Highly corrosion-resistant double-sided stainless steel composite pipe and preparation process thereof

Abstract

The application discloses a high-corrosion-resistance double-face stainless steel composite pipe and a preparation process thereof, and relates to the technical field of metal composite pipe preparation. The application takes a stainless steel pipe as an inner lining and an outer wall, takes a carbon steel pipe as an intermediate base pipe, fills tin powder and powdered molybdenum disulfide between the inner lining and the intermediate base pipe and between the outer wall and the intermediate base pipe, and further adopts a production technology of drawing and reducing diameter in cooperation with water injection and pressure boosting, so that the interface bonding strength of the composite pipe is greatly improved, and the high-corrosion-resistance double-face stainless steel composite pipe is prepared. The inner lining stainless steel ensures that the inner part in contact with a solution does not corrode, the outer wall stainless steel solves various corrosion problems in a complex environment, meanwhile, the intermediate carbon steel material greatly reduces the pipe manufacturing cost and provides high strength, so that the problems of short pipe service life and poor corrosion resistance in the chemical industry are solved.

Description

Technical Field

[0001] This application relates to the field of metal composite pipe manufacturing technology, specifically to a high corrosion-resistant double-sided stainless steel composite pipe and its manufacturing process. Background Technology

[0002] Traditional single-material steel pipes, such as ordinary carbon steel pipes, while possessing certain strength and relatively low cost, have poor corrosion resistance. In corrosive environments such as humid, acidic, or alkaline conditions, single-material steel pipes are highly susceptible to rust and corrosion. This not only shortens the pipe's service life but can also lead to contamination of the transported medium, causing safety hazards. In the petrochemical industry, the consequences of corrosion leaks in pipelines transporting corrosive chemicals are unimaginable. Therefore, stainless steel composite pipes have gradually gained widespread research and application. They combine the mechanical strength advantages of base materials such as carbon steel with the corrosion resistance advantages of the stainless steel layer. By compositing stainless steel sheets with carbon steel base pipes, they meet corrosion resistance requirements while reducing costs.

[0003] Chinese patent application CN 105465491A discloses a high-precision anti-corrosion and wear-resistant oil pipe and its manufacturing method. The steel pipe includes a pipe body with an inner coating and an outer coating on its inner and outer walls, respectively. The inner coating is hot-dip galvanized or chemically plated nickel-phosphorus alloy, and the outer coating is electroplated chromium, a nickel-chromium composite coating, or chemically plated nickel-phosphorus alloy. This method uses a surface treatment to form anti-corrosion layers on the inner and outer walls of the steel pipe, effectively improving its corrosion resistance, meeting the requirements of coastal areas, and facilitating precision control. Furthermore, the oil pipe is manufactured through cold plastic forming, local upsetting, and the formation of a coating on the outer surface. The manufacturing process is simple, and the resulting steel pipe exhibits high wear resistance and corrosion resistance while ensuring precision. It can be applied to hydraulic oil pipes requiring high corrosion resistance on both inner and outer surfaces, and where the outer diameter and sealing fit form a friction pair.

[0004] However, the stainless steel composite pipes produced by this method still have some shortcomings. On the one hand, the interfacial bonding strength is not ideal. Under long-term pressure, vibration, or temperature changes, the stainless steel layer is prone to delamination from the base layer, affecting the overall performance and service life of the pipe. On the other hand, there is room for improvement in its corrosion resistance. When facing high-concentration, highly corrosive media, its corrosion resistance is difficult to meet the requirements. Moreover, the materials used for the inner and outer coatings are relatively expensive. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a high corrosion-resistant double-sided stainless steel composite pipe and its manufacturing process. Using a stainless steel pipe as the inner lining and outer wall, and a carbon steel pipe as the intermediate base pipe, a production technique combining drawing and diameter reduction with water injection pressurization is employed, significantly improving the interfacial bonding strength of the composite pipe and resulting in a high corrosion-resistant double-sided stainless steel composite pipe. The stainless steel inner lining ensures that no corrosion occurs inside the pipe in contact with the solution, while the stainless steel outer wall addresses various corrosion problems in complex environments. Simultaneously, the use of carbon steel in the middle significantly reduces pipe manufacturing costs and provides high strength, thereby solving the problems of short pipe life and poor corrosion resistance in the chemical industry.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a high corrosion-resistant double-sided stainless steel composite pipe, comprising an inner liner pipe, an intermediate base pipe, and an outer pipe from the inside out; it also includes an interface connecting layer for bonding and connecting the inner liner pipe and the intermediate base pipe, as well as the intermediate base pipe and the outer pipe; the interface connecting layer includes a main component and a filler component, the main component including tin powder, and the filler component including powdered molybdenum disulfide; the inner liner pipe, the intermediate base pipe, the outer pipe, and the interface connecting layer are composited together by a drawing-diameter reduction combined with water injection pressurization.

