A method of manufacturing a pipe with internal coating

 

(57) Abstract:

The invention relates to the construction and used for the construction of pipelines. Cylindrical inserts of stainless metal is placed within the ends of the metal pipes. The outer surface of the ear connects to the inner surface of the pipe ends by diffusion welding, while the contact pressure of the connected surfaces is provided by the different thermal expansion of connected elements, while heating. Recommendations on the choice of the temperature coefficients of linear expansion of connected elements. Improved reliability of the pipeline due to high corrosion resistance zone of welded pipe joints in the construction of the pipeline. 2 C.p. f-crystals, 2 Il.

The invention relates to the field of pipeline transport and can be used in the manufacture of pipes with internal coating for the construction of pipelines in the oil and gas industry and housing and communal services.

There is a method of joining pipes with an internal corrosion-resistant coating, where the ends of the inner pipe surface veneer by pressing sleeve high-speed plastic deformation, moreover, the pressing sleeve is produced with its flared on the end of the pipe or without flanging, prepare edges for welding and connecting pipes in two stages: first, produce a weld seam on the lining, and then perform the welding joint according to the main material [2].

There is also known a method of connecting pipes with an internal corrosion-resistant coating, where the ends of the inner surface of the pipes first veneer a thin-walled sleeve of antikorrozionnihe metal that are pressed offset from the pipe end, then pressed the sleeve on both sides or only from the end of the pipe weld ring weld pipe body and the facing inner surface of the pipe welded between the sleeve and the pipe end is carried out by welding corrosion-resistant material rollers with partial overlapping of the leg of the weld and rollers between themselves, with the amount of displacement of the sleeve relative to the pipe end and the number of surfaced rollers is determined from the ratio of L2(nh+k)/3, where L is the amount of displacement of the sleeve relative to the end of the pipe, mm; n is the number of surfaced rollers, equal to 1 or 2; h is the width of the ring surfaced roller, m; k - leg fillet weld, welding the sleeve from the sides of the ke, and then run welding of a joint according to the main material of the pipe [1].

These methods have significant drawbacks: first, it requires specialized expensive equipment for pressing sleeves on the ends of the pipes, namely magnetic-impulse installations Miu-30; secondly, with this technology, distribution sleeve accepts barrel-shaped, that is, there is the presence of edge effect, in which the outer surface of the ends of the sleeve will not come in contact with the inner surface of the pipe end. To eliminate this disadvantage of the second method the ends of the sleeves are welded to the inner surface of the pipe ends, and this leads to the appreciation of the connection, as you have to use for this purpose surfacing installation SFT-1 with power supply SVU-400. That is, increased energy costs. In addition, to obtain good corrosion resistant surfacing layer with metal pipes have to use filler material with a high content of alloying elements type of welding wire EP-367 (NM), where 90% of alloying elements: chromium, 15% Nickel - 60%, molybdenum - 15%, and the rest is only 10% iron, which leads to a significant appreciation of the connection.

The problem is solved as follows. In the method of manufacturing a pipe with internal coating, which provides for the fixing of the cylindrical inserts of stainless metal inside the ends of the pipe and the coating on the inner surface of the pipe, the difference is that the cylindrical liners are made of corrosion-resistant metal having a greater thermal coefficient of linear expansion than the metal of the pipe, and connect the outer surface of the cylindrical inserts with the inner surface of the pipe ends by diffusion welding by sharing their heating and create between them the contact pressure due to the difference in temperature coefficients of linear expansion of the metal cylindrical liners and pipes.

In another embodiment, the ends of the pipe internal diameter is pre-calibrated for length not less than the length of cylindrical inserts of corrosion-resistant metal, and the ends of the pipes, installed liners to connect them together by diffusion welding calibrated at the inner diameter to the length of the cylindrical inserts of stainless metal.

Because of those distinctive PA.

In Fig.1 shows a pipe with internal coating, obtained by the proposed method, where the inside of the metal pipe 1 is installed and fixed cylindrical liners 2 and put the inner cover 3 and the outer coating 4 of Fig.2 - option.

