Method of corrosion protection zone of a welded joint pipe

 

(57) Abstract:

The invention relates to construction and is designed to protect welded joints of pipelines with aggressive environments. In the ends of the pipes set sleeve o-cuffs and internal truss with curved edges. In the area of the weld to leave a gap through which by means of the probe serves under pressure sealing paste in the cavity formed by the inner band and the sealing elastic cuffs, until the paste through the holes drilled outside the heat-affected zone of the weld. After crimping pipe pressure in the hole choke, crack brewed. Increases the reliability of the corrosion protection of welded joints of pipelines. 5 C. p. F.-ly, 1 Il.

The invention relates to the protection of pipelines designed to transport various aggressive environments, namely internal corrosion protection of welded joints of pipes with internal anti-corrosive polymer coating.

Currently, due to increased requirements for the protection of the environment a great widespread use of pipelines, the inner surface of which is protect the th protection of external surfaces of pipelines are difficult to use to protect the internal surfaces.

For example, by anodic or cathodic protection is technically impossible to provide accommodation within the pipeline of the anode and connecting it to an external power source, which in remote areas are practically absent (1).

The principle of cathodic protection is that the destruction of the subject specially installed the anode (the protector), with more electronegative potential than the protected equipment, which serves as a cathode formed in salvanatura (1).

There is a method of internal corrosion protection of welded joints of pipes with factory internal epoxy polymer coating, which consists in applying to the zone of the weld tread aluminum alloy. The inner surface of the weld and adjacent areas previously peskostruyka, and then blown with compressed air. This is followed by deposition of plasma aluminum alloy.

The main disadvantage of this method is rapid wear of the tread ring in harsh oilfield environments, as well as the lack of sufficiently durable tread alloys, comparable in durability with a polymer coating inside the factory internal coating, consisting in the installation into the internal cavity of connected pipes before welding sleeve with a protective coating.

At the ends of the sleeve at a distance from its ends, has a special groove in which is mounted a rubber o-ring. In addition, before installing the bushing at its end areas located between the ends and grooves, under the rubber ring is applied to a special sealant. In the process of introduction of the sleeve into the internal cavity of the joined pipe sealant is squeezed out of the gap formed by the sleeve with the inner surface of the pipe and formed in the form of a roller before the ends of the sleeve, protects this backlash against the penetration of liquids transported by pipeline. Itself the rubber ring can not provide in these conditions, the tightness of the connection end sections of the sleeve coated pipes due to significant geometric errors of shapes and sizes last.

In the Central part of the sleeve on its outer surface has a special groove that allows you to create air space between sleeve and pipe in the weld zone, and therefore, to prevent thermal destruction of the protective coating of the sleeve. This zesty. To ensure centering of the sleeve relative to the welded pipe joints in the center groove of the sleeve on top of the heat-resistant gaskets installed wire ring with radial mustache placed between the welded ends of the tubes and forming a single unit with welded joint after welding (3).

Describes how internal corrosion protection of welded joints of pipes with coating requires calibration of the internal surface of the pipe ends before applying it in the factory paint finish to eliminate significant error size and shape of the surface of the pipes in place subsequent coupling with the sleeve.

The main disadvantage of the considered method, internal corrosion protection for pipeline welded joints of pipes with internal factory floor are the need for calibration of the internal surface of the pipe ends before coating, it is not enough reliable sealing of the connection of the sleeve with a coating of a pipe that is designed for the sealing ability of the cushion formed by the sealant on the edges of the sleeve during its introduction into the pipe. It is also possible peeling of the sealant from the coating of the pipe, ska.

The disadvantage of the considered method is the inability to control the tightness of the connection sleeve coated pipe.

Closest to the proposed method to the technical essence and the achieved result is a method of corrosion protection of the surface of welded joints of pipes during pipeline construction with factory internal paint coating, consisting in the installation prior to welding to the inner cavity of connected pipes bushings with seals at the ends and a groove on the outer surface with the formation of a cavity between the outer surface of the bushing and the inner surface of the pipe, which according to the invention before welding the ends of adjacent pipes in the area of the sleeve outside the heat-affected zone of the welding process perform hole, through one of which, after welding injected into the cavity pasta and serving pasta continue to output it through the second hole, and then produce a test pipe pressure in the fluid and in the absence of a through hole leak last choke (4).

