
• wire;
• kernel;
• mesh with small cells.

Depending on the shape of the product, the approaches to installation and the characteristics of the finished structure change, so these issues must be taken into account when designing and installing.

By the nature of the backfilling of the anode area

During installation, approaches to filling the space near the anode filler may differ.

The following filling options are available here:

• special activator to reduce spreading resistance;
• coal and graphite;
• coke mineral composition;
• conductive backfill;
• shungite;
• priming.

When choosing a backfill, the type of protected object and its features are taken into account.

By distance

Depending on the situation, the anode earthing switch can be installed at different distances from the protected object.

Available options:

• remote;
• approximate;
• distributed.

By design

When choosing a product, it is important to take into account its design features.

Main types:

• extended;
• sparingly soluble;
• distributed;
• concentrated (for example, pile).

In practice, other types of anode ground electrodes can also be used. The choice of type and features is carried out during the design.

According to climatic version

At the stage of creating a project, it is necessary to take into account the region with which climate the anode ground electrode system will be installed.

Given this fact, one of the following options is selected:

• for use on land – GOST-15150;
• operation at sea – category B (5).

The peculiarity of products in terms of climatic performance is specified in the technical conditions and standards.

Types of materials for anode grounding

Anode ground electrodes conventionally differ in the features of current conversion and further behavior of the material. Consider the main types.

Hardware

This group includes metal products, for example, rails, pipes and others. The average dissolution activity is 10 kg/A*year.

Pros:

• low price;
• availability.

Cons:

• groundwater pollution;
• rapid decline in efficiency.

Today, soluble anode ground electrodes are not used.

Platinum and Platinum Groups (MMO)

The peculiarity of such products is the low level of dissolution. The MMO category includes platinum materials (platinum titanium), but in practice only thin metal deposition is used.

Structurally, they are a pipe with a copper core. Product diameter 3-25,6 mm.

The average consumption of the anode ground electrode system during operation is from 1 to 10 g/A*year. The highest current density – 5000 A / m².

Pros:

• low destruction rate;
• high grounding efficiency.

Disadvantage:

• fragility and brittleness;
• high price;
• scarcity (for pure platinum).

When using an MMO anode grounding switch, it is necessary to monitor the potential level, because when 7,5 V is reached, the titanium film is destroyed, and the grounding device loses its effectiveness.

They are actively used in the chemical industry and soils with low resistivity. Suitable for use as extended flexible anode grounding devices with high current density.

Graphite

Graphite has a dissolution rate of about 1,2 kg/A*yr. The highest current density – 5 A / m². Depending on the binding materials used, they are flexible and rigid.

With a significant increase in the current level, oxygen is released, which increases the rate of damage to the product. The process stops at a high concentration of chlorine in the soil.

Advantages:

• low dissolution rate – up to 1,2 kg/A*year;
• big choice.

Cons:

• high resistance graphite material;
• lack of normal soil resistance;
• high brittleness (for pure formulations);
• low operating current density;
• risk of cold burning.

Graphite anodes are typically used in the electrochemical sector, marine environments and lands with high chloride content. Suitable for objects with minimum protective current and short service life.

Ferrosilid

Silicon-iron anode ground electrodes are used at low currents with minimal metal loss. The average parameter of “burning” of the material during operation is up to 0,5 kg/A*year. Maximum density – 100 A / m².

The function of protection against oxidation is taken over by the silicon dioxide film, which appears against the background of the reaction of silicon and O₂. After some time, it covers the surface of the grounding device and protects it from destruction.

Advantages:

• low damage rate;
• high efficiency (more than graphite);
• Possibility of application as point ground electrodes.

Disadvantages:

• high price;
• the scarcity of such anode ground electrodes.

Ferrosilid is actively used in all types of soils, including as a deep and surface ground electrode.

Polymers

The composition of polymer products includes a plasticizer with a carbon filler. The material is afraid of an increase in the anode current, which causes a thin anode film.

As a result, the grounding product loses its properties due to the appearance of an oxide film on the surface.

Pros:

• cost;
• a large selection of polymer products.

Disadvantages:

• minimum mechanical reliability;
• low indicators of the maximum anode current;
• increasing the transition resistance of the contour element;
• rapid loss of efficiency.

An additional minus of polymer anode ground electrodes is a negative impact on the environment. Plastic remains in the ground for many years and does not collapse.

Magnetite

It is believed that magnetite is one of the best materials for the production of anode grounding devices. It consists of the right iron oxide with the addition of special compounds.