[0008] Secondly, this application provides a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe, comprising:

[0009] After low-carbon steel is rolled, its inner and outer surfaces are successively subjected to alkaline washing, first pickling, sandblasting, and second pickling to obtain the intermediate base tube.

[0010] Stainless steel strip is rolled and welded by argon arc welding to obtain stainless steel tubes, which are then protected by inert gas.

[0011] The inner and outer surfaces of the stainless steel pipe are subjected to alkali washing, first pickling, sandblasting, and second pickling in sequence to produce the inner lining pipe and the outer pipe.

[0012] The tube blank is assembled by filling tin powder and powdered molybdenum disulfide between the inner liner tube and the intermediate base tube, and between the intermediate base tube and the outer tube, to obtain a composite tube blank.

[0013] Water is injected into the composite tube blank. After the tube is filled with water, the ends of the tube are sealed by welding.

[0014] The composite pipe blank is drawn and reduced in diameter while the water pressure inside the composite pipe blank is monitored to form an interface bonding layer. The inner liner pipe, the intermediate base pipe, the outer pipe and the interface bonding layer are then combined together to obtain a composite pipe pre-product.

[0015] The welded portions at both ends of the composite pipe are cut off to drain the water. The composite pipe is then cleaned and dried with hot air to obtain the finished composite pipe.

[0016] Beneficial technical effects:

[0017] (1) When preparing the composite stainless steel pipe, the inner liner, intermediate base pipe, and outer pipe are first surface treated to ensure better adhesion between them and the interface bonding layer formed by filling. Then, water is injected into the composite pipe blank, and a drawing and shrinking machine is used to draw and shrink the composite pipe blank after water injection. During the drawing and shrinking process, the water pressure inside the composite pipe blank rises rapidly because the pipe diameter is reduced and the injected water is incompressible. The water pressure causes the stainless steel inner liner to expand, thereby achieving a high-strength and tight fit between the carbon steel intermediate base pipe and the stainless steel inner liner. The water pressure is internal pressure and the circumferential pressure is very uniform, so even if an ultra-thin-walled stainless steel inner liner is used, the stainless steel will not become unstable, deformed, or bulged, and the circumferential bonding strength and the tightness of the fit can also remain uniform. In addition, the carbon steel pipe can be reduced in diameter during the drawing process, which can compensate for the springback shrinkage of the stainless steel inner liner after depressurization, ensuring the high interface bonding strength of the composite pipe.

[0018] (2) Due to the high temperature and high pressure conditions during the drawing, necking, and water injection pressurization processes, the tin powder in the interface bonding layer melts and mixes with powdered molybdenum disulfide. This mixture is then more evenly compressed and dispersed between the layers. Under high temperature and high pressure conditions, tin atoms and molybdenum disulfide diffuse into the pipe, forming a solid solution or intermetallic compound with the iron in the pipe, thus forming the interface bonding layer. This significantly improves the interface bonding strength of the composite pipe. The higher the interface bonding strength of the composite pipe, the fewer gaps between the interfaces, thereby greatly improving its corrosion resistance. At the same time, the pressure generated by the drawing, necking, and water injection pressurization processes is negatively correlated with the interface bonding gap of the composite stainless steel pipe. The bonding strength of each interface of the composite pipe can be flexibly adjusted by controlling the interface bonding gap, thereby meeting the different requirements for bonding strength in different application fields. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a high corrosion-resistant double-sided stainless steel composite pipe.

[0020] Figure 2 This is a schematic diagram of the process for preparing highly corrosion-resistant double-sided stainless steel composite pipes.