The method is as follows. The inner surface of the metal pipe 1 is cleaned from corrosion products, scale, etc., for example, drivescrubber. Inside the end of the pipe 1 is installed liner 2 of the corrosion-resistant metal by pressing. Then the end of the pipe 1 and the installed liner 2 are connected by diffusion welding, for example by heating in an electric furnace to a temperature of intensive flow diffusion processes between the metal pipe 1 and liner 2. Contact pressure in the process of diffusion welding is created due to the fact that the metal liner 2 has a greater thermal coefficient of linear expansion than the metal pipe 1. Diffusion welding is carried out in inert gas or vacuum. A similar method of preparing and the second end of the pipe 1. After that apply the coating 3 on the inner surface and the coating 4 on the outer surface of the pipe 1. And if necessary, prepare the edges of the Tr is nutrena diameter by carnerosana or rolling. Also the pipe 1 with the liner 2 can be calibrated internal diameter of the above technologies.

The proposed method can significantly improve the quality of the manufacture of pipes with internal coating, as the liner of corrosion-resistant metal connected with the pipe by diffusion welding over the entire surface of contact. Furthermore, the reduced cost of manufacturing pipes with internal coating, eliminating the need for additional securing liners to the inner surface of the pipe by welding with the formation of a continuous weld around the perimeter of the liner of corrosion-resistant metal. Besides, there is no need to use electrodes for welding of corrosion-resistant metal.

A specific example. The pipe from steel 20 made in accordance with the requirements of GOST 8732-78, with an external diameter of 159 mm and a wall thickness of 9 mm clear inside using drobestruynoy. Inside the end of the steel pipe install the liner of stainless steel 18CR10NITI with an outer diameter of 141 mm, with a wall thickness of 3 mm and a length of 150 mm by pressing using a horizontal hydraulic press. Then to the group of 10 minutes, where in the atmosphere of ammonia produce diffusion welding. However due to the fact that the insert is made of corrosion-resistant metal brand 18CR10NITI having a temperature coefficient of linear expansion =16,610-6and pipes - steel 20, having a temperature coefficient of linear expansion =12,110-6when heating occurs an increase in the diameter of different size, the contact pressure between the liner and the pipe. After connection of the liner pipe is applied on the internal surface of the pipe coating based on epoxy resin, and the outer surface of the plastic coating. If necessary, the pipe end make the chamfer angle 273ofor welding.

This method can be used in the manufacture of pipes with different internal coatings (polymer, glass, cement-sand, lined, and so on) for the construction of pipelines in various industries.

Literature

1. RF patent 2103594, IPC F 16 L 58/02. The method of connecting pipes with an internal corrosion-resistant coating (Voinov A. K., Olovyannikov C. F., P. Anisimov, A. and others) - 96111759/06 declared 11.06.96 published 27.01.98, bull. 3.

2. RF patent 2103593, IPC F 16 L 58/02. SPO is - 5119761/06 declared 21.01.95, published 27.01.98, bull. 3.

1. A method of manufacturing a tube with an inner coating comprising fastening cylindrical inserts of stainless metal inside the ends of the pipe and the coating on the inner surface of the pipe, characterized in that the cylindrical liners are made of corrosion-resistant metal having a greater thermal coefficient of linear expansion than the metal of the pipe, and connect the outer surface of the cylindrical inserts with the inner surface of the pipe ends by diffusion welding by sharing their heating and create between them the contact pressure due to the difference in temperature coefficients of linear expansion of the metal cylindrical liners and pipes.

2. The method according to p. 1, characterized in that the ends of the pipe internal diameter is pre-calibrated for length not less than the length of cylindrical inserts of stainless metal.

3. The method according to p. 1 or 2, characterized in that the ends of the pipes, installed liners to connect them together by diffusion welding calibrated at the inner diameter to the length of the cylindrical inserts of stainless

 

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FIELD: non-disconnectible pipe joints.

SUBSTANCE: pipe is provided with coupling members at its ends. The coupling members are hermetically sealed, overlap the axis and form coaxial ring space near the free end. The length of the wall of the coupling members exceeds the length of the zone of destructive heating of covering during welding. The minimum thickness of the coupling member wall is determined from the formula SCM=STRTDM/RCMDT, where ST and SCM are the thickness of pipe and coupling member, DT and DM are the outer diameter of pipe and coupling member, and RT and RCM are the limiting yield of materials of pipe and coupling member, respectively. The section of outer surface of the pipe adjacent to the face, inner diameter of the coupling member, and the length of ring space allow receiving the aligning unit to provide abutting the faces of coupling members for welding. The aligning unit is made of a bushing which receives the sealing rings for sealing the faces and outer surfaces of the pipe in the ring space.

EFFECT: enhanced operate reliability and service life.

19 cl, 3 dwg

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