The method of isolation of metal pipes

 

(57) Abstract:

The invention relates to the field of corrosion protection of steel pipes for hot water supply systems, gas and oil pipelines, in particular to the coating on the outer surface of the pipe. On the cleaned surface of the pipe cause the porous layer of corrosion-resistant material, such as aluminum, the tube is heated to 70 - 90oC, then layers applied anti-corrosion coating, which is used as a solution of phenol-formaldehyde resin, such as bakelite varnish, after which the tube is wound reinforcing material, which is used as fiberglass impregnated with the same solution, the tube is heated to 160 - 200oC, stand 10 - 15 min and cooled. The invention provides reliable corrosion protection of pipes when exposed to temperatures up to 300oC at 100% humidity in an environment contaminated with acids, alkalis and petroleum products, high dielectric and mechanical strength.

The invention relates to the field of corrosion protection of steel pipes for hot water supply systems, gas and oil pipelines, in particular to the coating on the outer surface of the pipe.

It is known that TRU is ery difficult conditions. In real conditions, frequent leaks of hot water, flooding by sewage from malfunctioning sewage, which may contain acids, alkalis and petroleum products. Given the high temperature it is a powerful factor in the corrosion of pipes. But even more dangerous is the electrocorrosion, which is due to leakage currents from passing near pipelines tramways, power cables and communication cables. Hence the requirements for protective coatings against corrosion:

1. The temperature resistance up to 150oC at 100% humidity (GOST requirements).

2. High insulating quality when 150oC and 100% humidity.

3. Chemical resistance to acids, alkalis and petroleum products.

4. The availability of reliable protective shell for corrosion-resistant coating that eliminates damage during installation and transportation.

In a known method of applying a corrosion-resistant coating [1] on the cleaned surface of the pipe put a layer of liquid glass, cover it flexible synthetic wrapping material is dried in thermosuit, and then put a layer of waterproofing, waterproofing use paraffin. This coating has low mechanicaly metal heat pipes [2], to use layering anticorrosive bituminous mastic at a temperature of 170-190oC, between layers of mastic wound layers of reinforcing material, such as fiberglass, then after curing mastic put a layer of insulation and tie reinforcing mesh.

This method has serious technological deficiencies and low maintenance qualities of the coating.

1. The complexity and increased hazard to personnel when working with mastic, preheated 170-190oC.

2. The need for long-term (three hours) preparation of mastic before applying to the pipe.

3. The need to accurately maintain the temperature (170-190oC) mastics for producing high-quality coverage, which is problematic for a large amount of thick mass.

4. In an environment with high temperature and 100% humidity, characteristic for closed heating, electrical properties of mastic quickly broken and the metal becomes unprotected against electrical corrosion.

5. Protective coating of pipes on the basis of bitumen mastic is very unstable against oil, which together with wastewater fall into closed Talgat easily be damaged during transportation and installation.

In the present method of isolating metal pipes, including layering corrosion-resistant coating and winding reinforcing material, before applying anti-corrosion coating on the cleaned surface of the pipe put-porous metal layer from corrosion-resistant metal, such as aluminum, the tube is heated to 70-90oC, and after application of each layer anti-corrosion coating, it is dried, then the pipe is wound reinforcing material, after which the tube is heated to 160-200oC, as a corrosion-resistant coating using a solution of phenol-formaldehyde resin, such as bakelite varnish, and as a reinforcing material is glass fiber cloth impregnated with a solution of phenol-formaldehyde resin, such as bakelite varnish.

The inventive method due to the solid dielectric composite coating and its strong connection with the surface of the pipe provides reliable corrosion protection of pipes when exposed to temperatures up to 300oC at 100% humidity in an environment contaminated with acids, alkalis and petroleum products, high dielectric and mechanical strength approaching that of metal required for transportation and installation immoral requirements of the GOST requirements.

The technology of applying a protective coating is as follows. First, the pipe is passed through the cleaning line. Here the pipe is cleaned of dirt, metal brushes, cleaned from rust by shot blasting installation. The surface is then covered with a layer of spongy metal, for example aluminum, the method of electric arc spraying. The thickness of 30-50 μm. Then the pipe is placed in the installation of coating.

