Internal protective coatings of pipelines. Anti-corrosion coatings for pipelines of heating networks and pipeline elements

Metal pipelines in natural conditions are subject to the complex negative factors reducing their quality and service life. Progressive protection of pipelines against corrosion allows leveling the destruction and extending the service life.

Consider ways to combat the "rotting" of the metal, the types of materials used and the regulatory requirements for such protection.

Corrosion problem

Oxidation (corrosion) of a metal is the formation of chemical and ionic bonds from its free atoms. It is accompanied by the transition of electrons of such atoms to the composition of oxidizing agents.

Oxidation damages pipes and leads to losses

The process occurs on external and internal surfaces due to the impact of external aggressors and the characteristics of the transported raw materials. Comprehensive measures prevent material and economic losses associated with premature wear of structures, forced repairs, leakage of transported products.

Oxidation is divided into types:

• superficial;
• local;
• slotted;
• ulcerative;
• intergranular;
• fatigue cracking.

The need for anti-corrosion protection of pipelines arises for a number of reasons related to climate, soil conditions, conditions of use:

• humidity of air and earth;
• the chemical composition of the earth and air (salts, organics, alkalis and acids);
• acidity;
• soil structure;
• thermal loads (internal and external);
• harmful microfauna and microflora;
• wandering currents.

These factors lead to the formation of through fistulas and ulcers on metal surfaces, putting pipelines out of action.

Methods of anti-corrosion protection

There are 4 types of anti-corrosion protection of pipelines:

1. Insulation (prevention of contact with aggressive media).
2. The use of materials resistant to oxidation in the manufacture of structures.
3. Reduced aggressiveness external factors.
4. Electrical protection of underground structures made of metals.

Insulation

Isolation is a passive method that involves the application of protective coatings, special technologies for laying pipelines, and treatment with special solutions.

Insulation is a radical passive way to prevent corrosion

As coatings, mastics, paints, enamels, plastic compounds and varnishes, inert to the metal and the environment, and other metals with less susceptibility to corrosion (zinc, chromium, nickel) are used. The resulting film prevents the wire from breaking.

Thermally stabilized, powdered polyethylene, fiberglass, polyvinyl chloride, bituminous coatings are used. Welded joints and joints are insulated using heat-shrink cuffs, couplings, polymer tapes with a sticky coating. Paints and mastics (epoxy or powder), coal and bituminous compositions are also used.

Joints are insulated with heat shrink fittings (cuffs, tapes and sleeves)

In industrial zones and urban areas, fitters for protecting underground pipelines from corrosion use the collector laying method (the structures are placed in channels, oxidation does not occur due to the air cushion between the surfaces).

Solutions that form a film of poorly soluble salts on the walls of the metal are aluminum oxide for aluminum products, phosphating for steel structures. Sometimes, solutions of passivators (mixtures that reduce the intensity of the transition of metal ions into solution) are used to transfer a metal surface to a passive state. Passivators reduce the rate of corrosion damage.

Passivation of pipelines prevents oxidation due to the impermeable film of the insulating solution

Corrosion-resistant pipelines

The method consists in introducing into the composition of the metal substances that increase the resistance of pipes to oxidation, or the elimination of harmful additives that accelerate this process. Such protection of pipelines of engineering systems from corrosion is carried out at the stage of their manufacture, during thermal and chemical treatment of products.

The introduction of stronger metals into the composition of pipes will reduce the cost of additional insulation

Essence: alloying a metal that is not prone to passivation with a similar metal with high passivation rates under given conditions. As a result, the alloy acquires the characteristics of an alloying component. Apply stainless steel interspersed with nickel and chromium, aluminum and titanium alloys, concrete additives, ceramic compounds, asbestos cement, glass.

The disadvantage of the method is the high cost.

Reducing the aggressiveness of operating conditions

The third option is anti-corrosion protection of pipelines, aimed at improving external conditions. Possible Solutions:

1. Deactivation of oxidative processes - the introduction of inhibitors and the removal of harmful components from the environment (drying and purification of air from impurities, deaeration of solutions).
2. Treatment with poisons and active chemicals to get rid of microflora and microfauna, the activity of which leads to biocorrosion.
3. Hydrophobization, deaeration of the soil (in case the structure is underground), neutralization with alkaline and acidic compounds, introduction of special into the soil. impurities.