The main disadvantage of the considered method is the lack of control over the filling of the cavity of the sleeve sealant, the P CLASS="ptx2">

The objective of the invention is to enhance reliability of corrosion protection of welded joints by increasing the tightness of the connection of the sleeve with the pipe, the durability of the bushing and quality control fill the cavity sealant when connecting pipe sleeve.

The problem is solved by the proposed method of corrosion protection zone of a welded joint of pipeline, including installation before welding to the inner cavity of the connected pipe sleeve with sealing sleeves on the ends and cavities formed between the inner band with curved edges, the sealing lip and the inner surface of the pipe, which according to the invention before welding the ends of adjacent pipes in the area of the sleeve, in the region of the second cavity outside the heat-affected zone of the welding process perform holes, and the sealant serves tube through the gap left when welding in the weld seam area, the flow of sealant perform under pressure prior to going through the holes, and then produce a test pipe pressure and in the absence of a leak hole zaglushit and the crack is brewed. The curved edges of the inner band on the outer surface of W is due to the elasticity of the material.

The drawing shows a circuit implementation of the proposed method, where 1 - sleeve, 2 - pipe, 3 - probe for insertion of sealant, 4 - hole in the pipe, 5 - seal, 6 - weld, 7 - tube, 8 - polymeric coating, 9 - internal brace sleeve, 10 - hole band, 11 - guides.

The method is as follows.

At the ends of the pipe 2 with the cover 9 are drilled outside the heat-affected zone during welding of the transverse holes 4 with subsequent tapping. Inside the joined pipe ends with a transverse hole is inserted a sleeve 1 of corrosion-resistant material. At the ends of the sleeve between the edge of the sleeve and the inner brace installed sealing lip 5. In the middle part of the sleeve on its outer surface through the inner band has a cavity formed by the inner surface of the pipe, for a sealant and a hole on sinocom edge of the band to fill the second cavity and forming a roll of sealant in the second cavity before sealing lip. The hole on the pipe ends is in the area of the second cavity and Orient it so that it was on the diametrically opposite side relative to the holes in the brace.

In a preferred embodiment, the method as a sealing paste is used polymeric coating type Armourcoat with high adhesive properties. It is possible to manufacture the sleeve of corrosion resistant, elastic, thin-walled material.

LITERATURE

1. Kuznetsov M. C., Novoselov C. F. and other Corrosion protection of pipelines and tanks. M.: Nedra, 1992, S. 157.

2. Patent of the Russian Federation 2103592, CL 6 F 16 L 58/02, 1995.

3. Advertising is the procedure of corrosion protection zone of welded joints of pipes with an inner polymer coating, including installation before welding in the inner cavity of the connected pipe sleeve seal at the ends of an elastic cuffs and cavities on the outer surface of the sleeve and the inner surface of the pipe formed due to internal band with curved edges, characterized in that prior to welding the ends of adjacent pipes in the area of the cavity formed by the inner bandage and elastic cuff, outside the heat-affected zone of the welding process, perform hole, and the sealing paste is injected through the zone of the weld by means of the probe until its through hole, then produce a test pipe pressure and in the absence of a leak last choke.

2. The method according to p. 1, characterized in that use sleeve of corrosion resistant elastic, thin-walled material.

3. The method according to p. 1, characterized in that the edges of the inner brace are bent inward on the outer surface of the sleeve and dividing the space between the inner pipe and the outer surface of the sleeve into two cavities.

4. The method according to p. 1, characterized in that on the curved plane of the inner band has one hole for the uniform distribution is about the band and the sealing elastic cuff.

5. The method according to p. 1, characterized in that between the inner band and the outer edge of the sleeve in the second cavity is placed a sealing elastic cuff to limit the amount of sealant and reduce the likelihood of leakage him over the edge of the sleeve.

6. The method according to p. 1, characterized in that on the inner surface of the sleeve guides are located in a spiral to the swirling flow of the transported fluid.

 

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