The unit is a heat insulating bunker, inside of which there are roller bearings with drive, sprayers and a mechanism for winding reinforcing material moving along the guides, and the heater pipe. Here the pipe is installed with the ends of the rotating roller support, heated to 70-90oC. the Speed of rotation of the pipe in roller bearings 4-10 rpm depending on pipe diameter. Then by rotating the pipe nozzles, moving the guide along the pipe at a rate of 1-3 m/min, is applied with simultaneous drying of 3-5 layers of lacquer. Then with a special carriage moving along the guide along the pipe, it leaves the overlapping 10-66% fiberglass, impregnated with bakelite varnish. After winding raise ptx2">

Sources of information

1. RF patent N 2033568, F 16 L 58/00, 20.04.95.

2. USSR author's certificate N 1629611, F 16 L 59/00, 23.02.91.

The method of isolation of metal pipes, including pre-cleaning, layering corrosion-resistant coating and winding reinforcing material, characterized in that before applying anti-corrosion coating on the cleaned surface of the pipe cause the porous layer of corrosion-resistant metal, such as aluminum, the tube is heated to 70-90oC and layers applied anti-corrosion coating, then the pipe is wound reinforcing material, after which the tube is heated to 160-200oC, incubated 10 min and cooled; as a corrosion-resistant coating using a solution of phenol-formaldehyde resin, such as bakelite varnish, and as a reinforcing material is glass fiber cloth impregnated with the same solution.

 

Same patents:
The invention relates to construction and is used for corrosion protection of underground pipelines from cast iron pipes

The invention relates to the construction and can be used to protect pipelines from corrosion
The invention relates to a submerged pipeline, consisting of an iron tubular elements, in particular of cast iron

The invention relates to the construction of pipelines, mechanical engineering and can be used in the manufacture of containers, fuselage and other shell-type structures, in particular in the protective shells made of composite materials

The invention relates to the production and repair of underground gas and oil pipelines and can be used, for example, to protect steel pipes from corrosion at operating temperatures from -60 to +60oWith

The invention relates to valves and can be used in oil, gas and chemical industries for the transportation of corrosive environments pipes

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.

3 cl, 6 dwg

FIELD: corrosion prevention technologies.

SUBSTANCE: method includes serial application of layers of polymer compositions to metallic surface, while serial layers of polymer compositions are made with various thermal expansion coefficients. As said polymer composition polyurethane compound is used with special admixtures and filling agent, influencing thermal expansion coefficient of covering layer, and content of said filling agent in each following layer is set less than content of said filling agent in previous layer.

EFFECT: higher efficiency.

2 cl, 9 ex

FIELD: construction.

SUBSTANCE: protecting coating comprises several layers. One of the layers is made of an elastomer. The elastomeric sealing layer is made of a calendered raw rubber which is protected with the fiber glass fabric from both sides. The fiber glass fabric is impregnated with phenol-formaldehyde resin with subsequent solidifying and vulcanizing the rubber.

EFFECT: enhanced reliability.

1ex

FIELD: construction.

SUBSTANCE: method comprises removing the exhaust insulation from the pipeline, preparing the outer side, applying the primer coat, and winding belt coating made of oil polymer. The belt coating is reinforced with glass net.

EFFECT: enhanced reliability.

FIELD: pipeline transport.

SUBSTANCE: method comprises fusing corrosion-resisting metal on the zone of the inner surface directly adjacent to the faces of pipes, lining the inner surface of the pipe ends including the surface of the fusing by adhesion coating made of heat-resistant corrosion-resisting material, applying anticorrosion coating on the inner surface of pipes including the surface of lining, and joining pipes by welding. The adhesive coating made of the heat-resistant corrosion-resistant material is made by gas-thermal spraying of the corrosion-resistive metal.

EFFECT: enhanced reliability.

1 cl, 2 dwg

FIELD: protection of metals against corrosion; protection of extended underground gas lines against corrosion.

SUBSTANCE: proposed method includes restoration of defective sections of gas lines by application of insulating protective coats and connection with cathode protection system; defective section of gas line is preliminarily disconnected from gas main and is freed from natural gas; gas released from this section is compressed and is charged in reservoirs under pressure; gas line surface is cleaned from soil and defective coat by forming temperature gradient and stresses between defective coat and gas line; then finish cleaning of outer surface of gas line is performed at simultaneous suction of dust and gas line is heated to temperature of 70 to 175°C, after which layers of adhesive composition and dielectric insulating coat are applied at succession at overlapping joints between steel pipes of gas line and layer of spiral-shaped coat made from metal at potential more negative as compared with potential of gas line being protected; metal coat is applied in form of tape or foil whose ends are brought out at distance of (0.01-1)d, where d is diameter of pipe. Then, insulating plastic coat is applied on metal coat and after erection of gas line, ends of tape or foil are electrically connected at points of joints of steel pipe over entire length of gas line through switching units and parameter measuring units.

EFFECT: enhanced reliability of corrosion protection; considerable reduction of energy expenses; increased service life of metal coat.

3 cl, 10 dwg

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.

2 dwg

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

FIELD: pipeline construction.

SUBSTANCE: method comprises applying interrupted layer of concrete-sand coating along the section of the pipeline to be repaired, allowing the layer to solidify, and applying the coating throughout the length of the pipeline section to be repaired. The coating mixture is supplied through the step hose thus allowing the thickness of the coating to be up to 400 mm for the diameter of the pipeline up to 5000 mm.

EFFECT: enhanced reliability.

2 cl, 5 dwg

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

Up!