Anti-cracking composite three-way pipe fitting with stainless steel lining and enhanced sealing performance

Abstract

The invention discloses an anti-cracking stainless-steel-lined composite three-way pipe fitting with enhanced sealing performance, and belongs to the technical field of three-way pipe fitting preparation. The anti-cracking stainless-steel-lined composite three-way pipe fitting comprises a stainless steel layer, a carbon steel layer is fixedly connected to the outer layer of the stainless steel layer, and a resin layer is fixedly connected to the outer side of the carbon steel layer; the lining of the composite three-way pipe fitting lined with the stainless steel is made of the stainless steel material, the stainless steel pipe has high strength and toughness and can bear large pressure and impact, and the composite three-way pipe fitting lined with the stainless steel has excellent corrosion resistance, can resist corrosion of water and air and corrosion of weak acid and weak base, and is good in corrosion resistance. And scaling, nodulation and oxide are not prone to being generated, and the interior of the pipeline can be effectively kept clean.

Description

Technical Field

[0001] The invention relates to the technical field of three-way pipe fitting preparation, in particular to a crack-resistant inner-lined stainless steel composite three-way pipe fitting with enhanced sealing performance. Background Art

[0002] Tee fittings, also called tees or tee fittings, are a type of pipe connector that is mainly used to change the direction of the fluid and is usually installed at the location where the main pipe needs to branch. Tee fittings are divided into equal diameter and reducing diameter. The ends of the pipes of equal diameter tees are all the same size, while the main pipes of reducing tees have the same size, and the pipe size of the branch pipe is smaller than the pipe size of the main pipe.

[0003] Tee fittings can be made of a variety of materials, including carbon steel, cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, etc. The manufacturing process usually includes two methods: hydraulic bulging and hot pressing. Hydraulic bulging is a forming process that expands the branch pipe through axial compensation of metal materials, while hot pressing is to flatten the tube blank larger than the tee diameter to the size of the tee diameter, then open a hole at the part where the branch pipe is stretched, and form the branch pipe through heating and pressing.

[0004] Common steel tee pipe fittings have poor corrosion resistance and are prone to produce oxides, which cause scaling and nodules on the inner wall of the pipe, polluting the pipeline. They are prone to damage and cracking under high-pressure environments, resulting in poor sealing performance and reduced service life. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance.

[0006] The technical solution of the present invention is: a crack-proof lined stainless steel composite three-way pipe fitting with enhanced sealing performance, comprising a stainless steel layer, the outer layer of the stainless steel layer is fixedly connected to a carbon steel layer, and the outer side of the carbon steel layer is fixedly connected to a resin layer;

[0007] The stainless steel layer is composed of the following components in mass percentage: Mn: 5.0-8.0%, Cr: 20.0-25.0%, Ni: 5.0-12.0%, Mo: 1.0-3.0%, Al: 0.1-1.0%, Sn<1.0%, W: 1.0-3.0%, Co: 1.5-2.3%, Ti: 0.8-1.5%, and the balance is Fe; the average Md value is <0.7840, and the area ratio of the σ phase is <1.5%;

[0008] The carbon steel layer is composed of the following components in mass percentage: Mn: 1.5-2.2%, Si: 0.2-0.8%, Cr: 0.1-0.5%, Ni: 0.5-1.5%, Mo: 0.1-0.4%, and the balance is Fe;

[0009] The resin layer is composed of the following components in percentage by mass: 20-25.5% of boron trinitride ethylamine complex, 18-22% of alkylene glycidyl ether, 7-9.8% of fatty alcohol ethoxysiloxane, 3-5% of dimethyl tin, and the remainder is epoxy resin.

[0010] Furthermore, a method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance comprises the following steps:

[0011] S1. Cut the stainless steel pipe and the carbon steel pipe according to the production requirements, and obtain the carbon steel main pipe, the carbon steel branch pipe and the stainless steel pipe after cutting;

[0012] S2. Drill holes in the side wall of the carbon steel main pipe. After the drilling is completed, weld the carbon steel branch pipe to the notch of the carbon steel main pipe. Then remove the welding slag at the welding place and remove the protruding part of the surface by a hand-held grinder to form a carbon steel tee pipe. Grind the inner wall of the carbon steel tee pipe to remove burrs.