[0021] Reference numerals: 1. Inner liner tube; 2. Intermediate base tube; 3. Outer tube; 4. Interface bonding layer. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0023] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0024] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] Firstly, such as Figure 1 As shown, this application provides a high corrosion-resistant double-sided stainless steel composite pipe, including an inner liner pipe 1, an intermediate base pipe 2, and an outer pipe 3 from the inside out; it also includes an interface connecting layer 4 for connecting the inner liner pipe 1 and the intermediate base pipe 2, as well as the intermediate base pipe 2 and the outer pipe 3; the interface connecting layer includes a main component and a filler component, the main component includes tin powder, and the filler component includes powdered molybdenum disulfide; the inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3, and the interface connecting layer 4 are composited together by a drawing-dip diameter reduction combined with water injection pressurization.

[0027] In one possible implementation, the drawing temperature range is 300~500℃; the material of the intermediate base tube 2 includes low-carbon steel with a carbon content of less than 0.15%; the surfaces of the inner liner tube 1 and the outer tube 3 close to the intermediate base tube 2 are both treated with low carbon.

[0028] In one possible implementation, the mass ratio of the main component to the filler component in the interface connection layer 4 is (70~80):(20~30).

[0029] The tin powder, the main component of the interface bonding layer 4, melts and undergoes a phase transformation within the range of 300-500℃, existing in a liquid state. This liquid tin mixes thoroughly with the filler component in the interface bonding layer 4, namely powdered molybdenum disulfide, and is more evenly compressed and dispersed between the inner liner tube 1, the intermediate base tube 2, and the outer tube 3 under the high pressure generated by the drawing, diameter reduction, and water injection pressurization process, forming an interface bonding layer and improving the interfacial bonding strength of the composite tube. Furthermore, the material of the intermediate base tube 2 can be medium-carbon steel with a carbon content of 0.25-0.60% or low-carbon steel with a carbon content of 0.15-0.25%; however, low-carbon steel with a carbon content below 0.15% is preferred. This is because lower carbon content results in better processing properties such as toughness and plasticity. Thus, the filler component in the interface bonding layer 4 can better bond with the intermediate base tube 2 under high pressure, significantly improving the interfacial bonding strength of the composite tube. Furthermore, steel can better absorb energy when subjected to external impact, resisting the generation and propagation of cracks and improving corrosion resistance. In addition, lower carbon content means fewer carbides and other impurities in the steel. In corrosive environments, this reduces the formation of micro-cells and the possibility of electrochemical corrosion, further enhancing the steel's corrosion resistance. The surfaces of the inner liner 1 and outer liner 3 closest to the intermediate base pipe 2 undergo low-carbon treatment. This is to ensure that the filler components in the interface bonding layer 4 can better bond with the inner liner 1 and outer liner 3 under high pressure, thereby improving the interfacial bonding strength of the composite pipe. Higher interfacial bonding strength results in fewer gaps between the interfaces, further significantly improving corrosion resistance.

[0030] In one possible implementation, the thickness of the inner liner tube 1 is 1.2~1.8mm; the thickness of the intermediate base tube 2 is 3.0~8.0mm; and the thickness of the outer tube 3 is 1.2~2.5mm.

[0031] Secondly, this application provides a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe, such as... Figure 2 As shown, it includes:

[0032] After the low carbon steel is rolled, the inner and outer surfaces are successively subjected to alkaline washing, first pickling, sandblasting, and second pickling to obtain the intermediate base tube 2.

[0033] Stainless steel strip is rolled and welded by argon arc welding to obtain stainless steel tubes, which are then protected by inert gas.

[0034] The inner and outer surfaces of the stainless steel pipe are subjected to alkali washing, first pickling, sandblasting, and second pickling in sequence to produce inner liner 1 and outer liner 3.

[0035] The tube blank is assembled by filling tin powder and powdered molybdenum disulfide between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3, to obtain a composite tube blank.

[0036] Water is injected into the composite tube blank. After the tube is filled with water, the ends of the tube are sealed by welding.

[0037] The composite pipe blank is drawn and reduced in diameter while the water pressure inside the composite pipe blank is monitored to form an interface connection layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface connection layer 4 are then combined together to obtain a composite pipe preform.

[0038] The welded portions at both ends of the composite pipe are cut off to drain the water. The composite pipe is then cleaned and dried with hot air to obtain the finished composite pipe.

[0039] In one possible implementation, the alkaline washing involves immersing the patient in a 7-10 wt% NaOH solution at 45-50°C for 4-8 minutes.

[0040] In one possible implementation, both the primary and secondary pickling processes use a 10-15 wt% H2SO4 solution, a 50-70 wt% HCl solution, or a mixture of both, and are performed at 40-45°C for 10-15 minutes.

