Method of pipeline corrosion protection

FIELD: construction.

SUBSTANCE: pipeline external surface is cleaned, prime coating is applied on it, and rolled mastic reinforced material on the basis of bitumen-polymer or asphalt-resin putty is successively spirally wound with an overlap, as well as heat-shrinkage wrapping with its subsequent thermal treatment. Prior to wrapping application polymer tape is additionally wound with the layer of the same putty on the whole of its surface that faces the pipeline, and simultaneously it is rolled with elastic rollers. Wrapping is double-layer polymer heat-shrinkage tape with hard thermomelting adhesive layer.

EFFECT: increase of pipeline reliability.

 

The invention relates to the field of protection of underground pipelines from corrosion, in particular to the technology of applying a protective coating on their outer surface.

Known methods of protection against corrosion of the outer surface of the pipeline, which consists in cleaning, applying a layer of primer, serial wound with a tension of polymer and insulation tape with mastic layer on the basis of bitumen-polymer or wax mastic and wrapper out of a sticky polymer in either single-layer heat-shrinkable tape with its subsequent shrinkage (GOST R 51164-98 "steel pipe mains. General requirements for corrosion protection". M, Gosstandart of Russia, IPC Publishing standards, 1998, table 1, structure No. 18, 21. THE 2245-023-16802026-2000 Coverage on the basis of LIAM tape and heat shrink tape", 01.11.2000,, pp.2-4, 13-15. RF patent №2265151, F16L 5 8/04, publ. 2005.11.27).

However, with this method of applying the coating layers due to the tension of the tape when wound is not filling mastic tent areas along ridges pipeline welds, which creates conditions for corrosion. In addition, the thus obtained coating is unstable relative to arise during operation of the pipeline shear loads due to the low adhesive strength to them layer of mastic tape. This leads to the formation of the corrugation the folds, especially on large diameter pipes. Use as wrappers sticky polymer or single-layer heat-shrinkable tape does not protect the coating from such loads sufficiently, because the wrapper of this type do not form on the pipe hard monolithic shell.

A known method of protecting the outer surface of the pipes from corrosion (instructions for use IN 1394-016-46541379-2005 "instructions for applying the combined protective coating based on the roll of the reinforced material FRAMES and ribbons radiation-crosslinked mastic CONRAD-GAS, www.gefestrostov.ru), in which the cleaned surface of the pipe a layer of primer and sequentially wound with tension in a spiral roll reinforced with fiberglass mesh and mastic material FRAMES (in one or two layer) and a layer of wrappers of radiation-cross-linked polymer tape with mastic layer CONRAD-GAS.

When this option is not excluded in the education tent area under the tape FRAMES along the base rollers welds. The presence in the design ribbon-wrapper CONRAD-GAS mastic layer prevents heat it to the temperature required for thermal shrinkage of radiation-cross-linked polymer basis, due to the draining of mastic, and not affected by the shrinkage of the tape is not able to prevent the formation of bumps and creases in the process of operation. This creates conditions for the Oia to penetrate the environment, including soil electrolyte, as the mastic layer, which reduces its service life due to leaching of components, and metal.

The technical problem solved by the invention is to increase the reliability of protection of the outer surface of a pipeline against corrosion by providing a snug fit of the protective coating over the entire surface of the pipeline and increase the resistance of the coating to shear loads.

The problem is solved by a method of corrosion protection of the outer surface of the pipeline, which consists in cleaning the surface, the application of a primer, serial spiral winding with overlapping roll mastic reinforced material on the basis of bitumen-polymer or wax mastic and heat shrink wrappers and subsequent heat treatment, according to the invention before application of the wrapper is conducted additionally, the wound polymer tape with a layer of the same mastic across its surface facing to the pipeline, and at the same time have it rolling elastic rollers, and as the wrapper used a two-layer heat-shrinkable polymer tape solid hot-melt adhesive layer.

Application of polymer tape with mastic layer on top of the reinforced mastic material with simultaneous is sushestvennee rolling elastic roller formed of double insulation mastic polymer layer allows for redistribution of mastic on pipe surface, filling all terrain and void, including in the area of the rollers welds. The application wrapper of heat-shrinkable tape with a solid hot-melt adhesive layer and subsequent heat treatment allows to form a rigid monolithic, tightly squeezing floor cover, not prone to the formation of corrugations and offsets during operation of the pipeline. Solid hot-melt adhesive that is melted during the heat treatment, provides after cooling, a strong coupling of coils wrappers in areas of overlap between them, increases the stiffness of the shell. Heat wrap, in particular, the radiation of the halogen incandescent lamp as compared with other types of heating (for example, gas heating or heating by the Heaters allows shallow surface heat heat-shrinkable polymeric wrapper, and poplulate adhesive layer at its edges in areas of overlap, excludes fusion wrapping and insulating layers, almost without affecting the internal mastic base, and thereby to hold sufficient shrinkage, thus forming a monolithic casing and not allowing the mastic layer.

