RU1818192C - Process of joint of metal pipes with inner coat - Google Patents

Abstract

Usage: the invention relates to the field of joining pipes with internal coatings by welding in the manufacture of pipelines intended for the transport of corrosive media. SUMMARY OF THE INVENTION: The end of one of the pipes to be joined is coated prior to coating to the inside diameter, which ensures that, after coating, an undeformed pipe can be inserted into the formed socket. The deformation of the other connected end is performed by compression to the size of the outer diameter, which allows it to be inserted inside the undeformed coated pipe. Pipes prepared in this way are coated internally. When joining, the compressed end is inserted through the socket until it enters the undeformed portion of the pipe while filling the cavity formed between the compressed end and the socket with a corrosion-resistant material with its sealing, after which an annular weld is applied.

Description

The invention relates to joints of pipes with internal coatings by welding and can be used in the manufacture of pipelines intended for the transport of corrosive media.

The aim of the invention is to simplify the method.

The method is carried out as follows.

The end of one of the pipes to be joined before coating is dispensed using one of the known methods, for example, using a press or by flaring. In this case, the inner diameter of the formed bell should provide after coating

the possibility of introducing an undeformed pipe into the bell. The end of the other pipe to be joined is crimped externally to an outer diameter that allows it to be inserted inside the undeformed coated pipe. Pipes prepared in this way are coated by any known method. When docked, the crimped end is inserted through the socket until it enters the undeformed portion of the pipe. To fill the cavity, elastic and deformable materials, for example rubber, lead, polyethylene, etc., can be used as sealing corrosion-resistant material. In this case, the ring of

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elastic material with an outer diameter equal to the outer diameter of the undeformed pipe is pre-worn on the crimped end before joining. When docked, the ring is compressed by axial displacement of the pipes to be joined towards each other, filling the entire space of the cavity. Thereafter, an overlap annular weld is applied. As corrosion of unstable material, bulk, molten or liquid curable materials can also be used to fill the cavity. In this case, the cavity is filled through technological openings, which can be made, for example, in the form of a gap at the end of the socket located at the top of the butt. In this case, the filling of the cavity upon joining begins after the end of the compressed part enters the undeformed portion of the pipe with the bell. This eliminates the ingress of corrosion-resistant material into the pipeline. After filling the cavity and sealing the corrosion-resistant material by axial displacement of the pipes, an overlap annular weld is applied and the process hole is sealed.

Example. The end of the oil pipe with an outer diameter of 114 mm and a wall thickness of 4 mm is dispensed with a press on a length of 60 mm to an inner diameter of 116 cm. The end of the second joint in my pipe is also crimped externally to an outer diameter of 104 mm at a length of 60 mm. On the inner surface of pipes thus prepared, including portions of the socket and the compressed end, a 0.3 mm thick primer-free enamel coating 1-B5 is applied in a known manner. A ring made of corrosion-resistant and heat-resistant fluorine rubber of the IIIRP-1345 brand is put on the crimped end. Ring width 25 mm, outer diameter 114 mm, inner diameter 104 mm. When docked, the crimped end with the ring on it is inserted through the socket until it enters the undeformed portion of the pipe, while the sealing ring abuts against the transition section of the pipe with the socket. An existing 0.7 mm gap per side provides a tight fit for abutting pipes. The axial displacement of the pipes towards each other deforms the ring, which densely fills the cavity, excluding the ingress of the medium transported by the pipeline into it. After this, an annular weld is applied. Removing the seam to a distance of more than 35 mm from the O-ring from fluorine rubber ensures that the ring will not be damaged during welding (the heat resistance of IRP-1345 fluorine rubber is 200 ° C).

The proposed method in comparison with the method of the prototype greatly simplifies the joining of metal pipes with internal coating by welding. This is ensured both by eliminating a number of operations and by making them easier to carry out. The proposed method eliminates the need to weld inserts, the effect of welding on the coating through the gap between the inserts, the possibility of corrosion-resistant material entering through the gap between the inserts. The deformation of the ends of the pipes according to the proposed method, in contrast to the known one, is performed by no more than the wall thickness of the pipes (taking into account the coating and the gap), which is technologically simpler and which does not lead to deterioration of the properties of the metal in the deformed sections. Filling the cavity with corrosion-resistant material according to the proposed method is greatly simplified, while due to the possibility of sealing the material, reliable filling of the cavity is guaranteed. The proposed method also allows for hot-docking to provide greater joint tightness. In this case, the socket end is heated before joining to a temperature ensuring the preservation of the coating material and - the material filling the cavity. Formula of the invention A method of joining metal pipes with an inner coating, comprising forming at the ends of the pipes to be connected bell-shaped pipes, sideways of pipes with each other, welding an annular seam and filling the cavity between the bell-shaped pipes with a corrosion-resistant material, characterized in that, to simplify the technology, at the end one of the pipes forms a bell by upsetting with an inner diameter equal to the outer diameter of the other pipe; at the end of the other pipe, a bell is formed by compressing it from the outside with an external diameter equal to the inner the diameter of the first coated pipe; during assembly, the compressed end is inserted into the outer socket until it partially overlaps with the undeformed portion of the outer pipe, then the cavity between the bells is filled with corrosion-resistant material and the outer pipe is welded to the second pipe.