Microorganisms along with moisture and active currents lead to oxidation

electrical protection

Algorithms for active fight against oxidation:

• protective protection against corrosion of pipelines (coating the structure with metals with a negative electrode potential, for example, magnesium);
• static or periodic cathodic polarization of structures in an electrically conductive medium to change their thermodynamic characteristics;
• electrical drainage (prevention of stray currents and removal of existing stray currents).

Protective work will allow the surface of the structure to actively resist oxidation

Requirements for protective measures according to SNiP

According to SNiP, corrosion protection of pipelines must comply with a number of standards:

1. Measures aimed at preventing corrosion of structures must guarantee their trouble-free operation within the periods declared by the manufacturer.
2. Underground structures require comprehensive measures (the use of coatings and electrochemical agents).
3. The intensity of protection is determined by the degree of aggressiveness of the operating conditions of the structure (normal or enhanced).
4. Corrosion protection of pipelines is carried out in accordance with GOST 25812 - 83.

Requirements for the materials used

Terms of Use metal structures are diverse, therefore the industrial market offers a variety of coatings. The materials differ in application methods, chemical and mechanical characteristics.

Having a choice allows you to solve the problem of oxidation, regardless of operating conditions. But corrosion protection of pipelines, according to SNiP, can only be carried out using materials that have regulatory properties:

• integrity of the coating (no pores and electrolytic cells);
• water resistance - preventing the metal from contacting the electrolyte through moisture;
• electrochemical neutrality - the composition should not enter into cathodic reactions;
• high adhesion to prevent delamination of the insulation and the ingress of electrolytes on the work surface;
• resistance to chemicals;
• resistance to mechanical loads during the operation of the structure;
• resistance to currents;
• heat resistance (for objects operated at extreme temperatures for the metal and insulating coating used; if the transported substances are distilled at high temperatures or insulation is carried out in the cold season);
• chemical and corrosion neutrality in relation to the working structure.

Also, materials for protecting pipelines from corrosion cannot be in short supply, the advantage is the possibility of automating the coating in the field and factory conditions, and cost-effectiveness.

None of the known insulating materials meets all these requirements, therefore the choice of coating depends on the conditions of construction, the use of the pipeline, the raw material, economic and technological base.

Corrosion is an inevitable, natural process. Keep working pipeline system only timely competent protection can.

Video: corrosion protection of pipelines

Corrosion of pipelines is the main cause of depressurization, as a result of which cracks, ruptures and cavities appear on the surface of the pipe. And therefore, the protection of pipelines from corrosion is a task not only for builders or manufacturers, but also for specialists who create projects and those who will use them.

The cause of rust and corrosion on steel tanks can be the wrong composition of the fluid flowing through them, the wrong combination of different metals, as well as insufficient corrosion control and poorly chosen protection methods. The danger of corrosion lies in the fact that it can cause leaks in pipelines. Repair of pipes after damage can only be done using welding.

Causes

Corrosion of steel underground pipes is a phenomenon, the main cause of which can be called the electrochemical oxidation of metals from their constant interaction with moisture. As a result of such reactions, the composition of the metal changes at the ionic level, becomes covered with rust, decays and simply disappears from the surface.

The oxidation process can be influenced by the nature of the fluid that flows through the underground heating pipeline or the properties of the environment in which it is located. It is for this reason that when choosing the appropriate means to combat rust, it is necessary to take into account all the features that preceded its occurrence. Otherwise, repair by welding is inevitable.

Types of protection

To date, there are several different methods for treating underground heating pipes from rust and corrosion. All of them are based on the principle of special treatment, during which the metal from which the tanks are made reacts with the substances and solutions introduced. As a result of such actions, a special film is formed, which provides protection.

There are several main types of anti-corrosion protection methods:

• liquid treatment by means of chemical reagents;
• wall processing;
• stray current;
• cathodic;
• anode.

Fluid Handling

The liquid that flows through the pipeline may have some aggressive qualities. The aggressive composition of water may be due to the content of carbonates, bicarbonates or oxygen in it, which cause the metal to rust.

It is quite technically difficult to perform high-quality cleaning of the walls of underground pipes or to clean them completely. The main task of chemical water treatment is the transformation of its composition from aggressive to slightly calcifying. Such treatment of underground heating pipes from rust often comes down to adding soda, calcium or sodium carbonate to the water.

In those sections of water pipes in which water can be distributed to individual points of water intake, its further processing is carried out by adding polyphosphates.

Anti-corrosion protection of galvanized underground tanks is carried out by adding silicates, phosphates and polycarbonates. Thus, a special film appears on the inner surface of galvanized pipes, which prevents the occurrence of corrosion.

