Method of applying isolation coating on metallic surface

FIELD: protection of pipe against corrosion.

SUBSTANCE: method comprises applying prime coat on metallic surface at a temperature of no less than 10°C, applying insulating polymeric belt coating on metallic surface, and heating the coating to provide its shrinking.

EFFECT: enhanced corrosion protection.

6 cl, 1 tbl, 3 ex

 

The invention relates to the field of corrosion protection of metal surfaces, preferably, pipeline transport and armoured electric cables, in particular to the construction and repair of underground utilities, and can be used to isolate the metal surface from the combined action of moisture and oxygen, it is preferable for the insulation surfaces of steel piping and electrical cables in a metal shell.

Known (DE, application No. 3415456 F 16 L 59/14, 1984) a method of creating a protective coating on the pipe insulation. According to a known method on the pipe is applied covering the insulation of the outer shell, heat it in the oven and put on the end surface of the pipe insulation.

The disadvantage of this method should recognize its low efficiency, due to the low adhesion of additional shells to the main floor.

Known (RU, patent No. 2188980 F 16 L 58/04, 2002) way of protection of underground pipelines and steel structures against corrosion. According to a known method pre-mix the primer with corrosion inhibitor, then clean the metal surface from dirt, put the prepared primer on treated metal surface followed by the application of an insulating coating.

The disadvantage know what about the way it should be recognized as insufficient adhesion of the adhesion of the coating to the primer, which leads to the access of moisture and air to the metal surface from further corrosion coating.

Known (Construction of main and field pipelines. Anti-corrosion and thermal insulation. VSN 008-88. - M, Minneftegazstroy, 1990, p.10) the method of applying the insulating tape on the external surface of the pipeline. According to a known method performed pre-treatment, application of a primer and an insulating polymer tape coating on the pipeline, and when the ambient temperature is below 10°With the pipe surface is heated to a temperature of not lower than 15°and not more than 50°C.

The disadvantage of this method should be recognized as insufficient adhesion of the adhesion of the coating to the primer, which leads to the access of moisture and air to the metal surface from further corrosion coating.

The technical problem to be solved by the proposed method, is to develop a method of applying an insulating coating on a metal surface, curing using a small heating and high adhesion.

The technical result is obtained when implementing the method, consists in a significant improvement of the corrosion characteristics of the coating and, consequently, reducing the cost of capital repairs of metal on top of the spine by increasing its service life.

To achieve the technical result used method of applying an insulating coating on a metal surface, comprising applying an insulating polymer tape coating on the metal surface. A primer layer is applied on a metal surface having a temperature of not lower than 10°and after applying the insulating polymer tape coating on the metal surface is being heated to its thermocontracting, and as an insulating polymer tape coating using heat-shrinkable multilayer adhesive tape, consisting at least of radiation-chemically modified polymer base polyolefin and adhesive layer containing a copolymer of ethylene and vinyl acetate, mica ground, low molecular weight polyisobutylene, acetonyl-R in the following ratio of components (wt.%):

mica ground18-24
low molecular weight polyisobutylene4-10
acetonyl-P0,5-2,5
a copolymer of ethylene and vinyl acetaterest

The used adhesive is softened at a temperature of about 50°that lowers the temperature of the warm-up is obrabatyvaemoi metal surface, reducing the expenditure of energy and time usually spent on heating, which reduces the cost of the work. The adhesive in combination with a compressible when termosifon polymer base provides, firstly, the complete removal of air bubbles from under the film, and secondly, a good adhesion of the polymer base to the underlying layers, and, thirdly, filling adhesive all voids between the polymer base and the underlying layers. All of the above protects metal surfaces against penetration of moisture and air. In that case, if the implementation method, the ambient temperature and, of course, the metal surface have a low temperature, it is desirable to heat it to a temperature not lower than about 15°C. This will facilitate the consolidation on a metal surface primer - primer. Usually before applying primer clear insulated from the surface of the old insulation, and corrosion. For the best insulation on the primer layer may be additionally applied mastic-asphalt-polymer coating curing at a temperature of 80-85°C. After application of the primer sometimes spend additional heating of the metal surface to a temperature of 40-50°to better consolidate a layer of primer on the insulated surface. In predpochtitel the om implementation before applying insulating polymer tape coating spend heating the adhesive layer up to a temperature of 60-70° C. Termowizyjne insulating polymer tape coating is usually carried out at a temperature of 100-120°C.

