RU2481367C1 - External polyurethane two-component protective coating (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to pipeline construction and is used in field and basic conditions when laying underground main pipelines for protection thereof from corrosion, mechanical damage and during construction of gas or liquid transporting field and industrial pipelines in conditions of permanently frozen soil, when laying pipelines on swamps, on waterlogged areas, particularly for repairing anti-corrosion coatings of oil pipelines, oil product pipeline and gas pipelines during repair thereof in field conditions, including without stopping transportation of the product, and during corrosion protection of piping of compressor stations at pipeline temperature of 70-90°C, on a section of a pipeline transporting gas at temperature above zero after a compressor station, e.g. at a section of a discharge line transporting compressed gas at temperature of plus 40°C. Versions of anti-corrosion paint for obtaining an external polyurethane two-component protective coating are given. The paint is obtained by mixing component A and component B - polyisocyanate based on diphenyl methane diisocyanate with equivalent mass of 131-135. Component A is a suspension of substances in a hydroxyl-containing polyatomic alcohol with ether and ester bonds with equivalent mass of 230….250.

EFFECT: providing high rate of hardening of the coating with improved protective properties thereof, which prevents development of underfilm and stress corrosion on the pipeline for a period of time comparable with the life of the pipeline.

6 cl

Description

The group of inventions relates to the construction of pipeline transport and is used in route conditions when laying underground trunk pipelines to protect them from corrosion, mechanical damage, as well as in the construction of field and process pipelines transporting gas or liquid in the conditions of permafrost spreading, when laying pipelines in swamps, in flooded areas, in particular for the restoration of anti-corrosion coatings for oil pipelines, oil product pipelines and gas when repairing them under route conditions, including without stopping the transport of the product, as well as when protecting compressor compressor piping at pipeline temperatures of 70-90 ° C, in a pipeline section transporting gas with a positive temperature after the compressor station, for example, plot of the discharge loop transporting compressed gas with a temperature of plus 40 ° C.

The prior art material used in the method of insulation of pipelines with thermoplastic mastics, which consists in applying to the outer surface of the pipeline, after cleaning, priming and melt the mastic using a wrapping layer. The disadvantages of this method are the significant energy intensity of the method due to the need for heating the mastic to 200 ° C and heating the surface of the pipeline. When using bitumen-polymer mastics, it is necessary to reinforce the insulating layer with a fiberglass mesh to prevent the mastic from draining from the walls of the pipeline. In addition, the service life of bitumen coatings does not exceed 15 years, which is 2 times less than the service life of pipelines. The known method is characterized by low productivity and a large number of used equipment (up to 21 units). It should be noted that bitumen-polymer mastics are fire hazardous and toxic when applied (see RU 2005105440/06 (006826), 02.28.2005).

Known material used in the implementation of the method of corrosion protection in basic and route conditions with sticky polymer tapes made of PVC or polyethylene, as well as heat-shrinkable tapes, in which the coating is applied manually to non-stretched sections of pipelines (RU 2151942 C1, 06.27.2000).

The disadvantages of this method are:

- high requirements for surface preparation;

- the need for heating the pipeline in some cases to 30-50 ° C, regardless of the ambient temperature;

- the presence of a tent effect (voids) in the weld zone;

- the service life of the coating is 7-14 years, which is significantly less than the service life of the pipeline;

- relatively high cost of coverage.

Known steel pipe with a protective coating of its inner surface from deposits and corrosion, which used a two-component composition based on a polyurethane binder with a ratio of components from 1: 5 to 5: 1 (see RU 92509, 03.20.2010). The composition of a two-component composition based on a polyurethane binder includes: a) polyol (resin), b) polyisocyanate (hardener).

In the process of curing the coating, the polymerization of the components occurs due to the moisture contained in the air and the residual moisture on the inner wall of the pipe.

A disadvantage of the known solution is the requirement of moisture on the prepared surface of the pipe, the dependence of the curing of the coating on the state of atmospheric humidity at the time of coating, which leads to an uncontrolled process of obtaining a coating on the surface of a steel pipe. It is known that, in order to avoid corrosion on the prepared external surface of the pipeline, it is forbidden to apply a coating to its wet external surface, and the time gap between cleaning the surface of the pipeline and coating it should be minimal and should not exceed two hours. If these requirements are not met, the process of cleaning the surface of the pipeline is repeated.

Closest to the claimed invention is a known composition for thermostable and compatible with cathodic protection coatings, comprising a solvent-free reactive two-component polyurethane system (see RU 2278139 C2, 20.06.2006). The composition known from the prior art is used for corrosion protection of pipes and ballast tanks of ships, while the thickness of the coating layer exceeds 1000 microns.