Subject to the technology, the finished ground electrode has high hardness and density, and outwardly resembles a glass product. The average dissolution activity of magnetite is 0,04 kg/A*year. Maximum current density – 500 A / m².

Pros:

• minimum destruction rate;
• lightness and compact design;
• stable resistance to current spreading;
• Possibility of installation in various soils, including sea water.

Cons:

• complex manufacturing process;
• high price of finished products.

Due to their excellent qualities, magnetite anode ground electrodes are popular and serve for decades. They are actively used to repair deep-seated analogues made of iron pipes. There is even a special project for such events.

manganese dioxide

It is made by depositing a compound on a titanium base. In terms of design features, it has much in common with MMOs. Differs in the minimum rate of destruction – up to 0,04 kg / A * year.

Due to the impossibility of applying a thick film, anode manganese dioxide has a small resource. Potential limitation is not more than 7,5 V. The highest current density is 500 A / m².

Pros:

• low cost;
• long service life.

Cons:

• low resource;
• low efficiency of application in real conditions.

The materials discussed above differ in characteristics, therefore, for their correct use, it is necessary to take into account all the pros and cons. Knowledge of these features allows you to correctly select the material, taking into account the planned resource and financial costs.

At the same time, non-metallic variants of anode ground electrodes have a number of advantages in comparison with metal competitors.

Their advantages are resistance to the action of a negative environment, harmlessness, ease of transportation. They are slowly destroyed and have a greater resource.

Design and installation

Before installation, design is carried out taking into account the type of soil, service life requirements, features of the protected device and financial capabilities. At the same time, the work is carried out taking into account the current standard, GOST R 51-164, the project, rules and regulations in force in a certain area.

Also, these instructions and passports for the installation of an anode ground electrode are taken into account.

Installation of anode earthing is necessary in the following cases:

• protection of responsible communications;
• reduction of dangerous impact on other metal structures;
• areas of low resistance.

When working on industrial sites, the installation of grounding devices is necessary in places:

• with tight placement of pipelines in poor condition;
• in areas with a dense network of communications;
• in the area of ​​the pipeline with poor condition of the coating.

General installation rules:

1. The electrodes in the garland must be below the freezing line of the land. This is especially important for lands that often freeze through due to the local climate.
2. Installation sites must have special markings that can be read at any time of the day.
3. When the current of the cathode station is above 25 A, it is necessary to clean the garland using a perforated tube to remove gas that appears during the operation of the equipment. The gas sphere that appears near the anode contributes to the growth of resistance and reduces the efficiency of the ground electrode.
4. To increase the resource, it is recommended to fill the well with coke shavings, and not with ordinary earth.
5. The surface of the anode ground electrodes must not come into contact with the protected or other conductive object (above or below the ground) that is not part of the circuit. The distance from the grounding device to such an element should be three times the distance between the surfaces of the protected structure and the electrode.
6. If there is damage on the surface, putting the grounding product into operation is prohibited.
7. The optimum temperature for laying grounding devices is from 10 to 40 degrees Celsius.

During installation it is forbidden:

• lay equipment at temperatures below 10 degrees below zero;
• make the bending radius less than 15 outer diameters of the earth electrode;
• connect several cathode converters to one anode grounding device;
• keep the product in direct sunlight for more than 10 days;
• the use of ground electrodes in power and lighting networks.

After commissioning, the manufacturer is engaged in the repair of anode earthing switches, taking into account the current instructions. If necessary, dielectric polymers and couplings designed for such purposes are used to isolate contacts.

Compliance with GOST 58344-2019 and other regulatory documents allows you to avoid design and installation errors, protect the facility as much as possible and extend the life of the product.

Popular Models

The modern market offers a large selection of anode ground electrodes. Below we consider the features and device of the most popular models.

Mendeleev

Under the brand name “Mendeleevets” many modern models of anode ground electrodes are produced – magnetite, ferrosilide and MMO.

This is a Russian manufacturer with extensive experience in the manufacture of cathodic protection equipment for various metal structures – tanks, tanks, pipes, etc.

In addition, the company is engaged in the production of instruments and equipment for testing underground pipes, as well as PKZ equipment.