When applying the proposed method on the entire surface of the protected pipeline is formed by a continuous adhered insulation mastic layer is protected from external influences is estcoy monolithic polymeric shell, and thus provides a reliable long-term corrosion protection of the pipeline.

The proposed method is implemented as follows.

The surface of the protected pipeline is cleaned from dirt and rust, for example, metal brushes or high-speed flow of abrasive through sandblasting nozzles. To clean the surface, apply a layer of liquid primers prepared on the basis of the applied mastic, any known method (for example, by brush, roller, spray or rubbing with a towel). While the primer is drying up on the pipeline deal spiral winding with normalized tension roll mastic reinforced material, the reinforcement of which is performed, for example, fiberglass mesh, is placed in the thickness of the mastic layer. Spiral winding is performed with overlapping manually or with the winding device, and directly before applying with mastic surface of the roll of material is removed with a release film for preventing adhesion of his turns in the coil. On top of the applied roll mastic material similarly applied polymer tape with mastic layer. This mastic layer of the tape facing the pipe surface. Put layers of insulation simultaneously rolled down with a force through the outer layer polymer Les which you elastic roller or group of rollers, rotating around the pipe and obkatyvalisj the entire surface of the pipeline. The use of elastic rollers allows a uniform compacting of the coating across the surface of the pipe, including the heat-affected zone. The force of the rolling rollers is selected taking into account the degree of plasticity of mastic. On the thus formed insulating coating spiral winding with overlapping put two-layer polymer wrapping of heat-shrinkable tape with a solid hot melt adhesive, when facing the winding to the surface of the pipe. Applied the wrapper is subjected to heat treatment, Progresa outside a polymer base to the temperature required for shrinkage and melting the hot-melt adhesive. The mode of heat treatment are selected so that the mastic layer of insulation coating is not subjected to excessive heat, which may result in runoff of mastic, warping polymer base tape with mastic layer. This mode of treatment is provided by surface heating, in particular, with the use of halogen lamps, which can be placed, for example, in covering the pipe casing, movable on him after the application of the wrapper. Winding all three types of roll materials is offset so that the laps coils were shifted relative to each other. P and mechanized application of winding all roll materials and compacting rollers of the insulating layer should be made one winding device, with three spool for mounting rolls.

The proposed method was applied for corrosion protection section of the main pipeline with a diameter of 1020 mm pipe Surface was cleaned of old coatings, dirt and rust using a small cutter cutting machine MRA-1220. On the cleaned surface consistently applied the primer layer "TRANSKOR-GAS (TU 5775-005-32989231-2005), rolled, reinforced with fiberglass mesh and mastic material FRAMES (TU 5774-014-05801845-2006), mastic polymer tape LIDAR (TU 2245-019-05801845-2006) and a wrapper from a two-layer heat-shrinkable tape THERMA-40 (TU 2245-002-44271562-00).

Application of primers was performed priming machine MGM 1220. Rolled materials FRAMES, LIDAR and THERMA-40 was applied by means of an insulating machine IMM-1220, which was equipped with two spiderites with devices for coiling of antiadhesive with mastic roll materials and sixteen spring-loaded anchor-stitcher urethane rollers for rolling after applying a layer of LIDAR, and one spidergate for tape THERMA-40 with a wide stitcher roller. After applying the wrapper was carried out by heating the surface up to 80÷100°using roaming through the pipeline device of radiant heat.

Survey of the corrosion-resistant coating after a year of operation showed that Oberto is tightly adheres to the surface of the pipeline, without bumps and folds, laps coils wrapper sealed melt its adhesive layer. Mastic insulating coating layer adhered to the metal across the surface of the pipe, including the heat-affected zone and deepening of relief. The adhesion of the coating to the metal was 16÷50 N/a see signs of corrosion of the metal and changes mastic was not found.

The proposed method provides high-tech, reliable and long-term protection of pipelines against corrosion.

Method of corrosion protection of the outer surface of the pipeline, which consists in cleaning the surface, the application of a primer, serial spiral winding with overlapping roll mastic reinforced material on the basis of bitumen-polymer or wax mastic and heat shrink wrappers and subsequent heat treatment, characterized in that before applying the wrapper is conducted additionally, the wound polymer tape with a layer of the same mastic across its surface facing to the pipeline, and at the same time have it rolling elastic rollers, and as the wrapper used a two-layer heat-shrinkable polymer tape solid hot-melt adhesive layer.



 

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