Manufacturing method of metal pipe with inner anti-corrosion coating

FIELD: machine building.

SUBSTANCE: anti-corrosion coating is applied to inner pipe surface, bushes made from corrosion-resistant metal and having on outer surface the sealing layers in the form of elastic coating are installed inside ends of pipe with covering some part of coating and bushes are fixed by their expansion till they tightly touch inner pipe surface. Sealing layer can be made from elastic polymer material.

EFFECT: reducing labour intensity of production and reducing the cost of products.

6 cl, 3 dwg

 

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

A known method of manufacturing a pipe with an internal corrosion-resistant coating comprising securing liners, made from a strip of corrosion-resistant metal, the inside of the pipe ends contact welding over the entire surface of the contact pads with the pipe and applying a corrosion-resistant coating on the inner surface of the pipe and partially inserts (U.S. Pat. Of the Russian Federation No. 2177101, CL F16L 58/04, publ. 20.12.01, bull. No. 35).

The disadvantage of this method is the complexity of the technological process of formation and consolidation of the liners on the inside of the pipe ends from the point of view of its mechanization and automation in mass production. In addition, there are high requirements for precision forming inserts on the outer diameter, since a gap between the sleeve and pipe welding over the entire surface of their contact is impossible.

The closest in technical essence to the present invention is a method of manufacturing a steel pipe with an internal anti-corrosion coating, including the calibration of the ends of the pipe internal diameter up to the largest size limit for this assortment of pipes, application of anti-corrosive treatment is Oia on the inner surface of the pipe, the installation of the sleeves of stainless steel, having on the outer surface of the sealing layers, placed in the annular grooves of the sleeves, the inside of the pipe ends overlapping portion of the cover and attaching the sleeves by hand cornerwise device before contact with the interference fit with the inner surface of the tube (U.S. Pat. Of the Russian Federation No. 2262028, CL F16L 13/02, publ. 10.10.05, bull. No. 28).

The disadvantage of this method is the complexity of manufacturing and the relatively high consumption of stainless steel in the manufacture of bushings due to the necessity of forming annular grooves lathe way that collectively leads to an increase in their value.

The objective of the invention is to reduce the complexity of the manufacturing process and reduce the cost of production.

The problem is solved in that in the method of manufacturing a metal pipe with an internal anti-corrosion coating, including the application of anti-corrosive coating on the interior surface of the pipe, the installation of bushings of corrosion-resistant metal, having on the outer surface of the sealing layers, the inside end of the tube with overlapping portion of the cover and attaching the sleeves by hand until it touches the interference fit with the inner surface of the pipe, according to the invention the sealing layers applied on the outer surfaces of the bushings outside of those areas the economic impact, occurs during welding of pipes, in the form of the elastic coating.

The sealing layer may be made of elastic polymer material.

The sealing coating may be made of thermosetting plasticized polymer compound.

The sealing coating may also be applied in closed or open side of the inner end of each bushing is provided with an annular groove to fill the groove.

Uncovered portion of each of the bushings in the immediate vicinity of the border of the coating can be provided with an annular groove.

In addition, the inner ends of the sleeves can be made with a sloping outer chamfers, equipped with a flexible coating.

In the investigated us patent and technical literature such solutions have been identified that allows to make a conclusion on the conformity of the proposed solutions to the criteria of "novelty" and "inventive step".

The method is illustrated in the drawings, which show longitudinal sections of the upper half of the end portion of the pipe (the lower half is a mirror image of the upper)made by this method.

The method is as follows.

On the inner surface of the grooved pipe 1 (see figure 1), excluding the end zones tube length of 50-100 mm, subjected to a heat treatment welding, UNOSAT anti-corrosive heat-sensitive, for example, polymer, floor 2. Inside the ends of the pipe with an overlap part of the anticorrosive coatings set of thin-walled sleeve 3 from corrosion resistant metal, having on the outer surface of the flexible sealing cover 4. The thickness of the sealing coating is selected with consideration of filling irregularities of the outer surface of the bushing and the inner surface of the pipe and for raw lathe way and unpolished surfaces is 0.2-0.4 mm Length covered area of the sleeve is 10-30 mm

In the case of strong irregularities of the parts which come into contact surfaces of the pipe and the bushing on the outer surface of the sleeves can be made open from the inner ends of the sleeves (see figure 1) or closed (see figure 3) annular grooves, a depth slightly greater than the maximum possible irregularities. The width of the grooves is 10-30 mm In this case, the grooves are completely filled with sealant.

In the case of hand sleeves cornerwise device, when the distribution process begins with the inner end of the sleeve, to avoid displacement of the mandrel excess sealant coating in the weld zone of the sleeve, the uncovered portion of each of the bushings in the immediate vicinity of the border of the coating provide the circular groove 5, which serves as a reservoir for excess sealant (see figure 3). Experiments showed that when injected sealant in the area of welding the welding process becomes much more difficult. With this method of distribution there is also the danger of damage to the corrosion coating of pipes extending inner end of the sleeve so that the inner ends of the bushings carried out with gentle (under an angle of 9-12°) outer chamfers, equipped with a flexible coating 6. In the case of a distribution of calibrating sleeves punch, which starts to give out sleeve with their outer end, these drawbacks are not available, therefore the need for the elements 5 and 6 is eliminated. However, for technological reasons, the method of distribution of the sleeves with the help of the mandrel may be preferable.

