Method of repairing corrosion protection of pipeline

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.

 

The invention relates to the construction of pipeline transport and is used for corrosion protection of transporting gas or liquid trunk, commercial and industrial pipelines, in particular to restore corrosion protection coatings of oil pipelines, oil pipelines and gas pipelines in the repair and construction in route conditions, including without stopping the transport of the product.

It is known that during the operation of metal-loaded internal pressure of the pipeline is a violation of the outer insulating corrosion-resistant coating, the durability of which is significantly less than the lifetime of the pipeline. The result is a sub pellicle corrosion loss of metal on the surface of the pipeline or stress corrosion (SCC) cracking of the metal of the pipe wall under tension. This leads to the destruction of the integrity of underground pipelines.

Known way to restore the protective coating, which consists in cleaning the pipeline from the old insulation, sand blasting surface treatment, degreasing, applying primer and spraying polyurethane, or apoxyomenos, or polyurea composition. However, this method has several disadvantages: it requires a thorough preparation of the surface, which is difficult in field conditions, etc the only change is positive when ambient temperatures. In addition, the known solution is distinguished by low productivity due to the lack of comprehensive mechanization and automation of the coating process; the high cost of coverage due to the high cost of components, which prevents its wide application, and it is known that polyurethane compositions based on coal tar pitch environmentally hazardous to human health and the environment.

There is a method of re-insulation of pipelines thermoplastic resin, which consists in cleaning pipes from the old insulation, sanding, priming the surface, causing the melt mastic and wrapping layer. The disadvantages of this method are the need for careful surface preparation of piping not less than degree 3; the energy intensity due to the necessity of heating the putty to 200°and heating the surface of the pipeline, which is difficult in sub-zero temperatures of atmospheric air. It is known that the application of bitumen-polymer mastics necessary to ensure the prevention of Oceania mastic from the walls of the pipeline, while the service life of asphalt pavements is up to 15 years, which is 2 times less than the service life of pipelines. In addition, there is a method characterized by low productivity and a significant amount of used equipment - up to 21 units.

Know the ten adopted for the prototype method of protection against corrosion in the base and route conditions tacky polymeric tapes of PVC or polyethylene, as well as heat-shrinkable tape, which has a number of significant advantages compared to the previously described solutions. Thus, the known method:

- high performance, especially on pipelines of large diameters;

the possibility of applying in summer and winter conditions;

- applied manually on short pipeline sections (see EN 2151942 C1, 27.06.2000).

The disadvantages of this method are high requirements for surface preparation, the need for heating of the pipeline in some cases up to 30-50°regardless of the ambient temperature. Thus the service life of the coatings is 7-14 years, much less than the lifetime of the pipeline. In addition, the known method does not eliminate the presence of a tent effect (voids) in the zone of the weld and has a relatively high cost.

The claimed solution aimed at eliminating the above disadvantages. The invention solves the problem of obtaining external protective composite coating having the advantages of protective coatings based on thermoplastic polymer-bitumen mastics, combined with the advantages of coatings on the basis of the sticky polymer tapes, improve quality, and improve the reliability of the protective properties, longer life coverage is comparable to the lifetime of the new pipeline and improve the program performance coating in route conditions on pipelines, including large diameter 1420 mm

Achievable technical result - a significant slowdown in the rate of development of sub pellicle and stress-corrosion on preizolowane when renovations pipelines, as well as preventing corrosion on new pipelines within a time comparable to the lifetime of the new pipeline.

This technical result is achieved in that in the method of restoring corrosion protection of pipelines, which consists in cleaning the pipeline from the old insulation, the preparation of its outer surface, consistent application to the outer surface of the pipe primer and winding with overlapping combined tape mastic coating containing ASMOL petroleum derivative polymer, for uniform adhesion anticorrosion layer and eliminate voids in the area of pipeline welds used previously reinforced at the factory mastic layer, and as a wrapping layer combined tape mastic coating polymer tape with a deposited in the zone of overlap of the mentioned mastic layer, or heat-shrinkable tape, followed after its winding and heat at a temperature of 95-120°With reinforcement layer of mastic perform placed in the middle steklosetka the or outside polymer tape.