The most popular models of anode ground electrode systems Mendeleevets include:

1. MM (23, 43) – ferrosilide, surface. It is used for cathodic protection of underground structures, including pipes. Can be placed vertically and horizontally. Outwardly, they look like an electrode made of an iron-silicon alloy with an additional cable. In the basic configuration, the cable length is two meters. Made in the form of a rod with a thickening towards the top. To reduce the degree of current spreading, the cavity near the anode is filled with a coke-mineral composition. The resource is about 35 years.
2. MK (23, 43) – ferrosilide, complete, surface. They are a steel container filled with a coke-mineral activator. It is completed with an anode cable 35 meters long. The number of groundings is selected taking into account the type of protected object. The anode cable is fastened with a clamp or a thermite welding machine. When insulating cable connections, heat-shrink sleeves are used. Resource – XNUMX years.
3. MG – ferrosilicon, deep, surface. It is used in places with a large number of buildings. Structurally, it is represented by two sections, each of which has ferrosilide electrodes. The current flows through the connecting cable, which combines several elements into a common garland. Gases are removed by means of a special tube. To fill the near-anode space and reduce the resistance to current spreading, a coke-mineral composition is used. It has four electrodes in the ground electrode system and a total weight of 43 kg. The dissolution activity is 0,3 kg/A*year.
4. MGB – ferrosilicon, block, deep. It is used in the field of electrochemical protection. They are used in areas where the earth has a resistivity of less than 100 Ohm * m. It has a simplified design, gas outlet tube, light weight. Easy to install and affordable price. The rate of anodic dissolution is 0,3 kg/A*m. The average resource is from 35 years.
5. MCG – ferrosilicon, complete, deep. Suitable for installation in soils with high anode resistance. It has the form of a container with an electrode, near which there is a coke-mineral activator. The casing of the anode earthing switch is fixed with the help of special clamps, which makes it possible to form a block structure. A perforated gas vent pipe is provided. The product is characterized by a short time to enter the operating mode and minimal resistance to current spreading. The rate of anodic dissolution is 0,25 kg/A*year, weight is 43 kg, service life is from 35 years.
6. MTP – magnetite, surface. It is used to protect metal underground structures from corrosion. Structurally, it has the form of an electrode two meters long. The cable is fastened to the contact surface using a special spring. The number of ground electrodes can be adjusted. The dissolution activity of the anode is up to 0,03 kg/A*year. Resource – from 35 years.
7. MTCP – magnetite, complete, surface. It is used in areas with high resistivity. Available for vertical and horizontal installation. It has the form of a container with an electrode located inside. The casing is made of galvanized steel and actively dissolves in the ground. Connecting the cable to the main anode is carried out using a clamp or welding. The anode destruction rate is up to 0,03 kg/A* year. Service life – from 35 years. The design is similar to the MK.
8. MTG – magnetite, deep. Suitable for installation in open and closed wells. It is often used in the restoration of GAS and steel pipe structures. It looks like a chain of anodes (five pieces) connected with a cable. It happens through passage and end type. The anode destruction rate is up to 0,03 kg/A*yr. Resource – from 35 years.
9. MTCG – magnetite, complete, deep. Suitable for soils with high resistivity. Mounted vertically. They look like a container with a magnetite electrode. Guide brackets are used to fix the case, which allows you to assemble the elements into a garland. The rate of active dissolution is up to 0,03 kg/A*year. Resource – up to 35 years. A similar design of the MCG.
10. MTV – magnetite, internal. It is used to protect against destruction of the internal parts of pipelines, tanks and underwater structures. Mounted inside the protected structure. They look like an electrode with a special cable located in a special screen. Installation is done manually. The rate of anodic dissolution is 0,03 kg/A*year. Service life – from 35 years.

In addition to those discussed above, other types of sparingly soluble anode ground electrodes Mendeleevets are also used:

• MCI – superficial.
• MRCP – complete.
• MRG – deep.
• MRCG – deep complete.
• MRV – internal.

All the above models are of high quality and reliability.

Magnet

Structure LLC Magnit is a well-known company engaged in the development of cathodic protection, which prevents the appearance of rust on pipelines and other underground structures.