Wall processing

Wall treatment has been used as corrosion protection for walls for many years. To perform such a set of measures, the coating is applied to the outer or inner wall of the underground pipe.

Thanks to electroplating, an active or passive film of high strength is formed on the surface, which does not allow an aggressive environment to penetrate into the deep layers of the metal. The effect of such actions can easily persist for a sufficiently long period.

As a rule, another metal is applied to the surface of the product. Most often, zinc is used for this, which is not affected by corrosion. Paint, varnish or enamel can be applied to the metal surface, which also act as an effective treatment for gas pipelines.

For achievement maximum effect in rust control, alloys of metals such as zinc or magnesium are often used. Experts say that galvanizing pipes is the most popular of all the processing methods that exist today.

stray current

The stray current is the current that is formed in soils during the dispersion of electrified paths. Energy enters at the point that is the cathode and exits at the point that is the anode.

During the process, electrolysis occurs, which can cause rust and damage to the tank. In this case, the anti-corrosion insulation of underground pipelines is electrical drainage.

Cables with low resistance are connected to the current source in specially defined places.

induced current

Cathodic anti-corrosion protection of underground tanks is based on the use of electric current, which is supplied in a constant mode and does not allow the film to protect the metal to be destroyed.

This method is achieved by using a cable with low electrical resistance, but with excellent insulation. The pipeline itself in this case acts as a cathode and thus protected from possible corrosion processes.

Sacrificial anode

Another pretty effective view protection against stray currents is anode chemical protection. The buried magnesium block functions as an anode in a corrosive environment. Due to the slow decomposition of magnesium, the isolation of the main steel pipes conductors from underground stray currents. This type of protection is most often used to protect products of limited length or for tanks that are made of steel.

Typically, the anode is placed in a cotton or jute bag, which in turn is immersed in the clay mixture. The main task of such packaging is to ensure the uniform consumption of the anode, as well as maintaining the required level of humidity.

Such a system will prevent the formation of a film that can hinder the decomposition of the anode.

It can be noted that the best way protection of the inner and outer surface of pipes from the occurrence of corrosive processes will be the use of materials that are least susceptible to them. And, nevertheless, even on such materials, due to certain reasons, foci of corrosion and damage of various kinds can occur. And therefore, it is best to use one of the most suitable protection methods used today during the use of pipes.

All metal pipe products used in construction and industry must have a special protective coating that will protect their inner and outer surfaces from the negative effects of factors external environment. And in particular, pipes made of steel alloys need protection against corrosion. What materials create the internal anti-corrosion coating of pipes - we will try to understand this article in detail.

Why is it important to protect steel products from corrosion?

Corrosion or rusting is a special physical and chemical process in which the material actively interacts with the external environment.

During this interaction, reactions occur that change the quality and properties of the material. Under the influence of rusting processes, the metal is gradually destroyed and the steel alloy product itself gradually becomes unusable, which is why the timely application of an anti-corrosion coating of pipes is so important.

Types and properties of coatings against corrosion

To protect the material from the rusting process, various types of anti-corrosion special coatings can be used. The most popular among the compositions of this variety are paints, enamels and primers. These substances have a number of advantages:

1. They can process products of large dimensions and components of complex shapes;
2. Primers, enamels and paints that provide protection against rust are applied to the metal surface quickly and easily;
3. The funds are economical in consumption, they can be used during repair work, without stopping the operation of the pipeline;
4. Paints, primers and enamels are sold by affordable price and in a huge range.

In addition, the use of these substances allows you to get a certain color of the outer coating.

Popular brands of compounds

The production of pipes with anti-corrosion coating is the main activity of many modern industrial enterprises. For the protective treatment of products, manufacturers use a variety of compositions. Let's get acquainted with the most popular brands:

1. "Nerzhamet" is a special anti-corrosion enamel that is applied to clean surfaces of newly manufactured products, but it is also possible to use the substance in the repair of pipelines and treat elements already covered with rust;
2. "Nerzhaluks" - this coloring composition is valued by professionals for a high degree of adhesion and the possibility of application on different surfaces. For example, it is possible to process aluminum, brass, titanium, copper and zinc surfaces with it;
3. Paint "Cycrol" is used for processing pipes made of galvanized steel;
4. The composition with the name "Phosphorgrunt" is used in the process of anti-corrosion treatment of products made of ferrous and non-ferrous metals.

There are also compounds with silver, plastic, modifiers that convert rust.

