Method of joining pipes with inner anticorrosive coating

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

 

The invention relates to pipeline transport and can be used in the manufacture of tubes and pipes with internal anti-corrosion coating and pipeline construction.

The known method of joining metal pipes with an internal corrosion-resistant coating, which includes the installation with some clearance sleeves of stainless metal inside of the pipe ends, anchoring, applying to the inner surface of the pipe anticorrosion coatings, including part of the surface of the bushing and the connection pipe welding technology welding of two metals (U.S. Pat. Of the Russian Federation No. 2154221, CL F 16 L 13/02).

The disadvantages of this method are the low reliability of connection at the small wall thickness of the sleeve (up to 3 mm) because of the possibility of burn-through it in the process of welding joints and the high cost of connections with a large thickness (>3 mm), as the cost of corrosion-resistant metal, such as brand 18CR10NITI, more than 10 times higher than the cost of low-carbon steel pipe. In addition, this method is complicated, time-consuming and difficult to automate.

The closest in technical essence to the present invention is a method of connecting pipes with an internal corrosion-resistant coating, in which the ends of the inner pipe surface veneer heat-resistant corrosion-resistant metal, then on the inner surface is here pipes, including part of the surface of the lining, put heat-sensitive, for example a polymer, coating and make the connection pipe welding butt first on the tile, and then the base metal. The ends of the inner pipe surface veneer of thin-walled sleeve of corrosion resistant metal, which is pressed with the shift from the pipe end, then pressed the sleeve on both sides or only on one side of the end of the pipe weld ring joint pipe body, and the area between the end of the tube and sleeve being faced by welding corrosion-resistant material rollers. The press-fit bushing is carried out in a mode of high-speed plastic deformation energy of the pulsed magnetic field (U.S. Pat. Of the Russian Federation No. 2103594, CL F 16 L 58/02).

The disadvantage of this method is the difficulty of pressing and fixing the thin-walled sleeve of corrosion resistant metal with a small diameter pipes where access for welding to the inner end of the sleeve is difficult. In addition, the connection obtained in this way has a low reliability is related to the fact that on the inner end of the sleeve is formed a sharp transition between the inner surfaces of the sleeve and the pipe where corrosion-resistant coating may receive the defective when applied and during operation. This method is also difficult to build in automatic and avtomaticheskie line pipe with internal corrosion-resistant coating.

The task of the invention is to reduce the complexity of the method, the improving technology of its realization in modern enterprises and improving the reliability of the connection.

The task is solved by the fact that the connection of the pipes with an internal corrosion-resistant coating, including facing inner surfaces of the pipe ends, in corrosion-resistant material, the cladding of corrosion resistant metal on the area of the inner surface adjacent to the ends of the pipes, causing the inner surface of the pipe, including part of the surface coating, anticorrosion coatings and pipe welding technology welding of two metals, according to the invention, first do the welding corrosion-resistant metal, then faced the inner surface of the pipe ends, including partially or completely the surface of the cladding, the adhesive coating of heat-resistant corrosion-resistant material.

The adhesive coating of heat-resistant corrosion-resistant material receive thermal spray coating of corrosion resistant metal.

The method is illustrated in the drawings, which show longitudinal sections of the upper half areas of the pipe connection.

Figure 1 shows a case where the connection without grooves, as in figure 2 with groove on the inner surface of the pipe ends under gnapelet the ku corrosion resistant metal.

The method is as follows.

Connect the ends of the pipe 1 (see figure 1) to calibrate the internal diameter up to the largest size limit for the size of the pipes according to GOST that provides more accurate alignment of the edges of the pipe during welding and, therefore, higher quality weld. On an annular area of the inner surface of a width of 10-50 mm, directly adjacent to the ends of the pipes, any of the known methods napravlyayut corrosion resistant metal 2 thickness of 2-5 mm, If necessary, make the edge preparation of pipes for welding and machining the surface of the deposited metal with the purpose of its alignment. One of the known methods to obtain the adhesion of the coating without an open (through) porosity, for example, thermal spraying, revet the inner surface of the pipe ends on the anticipated length of thermal effects of welding on corrosion coating of pipes, including partially or completely the surface of the cladding, the adhesive coating 3 made of heat-resistant corrosion-resistant material. On the inner surface of the pipe, including part of the surface of the cladding, applied anti-corrosion coating 4. Connect these pipes butt welding technology welding of two metals: first, create the root welding seam 5 corrosion resistant what lectrode, then welding the main part of the seam 6 is the usual electrodes, for example UONI-13/55.