In the known solution, component A consists of 40-100 wt.% Simple polyether polyol with a functionality> 3.5 and a molecular weight of 280-1000 or a mixture of several such components, as well as 0-60 wt.% Simple polyether polyacrylates from 5.0 to 15 wt.% hydroxyl groups and viscosity at 23 ° C from 300 to 5000 MPa · s, as well as 0-60 wt.% of other compounds containing hydroxyl groups with a molecular weight of 32 to 1000, and the sum of the wt.% substances of component A is always equal one hundred%.

Component B consists of at least one organic polyisocyanate, wherein the equivalent NCO: OH ratio is in the range from 0.8: 1 to 1.5: 1.

In the case of component B, we can talk about aromatic organic polyisocyanate. A disadvantage of the known solution is the insufficient elasticity of the coating due to the absence of hydroxyl-containing compounds (polyether polyacrylates and other compounds containing hydroxyl groups with a molecular weight of 32 to 1000), since the indicated lower limit of their content in component A is zero, as well as the insufficient wettability of the composition and the degree of filling . When spraying the coating on the curved surface of the pipeline due to the short viability of the composition and insufficient wettability at the edges of the spray plume (in a thinner layer), the coating cures more intensively with the formation of "shagreen", which is a defect when applying the coating.

The invention solves the problem of increasing the protective properties of the outer coating of a steel pipeline by eliminating the development of sub-film and stress corrosion in the pipeline for a time comparable to the depreciation of the pipeline.

In addition, the proposed external polyurethane two-component protective coating allows complex automation of the process of applying a protective coating to the outer surface of the pipeline with the so-called combined method of insulation work, which is a single technological complex that combines all its components in one continuous stream: cleaning the outer surface of the pipeline with drainage and heating (if necessary), applying an external insulation coating, pipe laying rovoda in trench backfill.

The option of a polyurethane two-component protective coating has thermal stability when exposed to temperatures up to 70-90 ° С while being compatible with cathode protection and, in addition, can be used during repair work when airless spraying is applied using a hand gun on a pipeline with an external surface temperature from 40 to 90 ° C.

Achievable technical result in the implementation of the claimed group of inventions is to obtain coatings with anticorrosive and dielectric properties, high gas resistance, weather resistance, and abrasion resistance under highway conditions, increase the coating service life to a comparable period to the life of a new pipeline, and also increase the productivity of the coating process thickness on pipelines in route conditions, including large diameters (1200 mm and more), due to tomatizatsii and synchronization performance processes of preparation of the outer surface of the conduit and applying to it the coating. It is possible to use the declared external coating in basic conditions.

This problem is solved in that the outer polyurethane two-component protective coating is an anticorrosion paint in which component A and component B, which are mixed before use, and component B, a polyisocyanate based on diphenylmethanediisocyanate with an equivalent weight of 131 ... 135, are in the ratio, vol. h. 3: 1, respectively, while component A is a suspension of substances in a hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250, obtained in the process of dispersing them according to the presented formulation, wt.%:

hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250 10 ... 50 branched polyalcohol containing simple and complex ether groups or a simple linear polyol based on polypropylene ether 20, not less inorganic pigments 4, no more titanium dioxide 8 ... 12 barite 10 ... 25 talc 5 ... 15 solution of foam polymers 0.5 ... 2 3A molecular sieve 5 ... 10 substituted aromatic diamine with an NH equivalent of about 90 (i.e., 80-100) 0.6 ... 1.2 tertiary amine with a hydroxyl number of 560 mg KOH / g 0.5 ... 1 a solution of an alkyl ammonium salt of an acid copolymer, containing hydroxyl functional groups 0.25 ... 1,

the distribution of particles by microfraction size is

barite, 3 microns,% fifty barite, 10 μm,% fifty

In addition, when protecting piping of compressor stations with a pipe temperature of 70-90 ° C against corrosion, in the pipeline section transporting gas with a positive temperature after the compressor station, for example, in the discharge loop section transporting compressed gas with a temperature of plus 40 ° C, and / or when applying the coating manually by airless spraying, when a longer viability of the composition and increased wettability of the outer surface of the pipeline are required, this problem is solved by the option inventions - an external polyurethane two-component protective coating, which is an anticorrosion paint, in which component A and component B, which is miscible before use, and component B, a polyisocyanate based on diphenylmethanediisocyanate with an equivalent weight of 131 ... 135, are in the ratio, vol. 3: 1, respectively, while component A is a suspension of substances in a hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250, obtained in the process of dispersing them according to the presented formulation, wt.%:

hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250 10 ... 50 branched polyalcohol containing simple and complex ether groups or a simple linear polyol based on polypropylene ether 20, not less inorganic pigments 4, no more titanium dioxide 8 ... 12 barite 10 ... 25 talc 5 ... 15 solution of foam polymers 0.5 ... 2 3A molecular sieve 5 ... 10 substituted aromatic diamine with an NH equivalent of about 90 0.6 ... 1.2 tertiary amine with a hydroxyl number of 560 mg KOH / g 0.5 ... 1 a solution of an alkyl ammonium salt of an acid copolymer, containing hydroxyl functional groups 1,0 ... 1,5,

the distribution of particles by microfraction size is

barite, 3 microns,% one hundred talc, 7 microns,% one hundred

In addition, in particular cases of coating, molecular sieves are contained in a homogeneous dispersion, for example, 50% molecular sieves in castor oil, and inorganic pigments are represented by iron oxide and chromium oxide.