For the protective treatment of pipeline elements, the following compositions are more often used: Nerzhakhim, Polyurethol, Epostat, Zinconol and Urizol. Let's talk about the advantages of the latter type of anti-corrosion protection in more detail.

Features of using a protective coating Urizol

Steel pipe with anti-corrosion coating Urizol is most often used in pipelines intended for the transportation of oil and its derivatives, natural gas. Composed in without fail all elements are processed: nodes, fittings, connection details. Urizol treatment helps protect system components from corrosion different types- atmospheric and underground.

The unequivocal advantage of this protective composition is the ease of application. A special spray device is used to treat tubular elements, and as soon as the substance hits the metal surface, a chemical reaction will begin, as a result of which a sufficiently thick and reliable protective coating is formed on the metal.

It is important to know that in the oil industry, as well as in some other areas of communications construction, pipes with internal and external anti-corrosion coatings must be used. Protective painting of the inner walls of pipe components is carried out with epoxy compounds and in the factory!

The mandatory anti-corrosion treatment of pipeline parts is prescribed in SNiP 2.03.11-85.

How is the anti-corrosion treatment process carried out?

To begin with, we note that the anti-corrosion treatment of pipe surfaces is not an easy task, requiring compliance with many nuances. Preparations for work begin with a visual inspection of all elements of the system that need to be coated with a protective compound.

Attention! The condition of pipes and other elements that need protection against rust should be assessed exclusively by specialists. Professionals will accurately determine the extent to which the surface is damaged, as well as make an estimate for the work and purchase necessary materials. In choosing an anti-corrosion composition, experts will start from many factors: temperature regime, at which the system is operated, the material for the manufacture of elements, the specifics of the use of the pipeline.

Before the process of directly applying the composition to the surface, it must be carefully cleaned. All types of dirt, old paint must be removed from it. Next, the surface of the treated structure is degreased with a special hydrocarbon-based solvent.

Next, proceed to the processing of the protective composition. Various formulations are applied different conditions, and also prepared in the right proportions immediately before the application procedure. The protective layer is applied in several layers, and at the same time, each previous layer of the coating must dry.

After the required number of layers is applied, a control inspection of the pipeline and its elements is carried out. To determine the quality of the work done, special equipment is used (photo) and upon inspection, an act is drawn up confirming the performance of the work.

For transportation of technical and drinking water, petroleum products, raw materials and semi-finished products are widely used metal pipelines. The constant negative impact of chemically active substances in the form of acidic or alkaline residues leads to the formation of plaque and a violation of the integrity of the metal. Active corrosion processes adversely affect the speed and efficiency of technological operations. In this case, there is a rapid deterioration and failure of expensive equipment. As a result, businesses can suffer significant losses. Anti-corrosion treatment of pipelines involves the use of special compounds - corrosion inhibitors, which help slow down and stop the destructive action of chemically active substances. The implementation of anti-corrosion treatment of pipelines extends their service life by several years.

Anti-corrosion treatment of pipelines using inhibitors

The constant formation of insoluble salts leads to build-up and reduction bandwidth inside the pipeline. To solve this problem, compounds are most often used that slow down the processes of corrosion and scale on the inner walls of pipes. In this case, the anticorrosion treatment of the pipeline is carried out by introducing a corrosion inhibitor concentrate into the circulating liquid in a volume of 1 to 5% of the volume of the working liquid.

Most traditional corrosion inhibitors are unable to cope with two problems at the same time - the destruction of the metal from corrosion and the appearance of deposits on the walls. Their effectiveness is reduced in cases of partial immersion of metal surfaces in an aggressive environment. Recent developments and practical tests have led to the creation of fundamentally new inhibitors of the SP-B series, used in the following areas:

• Closed systems with water circulation at a temperature of +5 to +90 o C;
• Crimping technological equipment or individual nodes;
• Preservation of metal pipes, aggregates, containers;
• Implementation hydraulic tests;
• Removal of scale residues and corrosion products from the inner surface of pipes and structures.

Methods for anti-corrosion treatment of pipes

The SP-V product line is designed for anticorrosive protection of pipelines from the destructive effects of substances contained in the liquid. For each specific metal alloy or equipment, a specific brand of SP-B inhibitor is used, containing specific additives. This is due to the operating temperature of pipelines and units.

