RU2379574C1 - Plating method of multilayer anticorrosive coat on surface of pipe - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: in method, consisting in plating of pipe surface by ground coat, on which it is applied in the capacity of adhesion layer paste on the basis of petroleum polymer "asmol", and on adhesion layer it is extruded external protective layer on the basis of polyethylene, in the capacity of ground coat it is used 25-35% solution of petroleum polymer "asmol" in organic solvent, paste additionally contains bitumen, bivinyl styrene thermoplastic elastomer and plasticiser at following ratio of components, wt %: petroleum polymer " asmol " - 80-94, bitumen - 5-10, bivinyl styrene thermoplastic elastomer - 2-3, plasticiser - 3-6, herewith asmol paste is applied on ground coat by extrusion.

EFFECT: simplification of plating technology, reduction of power inputs and increasing of adhesion strength of coating.

2 cl, 1 tbl

Description

The invention relates to the field of corrosion protection of pipeline transport and can be used for factory and basic insulation of the outer surface of the pipe.

A known method of applying a multilayer anti-corrosion coating on the surface of a steel pipeline, through which the outer surface of the pipeline is coated with a powder epoxy primer, then an adhesive layer is applied based on a hot-melt polymer composition, after which an outer protective layer based on polyethylene is extruded [TU 1381-010-0054341 -2002].

The disadvantage of this method is the low adhesion of the powder epoxy primer to the metal surface with poor surface preparation (traces of oil, rust, etc.), which leads to a decrease in the protective properties of the coating.

Closest to the claimed object is a method of applying a multilayer anti-corrosion coating on the pipe surface, according to which the outer surface of the pipe is coated with a two-layer primer, which is used as a liquid anticorrosive epoxyurethane polymer material. Asmol mastic is applied to the primer as an adhesive layer, after which an outer protective layer based on polyethylene is extruded onto the adhesive layer [RF Patent No. 2292513, cl. F16L 58/02, publ. 2007].

The disadvantages of this method are the complexity and energy intensity of the coating technology on the pipe and the low adhesive strength of the resulting coating. In addition, the use of Asmol mastic, which has a low brittle temperature, as an adhesive layer, limits the use of such coatings at temperatures below 15 ° C.

The complexity and energy intensity of the method is explained by the fact that the application of epoxyurethane polymer material must be accompanied by a thorough preparation of the pipe surface to degree 2 BCN 008-88 (Sa 2 1/2 ISO 8501-1) by cleaning it from dirt, corrosion products using a sandblasting machine, washing surface with a solvent from grease stains and its subsequent chemical treatment, for example, chromium plating. In addition, to accelerate the drying of each layer of epoxyurethane primer, heating of the pipe surface to 70-80 ° C is necessary.

The low adhesive strength of the coating is due to the insufficient contact surface of the coating with the pipe due to the high viscosity of the primer, and also due to the different chemical nature of the epoxyurethane polymer material with “asmol” mastic.

In addition, the application of the “asmol” adhesive layer in the traditional way using an extruder to supply the adhesive layer is impossible, since the “asmol” mastic has low extensibility (ductility) and when applied to the pipe surface through the extruder it will not provide a continuous continuous supply of a melt film of sufficient length .

The invention is aimed at simplifying the technology of coating the pipe and reducing energy consumption while increasing the protective properties of the coating and increasing the operational capabilities of the pipe with an insulating coating obtained by the proposed method.

This is achieved by the fact that in the method of applying a multilayer anti-corrosion coating to the pipe surface, which consists in applying a primer to the pipe surface, onto which mastic based on Asmol oil is applied as an adhesive layer, followed by extrusion of an outer protective layer based on polyethylene onto an adhesive layer, according to the invention, a 25-35% solution of Asmol oil in an organic solvent is used as a primer, the mastic additionally contains bitumen, divinyl styrene thermo lastoplast and a plasticizer in the following ratio, wt.%:

Asmol oil polymer 80-94 Bitumen 5-10 Divinyl styrene thermoplastic elastomer 2-3 Plasticizer 3-6,

in this case, the asmal mastic is applied to the primer by extrusion.

It is advisable to use S-9 mineral oil or rapeseed oil as a plasticizer.

The proposed method is as follows.

They clean the surface of the pipe, after which it is primed with a 25-35% solution of Asmol oil in an organic solvent. An adhesive layer of mastic is applied to the primer by extrusion, containing asmol oil as a base - 89-90 wt.%, As well as bitumen - 5-10 wt.%, Divinyl styrene thermoplastic elastomer - 2-3 wt.% And plasticizer - 3-6 wt.%. A protective layer based on polyethylene is applied by extrusion to a layer of asmal mastic.

As a plasticizer, mineral oil C-9 or rapeseed oil is used.

When coating at low temperatures, the pipe may be blown with warm air to accelerate the drying of the primer.

Below are examples of the implementation of the proposed method.