[0041] In one possible implementation, the sandblasting grade is Sa2 or Sa2.5.

[0042] In one possible implementation, the inert gas comprises a mixture of argon and helium; wherein the volume fraction ratio of argon to helium in the mixture is (70%~90%):(10%~30%).

[0043] In one possible implementation, the method for sealing the pipe end includes any one of manual arc welding, argon arc welding, carbon dioxide shielded welding, manual TIG welding, plasma arc welding, and laser welding.

[0044] In one possible implementation, the drawing speed for the diameter reduction is 0.5~3m / min.

[0045] The following will describe in detail, with reference to different embodiments, a high corrosion-resistant double-sided stainless steel composite pipe and its preparation process provided in this application.

[0046] Example 1:

[0047] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0048] 1. After rolling low-carbon steel with a carbon content of 0.13%, the inner and outer surfaces are subjected to alkaline washing (immersion in 7wt% NaOH solution at 45℃ for 8min), first pickling (immersion in 10wt% H2SO4 solution at 40℃ for 15min), sandblasting (sandblasting grade Sa2.5), and second pickling (immersion in 10wt% H2SO4 solution at 40℃ for 15min) to obtain intermediate base tube 2;

[0049] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 70%:30%).

[0050] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 8wt% NaOH solution at 48℃ for 6 min), first pickling (60wt% HCl solution at 43℃ for 12 min), sandblasting (sandblasting grade Sa2.5), and second pickling (60wt% HCl solution at 43℃ for 12 min) in sequence to obtain the inner liner pipe 1 made of stainless steel 304L and the outer pipe 3 made of stainless steel 304.

[0051] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 70:30) to obtain a composite tube blank;

[0052] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0053] 6. The composite pipe blank with water injection is drawn and reduced in diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 0.5m / min, and the drawing temperature is 300℃), forming an interface bonding layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface bonding layer 4 are then combined together to obtain the composite pipe pre-product.

[0054] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0055] Example 2:

[0056] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0057] 1. After rolling low-carbon steel with a carbon content of 0.14%, the inner and outer surfaces are subjected to the following processes in sequence: alkaline washing (immersion in 9wt% NaOH solution at 47℃ for 5 min), first pickling (immersion in 13wt% H2SO4 solution and 60wt% HCl solution mixed in a 1:1 ratio at 42℃ for 13 min), sandblasting (sandblasting grade Sa2.5), and second pickling (immersion in 13wt% H2SO4 solution and 60wt% HCl solution mixed in a 1:1 ratio at 42℃ for 13 min), to obtain intermediate base tube 2;

[0058] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 80%:20%).

[0059] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 9wt% NaOH solution at 49℃ for 7min), first pickling (55wt% HCl solution at 44℃ for 11min), sandblasting (sandblasting grade Sa2), and second pickling (55wt% HCl solution at 44℃ for 11min) to obtain the inner liner pipe 1 made of stainless steel 304L and the outer pipe 3 made of stainless steel 316.

[0060] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 75:25) to obtain a composite tube blank;

[0061] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0062] 6. The composite pipe blank with water injection is drawn and reduced in diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 1.5m / min, and the drawing temperature is 400℃), forming an interface bonding layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface bonding layer 4 are then combined together to obtain the composite pipe pre-product.

[0063] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0064] Example 3:

[0065] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0066] 1. After rolling low-carbon steel with a carbon content of 0.12%, the inner and outer surfaces are subjected to alkaline washing (immersion in 10wt% NaOH solution at 50℃ for 4min), first pickling (immersion in 15wt% H2SO4 solution at 45℃ for 10min), sandblasting (sandblasting grade Sa2.5), and second pickling (immersion in 15wt% H2SO4 solution at 45℃ for 10min) to obtain intermediate base tube 2;

[0067] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of 90%:10%).

[0068] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 7wt% NaOH solution at 46℃ for 8min), first pickling (immersion in 70wt% HCl solution at 41℃ for 14min), sandblasting (sandblasting grade Sa2), and second pickling (immersion in 70wt% HCl solution at 41℃ for 14min) in sequence to obtain the inner liner pipe 1 made of stainless steel 316L and the outer pipe 3 made of stainless steel 316.