Spectrum of action of SP-B inhibitors:

• Protection of steel pipes or profiles, assemblies, tanks when stored outdoors or indoors. Upon exiting conservation, further operation is allowed without preliminary washing off of the inhibitor;
• Anti-corrosion treatment of the pipeline from the inside by introducing an inhibitor into the main composition of the working fluid;
• Commissioning of high pressure liquid equipment. The SP-V line copes well with the emerging corrosion processes during the check of the main line, individual units or shut-off valves for water leakage;
• Reducing the chemical activity of water vapor while inhibiting the formation of an insoluble precipitate, which leads to the appearance of plaque. The use of concentrate in an amount of up to 5% of the total volume of liquid in the heating system allows you to increase the duration of the operation of the boilers.

Conducted examinations, laboratory tests have proven the safety of SP-B inhibitors in relation to environment and human health. This makes it possible to use the concentrate in food production, in housing and communal services and in the transport sector.

Corrosion inhibitor SP-V can be used in metal pipelines made of carbon steel, copper and copper alloys, aluminum and its alloys. Anti-corrosion treatment of the pipeline is carried out after monitoring the operation of the system and analysis of the current working composition in the laboratory of Spektroplast LLC.

SP-V is packaged in 20 kg cans or 220 kg drums. Delivery across Russia and the CIS countries is possible.

To date, there are two directions in the field of factory internal insulation and protection of pipes:

• application of internal "smooth" anti-friction coatings;
• application of internal anti-corrosion coatings.

Internal "smooth" anti-friction coatings of pipelines

The main purpose of internal anti-friction coatings is to reduce the roughness of the inner surface of pipes and increase the throughput of pipelines. The development and implementation of the technology for applying internal "smooth" coatings to pipes began abroad quite a long time ago - from the mid-1950s. The experience gained during this time of their use on main gas pipelines transporting non-corrosive gas has shown that savings in the cost of pumping and compressing the product during pipeline operation, as a rule, ensures the payback of the internal coating within 3-5 years.

In recent years, internal "smooth" coatings, designed to increase the throughput capacity of main gas pipelines, have also been used in our country. The technology for applying such coatings has been mastered by almost all leading pipe plants, including Izhora Pipe Plant LLC, Vyksa Metallurgical Plant OJSC, Volzhsky Pipe Plant OJSC, Chelyabinsk Pipe Rolling Plant OJSC. At some of these plants, work is currently underway to apply an internal “smooth” coating to pipes with a diameter of 1420 mm for the Nord Stream gas pipeline.

Requirements "STO Gazprom 2-2.2-180-2007" for internal anti-friction coatings

In accordance with the requirements of STO Gazprom 2-2.2-180-2007, the thickness of internal anti-friction coatings should be from 60 to 150 microns, and the roughness should not exceed 13-15 microns. The length of the end non-insulated end sections of the pipes should be (40 ± 10) mm. The internal “smooth” coating must be flexible, have high adhesion to steel, be resistant to prolonged exposure to water, solvent, salt fog, and gas pressure changes (the coating should not bubble when the pressure is quickly released).

The main manufacturers and suppliers of insulating materials for "smooth" coatings are E.Wood (3M), Sika Deutschland Gmbh, Hempel, Tuboscope Vetco.

It should be noted that a sufficiently thin inner "smooth" coating cannot provide effective and long-term anticorrosion protection of the inner surface of pipelines transporting corrosive media.

If we talk about internal anti-corrosion coatings, then this topic is most relevant for field pipelines. The high water content of modern oil fields, the presence of corrosive water, salts, carbon dioxide, hydrogen sulfide in the transported products, and elevated operating temperatures contribute to intense corrosion of the inner surface of the pipes. In this case, the general corrosion rate can reach 0.01-0.4 mm/year, and the local corrosion rate can reach 1.5-6 mm/year.

The actual service life of steel field pipelines that do not have an internal protective coating can be 1-3 years

The actual service life of steel field pipelines that do not have an internal protective coating can be 1-3 years, and in some fields through corrosion of pipelines can occur after several months of putting them into operation. At the same time, when using sufficiently effective internal anti-corrosion coatings, the service life of field pipelines can increase by 8-10 times.

Insulation of pipelines in pipeline conditions

Numerous attempts to introduce the technology of internal insulation of pipelines in pipeline conditions did not lead to positive results. As in the case of external pipe insulation, the most high quality internal protective coatings of pipes can be provided only when carrying out insulation work in stationary factory or basic conditions.

At present, the technology of internal pipe insulation has been introduced at a number of domestic enterprises. Some of them (CJSC Negas, Penza, CJSC Plant Akor EEEK, Ulyanovsk) carry out internal insulation of pipes with silicate-enamel coatings; assortment with polyethylene sheaths, but factory-made epoxy coatings are most widely used for internal anti-corrosion protection of pipelines.