To give the required elasticity to the claimed coating, a hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250 is used as a binder, and a hydroxyl-containing compound with an equivalent weight of 340 ... 1000 is used as an additional binder - a branched polyalcohol containing simple and complex ether groups, simple linear polypropylene ether polyol. Moreover, as component B, a polyisocyanate based on diphenylmethane-diisocyanate with an equivalent weight of 131 ... 135 is used. These materials provide chemical curing of the coating (crosslinking) due to the polymerization process, that is, their conversion from a liquid state to a solid three-dimensional spatially crosslinked state with the formation of a polymer skeleton. These transformations are due to the growth of macromolecules, the formation of a crosslinked spatial framework due to the intermolecular interaction of individual functional groups (hydroxyl and other chemical groups capable of interaction) of these components. Upon curing of the coating components, functional groups are formed that are capable of interacting with the surface of the steel pipe, which provides a high degree of adhesion and the required coating strength.

Introduced additives contribute to improving the properties of the formed polymer frame, the density of the coating, its elasticity.

The addition of talc with a scaly shape of microparticles as a filler improves the resistance of the coating to ultraviolet rays, additional “barrier” protection against gas diffusion and water vapor, an increase in the adhesion of the material to the substrate and interlayer adhesion.

Barite microparticles contribute to adhesion to the substrate, while the coating has the necessary moisture and vapor permeability and increased resistance to corrosive environments, weathering and high temperatures.

The use of inorganic pigments as color pigments gives the composition, in addition to color, opacity and protects the coating from photodestruction. Solid particles of inorganic iron oxide pigments, especially needle and scaly forms, structure and reinforce the coating, increase its strength, hardness, water and weather resistance, and also chemically protect the pipeline from corrosion.

As a defoamer, a solution of foam-destroying polymers, Byk A 530, was used.

As an adsorption additive, 3A molecular sieves in the form of a homogeneous dispersion (50% molecular sieve in castor oil) were used, which greatly facilitates the production process.

As a thixotropic additive to prevent dripping of the coating in a thick layer from the curved surface of the pipeline, a substituted aromatic diamine with an equivalent of NH about 90 - Hardener DT was used.

A tertiary amine with a hydroxyl number of 560 mg KOH / g, Dabco 33 LV, was used as a catalyst.

Desmophen 1145 as a hydroxyl-containing polyhydric alcohol with simple and ester bonds.

As a branched polyalcohol containing simple and ester groups or a simple linear polyol based on polypropylene ether - Desmophen 1150.

As a solution of an alkyl ammonium salt of an acid copolymer containing hydroxyl functional groups, Byk W969.

As component B, a polyisocyanate based on diphenylmethane diisocyanate with an equivalent weight of 131-135, Desmodur VL.

The wetting additive is a solution of an alkylammonium salt of an acid copolymer containing hydroxyl functional groups, which helps to increase the wetting and dispersion rate of fillers, and also reduces the viscosity of the composition and provides a higher degree of filling.

An external polyurethane two-component coating is applied to the pipeline by airless spraying of the working mixture during separate heating of the components (component A at 50-60 ° C, component B at 30-40 ° C) and with the components being supplied with separate pumps when connecting components A and B in a given proportion in the mixer on the spray head. The mixture can be sprayed using a high-pressure spray gun for manual spraying or using automatic coating equipment. The curing time of the coating "on stick" at an ambient temperature of 25 ° C is 12-15 minutes After 30 minutes, intra-workshop transportation of coated products is possible. Start of operation of coated products is possible 3 hours after spraying. The time of complete curing of the coating is two days.

Examples of the use of the invention.

