Method of anticorrosive insulation of weld joints

FIELD: construction.

SUBSTANCE: method comprises applying epoxy primary layer and thermo-shrinking adhesion belt provided with a protecting layer on the surfaces to be insulated. The epoxy primary layer is applied on the surface heated up to a temperature of 60-90°C.

EFFECT: enhanced reliability.

4 cl, 1 tbl

 

The invention relates to the production of corrosion-resistant insulating materials and is designed for insulation of welded joints, knees, elbows steel pipelines with external factory plastic coating in route conditions and repair of the pipeline.

There is a method of applying a protective coating on the insulated surface of welded joints of steel pipes (p. the Russian Federation No. 2130149, IPC 7: F16L 58/10, Appl. 1998.04.17, publ. 1999.05.10. "The method of applying a protective coating on the insulated surface of welded joints of steel pipes with factory polymer coating in field conditions"), including pre-heating of the insulated surface, applying and forming therein a thermoplastic adhesive layer and then applying and forming at least one layer of polymer protective coating. Before applying the polymeric protective coating on thermoplastic adhesive layer is applied an intermediate layer having high adhesion to thermoplastic adhesive layer and the polymeric material of the protective coating. This method does not allow to obtain reliable high coverage.

The closest (EN 2228910 C1, 20.05.04) of the claimed invention to the technical essence and the achieved result is a way to protect the weld is tikov and repair of the pipeline by drawing on the insulated surface of the first epoxy compositions and then heat-shrinkable multilayer tape containing layer of plastic tape base, electro-chemically modified to absorption dose of 25 to 50 Mrad and oriented in a shared direction for 25-75%, and the adhesive layer. The disadvantages of this method are the relatively low strength characteristics of the coating due to the use of high-pressure polyethylene for the manufacture of tapes in heat-shrinkable adhesive tape and uniaxial its orientation does not give the opportunity to get a quality coating that shrinkage is not formed would be bumps and bubbles. In addition, heat insulated surface before applying the epoxy primer to a high temperature increases the complexity of the process in route conditions.

Object of the present invention to provide a high-strength, reliable protective coating, without bumps and folds, as well as reducing the complexity of the coating field.

The problem is solved in that in the method of anti-corrosion insulation of welded joints and pipeline repair, including drawing on the insulated surface of epoxy primer, and then heat-shrinkable adhesive tape containing a protective layer of plastic tape base, electro-chemically modified and oriented in food is enom direction, and the adhesive layer, an epoxy primer is applied on the insulated surface is heated to a temperature of 60-90°and heat-shrinkable adhesive tape plastic tape-based is made from termoventilatore linear low density polyethylene, electro-chemically modified to absorb a dose of 10-15 Mrad and optionally oriented in the transverse direction by 5-15%, while the heat-shrinkable adhesive tape is applied in the form of a cuff, the edge of which is fixed multilayer electro-chemically modified reinforced tape. Epoxy primer consists of plasticized epoxy resin, modified amine hardener which are mixed immediately before use, and heat-shrinkable adhesive tape is applied on the uncured epoxy primer. Use multi-layer electro-chemically modified to absorption dose 5-15 Mrad reinforced tape, which is obtained by extruding a ribbon-fundamentals of termoventilatore low density polyethylene, electro-chemical modification of it to absorb a dose of 10-25 Mrad and applying the adhesive layer, the thickness of which is placed a reinforcing material. The finished multi-ply electro-chemically modify from the side of the adhesive layer until absorbed by the I-dose 5-15 Mrad.

To obtain tape-basics use thermometerplayboy linear low density polyethylene, such as the brand "Exceed 1327CA".

Epoxy primer is used on THE 2257-021-46541379-01.

Heat-shrinkable adhesive tape made in accordance with THE 2245-027-46541379-2004.

Multi-layer electro-chemically modified reinforced tape get in line with THE 2245-031-46541379-2004.

The method is as follows.

Made of heat-shrinkable adhesive tape.

Get a tape-based from termopechatayuschee linear low density polyethylene by the method of cast extrusion and calendering on a three-roll calender, and then subjected to a first electro-chemical modification on the accelerator of electrons to absorb a dose of 10-15 Mrad, and then biaxial orientation. Biaxial orientation of the electro-chemically modified tape-fundamentals spend on installing a roll orientation, one of the shafts which is heated to a temperature of 150-170°and the second is water-cooled, while the rotation speed of the cooling shaft 1.25-1.43 times the speed of heating of the shaft. Tape-based oriented in the longitudinal direction of 25-43%, in the transverse 5-15%. Biaxial oriented tape-based heated to a temperature of 105-115°and a method of cast extrusion of the calendering applied adhesive layer. Ready heat-shrinkable tape wound into a roll.