It produces the following models of anode grounding switches:

1. ElNAZ, packed. Suitable for protecting metal structures in water and soil. It has a cylindrical shape with a large number of gas outlet holes. It is distinguished by a low anode dissolution rate – up to 0,1 kg / A * year, a diameter of 11 cm and a weight of 24 kg. Serves an average of 15 years or more.
2. ELPG, polymer-graphite. It is used for deep and surface grounding. It is made of low-soluble composite and is made in the form of a cylinder. A special polymer is used as a binding element. Maximum thermal conductivity is achieved at room temperature. The anode dissolution activity is up to 0,1-0,15 kg / A * year, the service life is from 15 years, the diameter is 6 cm.
3. ElZhK-KG, deep, complete. Suitable for protection of underground metal structures. It is used in areas with a resistance of more than 30 ohm * m. Works together with cathode converters in any climate conditions. The main thing is that the product is placed under a layer of freezing. Prohibited installation in swampy areas and flooded soils. They look like a metal container with a ground electrode installed inside. The maximum number of blocks is up to 16. The service life is up to 35 years.
4. ELZhK, ferroside, slightly soluble. It is used under the condition of climate temperature from 0 to +60 degrees Celsius. The electrode has a section in the form of a cross or a circle. The composition includes molybdenum, titanium and chromium. The dissolution activity of the anode is up to 0,3 kg/A*year.
5. ElZhKT, ferroside, club-shaped, superficial. Works in conjunction with cathodic protection. It is located below the soil freezing layer. It has a section of a circle or a cross. The anode damage rate is up to 0,3 kg/A*year.
6. ElZhKtr, tubular, ferrosilide. Suitable for surface and deep installations. Made of cast iron and has a cylindrical shape. Special reinforcing protrusions reduce contact resistance and increase the service life of the product. The anode dissolution rate is up to 0,1 kg/A*year.

AZM

The production of anode ground electrodes AZM is carried out by the manufacturer OOO NPIF Splav. The company’s products have been certified and meet the requirements of customers.

There are standard solutions for grounding switches used to protect underground utilities. During the activity, the manufacturer received a lot of positive feedback, gained a great resource and partner base.

Популярные модели:

• AZM-ZKhK-SUGAZ (P) – subsurface, ferrosilide.
• AZM-3KhK-SUGAZ – deep, ferrosilide, in a container with KMA.
• AZM-3HK-SUGAZ (PK) – subsurface, ferrosilide, in a container with KMA.
• AZM-3KhK-SUGAZ (G-2) – ferrosilide, two-block, deep.
• AZM-3HK-SUGAZ (G2) – ferrosilide, two-block.

Consider the design features using the example of AZM-3X.

The device is used in cathodic protection systems. Suitable for land areas characterized by increased corrosive activity, as well as in sea water.

Structurally, it is a cylindrical flask with copper wires of reinforced insulation, as well as a special sleeve for connecting to the cable of the cathode station.

The solubility parameter depends on the current density and the soil in which the device operates. Average indicators – up to 0,1-0,5 kg / A * year. Resource – from 50 years.

GAZ-M

GAZ-M anode ground electrode systems are used to protect underground metal structures when it is impossible to use cheaper protection.

Structurally, the product consists of a module-electrodes, combined into a garland with the help of special couplings (included). The number of modules and wires, as well as the length, is determined individually. Gases are discharged through special openings.

No special equipment is needed to install the grounding conductor, because the structure is assembled from special modules along the course of the deepening.

Pros:

• reliable protection against corrosion;
• small footprint;
• rational use of current;
• no dependence of current spreading resistance on changes in temperature and moisture level in the ground;
• the possibility of placement on sites with complex communication;
• low capacity gradient, etc.

The electrode is made of iron-silicon alloy type ChS-15 GOST 7769-86. The total amount of silicon in the composition is 14,5%.

What is KMA

Coke-mineral activator is one of the elements of many anode ground electrodes, used to reduce the transient resistance.

It is recommended when installing anode ground electrodes in lands with high soil resistance (more than 30 Ohm*m).

Structurally, it consists of the following components:

• coke breeze – up to one centimeter;
• coke fraction – from 1 to 2,5 cm;
• halide-free activator.

The structure of the coke-mineral activator is clearly defined and recorded in the patent, and only the Khimservice enterprise has the right to release it.

There is a conclusion of the SES for the manufacture, use and sale. Resistivity parameter – from 0,03 to 0,06 Ohm * m.

KMA action:

• decrease in the dissolution activity of the electrodes of the grounding device;
• reduction of transient resistance between the anode and the ground;
• drainage of the anode space;
• an increase in the surface area that gives off current, thanks to coke breeze.

KMA is sold in 40 kg bags. Must be stored in sealed containers. The maximum storage period is not limited.

Results

The importance of the anode ground electrode system cannot be overestimated. Its action guarantees protection for expensive metal underground utilities.

But you need to understand that the effectiveness of the device depends on the correct choice, taking into account the type of soil, the density of structures, the installation location and other factors.

That is why it is so important to approach the design stage, carry out the necessary calculations, and then proceed to installation.