[0069] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 80:20) to obtain a composite tube blank;

[0070] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0071] 6. The composite pipe blank with water injection is drawn and reduced in diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 2m / min, and the drawing temperature is 450℃), forming an interface bonding layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface bonding layer 4 are then combined together to obtain the composite pipe pre-product.

[0072] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0073] Example 4:

[0074] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0075] 1. After rolling low-carbon steel with a carbon content of 0.13%, the inner and outer surfaces are subjected to the following processes in sequence: alkaline washing (immersion in 8wt% NaOH solution at 48℃ for 7 min), first pickling (mixing 12wt% H2SO4 solution and 55wt% HCl solution in a 2:3 ratio and immersion in 43℃ for 12 min), sandblasting (sandblasting grade Sa2), and second pickling (mixing 12wt% H2SO4 solution and 55wt% HCl solution in a 2:3 ratio and immersion in 43℃ for 12 min), to obtain intermediate base tube 2;

[0076] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 75%:25%).

[0077] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 8wt% NaOH solution at 47℃ for 6 min), first pickling (65wt% HCl solution at 42℃ for 13 min), sandblasting (sandblasting grade Sa2.5), and second pickling (65wt% HCl solution at 42℃ for 13 min) in sequence to obtain the inner liner pipe 1 made of 316L stainless steel and the outer pipe 3 made of 304L stainless steel.

[0078] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 76:24) to obtain a composite tube blank;

[0079] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0080] 6. The composite pipe blank with water injection is drawn and reduced in diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 2.5m / min, and the drawing temperature is 350℃), forming an interface bonding layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface bonding layer 4 are then combined together to obtain the composite pipe pre-product.

[0081] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0082] Example 5:

[0083] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0084] 1. After rolling low-carbon steel with a carbon content of 0.13%, the inner and outer surfaces are subjected to alkaline washing (immersion in 7.5wt% NaOH solution at 49℃ for 6 min), first pickling (immersion in 14wt% H2SO4 solution at 44℃ for 11 min), sandblasting (sandblasting grade Sa2.5), and second pickling (immersion in 14wt% H2SO4 solution at 44℃ for 11 min) to obtain intermediate base tube 2;

[0085] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 85%:15%).

[0086] 3. The inner and outer surfaces of the obtained stainless steel tubes are subjected to the same alkaline washing (immersion in 9.5wt% NaOH solution at 46℃ for 7 min), first pickling (immersion in 60wt% HCl solution at 43℃ for 12 min), sandblasting (sandblasting grade Sa2), and second pickling (immersion in 60wt% HCl solution at 43℃ for 12 min) in sequence to obtain the inner liner tube 1 made of stainless steel 304 and the outer tube 3 made of stainless steel 316.

[0087] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 72:28) to obtain a composite tube blank;

[0088] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0089] 6. The composite pipe blank with water injection is drawn and reduced in diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 1m / min, and the drawing temperature is 500℃), forming an interface bonding layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface bonding layer 4 are then combined together to obtain the composite pipe pre-product.

[0090] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0091] Example 6:

[0092] like Figure 2 As shown, a manufacturing process for a high corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0093] 1. After rolling low-carbon steel with a carbon content of 0.14%, the inner and outer surfaces are subjected to the following processes in sequence: alkaline washing (immersion in 9wt% NaOH solution at 45℃ for 8 min), first pickling (immersion in 11wt% H2SO4 solution and 50wt% HCl solution mixed in a 3:2 ratio at 41℃ for 14 min), sandblasting (sandblasting grade Sa2), and second pickling (immersion in 11wt% H2SO4 solution and 50wt% HCl solution mixed in a 3:2 ratio at 41℃ for 14 min), to obtain intermediate base tube 2;

[0094] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 70%:30%).

[0095] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 8wt% NaOH solution at 48℃ for 6 min), first pickling (65wt% HCl solution at 42℃ for 13 min), sandblasting (sandblasting grade Sa2.5), and second pickling (65wt% HCl solution at 42℃ for 13 min) in sequence to obtain the inner liner pipe 1 made of 316L stainless steel and the outer pipe 3 made of 304L stainless steel.

[0096] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 75:25) to obtain a composite tube blank;

[0097] 5. Fill the composite tube blank with water. After the tube is filled with water, seal the ends of the tube.

[0098] 6. The composite pipe blank with water injection is drawn and reduced in diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 3m / min, and the drawing temperature is 500℃), forming an interface bonding layer 4. The inner liner pipe 1, the intermediate base pipe 2, the outer pipe 3 and the interface bonding layer 4 are then combined together to obtain the composite pipe pre-product.