Fabricate multi-layer electro-chemically modified reinforced tape. To get this tape is the basis of termopechatayuschee low density polyethylene by the method of cast extrusion and calendering on a three-roll calender, and then subjected to electro-chemical modification on the accelerator of electrons to absorb a dose of 10 to 25 Mrad. Electro-chemically modified tape-based heated to a temperature of 120-140°and a method of cast extrusion and calendering put on her adhesion layer with simultaneous introduction of fiberglass reinforcing mesh, after which the electron accelerator is subjected to electro-chemical modification on the part of the adhesive layer to absorb a dose of 5-15 Mrad. The finished tape is wound into a roll. The insulated surface is subjected to sand-blasting and heated to a temperature of 60-90°C. On a heated surface, apply epoxy primer, which is prepared immediately before application to the insulated surface, which is mixed plasticized epoxy resin and a modified amine hardener. On the uncured epoxy primer is applied dimensional piece of heat-shrinkable adhesive tape (depending on pipe diameter) in the ideal cuff, edges of which are secured in the ring dimensional cut layered electro-chemically modified reinforced tape. The cuff sits gas burners. Molten core when the shrinking of the adhesive layer in heat-shrinkable tape comes into contact with the still uncured epoxy primer. Due to the heat pipes and additional heating of the coating gas burners in 3-5 minute epoxy primer cures and receive high-strength insulating coating without bumps and folds of dependable protective properties.

The application of epoxy primer at a temperature of 60-90°reduces the complexity of the process of obtaining coverage in route conditions.

Heat-shrinkable adhesive tape, tape-based manufactured from linear low density polyethylene and electro-chemically modified to absorb a dose of 10-15 Mrad and biaxial oriented in the longitudinal direction of 25-43%, in the transverse 5-15%, which can alter the linear dimensions when heated, which enables to obtain a high-quality coating with good mechanical strength.

The table shows the average values of the coatings obtained by the claimed method in comparison with the prototype.

As can be seen from the table, the coating obtained by the proposed method has higher so the and properties in comparison with the prototype, droprate, has high adhesion to steel praimirovanie surface and resistance to cathodic destruction, the induction period of oxidation ranges from 40 min, all it shows it the best protective ability and durability.

The use of the proposed method will improve the reliability of the corrosion protection of the insulated surface.

TABLE
IndexValue
The placeholderThe inventive object
Dose of heat-shrinkable adhesive tape, Mrad25-5010-15
The tensile strength, MPa1725
Elongation, %>500>500
Shrinkage, %
In the longitudinal direction20-4520-30
In the transverse direction-(-2)-(-5)
The force of shrinkage, MPa0,240,25
Temperature application of epoxy primer, °60-90
Hell is Asia to steel praimirovanie surface, kN/m1717
Dielectric continuity, kV12>20
Resistance to cracking, h>1000>1000
Cathodic delamination at a temperature of 60°cm205
The increase of the radius (cm)2,51,3
Adhesion to steel praimirovanie surface after 1000 hours exposure to water at temperatures kN/m
60°-15
98°6-
The induction period of oxidation, min->40
Impact strength, j/mm-6

1. Method of anti-corrosion insulation of welded joints and pipeline repair, including drawing on the insulated surface of epoxy primer, and then heat-shrinkable adhesive tape containing a protective layer of plastic tape base, electro-chemically modified and oriented in the longitudinal direction, and the adhesive layer, characterized in that the epoxy primer is applied on the insulated surface is heated to a temperature of 60-90°and in thermo Givaudan adhesive tape plastic tape-based is made from termoventilatore linear low density polyethylene, electro-chemically modified to absorb a dose of 10-15 Mrad and optionally oriented in the transverse direction by 5-15%, while the heat-shrinkable adhesive tape is applied in the form of a cuff, the edge of which is fixed multilayer electro-chemically modified reinforced tape.

2. The method according to claim 1, characterized in that the epoxy primer consists of plasticized epoxy resin, modified amine hardener which are mixed immediately before use.

3. The method according to claim 1, characterized in that the heat-shrinkable adhesive tape is applied on the uncured epoxy primer.

4. The method according to claim 1, characterized in that use multi-layer electro-chemically modified to absorption dose 5-15 Mrad reinforced tape.

5. The method according to claim 1 or 4, characterized in that the multilayer electro-chemically modified reinforced tape is produced by extruding a ribbon-fundamentals of termoventilatore low density polyethylene electro-chemical modification of it to absorb a dose of 10-25 Mrad and applying the adhesive layer, the thickness of which is placed a reinforcing material, and then the finished multi-ply electro-chemically modify from the side of the adhesive layer to absorb a dose of 5-15 Mrad.



 

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