Example 1

The surface of the new metal pipe with a diameter of 89 mm (two-pipe) was cleaned of dirt, rust, loosely adhered to the metal of the scale with metal brushes. Under the conditions of factory insulation, the primer, which was a 30% solution of “asmol” mastic in an organic solvent (“nefras”), was applied to the pipe surface, without preliminary heating, using a device equipped with a rubbing towel. The primed surface of the pipe, which had dried up to “sticking”, was rotationally applied at a temperature of 100-110 ° С as an adhesive layer with asmalny mastic using a slit head extruder using lateral extrusion method. The content of the components of asmal mastic and its physicochemical properties are given in the table.

A polyethylene melt at a temperature of 130-150 ° C was deposited on a layer of asmoline mastic through a slit head of a second extruder using a lateral extrusion method. Then the insulated pipe was installed in the water cooling chamber to reduce the temperature of the coating.

Example 2

The surface of the 219 mm diameter metal pipe that was in use was first cleaned of old insulation and earth with scrapers, and then of the corrosion products with metal brushes on the insulation coating line. A coated pipe was coated, as in Example 1, with the difference that the asmal mastic was obtained with a different ratio of components.

The content of the components of the asmal mastic according to example 2 and its physicochemical properties are shown in the table.

For comparison, the table shows the physico-chemical properties of the asmol mastic according to the prototype.

As can be seen from the table, the asmal mastic used in examples 1 and 2 according to the proposed method is superior in physical and chemical properties to the mastic “asmol” in the prototype method: it has a higher softening temperature according to KiS, as well as higher penetration and ductility ( elongation) and higher adhesive properties to metal and polyethylene.

The indicated physicochemical characteristics of the asmal mastic used by the proposed method will allow the coating to be provided with high protective properties, and high adhesion to the metal and polymer will provide a bond between the coating layers.

The increased extensibility of the obtained mastic will allow it to be applied to the pipe surface by extrusion (in the prototype method, due to the low extensibility of the mastic, the extruder will not provide continuous continuous supply of a melt film of sufficient length), and a lower brittle temperature of the mastic will allow the use of pipes with an insulating coating obtained by the proposed method, at lower temperatures (asmol mastic has a low brittle temperature, which limits the operational capabilities of isolated t K according to the method-prototype at temperatures below minus 15 ° C).

Using the proposed method will allow, in comparison with the method of the prototype, to simplify the technology of coating the pipe and reduce energy consumption by simplifying the process of applying the mastic adhesive layer. Application of a mastic adhesive layer by extrusion eliminates the use of additional traditional mastic application equipment and does not require sophisticated equipment for thorough pipe cleaning; a sufficient degree of cleaning is 4 BCN 008-8 (St 2 ISO 8501-1), achieved by cleaning with metal brushes.

In addition, the proposed method provides the sufficiency of one coat of primer (“asmole” solution in gasoline), which as a result will eliminate the heating of the pipe to dry the coat of primer (in the prototype method, a drying process is required after applying each coat of primer).

The low viscosity of the asmole primer will ensure that all the irregularities of the pipe surface are filled, while the "asmole" interacts with the surface of the pipe metal at the atomic-molecular level to form a strong nanostructured iron-oil polymer complex in the surface layer of the metal, which is enhanced by the fact that the primer has one chemical nature with the main component of the mastic layer. In addition, “Asmol” has the ability to modify and transport corrosion products deep into the coating, which prevents peeling of the coating from the surface to be protected and enhances the anticorrosive effect of the coating, increasing its operational characteristics: it increases the adhesion of the coating to metal, reduces the rate of corrosion of the metal under the coating, and increases the cathodic resistance polarization and retains all these properties during prolonged use.

Table The composition and physico-chemical characteristics of the mastics used in the proposed method and in the prototype method Indicators Asmal Mastic by the proposed method according to the prototype ("asmol") example 1 example 2 The content of components, wt.%: 1. "Asmol" 91 81 one hundred 2. Bitumen four 10 - 3. Divinyl styrene thermoplastic elastomer 2 3 - 3. Plasticizer: - - Mineral oil S-9 3 - - rapeseed oil - 6 - Physico-chemical properties of the adhesive mastic layer: - Softening temperature according to KiSh, ° С 96.5 98.6 84 - Penetration of mastic at 25 ° C, 0.1 mm 27.1 33,4 23.3 - Ductility (extensibility) at 25 ° С, cm 4.2 5.5 3,1 - Shear adhesion to metal at (20 ± 5) ° С, MPa 0.33 0.36 0.24 - Shear adhesion to polyethylene at (20 ± 5) ° С, MPa 0.32 0.34 0.26

Claims (2)

1. The method of applying a multilayer anti-corrosion coating on the pipe surface, which consists in applying a primer to the pipe surface, onto which mastic based on Asmol oil is applied as an adhesive layer, after which an external protective layer based on polyethylene is extruded onto the adhesive layer, characterized in that as a primer using a 25-35% solution of Asmol oil in an organic solvent, the mastic additionally contains bitumen, divinyl styrene thermoplastic elastomer and a plasticizer when blowing ratio, wt.%:
Asmol oil polymer 80-94 Bitumen 5-10 Divinyl styrene thermoplastic elastomer 2-3 Plasticizer 3-6
in this case, asmalny mastic is applied to the primer by extrusion. 2. The method according to claim 1, characterized in that C-9 mineral oil or rapeseed oil is used as a plasticizer in asmal mastic.