[0099] 7. Cut off the welded parts at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0100] Comparative Example 1:

[0101] A manufacturing process for a highly corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0102] 1. After rolling low-carbon steel with a carbon content of 0.13%, the inner and outer surfaces are subjected to alkaline washing (immersion in 7wt% NaOH solution at 45℃ for 8min), first pickling (immersion in 10wt% H2SO4 solution at 40℃ for 15min), sandblasting (sandblasting grade Sa2.5), and second pickling (immersion in 10wt% H2SO4 solution at 40℃ for 15min) to obtain intermediate base tube 2;

[0103] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 70%:30%).

[0104] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 8wt% NaOH solution at 48℃ for 6 min), first pickling (60wt% HCl solution at 43℃ for 12 min), sandblasting (sandblasting grade Sa2.5), and second pickling (60wt% HCl solution at 43℃ for 12 min) in sequence to obtain the inner liner pipe 1 made of stainless steel 304L and the outer pipe 3 made of stainless steel 304.

[0105] 4. Perform tube assembly: fill the space between the inner liner tube 1 and the intermediate base tube 2, and between the intermediate base tube 2 and the outer tube 3 with tin powder and powdered molybdenum disulfide (the mass ratio of tin powder and powdered molybdenum disulfide is 70:30) to obtain a composite tube blank, and seal the ends of the composite tube blank.

[0106] 5. The composite tube blank is drawn to reduce its diameter (the drawing speed for diameter reduction is 0.5 m / min, and the drawing temperature is 300℃) to obtain the composite tube preform;

[0107] 6. Cut off the welded portions at both ends of the composite pipe, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0108] Comparative Example 2:

[0109] A manufacturing process for a highly corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0110] 1. After rolling low-carbon steel with a carbon content of 0.12%, the inner and outer surfaces are subjected to alkaline washing (immersion in 10wt% NaOH solution at 50℃ for 4min), first pickling (immersion in 15wt% H2SO4 solution at 45℃ for 10min), sandblasting (sandblasting grade Sa2.5), and second pickling (immersion in 15wt% H2SO4 solution at 45℃ for 10min) to obtain intermediate base tube 2;

[0111] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of 90%:10%).

[0112] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 7wt% NaOH solution at 46℃ for 8min), first pickling (immersion in 70wt% HCl solution at 41℃ for 14min), sandblasting (sandblasting grade Sa2), and second pickling (immersion in 70wt% HCl solution at 41℃ for 14min) in sequence to obtain the inner liner pipe 1 made of stainless steel 316L and the outer pipe 3 made of stainless steel 316.

[0113] 4. Perform pipe-to-pipe assembly to obtain composite pipe blanks, and inject water into the composite pipe blanks. After the pipe is filled with water, seal the pipe ends.

[0114] 5. The composite pipe blank filled with water is drawn to reduce its diameter, while the water pressure inside the composite pipe blank is monitored (the drawing speed for the diameter reduction is 2m / min, and the drawing temperature is 450℃) to obtain the composite pipe pre-product.

[0115] 6. Cut off the welded portions at both ends of the composite pipe to drain the water, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0116] Comparative Example 3:

[0117] A manufacturing process for a highly corrosion-resistant double-sided stainless steel composite pipe includes the following steps:

[0118] 1. After rolling low-carbon steel with a carbon content of 0.14%, the inner and outer surfaces are subjected to the following processes in sequence: alkaline washing (immersion in 9wt% NaOH solution at 45℃ for 8 min), first pickling (immersion in 11wt% H2SO4 solution and 50wt% HCl solution mixed in a 3:2 ratio at 41℃ for 14 min), sandblasting (sandblasting grade Sa2), and second pickling (immersion in 11wt% H2SO4 solution and 50wt% HCl solution mixed in a 3:2 ratio at 41℃ for 14 min), to obtain intermediate base tube 2;

[0119] 2. The stainless steel strip is rolled and welded into a stainless steel tube by argon arc welding. The tube is protected by passing an inert gas (the inert gas is a mixture of argon and helium, with a volume fraction ratio of argon to helium of 70%:30%).