An external polyurethane two-component coating (trademark RPU-1001) is applied to the prepared external surface of a steel pipeline under route conditions in the form of a continuous layer. The components are heated, mixed, and the coating is sprayed by airless spraying in automatic mode with bands equally spaced around the circumference of the pipeline using a device containing two high-pressure spray guns. The device provides them oscillating in the transverse and continuous movement in the longitudinal direction relative to the pipeline. When spraying the coating by means of the nozzle of each specified gun, a flat finely formed torch is formed with a less saturated area of spread of the applied material around the periphery, while providing a partial circumferential overlap of the ends of these strips with the formation of a uniform coating thickness, and each specified torch is oriented perpendicular to the outer surface of the pipeline, the plane of the torch is directed along the generatrix of the pipeline. When using the heating of the components of the applied coating, its losses are reduced, in addition, due to the reduction in surface tension and viscosity when heating, it becomes possible to spray the material at a much lower pressure and the required coating curing speed (to “tack”) is achieved by polymerizing the coating of each applied strip. A gradual decrease in the saturation of the sprayed material at the edges of the strip is necessary to avoid smudges and thickness variations of the coating when applying one strip to another. At the same time, the frequency of double oscillations of the rotor carrier pistols is 5-10 per minute.

The width of the strips of the applied material, their number depends on the diameter of the insulated pipeline, the required process capacity and are provided by the number of high pressure spray guns, the angle of the nozzle axis of the spray guns relative to the longitudinal axis of the translational movement of the device containing these guns, as well as the choice of vibrational and translational speeds their movements.

For example, the productivity of coating a pipeline with a diameter of 1020 mm is 0.5-0.7 linear m / min. The consumption of coating material RPU-1001 is at a coating thickness of 1 mm - 2.4 ... 2.5 kg / m ² with a coating thickness of 2 mm - 4.5 ... 4.9 kg / m ² .

Field tests showed that the material used to isolate the pipeline according to the invention is an external polyurethane two-component protective coating (RPU-1001), its application modes and the used device provide a coating having the necessary adhesion, high physical and mechanical properties, in particular high stability abrasion and corrosion resistance, which is important when operating underground pipelines subject to operational displacement.

Improving the reliability of the external protective coating of the pipeline is provided due to the high protective properties of the coating, which eliminates the development of sub-film and stress corrosion on the pipeline for a time comparable to the depreciation of the pipeline.

Claims (6)

1. An external polyurethane two-component protective coating, which is an anticorrosive paint, in which component A and component B, which are mixed before use, and component B, a polyisocyanate based on diphenylmethanediisocyanate with an equivalent weight of 131 ... 135, are in the ratio, vol.h. 3: 1, respectively, while component A is a suspension of substances in a hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250, obtained in the process of dispersing them according to the presented formulation, wt.%:
hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250 10 ... 50 branched polyalcohol containing simple and complex ether groupings or simple linear polyol based on polypropylene ether not less than 20 inorganic pigments no more than 4 titanium dioxide 8 ... 12 barite 10 ... 25 talc 5 ... 15 solution of foam polymers 0.5 ... 2 3A molecular sieve 5 ... 10 substituted aromatic diamine with an NH equivalent of about 90 0.6 ... 1.2 tertiary amine with a hydroxyl number of 560 mg KOH / g 0.5 ... 1 a solution of an alkyl ammonium salt of an acid copolymer, containing hydroxyl functional groups 0.25 ... 1,
the distribution of particles by microfraction size is
barite, 3 microns,% fifty barite, 10 μm,% fifty talc, 7 microns,% one hundred 2. The coating according to claim 1, in which the molecular sieve is contained in the form of a homogeneous dispersion, for example, 50% molecular sieve in castor oil. 3. The coating according to claim 1, in which the inorganic pigments are iron oxide and chromium oxide. 4. An external polyurethane two-component protective coating, which is an anticorrosion paint, in which component A and component B, which are mixed before use, and component B, a polyisocyanate based on diphenylmethanediisocyanate with an equivalent weight of 131 ... 135, are in the ratio, vol.h. 3: 1, respectively, while component A is a suspension of substances in a hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250, obtained in the process of dispersing them according to the presented formulation, wt.%:
hydroxyl-containing polyhydric alcohol with simple and ester bonds with an equivalent weight of 230 ... 250 10 ... 50 branched polyalcohol containing simple and complex etheric groups or simple linear polyol based polypropylene ether not less than 20 inorganic pigments no more than 4 titanium dioxide 8 ... 12 barite 10 ... 25 talc 5 ... 15 solution of foam polymers 0.5 ... 2 3A molecular sieve 5 ... 10 substituted aromatic diamine with an NH equivalent of about 90 0.6 ... 1.2 tertiary amine with a hydroxyl number of 560 mg KOH / g 0.5 ... 1 a solution of an alkyl ammonium salt of an acid copolymer, containing hydroxyl functional groups 0.25 ... 1,
the distribution of particles by microfraction size is
barite, 3 microns,% one hundred talc, 7 microns,% one hundred 5. The coating according to claim 4, in which the molecular sieve is contained in the form of a homogeneous dispersion, for example, 50% molecular sieve in castor oil. 6. The coating according to claim 4, in which the inorganic pigments are iron oxide and chromium oxide.