A bimetallic wear-resistant composite pipe

Abstract

The utility model discloses a bimetallic wear -resisting composite pipeline, including the butt joint of first pipeline, second pipeline, first pipeline includes first base layer pipeline and sets up first wear -resistant stainless steel layer in first base layer pipeline inside, and second pipeline includes second base layer pipeline and sets up second wear -resistant stainless steel layer outside second base layer pipeline, and the butt joint end between first wear -resistant stainless steel layer and second wear -resistant stainless steel layer forms first weld groove for welding connection, and the butt joint end between first base layer pipeline and second base layer pipeline is provided with the isolating ring, and the butt joint end of isolating ring two ends with first base layer pipeline respectively forms second weld groove for welding, and the butt joint end of isolating ring with second base layer pipeline forms third weld groove for welding. The utility model discloses connecting structure good stability, and the service life of pipeline is long.

Description

Technical Field

[0001] This utility model relates to the field of metal pipe connection technology, and in particular to a bimetallic wear-resistant composite pipe. Background Technology

[0002] In industries such as petroleum, mining, power, and metallurgy, wear-resistant pipes endure the combined effects of erosion from high-speed particulate matter and corrosive media. Bimetallic composite pipes (such as a carbon steel base layer with a stainless steel wear-resistant layer) are widely used due to their excellent overall performance. However, butt welding of dissimilar metals remains a technical bottleneck in the industry, mainly in the following aspects:

[0003] Poor welding process compatibility makes it difficult to coordinate welding parameters for bimetallic pipes (such as composites of carbon steel Q235 and stainless steel 06Cr19Ni10) due to differences in physicochemical properties. Differences in thermal expansion coefficients lead to concentrated welding thermal stress; differences in thermal conductivity result in uneven temperature distribution in the molten pool; and differences in melting points easily cause overheating and grain coarsening in the carbon steel layer (measured grain size decreased from grade 8 to grade 3), while alloying elements in the stainless steel layer are burned off (Cr loss reaches 5%). Currently, direct butt welding is prone to incomplete fusion / penetration, and due to the difficulty of fusion between dissimilar metals, continuous defects are easily observed at the weld joint surface. Furthermore, uneven mechanical properties and abrupt hardness gradients (HV180 in the carbon steel weld zone → HV280 in the stainless steel zone) result in a stress concentration factor >2.5; carbon migration induces intergranular corrosion (the width of the chromium-depleted zone in the stainless steel layer reaches 50 μm, increasing the intergranular corrosion rate by 8 times); and galvanic corrosion is accelerated (corrosion current density reaches 1.2 μA / cm² when dissimilar metals are in direct contact).

[0004] Existing small-diameter bimetallic pipes use traditional butt welding, which can only be welded from the outside. After welding, they leak due to weld corrosion and perforation after only 6 months of operation, with an average replacement cycle of less than 40% of that of traditional single-metal pipes. Currently, the industry is trying to improve the welding effect by using transition layer welding and nickel-based welding materials (such as ERNiCr-3) to alleviate carbon migration, but the cost increases by 200% and cannot solve the thermal stress problem.

[0005] In summary, there is an urgent need for a bimetallic pipe butt structure that can completely isolate the fusion of dissimilar metals and optimize the distribution of welding stress, in order to overcome the technical barriers to the long-term operation of wear-resistant pipes. Utility Model Content

[0006] This invention provides a bimetallic wear-resistant composite pipe that solves the problems of poor stability and short service life of traditional bimetallic pipe butt welded connection structures.

[0007] This utility model provides a bimetallic wear-resistant composite pipe, including a first pipe and a second pipe connected in opposite directions. The first pipe includes a first base pipe and a first wear-resistant stainless steel layer disposed inside the first base pipe. The second pipe includes a second base pipe and a second wear-resistant stainless steel layer disposed outside the second base pipe. A first weld groove for welding is formed between the mating ends of the first wear-resistant stainless steel layer and the second wear-resistant stainless steel layer. An isolation ring is provided between the mating ends of the first base pipe and the second base pipe. The two ends of the isolation ring respectively form second weld grooves for welding with the mating ends of the first base pipe and the second base pipe. A third weld groove for welding is formed between the isolation ring and the mating end of the second base pipe.

[0008] In the above technical solution, preferably, the isolation ring is composed of two semicircular rings spliced ​​together, and the two mating ends of the two semicircular rings are connected by welding.

[0009] In the above technical solution, preferably, the wall thickness of the isolation ring is equal to the wall thickness of the first base pipe or the second base pipe.

[0010] In the above technical solution, preferably, the outer diameter of the first pipe is 600mm, the wall thickness of the first base pipe and the second base pipe is 8mm, and the wall thickness of the first wear-resistant stainless steel layer and the second wear-resistant stainless steel layer is 2mm.

[0011] In the above technical solution, preferably, the cross-section of the first weld groove is an isosceles triangle.