In the future, the nature and advantages of the proposed method will be disclosed using the examples of implementation.

1. On a steel pipe with a diameter of 1020 mm during repair works after removing mechanically the old insulation caused primer "Transkor-Gas with a thickness of 150 μm, the temperature of the pipe was 19°C. Then, on the primer layer caused additional mastic-asphalt-polymer coating "Transkor-Gas at a temperature of 140-150°curing at a temperature of 80-85°and then by winding the polymer tape is made of compounded polyethylene-based polyethylene of high and low pressure, as well as light and thermal stabilizers and processed using electron accelerator (Elektron-10") with a dose of 18.1 Mrad, which gives new physico-chemical properties of the basis. In addition, performed thermodynamic two-axis orientation, leading to the ability of the tape to shrink.

The adhesive contains components in the following ratio (wt.%):

mica ground22
low molecular weight polyisobutylene8
acetonyl-P1
Sevilen69

Used the adhesive has a softening temperature 51°C. Then, the resulting insulating coating was heated for shrinking polymer base to a temperature of 115°C.

The averaged results are given in the table.

2. On a steel pipe with a diameter of 1420 mm during repair works after removing mechanically the old insulation and heating it to a temperature of 19°caused primer "EAF" thick 139 μm and conducted additional heating of the metal surface to a temperature of 40-50°C. Then for primer layer was applied by winding a polymer tape, made of compounded polyethylene-based polyethylene of high and low pressure, as well as light and thermal stabilizers, and processed using electron accelerator (Elektron-10") with a dose of 18.3 Mrad, which gives new physico-chemical properties of the basis. In addition, performed thermodynamic two-axis orientation, leading to the ability of the tape to shrink.

The adhesive contains components in the following ratio (wt.%):

mica ground21
low molecular weight polyisobutylene7
acetonyl-P2
Sevilen70

Used the adhesive has a softening temperature 52°C. Then, the resulting insulating coating was heated for shrinking polymer base to a temperature of 120°C.

The averaged results are given in the table.

3. On a steel pipe with a diameter of 1020 mm during repair works after removing mechanically the old insulation and heating it to a temperature of 22°caused primer "EAF" thickness of 100 μm and conducted additional heating of the metal surface to a temperature of 40-50°C. Then for primer layer was applied by winding a polymer tape, made of compounded polyethylene-based polyethylene of high and low pressure, as well as light and thermal stabilizers, and processed using electron accelerator, Electron 10" with a dose of 18.9 Mrad, which gives new physical-chemical properties of the basis. In addition, performed thermodynamic two-axis orientation, leading to the ability of the tape to shrink, and before applying the insulating polymer tape coating spent heating the adhesive layer up to a temperature of 60-70°C. Then, the resulting insulating coating was heated for shrinking polymer base to a temperature of 120� C.

The adhesive contains components in the following ratio (wt.%):

mica ground18
low molecular weight polyisobutylene5
acetonyl-P1
Sevilen76

The averaged results are given in the table.

For all four samples the deviation from the average value did not exceed 5%.

The application of the proposed method can significantly improve the characteristics of the coating, resulting in increased time between overhauls.

Table
№ p/pName of indicatorThe norm on THE otherThe test result
Plastic base, adhesive
1The tensile strength of PE-basics, MPa823
2Elongation PE basis at break (20±5)°,% >400500-520
3Thermal-oxidative stability of PE-basics at 200°C, min.>3030-32
4Low temperature brittleness of edge the ion layer, not above °minus 30°below minus 30°
5The softening temperature of the adhesive (TMA, 1.4 kg/cm2, 10°C/min), °C60±355±3
6Allowable penetration PE-basics under load at 200° (TMA, 1.4 kg/cm2, 10°C/min), not more than %2010
Tape in General
7Free shrinkage in the floor (without load), %20±518(130°)
(150°)15(150°)
8Volumetric shrinkage of the coating under load (0.3 kg/cm2), % not less than2(100°)

