Эффективные полимерные антикоррозионные покрытия стальных трубопроводов в нефтегазовой отрасли


технические науки

Показано, что одним из результативных методов защиты поверхности металлических трубопроводов от действия агрессивных сред является антикоррозионные покрытия инновационными макромолекулярными пленками. Композиционные защитные покрытия состоят из двух компонентов: тонкослойной адгезионной пленки полиэпоксидной грунтовки и наружного макромолекулярного полиуретановый слоя толщиной 2-4 мм. Установлено, что полимерные антикоррозионные покрытия обладают следующими характеристиками: гарантированным температурным диапазоном от минус 40ºС до плюс 50ºС, устойчивостью к механическим деформациям; адгезией покрытия не менее 10–15 МПа и др.

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High rates of construction, repair and reconstruction of buildings and structures for petroleum and gas use highlight the problem of ensuring the durability of metal structures, especially in extreme conditions of the Far North [1]. Failure to comply with the requirements during the construction and operation of pipelines, exposure to aggressive environmental factors (groundwater, negative temperatures, aggressive gases, etc.) can lead to premature destruction and failure of metal structures long before the design life of their structures is exhausted.

The aim of this work is to study composite anticorrosive macromolecules as protective coatings on metal pipelines of the petroleum and gas industry in Siberia.

For anticorrosion protection of the outer surface of pipelines, coatings from various paints and varnishes and polymeric materials are mainly used in combination with electrochemical protection for main pipes and tanks, as well as the use of inhibitors [2]. A significant part of the coatings and polymeric materials used for the external coating of oil and gas pipelines are composites. The most important advantages of macromolecular protective composites are expressed in the manufacturability of applying complex configurations to metal surfaces.

One of the effective means of protecting the surface of metal pipelines of the petroleum and gas industry in Siberia from the action of aggressive media is the use of polymer protective coatings. A very effective method of protection from environmental influences of metal parts, products, structures are anticorrosion films made of polymer resins and liquid rubbers [3]. The oligomers and polymer macromolecules used for these purposes are very diverse: polyethylene, polyisobutylene, fluoroplastics, epoxies, etc.

Polymeric composite anticorrosive coatings isolate the outer and inner surfaces of oil pipelines and pipe fittings to protect against corrosion, reduce hydraulic resistance, and surface centrifugal pumps to protect against corrosion and mechanical wear. In factory application, the main anticorrosive protection of oil pipes is an extruded polyethylene coating.

To improve the adhesion of the protective coating to the metal surface during the extrusion with polyethylene, adhesive composites are used. The technology of oxidizing the surface of a metal pipe leads to the formation of a strong oxide film several micrometers thick, which also acts as an adhesive binder between the epoxy coating and the steel surface. Petroleum and gas pipelines, which operate at high pressures and temperatures, are insulated with composite fiberglass materials: this significantly increases the strength of the protective coatings and their thermal and corrosion resistance.

High-quality application of macromolecular coatings of pipelines of the petroleum and gas industry in Siberia takes place in the factory and every step is controlled: from checking the starting materials to finishing acceptance tests of the products. First, cleaning (preparing the surface of the pipes) is carried out, then applying an adhesive primer (Fig. 1). After completion of the application, the macromolecular protective coating is examined by a flaw detector to determine the continuity, marked and received a certificate of compliance.

Technological scheme of applying anticorrosive macromolecular coatings to pipelines (1 — cleaning, 2 — technological heating, 3 — priming, 4 — application of polymer layers, 5 — cooling)
Figure 1. Technological scheme of applying anticorrosive macromolecular coatings to pipelines (1 — cleaning, 2 — technological heating, 3 — priming, 4 — application of polymer layers, 5 — cooling)

An innovative technology for the construction of protective coatings for petroleum and gas pipelines is the application of solvent-free copolymer granules onto the surface of sintered powder granules. The powder composition of the initial composite consists of epoxy and polyester resins, the thermal effect forms a dense layer, the service life of such anti-corrosion macromolecular coatings on pipelines of the petroleum and gas industry in Siberia is at least 20 years.

In the technology of route conditions for the insulation of pipes that have a complicated configuration (bent bends, valves, etc.), protective mastics are used. Composite protective coatings consist of two components: a thin-layer adhesive film of a polyepoxy (primer layer) and an external macromolecular coating (polyurethane layer 2-4 mm), which protects against corrosion damage. Polyurethane protective coatings are often also used to protect molded fittings (bends, fittings, tees, etc.) of steel petroleum and gas pipelines.

Polyureaurethane thermosetting coatings [4] of adjustable thickness (1-5 mm) are often used for anticorrosive insulation of the linear part of steel pipelines and field pipelines, as well as for the protection of fittings, valves compressor and pump stations. Today, technical specifications are standardized for the external composite anti-corrosion coating of petroleum pipes, underground storage tanks for liquefied gas and petroleum storage facilities in the conditions of factory and route (field) coating during capital construction in Siberia.

Polyurethane anti-corrosion insulation macromolecules contain unsubstituted and (or) substituted urethane groups –N(H)–C(O)–O–. The technology for producing a two-component sprayed polyureaurethane composite consists in compounding isocyanate oligomers and diamine hardeners. Three-dimensional polyurethane foam coatings of petroleum and gas pipelines are characterized by a mesh spatial structure: the structure formation of such composite materials is correctly interpreted within the framework of the fractal concept [5].

Polymeric anticorrosive coatings of pipes in the petroleum and gas industry of Siberia have the following characteristics: guaranteed temperature range of operation from –40ºС to +50ºС; coating adhesion of at least 10-15 MPa; resistance to mechanical deformation, etc. Corrosion-resistant coatings from extruded reinforced polyethylene are successfully used for the production of metal pipelines with a diameter of 57-820 mm. Insulation is especially effective when used in aggressive environments due to the inertness of the coating materials, and the adhesion of the polyethylene coating to steel of at least 35 N/cm2 determines the life of petroleum and gas pipelines up to 50 years. Quality control of the water tightness of macromolecular coatings with active solid-phase and inhibitory additives allows the use of such steel pipes when laying offshore pipelines [6].

It is not possible to list all the polymer-based anti-corrosion coatings for each petroleum and gas industry, all type of aggressive environment, form of construction and equipment [7-10]. It should be noted that the use of macromolecular anti-corrosion coatings of metal pipes significantly reduces the complexity of the repair work of water supply facilities [11] during the production and processing of gas and petroleum. Improving the corrosion resistance of building structures is also ensured by the optimal selection of binders and fillers; treatment of the surface layer with protective coatings [12].

In conclusion, we can finish that the use of macromolecular anticorrosion composite coatings significantly reduces the construction investment, as well as reduces the laboriousness of operating petroleum and gas metal pipelines in extreme conditions of the Far North.

Список литературы

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