The most widely used for internal anti-corrosion protection of pipelines are factory-made epoxy coatings.

As initial insulating materials for applying epoxy coatings with a thickness of 400 to 700 microns, either two-component (resin, hardener) liquid paints or powder paints are used. The technology of applying internal protective coatings on pipes and connecting parts of pipelines based on epoxy powder paints has been introduced at the enterprises of LLC Truboplast, Yekaterinburg, CJSC UpoRT, Nizhnevartovsk, LLC Celer, Samara, at the Bugulma Mechanical Plant OAO Tatneft, at the Neftekamsk plant of oilfield equipment of OAO Bashneft.

Internal protective coatings based on liquid epoxy paints are applied to pipes at the factories of Yukort LLC, Nefteyugansk, Arm-Coating, Usinsk, at the enterprises of NPO ZNOK and PPD, Bugulma, Pipe Insulation Plant LLC ”, Timoshevsk, Krasnodar Territory. In addition, all the previously named domestic pipe plants that have mastered the technology of applying internal “smooth” coatings based on liquid epoxy paints can also apply internal anti-corrosion coatings intended for field pipelines on pipes.

Technology for applying internal protective coatings

The technology for applying internal protective coatings based on liquid epoxy paints (with solvent content below 30%) seems to be simpler. The coating is applied to the prepared inner surface of the pipes in one pass by spraying the working mixture of insulating materials. Polymerization of this type of coating is carried out at temperatures of 50-70°C, while curing of powder epoxy paints requires heating pipes up to 200-210°C. In addition, before applying epoxy powder coatings, as a rule, it is required to apply a layer of liquid phenolic primer, which increases the resistance of the coating to aggressive media (hydrogen sulfide).

After applying the primer, an additional operation is carried out - drying. In the same time technological process drawing powder coating is more productive and less harmful to the environment. The advantages of powder technology include the possibility of applying a protective coating to pipes of the smallest diameters (tubing assortment), while the minimum diameter of pipes with an internal coating based on liquid paints is usually 114 mm.

To date, there is a large selection of both domestic and imported insulating materials intended for applying internal protective coatings to pipes. Epoxy powder paints are widely used for internal factory insulation of pipes:

• P-EP-585, produced by LLC NPK Pigment, St. Petersburg;
• Scotchkote 134, 3M company.

Liquid two-component epoxy paints for internal pipe insulation are offered by Russian companies: Akrus LLC, Khimik LLC, Gamma. Industrial Paints". Tests have shown good performance characteristics of Amercoat 391, Sika Permacor 128 protective coatings based on liquid epoxy paints. A whole series of both powder and liquid epoxy paints intended for internal pipe insulation is offered by 3M.

The problem of isolating the zone of welded pipe joints

For a long time, an urgent and difficult to solve problem for the internal anti-corrosion protection of pipelines was the problem of isolating the zone of welded pipe joints. In the case of internal "smooth" coatings, the zone of welded joints is not isolated, since according to main gas pipelines purified, non-corrosive gas is transported, and the area of ​​welded joints is insignificant in comparison with the total internal surface of the pipeline.

Another thing is when it comes to field pipelines, where the zones of welded joints of pipelines must be provided with effective anti-corrosion protection. A variety of methods were used to protect against corrosion of welded joints of pipelines with an internal coating, including plasma spraying of protective protective rings on the end sections of pipes, thermal spraying of zinc and aluminum, and welding of stainless steel rings.

To date, the most popular method of internal anti-corrosion protection of the zone of welded joints of pipelines is the use of plug-in insulated sleeves developed by Tuboskop Vetco.

This technology has been successfully developed and implemented at the LLC Celer enterprise, Samara. On the this enterprise mastered the industrial production of a wide variety of insulated internal couplings intended for the construction of pipelines with an internal anti-corrosion coating with diameters from 57 to 820 mm inclusive.

Another method of internal protection of pipeline welded joints has been implemented at Truboplast LLC, Yekaterinburg. For this purpose, the method of gas-thermal spraying is used on the inner end sections of the pipes with a special coating made of stainless alloy. The internal epoxy coating is applied with an overlap on the metallization coating, and the final formation of the protection of the welded joint zone is carried out already when welding pipes in a whip, when the metallization coating melts at elevated temperatures and the root weld zone is alloyed.