[0012] In the above technical solution, preferably, the second weld groove and the third weld groove are both X-shaped groove weld grooves.

[0013] In the above technical solution, preferably, both the first base layer pipe and the second base layer pipe are made of carbon steel.

[0014] In the above technical solution, preferably, the first wear-resistant stainless steel layer and the second wear-resistant stainless steel layer are made of austenitic stainless steel or duplex stainless steel.

[0015] The beneficial effects of this utility model are:

[0016] This invention utilizes a sequential welding process from the outside of a small-diameter bimetallic pipe, resulting in high welding efficiency and significantly reduced construction difficulty. An isolation ring physically separates the carbon steel base layer from the stainless steel wear-resistant layer, preventing intergranular corrosion caused by carbon migration during welding and extending weld life. The X-shaped bevel design ensures symmetrical distribution of welding thermal stress, reducing weld deformation and improving connection stability. The continuous stainless steel layer covering both the inner and outer walls of the pipe contributes to a longer service life compared to ordinary steel pipes. Attached Figure Description

[0017] To more clearly illustrate the technical solution of this utility model, the drawings used in the implementation examples will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of a bimetallic wear-resistant composite pipe proposed in this utility model;

[0019] Figure 2 This is a front view schematic diagram of the overall structure of a bimetallic wear-resistant composite pipe proposed in this utility model;

[0020] Figure 3 Appendix to this utility model Figure 2 AA sectional view;

[0021] Figure 4 Appendix to this utility model Figure 3 A partially enlarged structural diagram of position I;

[0022] Figure 5 This is a front view schematic diagram of the overall structure of the isolation ring of a bimetallic wear-resistant composite pipe proposed in this utility model.

[0023] In the picture:

[0024] 1-First pipe; 11-First base pipe; 12-First wear-resistant stainless steel layer; 13-Second weld groove; 14-Third weld groove; 2-Second pipe; 21-Second base pipe; 22-Second wear-resistant stainless steel layer; 23-First weld groove; 24-Isolation ring; 241-Semi-circular ring. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0026] Example 1:

[0027] See Figure 1-5A bimetallic wear-resistant composite pipe includes a first pipe 1 and a second pipe 2 connected in opposite directions. The first pipe 1 includes a first base pipe 11 and a first wear-resistant stainless steel layer 12 inner sleeve disposed inside the first base pipe 11. The second pipe 2 includes a second base pipe 21 and a second wear-resistant stainless steel layer 22 inner sleeve disposed outside the second base pipe 21. A first weld groove 23 for welding connection is formed between the mating ends of the first wear-resistant stainless steel layer 12 and the second wear-resistant stainless steel layer 22. An isolation ring 24 is provided between the mating ends of the first base pipe 11 and the second base pipe 21. The two ends of the isolation ring 24 form second weld grooves 13 for welding with the mating ends of the first base pipe 11 and the second base pipe 21, respectively. A third weld groove 14 for welding is formed between the isolation ring 24 and the mating end of the second base pipe 21. By sequentially welding small-diameter bimetallic pipes from the outside, welding efficiency is high and construction difficulty is greatly reduced. The isolation ring 24 physically separates the weld between the carbon steel base and the stainless steel wear-resistant layer, avoiding intergranular corrosion caused by carbon migration during welding and improving weld life. The X-shaped groove design ensures symmetrical distribution of welding thermal stress, reducing weld deformation. The continuous stainless steel layer on the inner and outer walls of the pipe results in a longer service life compared to ordinary steel pipes.

[0028] In this embodiment, see Figure 4 , 5 The isolation ring 24 is composed of two semicircular rings 241 spliced ​​together. The two mating ends of the two semicircular rings 241 are connected by welding. The two semicircular rings 241 are easy to install, reducing the difficulty of construction.

[0029] In this embodiment, see Figure 4 The wall thickness of the isolation ring 24 is equal to the wall thickness of the first base pipe 11 or the second base pipe 21, so that the joint of the first pipe 1 and the second pipe 2 is flat after welding, which facilitates anti-corrosion treatment.

[0030] In this embodiment, see Figure 4 The outer diameter of the first pipe 1 is 600mm, the wall thickness of the first base pipe 11 and the second base pipe 21 is 8mm, and the wall thickness of the first wear-resistant stainless steel layer 12 and the second wear-resistant stainless steel layer 22 is 2mm. By using bimetallic composite, the overall thickness of the pipe is reduced, saving the manufacturing cost of the pipe, while increasing the wear resistance and internal corrosion resistance of the pipe, and also significantly increasing the service life.

[0031] In this embodiment, see Figure 4 The first weld groove 23 has an isosceles triangle cross section with a base angle of 90 degrees, which facilitates the positioning of the first base pipe 11 and the second base pipe 21, and also facilitates welding operations by the operators.