Material for sealing coating can serve as a single component (curing in contact with air) or two (with a special hardener) silicone sealants, which can withstand temperatures up to 350°C, which allows to reduce the length of the sleeves without the risk of thermal destruction of the sealing cover when welding pipes. You can also use curing vysokopastavlennye compounds based on epoxy and other resins. In all these cases, the length of the sleeves is selected taking into account short-term (not less than 2 hours) heat resistance of the materials used.

Use as a sealing cover sleeves elastic materials is dictated by the fact that the metal pipes and sleeves, perform their different functions, as a rule, have different coefficients of thermal expansion, which can cause displacement of the inner ends of the bushings relative to the tube and, as a consequence, damage to the protective coating of the pipe when the temperature changes in the case of a rigid bonding of the sleeve to the pipe surface.

Attaching sleeves with simultaneous sealing of the gap between the sleeve and pipe are made by hand (radial strain) bushings with calibrating or cornerwise device before contact with the interference fit with the inner surface of the pipe. Tension occurs when there is some plastic deformation of the pipe end in the process of distribution of the sleeves.

During the pipeline construction is made in such a way pipe butt weld in the welding of two metals: first weld sleeve of corrosion resistant metal with the use of corrosion resistant welding electrodes, then the pipe using conventional electrodes.

Examples of specific performance

Example 1. The ends of the steel pipes with an outer diameter of 426 mm and a wall thickness of 10 mm (on THE 14-3-1128-2000) grooved inner gauge diameter 414 mm (this is the largest inner diameter of the pipe at the specified TC) for a length of 250 mm On the inner surface of the pipe by known techniques caused epoxy coating thickness of 0.35 mm, except for anavah zones tube length 80 mm Sheet stainless steel 08KH18N10T made sleeve outer diameter 412 mm, a wall thickness of 2 mm and a length of 150 mm (see figure 1). Outer ends of the bushings has razvalivali with the formation of the outer flange height of 3 mm from the outer surface of the sleeve). On fat outer surface of the inner ends of the bushings 3 hours before installing them into the pipe struck the floor of the two-component silicone sealant brand Sealers-1-18 width of 30 mm, a thickness of 0.2-0.4 mm, an Inner surface of the pipe in the area of placement of the sleeves also cleaned and degreased gasoline. Set the sleeve into the tube until the stop shoulder on the ends of the pipe and using a punch-caliber diameter 411 mm distributed sleeves along their whole length by using a calibrating device.

In this method of manufacturing a pipe with an internal heat-sensitive anti-corrosive coating consumption, stainless steel, reaching for the manufacture of protective sleeves, is reduced to 1.5-2 times compared with the prototype. No turning of the sleeves and manufacture of thin-walled rubber sealing rings. All this significantly reduces the cost of protective sleeves while maintaining at least the same level of the main functions of the bushing - seal joint area from penetration of aggressive transported product pipeline.

Example 2. It is icy steel pipes with an outer diameter 114 and a wall thickness of 5 mm (according to GOST 8732-78) was calibrated to the inner diameter 106,6 mm length 200 mm On the inner surface of the pipe by known techniques caused epoxy coating thickness of 0.35 mm, excluding the end zones tube length of 50 mm From sheet stainless steel 08KH18N10T produced bushing outer diameter of 104 mm, a wall thickness of 3 mm and a length of 120 mm On the inner end of each sleeve has fulfilled the outer chamfer at an angle of 10° to the axis. All adjacent to the chamfer sharp edges have scrupoli and abraded with fine sandpaper. The inner end of each sleeve has trimmed on a lathe to the outer diameter 103 mm in a length of 20 mm with the formation open at this end of the ring groove (see figure 2). With an interval of 5 mm from the groove is formed with an annular groove 5 of a width of 8 mm, depth 1.5 mm for excess sealant. Outer ends of the bushings prepared for welding standard. On skimmed the surface of the chamfers of the inner ends of the bushings up to 1 day before their installation in the pipe was coated from a one-component silicone sealant brand GED-1 thickness of 0.2-0.3 mm. For 3 hours prior to the installation of the open ends of the grooves of the sleeves filled with sealant Sealers-1-18. The inner surface of the pipe in the area of placement of the sleeves were cleaned and degreased with gasoline. Set the sleeve into the tube and using cornerwise devices distributed bushings by moving the mandrel from the inside of the pipe to its ends.

Hidraulicas what their tests are made in this way pipes after connection butt welding showed no penetration pressing water to the area of the joints.

1. A method of manufacturing a metal pipe with an internal anti-corrosion coating, including the application of anti-corrosive coating on the interior surface of the pipe, the installation of bushings of corrosion-resistant metal, having on the outer surface of the sealing layers, the inside end of the tube with overlapping portion of the cover and attaching the sleeves by hand until it touches the interference fit with the inner surface of the pipe, characterized in that the sealing layer is applied on the outer surface of the sleeve outside the heat-affected zone that occurs during welding of pipes, in the form of the elastic coating.

2. The method according to claim 1, characterized in that the sealing cover is made of elastic polymer material.

3. The method according to claim 1, characterized in that the sealing coating made of a thermosetting plasticized polymer compound.

4. The method according to claim 1, characterized in that the coating is applied in a closed or open side of the inner end of each bushing is provided with an annular groove to fill the groove.

5. The method according to any one of claims 1 to 4, characterized in that the uncovered portion of the sleeve in the immediate vicinity of the border of the coating provide the circular groove.

6. The method according to any one of claims 1 to 4, characterized in that the outer surface of the inner end of the sleeve vypolnyaut sloping outer chamfer, covered with an elastic coating.



 

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