[0120] 3. The inner and outer surfaces of the obtained stainless steel pipe are subjected to the same alkaline washing (immersion in 8wt% NaOH solution at 48℃ for 6 min), first pickling (65wt% HCl solution at 42℃ for 13 min), sandblasting (sandblasting grade Sa2.5), and second pickling (65wt% HCl solution at 42℃ for 13 min) in sequence to obtain the inner liner pipe 1 made of 316L stainless steel and the outer pipe 3 made of 304L stainless steel.

[0121] 4. Perform pipe threading and assembly to obtain composite pipe blanks, and seal the ends of the composite pipe blanks.

[0122] 5. The composite tube blank is drawn to reduce its diameter (drawing speed is 3m / min, drawing temperature is 500℃) to obtain the composite tube preform;

[0123] 6. Cut off the welded portions at both ends of the composite pipe, clean the composite pipe and dry it with hot air to obtain the finished composite pipe.

[0124] Performance testing:

[0125] The interfacial bonding strength of the high corrosion-resistant double-sided stainless steel composite pipes prepared in the examples and comparative examples was determined by using a universal testing machine through shear testing, so as to effectively evaluate the interfacial performance of the stainless steel composite pipes, as shown in Table 1.

[0126] The activation current density, reactivation current density, and reactivation rate of the inner lining tube 1 of the high corrosion-resistant double-sided stainless steel composite pipe prepared by the test examples and comparative examples were measured in a petrochemical environment to effectively evaluate the ability of the stainless steel composite pipe to prevent intergranular corrosion, as shown in Table 2.

[0127] The corrosion potential, corrosion current, and repassivation potential of the inner lining tube 1 of the high corrosion-resistant double-sided stainless steel composite pipe prepared by the test examples and comparative examples were measured in a soil environment to effectively evaluate the ability of the stainless steel composite pipe to prevent crevice corrosion, as shown in Table 3.

[0128] Table 1. Test results of the interfacial bonding performance of the high corrosion-resistant double-sided stainless steel composite pipes prepared in the examples and comparative examples.

[0129]

[0130] Table 2. Test results of the intergranular corrosion resistance of the high corrosion-resistant double-sided stainless steel composite pipes prepared in the examples and comparative examples.

[0131]

[0132] Table 3. Test results of the crevice corrosion resistance of the high corrosion-resistant double-sided stainless steel composite pipes prepared in the examples and comparative examples.

[0133]

[0134] As shown in Tables 1 to 3, the interfacial bonding performance, intergranular corrosion resistance, and crevice corrosion resistance of Examples 1 to 6 are all superior to those of Comparative Examples 1 to 3.

[0135] This is because, in Examples 1-6, during the preparation of the composite stainless steel pipe, the inner liner, intermediate base pipe, and outer pipe are all surface-treated first, allowing for better adhesion between the inner liner, intermediate base pipe, outer pipe, and the interface bonding layer formed by the filling. Then, water is injected into the composite pipe blank, and a drawing and shrinking machine is used to draw and shrink the composite pipe blank after water injection. During the drawing and shrinking process, due to the reduction in pipe diameter and the incompressibility of the injected water, the water pressure inside the composite pipe blank rises rapidly. The water pressure causes the stainless steel inner liner to expand, thereby achieving a high-strength, tight bond between the carbon steel intermediate base pipe and the stainless steel inner liner. The water pressure is internal pressure and the circumferential pressure is very uniform, so even with an ultra-thin-walled stainless steel inner liner, the stainless steel will not experience unstable deformation or bulging, and the circumferential bonding strength and the tightness of the bond can remain uniform. Furthermore, the drawing process causes the carbon steel pipe to shrink, thus compensating for the springback shrinkage of the stainless steel inner liner after pressure relief, ensuring the high interface bonding strength of the composite pipe. Meanwhile, due to the high temperature and pressure conditions during the drawing, diameter reduction, and water injection pressurization processes, the tin powder in the interface bonding layer melts and mixes with powdered molybdenum disulfide. This mixture is then more evenly compressed and dispersed between the layers, forming an interface bonding layer under high pressure. This significantly improves the interfacial bonding strength of the composite pipe. The higher the interfacial bonding strength of the composite pipe, the fewer gaps between the interfaces, thus greatly enhancing its corrosion resistance.