[0032] In this embodiment, the second weld groove 13 and the third weld groove 14 are both X-shaped groove weld grooves, which makes the weld stable in the X-shaped groove weld groove, not easy to fall off, and has good mechanical stability.

[0033] In this embodiment, the first base pipe 11 and the second base pipe 21 are both made of carbon steel, and the isolation ring 24 is also made of carbon steel. This facilitates welding and connection with the first base pipe 11 and the second base pipe 21 using the same material, resulting in good welding stability and high welding strength.

[0034] In this embodiment, the first wear-resistant stainless steel layer 12 and the second wear-resistant stainless steel layer 22 are made of austenitic stainless steel or duplex stainless steel, which can achieve high corrosion resistance and wear resistance on the inner walls of the first pipe 1 and the second pipe 2, and extend the service life of the pipes.

[0035] The construction steps of this utility model are as follows:

[0036] 1. Docking sequence:

[0037] First, using an alignment tool, the first pipe 1 and the second pipe 2 are coaxially connected, so that the first wear-resistant stainless steel layer 12 and the second wear-resistant stainless steel layer 22 abut against each other to form the first weld groove 23.

[0038] 2. Welding sequence:

[0039] (1) The first weld groove 23 is circumferentially welded from the outside of the pipe (the first weld groove 23 is filled with ER309L stainless steel welding wire (TIG welding)) to connect the first wear-resistant stainless steel layer 12 with the second wear-resistant stainless steel layer 22.

[0040] (2) The two semicircular rings 241 are spliced ​​together from both sides to the outer wall of the wear-resistant layer. After positioning with a measuring tool, the splice seam is welded to form a complete isolation ring 24.

[0041] (3) Fill the second weld groove 13 and the third weld groove 14 with welding material and weld the isolation ring 24 to the first base pipe 11 and the second base pipe 21 (E5015 carbon steel welding rods are used in the second weld groove 13 and the third weld groove 14, and multi-layer multi-pass welding is adopted).

[0042] This invention uses an isolation ring 24 to physically separate the carbon steel base layer and the stainless steel wear-resistant layer, avoiding intergranular corrosion caused by carbon migration during welding and increasing the weld life by more than 3 times. The X-shaped bevel design ensures symmetrical distribution of welding thermal stress, reducing deformation (measured roundness deviation <0.8%). The continuous stainless steel layer covering the inner and outer walls of the pipe provides a service life 5 times that of ordinary steel pipes under material conveying conditions.

[0043] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of the invention is indicated by the claims.

[0044] It should be understood that this utility model is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The embodiments of this utility model described above do not constitute a limitation on the scope of protection of this utility model.

Claims

1. A bimetallic wear-resistant composite pipe, comprising a first pipe (1) and a second pipe (2) connected in opposite directions, characterized in that: The first pipe (1) includes a first base pipe (11) and a first wear-resistant stainless steel layer (12) disposed inside the first base pipe (11). The second pipe (2) includes a second base pipe (21) and a second wear-resistant stainless steel layer (22) disposed outside the second base pipe (21). A first weld groove (23) for welding connection is formed between the mating ends of the first wear-resistant stainless steel layer (12) and the second wear-resistant stainless steel layer (22). An isolation ring (24) is provided between the mating ends of the first base pipe (11) and the second base pipe (21). The two ends of the isolation ring (24) respectively form a second weld groove (13) for welding with the mating ends of the first base pipe (11) and the second base pipe (21). A third weld groove (14) for welding is formed between the isolation ring (24) and the mating end of the second base pipe (21).

2. The bimetallic wear-resistant composite pipe according to claim 1, characterized in that, The isolation ring (24) is composed of two semicircular rings (241) spliced ​​together, and the two mating ends of the two semicircular rings (241) are connected by welding.

3. The bimetallic wear-resistant composite pipe according to claim 2, characterized in that, The wall thickness of the isolation ring (24) is equal to the wall thickness of the first base pipe (11) or the second base pipe (21).

4. The bimetallic wear-resistant composite pipe according to claim 1, characterized in that, The outer diameter of the first pipe (1) is 600mm, the wall thickness of the first base pipe (11) and the second base pipe (21) is 8mm, and the wall thickness of the first wear-resistant stainless steel layer (12) and the second wear-resistant stainless steel layer (22) is 2mm.

5. The bimetallic wear-resistant composite pipe according to claim 1, characterized in that, The cross section of the first weld groove (23) is an isosceles triangle.

6. The bimetallic wear-resistant composite pipe according to claim 1, characterized in that, The second weld groove (13) and the third weld groove (14) are both X-shaped groove weld grooves.

7. The bimetallic wear-resistant composite pipe according to claim 1, characterized in that, The first base pipe (11) and the second base pipe (21) are both made of carbon steel.

8. The bimetallic wear-resistant composite pipe according to claim 1, characterized in that, The first wear-resistant stainless steel layer (12) and the second wear-resistant stainless steel layer (22) are made of austenitic stainless steel or duplex stainless steel.

Images