The claimed method of corrosion protection of the pipeline in the field is as follows. After opening of the pipe and clean it from the ground and the old insulation produce its outer surface for the subsequent application of a protective coating. The claimed method of corrosion protection of the pipeline does not require a high degree of surface preparation (4 or less). Cleaning, preparation and coating is performed with the use of the existing equipment, for example, known from RU 2151942 C1, 27.06.2000.

Previously reinforced at the factory mastic layer placed in the middle of the mesh or the outer side of the polymer tape PVC or polyethylene, supplied in rolls to the work site. While the application of the combined tape mastic coating is performed with an overlap of from 11 to 50% of the width of the tape and tightness to ensure the integrity of the coating. The magnitude of overlap depends on the composition and type of soil and determines the type of wrapping layer. On top of the combined reinforced tape mastic coating containing ASMOL petroleum derivative polymer, put a wrap of polymeric tape (PVC or polyethylene) with a layer of the above-mentioned thermoplastic resin for sealing wrappers in the zone of overlap, or Oberto is of the heat-shrinkable tape and subsequent shrinking at a temperature of 95-120° C. With a small amount of work heating of the heat-shrinkable tape is carried out manually in a gas burner. When large volumes of work heating of the heat-shrinkable tape is realized by means of a heating installation for the shrinking of the CNTS with the speed of installation 60-100 meters per hour.

In the proposed method using petroleum mastic "ASMOL" due to the higher stability of the composition, determining more than 2 times longer service life of the coating in comparison with polymer-bitumen mastics, and higher adhesion inhibitory properties and, as a consequence, a 10 times reduction in the flow speed of the sub pellicle corrosion and stress corrosion in aggressive environments at higher performance application (see "instructions for experimental use and application of mastic composition "ASMOL on the outer surface of the main pipelines for major repairs and construction in the field of RD 4859-1 OP 16802026-97, Ufa, SIC ' SEARCH', 1977).

The claimed method has a high degree of corrosion protection of underground pipelines and, in the first place, pipelines large diameter up to 1420 mm. A protective coating formed in route conditions directly in the installation and repair of main, commercial and technological t is unaproved, achieves quality factory coatings at lower cost, can be used without additional costs, heating and pipeline coating materials.

The proposed method differs from other methods of corrosion protection piping:

for corrosion protection used are derived from petroleum residues petroleum mastic "ASMOL";

as the anticorrosion layer is applied mastic in the form of mastic insulation tape, reinforced with fiberglass mesh (PVC or polyethylene film) and ruanruan in terms of plant production;

- apply the Assembly of the combined anti-corrosion coating directly on the track without stopping the operation and integrity of the pipeline or basic conditions;

- used the formation of the coating on the surface of the protected pipeline without additional heating in the cold season;

- applied termowizyjne wrapping layer to facilitate a smooth fit anticorrosion layer and to prevent the presence of voids in the area of pipeline welds;

- in the production process uses commercially available equipment for coating, and installation of heating termousazhivaemoy CNTS, excluding Oplev antiadhesive layer when etched Ober the key.

The way to restore corrosion protection of pipelines, which consists in cleaning the pipeline from the old insulation, the preparation of its outer surface, consistent application to the outer surface of the pipe primer and winding with overlapping combined tape mastic coating containing ASMOL petroleum derivative polymer, characterized in that for uniform adhesion anticorrosion layer and eliminate voids in the area of pipeline welds used previously reinforced at the factory mastic layer, and as a wrapping layer combined tape mastic coating polymer tape with a deposited in the zone of overlap of the mentioned mastic layer, or heat-shrinkable tape followed after her winding when shrinking the temperature 95-120°With reinforcement layer of mastic perform placed in the middle of the mesh or outside - polymer tape.



 

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