15(150°)
2,5(100°)

15(150°)
9Voltage shrinkage, not less than g/mm2section10(150°)10(130°)
10Water absorption at 60° within 1000 hours,%3,03,0
Coating based on epoxy primer "EAF"
11Adhesive strength to praimirovanie steel and polyethylene, N/cm at 20±5°>5055±5
12 Adhesive strength to praimirovanie steel after 100 days soaking in water at 60°C, N/cm>5062-65
13Transient electrical resistance in 3% NaCl, mm2
- original>10102,0 .1011
- after 100 hours of aging at 60°C>1098.109
14Cathodic delamination in 3% NaCl at a potential of polarization -1,5V at temperatures cm2no more:
20°=60 days106-8
50°=30 days09-10
15Impact strength (j) when temperature:
minus 40°C
plus 20°C
plus 40°C
16Shift at a temperature of 50° and the load of 0.25 kg/cm2coverage area mm<1,00,2-0,4
17Dielectric continuity. No breakdown when p is constant electrical voltage, kV>15>20
>15>20

1. The method of applying an insulating coating on a metal surface, comprising applying an insulating polymer tape coating on a metal surface, characterized in that the primer layer is applied on a metal surface having a temperature of not lower than 10°and after applying the insulating polymer tape coating on the metal surface is being heated to its thermocontracting, and as an insulating polymer tape coating using heat-shrinkable multilayer adhesive tape, consisting at least of radiation-chemically modified polymer base polyolefin and adhesive layer containing a copolymer of ethylene and vinyl acetate, mica ground, polyisobutylene low molecular weight, acetonyl-R in the following ratio, wt.%:

Mica ground18-24
Low molecular weight polyisobutylene4-10
Acetonyl-P0,5-2,5
a copolymer of ethylene and vinyl acetateRest

2. The method according to claim 1, wherein the pre-wire the t heating the metal surface to a temperature not lower than 15° C.

3. The method according to claim 1, wherein the pre-metal surface is sanded.

4. The method according to claim 1, characterized in that the primer layer is additionally applied mastic-asphalt-polymer coating curing at a temperature of 80-85°C.

5. The method according to claim 1, characterized in that after application of the primer shall conduct additional heating of the metal surface to a temperature of 40-50°C.

6. The method according to claim 1, characterized in that before applying the insulating polymer tape coating spend heating the adhesive layer up to a temperature of 60-70°C.

7. The method according to claim 1, characterized in that termowizyjne insulating polymer tape coating is carried out at a temperature of 100-120°C.



 

Same patents:

FIELD: construction.

SUBSTANCE: method comprises setting the tip in the end section of the pipe lined by a plastic shell. A protector is fit in the tip with interference. The tip clamps the end of the plastic shell by mandrelling. The tip is fit in the pipe with interference. The tip is mandrelled out of the zone of protector.

EFFECT: enhanced reliability.

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FIELD: pipeline transport.

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EFFECT: enhanced reliability.

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FIELD: construction.

SUBSTANCE: device comprises the assembling-arresting unit which locks the bushing against self-unscrewing. The bushing is provided with a heat insulating material and sealing composition and is made of the self-unscrewing spring, which accumulates mechanical energy. The inner end of the spiral belt is provided with a blade, which is mounted in the vicinity of the face edge of the inner end of the belt and the ends of which are provided with guiding projections. The method comprises setting the assembling-locking unit with the bushing on the pipe end to be welded, assembling the pipe butt by moving the end of the pipe to be welded onto the projections of the bushing and heat insulating material to provide a gap between the pipe faces, unlocking the bushing, and removing the assembling-locking unit. The spiral belt is unwound with sliding with respect to the inner end. The gap size depends on the thickness of the assembling-locking unit. The projections of the blade cooperate with the side edges of the belt turns and cause the sealing composition to move thus providing a protecting roll.

EFFECT: enhanced reliability of the pipeline.

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