Welding of corrosion-resistant metal 2 can be produced on the inner grooves of the pipe ends (see figure 2). In this case, the flow area of the pipe is almost not reduced.

Examples of specific performance.

Example 1. The ends of steel pipes according to GOST 8732-78 diameter of 114 mm and a wall thickness of 4.5 mm grooved on the inner diameter of up to 108 mm on a length of 150 mm At the area of the inner surface of the pipe 10 mm wide, adjacent to their ends, arc way by setting VD-506DK in shielding gas napravila layer of corrosion resistant metal with the use of filler wire from a metal brand HAM thickness of 3 mm Under optimal conditions for overlaying the surface of the weld metal is very smooth. Made a shot-blasting the inner surface of the pipe, pre-heating the pipe ends to a temperature of 150°and coating the first adhesive layer of the composite powder brand PT-ON consisting of Nickel (base) and 5.2% (by weight) of aluminum. The sprayed area has a width of 100 mm, including 5 mm wide zone weld metal. Then performed in several cycles of sputtering main corrosion resistant layer with a thickness of 800 μm from the composite powder brand PT-UNHCR, SOS is Vashego of Nickel (base), 13,5-16,5% chromium, 2.5 to 3.5% silicon, 2.0 and 2.8% boron and 1.2% aluminum. The total thickness of the sprayed coating was about 1000 microns. The coating of such thickness has almost no through pores and protects the surface of carbon steel from corrosion. The coating produced thermal air plasma method using install APR-404 with a plasma torch. After this has made the application of anticorrosion coatings based on epoxy resin with thickness of 250 μm on the inner surface of the pipe, including partial (width 20-40 mm) surface coating of deposited material. Next caused extrusion of polyethylene outer covering and connected pipe welding: first produced weld root weld stainless electrodes brand SL-6 (metal electrode HG), then subsequent layers of the weld electrodes UONI 13/55.

Example 2. The ends of steel pipes according to GOST 8732-78 diameter 159 mm, wall thickness 7 mm grooved on the inner diameter of up to 149 mm length 200 mm On the inner surface of the pipe end machining fulfilled groove width 15 mm, depth 3 mm, as shown in figure 2. These grooves have napravila metal brand HAM 4 mm machining lined the surface of the deposited metal with the inner surface of the pipe. Then made the shot blasting of the inner surface is the surface of the pipe, heating of the ends of the pipe, the corrosion resistant coating of metal on the ends of the pipe 150 mm wide, including the entire surface of the deposition, application of anti-corrosion coatings and welding pipes analogously to example 1. In the last example creates a connection without reducing the flow area of the pipe.

The proposed method allows to obtain the connection of pipes with an internal corrosion-resistant coating with full protection against corrosion of the weld zone with a minimum consumption of corrosion-resistant materials. In addition, the facing ends of the inner pipe surface coating allows to obtain a smooth transition from the pipe surface to the surface of the cladding, which eliminates the possibility of premature destruction of the anti-corrosion coating of pipes on the transition. And, finally, a way to easily fit in a modern automatic and semi-automatic production line pipe with internal corrosion-resistant coating.

1. The method of connecting pipes with an internal corrosion-resistant coating, including facing inner surfaces of the ends of the tubes of corrosion-resistant material, the welding of corrosion-resistant metal on the area of the inner surface adjacent to the ends of the pipes, causing the inner surface of the pipe, including part of the surface coating, anticorrosion coatings and connect the out pipe welding technology welding of two metals, wherein the first produce welding of corrosion-resistant metal, then faced the inner surface of the pipe ends, including partially or completely the surface of the cladding, the adhesive coating of heat-resistant corrosion-resistant material.

2. The method according to claim 1, characterized in that the adhesive coating of heat-resistant corrosion-resistant material was obtained thermally sprayed corrosion resistant metal.



 

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