[0136] In Comparative Example 1, the interface bonding strength was low and the corrosion resistance was even worse because the water injection pressurization process was not used. In Comparative Example 2, no tin powder and powdered molybdenum disulfide were filled between the inner liner tube 1 and the intermediate base tube 2, or between the intermediate base tube 2 and the outer tube 3, so an interface bonding layer could not be formed, resulting in a lower interface bonding strength than Comparative Example 1 and ultimately lower corrosion resistance. In Comparative Example 3, since neither the water injection pressurization process nor the filling of tin powder and powdered molybdenum disulfide was used, the interface bonding strength was the worst and the corrosion resistance was also the worst.

[0137] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0138] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A high corrosion-resistant double-sided stainless steel composite pipe, characterized in that, It includes an inner liner tube (1), an intermediate base tube (2), and an outer tube (3) from the inside out; it also includes an interface bonding layer (4) for connecting the inner liner tube (1) and the intermediate base tube (2), and the intermediate base tube (2) and the outer tube (3); the interface bonding layer (4) includes a main component and a filler component, the main component including tin powder, and the filler component including powdered molybdenum disulfide; the inner liner tube (1), the intermediate base tube (2), the outer tube (3), and the interface bonding layer (4) are connected by drawing and reducing diameter to fit the injection molding process. The components are combined using a water pressurization method; the mass ratio of the main component to the filler component is (70~80):(20~30); the main component undergoes a phase transformation within a drawing temperature range of 300~500℃; the material of the intermediate base tube (2) includes low-carbon steel with a carbon content of less than 0.15%; the materials of the inner liner tube (1) and the outer tube (3) are stainless steel; the surfaces of the inner liner tube (1) and the outer tube (3) close to the intermediate base tube (2) are treated with low carbon.

2. The high corrosion-resistant double-sided stainless steel composite pipe according to claim 1, characterized in that, The thickness of the inner liner tube (1) is 1.2~1.8mm; the thickness of the intermediate base tube (2) is 3.0~8.0mm; and the thickness of the outer tube (3) is 1.2~2.5mm.

3. The preparation process of a high corrosion-resistant double-sided stainless steel composite pipe according to any one of claims 1 to 2, characterized in that, Includes the following steps: After the low carbon steel is rolled, the inner and outer surfaces are successively subjected to alkaline washing, first pickling, sandblasting and second pickling to obtain the intermediate base tube (2). Stainless steel strip is rolled and welded by argon arc welding to obtain stainless steel tubes, which are then protected by inert gas. The inner and outer surfaces of the stainless steel pipe were subjected to alkali washing, first pickling, sandblasting and second pickling in sequence to obtain the inner lining pipe (1) and the outer pipe (3). The tube blank is assembled by filling tin powder and powdered molybdenum disulfide between the inner liner tube (1) and the middle base tube (2), and between the middle base tube (2) and the outer tube (3) to obtain a composite tube blank. Water is injected into the composite tube blank. After the tube is filled with water, the ends of the tube are sealed by welding. The composite pipe blank is drawn and reduced in diameter while the water pressure inside the composite pipe blank is monitored to form an interface connection layer (4). The inner liner pipe (1), the middle base pipe (2), the outer pipe (3) and the interface connection layer (4) are then combined together to obtain a composite pipe preform. The welded portions at both ends of the composite pipe are cut off to drain the water. The composite pipe is then cleaned and dried with hot air to obtain the finished composite pipe.

4. The preparation process of a high corrosion-resistant double-sided stainless steel composite pipe according to claim 3, characterized in that, The alkaline washing involves immersing the patient in a 7-10 wt% NaOH solution at 45-50°C for 4-8 minutes.

5. The preparation process of a high corrosion-resistant double-sided stainless steel composite pipe according to claim 3, characterized in that, Both the first and second pickling processes use 10-15 wt% H2SO4 solution, 50-70 wt% HCl solution, or a mixture of both, and are immersed at 40-45°C for 10-15 minutes.

6. The preparation process of a high corrosion-resistant double-sided stainless steel composite pipe according to claim 3, characterized in that, The sandblasting grade is Sa2 or Sa2.

5.

7. The preparation process of a high corrosion-resistant double-sided stainless steel composite pipe according to claim 3, characterized in that, The inert gas includes a mixture of argon and helium; in the mixture of argon and helium, the volume fraction ratio of argon to helium is (70%~90%): (10%~30%).

8. The manufacturing process of a high corrosion-resistant double-sided stainless steel composite pipe according to claim 3, characterized in that, The drawing speed for the diameter reduction is 0.5~3m / min.

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