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Anticorrosive coating of pipes

All metal structures used in construction must have a reliable protection against the effects of various environmental factors, and first of all, on corrosion. What materials are used for this? We will explain later.

General information

Corrosion is a physicochemical process in which metal interacts with the environment. During this reaction, the properties of the material change. As a result of such processes, it begins to collapse.

Anticorrosive protective coatings

They are used to process elements to prevent their destruction. Anticorrosion coating, presented in the form of special enamels or paints, has a number of advantages in comparison with other materials having similar properties. Among the main advantages of such products are:

  • The possibility of processing large-sized structures and elements of complex configuration.
  • Easy application.
  • Economical, possibility of recovery during operation.
  • Comparable cost in comparison with other materials.
  • Possibility to get a different color of the coating.

The most common formulations

Anticorrosive coating of metal structures for many manufacturing companies is the main activity. Various materials are used for processing structures and elements. Among them we can mention:

  • The paint "Nerzhamet". This enamel can be treated as clean surfaces, and covered with rust.
  • Paint "Nerzhalux". This composition has a high adhesion. This paint is used for decorative and protective treatment of surfaces from lead, duralumin, aluminum, brass, titanium, copper and zinc.
  • Paint "Aquametallic" - water acrylic composition.
  • The mixture "Quickness" is a quick-drying paint.
  • Urethane enamel "Polymeron". This composition is characterized by high wear resistance.
  • Paint "Circle". It is used in the processing of roofing structures, elements of galvanizing.
  • The composition "Silver". This anti-corrosion coating for metal has a silvery white color.
  • Decorative enamel "Nerzhaplast." It is a liquid plastic.
  • "Moloteks" - is a hammer paint.
  • "Nerzhamet-aerosol" - is produced in cans.
  • "Phosphogrunt" - is used for non-ferrous and ferrous metals.
  • "Phosphomet" - is a phosphating modifier, a rust converter.

How is corrosion-resistant coating of pipelines carried out? To process such elements, we use:

  • "Nerzhahim." This anti-corrosion coating of pipelines is a chemically resistant vinyl primer enamel.
  • "Polyurethol" is a polyurethane oil- and petrol-resistant mixture.
  • "Epostat" is an epoxy chemically resistant anticorrosion coating for pipes (primer-enamel).
  • "Tsinkonol" - polyurethane zinc-primed primer.

Mixture "Urizol"

With the help of this composition, anticorrosion coating of pipes transporting petroleum products, oil itself and natural gas is carried out. This mixture processes fittings, crane assemblies, connecting parts. The composition is used for protection against atmospheric and underground corrosion of pipelines of pumping, compressor, pumping gas distribution stations, head structures, oil depots, complex treatment facilities and storage facilities, and other similar structures with operating temperatures up to 60 degrees. The mixture "Urizol" is also used for the insulation of piles and other concrete elements.

Features of composition

First of all, it is necessary to note the ease and simplicity of applying the mixture. As a rule, the sprayer is used for processing. From the moment the compounds are combined, a reaction begins, during which polyurea is formed. Then the system goes from liquid to non-flowing gel-like, and after and into a solid state. If the polymerization rate is not high enough, streaks will form. They, in turn, prevent the necessary increase in the thickness of the coating. In this case, stickiness will remain for a long period. It prevents the control intermediate measurements of thickness and uniformity of the layer. If the polymerization rate is too high, the adhesion of the formulation to the surface is reduced. The thickness of insulation is uneven. The spray gun during operation in this case quickly clogs. To prevent such situations, careful selection of the components of the formulation and preparation of the mixture in accordance with the instructions are necessary.

Some recommendations

All components of the "Urizol" mixture are supplied in special steel drums. Storage of the material is carried out in closed rooms, in a sealed container. Quality mixing of components is carried out with the help of special equipment - a two-component spray plant. It provides accurate dosing of ingredients in a 1: 1 ratio. At the same time, the required pressure (not less than 150 atmospheres) and temperature (60-80 degrees) remain. Spraying is carried out in a thin layer. Prior to application, the components are pre-mixed in a container. For this, the barrels roll and shake.

Benefits of composition

The "Urizol" coating, unlike many other polymer mixtures that contain a certain amount of organic volatile solvents, is a composition containing one hundred percent of the solid phase. Polyurea does not contain plasticizers, which over time tend to "sweat". This process is accompanied by a gradual shrinkage and an increase in the fragility of the protective film. The mixture does not include tar and coal components, often added to reduce the cost of material, but have a carcinogenic effect on the human body. In addition, there are no solid fillers, which cause abrasive wear of pumping equipment, nozzles in spraying plants and mixing chambers. Due to their high reactivity, polyurea components have a high level of polymerization without catalysts. The increased reliability of the coating is also due to the relatively low sensitivity to temperature and humidity fluctuations. For example, other polyurethane mixtures of a similar effect have a higher propensity to form a porous film under the influence of moisture, which in turn is always present in the raw components of the feed. It should be noted, however, that the reliability of polyurea is ensured only if the requirements to the process of preparation of the treated structures and elements are carefully observed.

Application of anti-corrosion coating

The processing process involves several steps. First of all, it should be noted that applying an anti-corrosion coating is not an easy task. The final result will depend on the thoroughness of the preparation of the elements and the quality of the composition used. The greatest difficulty is usually the anti-corrosion coating of the bottom of a structure. Next, we consider the main stages of the work.

Visual inspection

Before the anticorrosive coating of metal structures is carried out, it is necessary to evaluate their condition. This is done by specialists in this field. During the visual inspection, the degree of surface damage is determined. Based on the results of the evaluation, estimates are compiled. In the course of this work, various factors are taken into account. They include, in particular, the temperature regime in which the facility is operated. And also the effect of atmospheric phenomena and other corrosive environments, the purpose of the elements, the type of material that was used in their manufacture. In accordance with this, one or another anticorrosion coating of the metal will be selected. For processing large-sized structures, as a rule, special equipment is required.

Surface preparation

Before using an anti-corrosion coating, the surface of the structure or element should be cleaned. In the process of preparation, pollution of different origin, old paint is removed. Cleaning of the object can be carried out by hydroabrasive, hydrodynamic, abrasive-jet method. Then it is necessary to degrease the surface. For this, hydrocarbon solvents are used. After the completion of this stage, the surface of the structure is inspected once more.

Treatment

Anticorrosion coating is used under certain conditions. Immediately prior to treatment, the formulation is prepared in accordance with the technology. As a rule, the procedure is carried out by the airless method. This is due to the maximum efficiency of this method. Anticorrosive coating is carried out in several layers. In this case, before applying the next, the previous one must dry to some extent (information on this is contained in the instructions for use).

The final stage

After the anticorrosive coating of the metal is finished, the inspection of the structure or element is carried out. In assessing the quality of the work performed, special equipment can also be used. As a result of the inspection, the presence or absence of untreated areas or defects is detected. The level of adhesion of the composition to the surface and the decorative properties of the coating are also evaluated. In addition, it is important to determine the dry film thickness. The optimum value is 240-300 μm. As it was said above, such processes are carried out by specialists. Upon completion of the processing, the customer takes the object. In doing so, he also receives all the necessary documentation.

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