[0013] S3, heat-treating the stainless steel pipe, and then inserting the heat-treated stainless steel pipe into the carbon steel tee pipe to form an assembly, placing the assembly into a hydraulic mold, filling the stainless steel pipe with emulsion through a hydraulic bulging device, and synchronously squeezing the stainless steel pipe from both ends of the carbon steel main pipe through a hydraulic rod, so that the stainless steel pipe is closely attached to the inner wall of the carbon steel tee pipe, and the stainless steel pipe is deformed to enter the carbon steel branch pipe and closely attached to the inner wall of the carbon steel branch pipe. After the hydraulic bulging is completed, a lined stainless steel tee blank is obtained;

[0014] S4, fix the lined stainless steel tee blank, drill a hole from the carbon steel branch pipe, remove the deformed stainless steel closed section, and then grind the drilled part to obtain a lined stainless steel composite pipe;

[0015] S5. The three pipe openings of the lined stainless steel composite pipe are sealed by a sealing cover, and then placed in a resin liquid tank for immersion treatment. The temperature of the liquid inlet tank is 20-30°C. After the immersion treatment is completed, it is dried at an ambient temperature of 100-120°C for 10-15 minutes. After the drying is completed, the sealing cover is removed to obtain a lined stainless steel composite three-way pipe fitting.

[0016] Description: The composite metal pipe is formed by using stainless steel pipe as the inner lining and carbon steel pipe. The lined stainless steel composite pipe has excellent corrosion resistance and can resist the corrosion of water and air, as well as the corrosion of weak acids and weak alkalis. It is suitable for the transportation of various chemical media. The lined stainless steel composite pipe will not produce scaling and nodules, keeping the inside of the pipe clean, and is suitable for drinking water systems and other occasions with high hygiene requirements.

[0017] Furthermore, the emulsion is composed of the following components in percentage by mass: 15-20% base oil, 6.5-8.3% sodium petroleum sulfonate emulsifier, 4.3-6.5% zinc cyclohexaneate rust inhibitor, 5.5-9% sodium dithiohyaluronic acid extreme pressure additive, 2.8-7.2% polyglycerol fatty acid ester stabilizer, and the balance is water.

[0018] Description: As a hydraulic medium, the emulsion can evenly transfer pressure to the inner wall of the pipe, helping the pipe to undergo plastic deformation in the mold, thereby achieving bulging of the pipe.

[0019] Furthermore, the axial pressure of the hydraulic bulging equipment is 190-200 MPa, and the bulging height is 30-50 mm.

[0020] Note: The above axial pressure helps to distribute the material more evenly in the mold, reduce material defects, and improve the surface finish and dimensional accuracy of the finished product.

[0021] Furthermore, the heat treatment method of the stainless steel pipe is: heating the stainless steel pipe to 450-600°C, keeping it warm for 1-2 hours, and cooling it to room temperature with the furnace.

[0022] Note: Stainless steel pipes may generate internal stress during the manufacturing process. These stresses are usually released during heat treatment. Heat treatment by the above method can reduce these internal stresses, thereby reducing cracks or deformation caused by stress concentration during hydraulic bulging.

[0023] Furthermore, the feed ratio during the hydraulic bulging is 4.5:1, the internal pressure of the stainless steel pipe is 150-160 MPa, the back pressure of the carbon steel pipe is 70-80 MPa, and the pressure holding time is 1-2 minutes.

[0024] Note: The above-mentioned holding time can ensure that the pipe is fully solidified in the mold, improve the dimensional accuracy and shape stability of the product, and the above-mentioned material ratio can fully compensate for the volume change of the pipe during the bulging process to avoid uneven wall thickness or cracks in the pipe.

[0025] Furthermore, the wall thickness of the stainless steel pipe is 5-10 mm.

[0026] Note: If the wall thickness of the stainless steel pipe is too thin, it will be unfavorable for axial extrusion, resulting in a decrease in the bulging height. If the wall thickness of the stainless steel pipe is too thick, the pressure required for deformation will be too large, which will increase the difficulty of bulging.

[0027] Furthermore, the stainless steel pipe is a seamless stainless steel pipe prepared by a perforation method, wherein the stainless steel billet is heated to 850-900°C, and then the heated billet is placed in a perforator for perforation to form a rough tube, and then the rough tube is subjected to a rolling process to reduce the tube wall thickness and increase the tube length, and the rolled rough tube is sizing processed by a sizing machine, and the sizing rough tube is placed in a cooling tower for cooling to obtain a stainless steel pipe.

[0028] Description: Stainless steel pipes are used for hydraulic bulging, and the internal structure is uniform, which is not prone to cracks and uneven wall thickness.

[0029] The beneficial effects of the present invention are:

[0030] (1) The inner lining of the stainless steel lined composite three-way pipe fitting described in the present invention is made of stainless steel. The stainless steel pipe has high strength and toughness and can withstand greater pressure and impact. The stainless steel lined composite three-way pipe fitting of the present invention has excellent corrosion resistance and can resist corrosion from water and air, as well as corrosion from weak acids and weak alkalis. It is not easy to generate scaling and nodules, and is not easy to generate oxides, and can effectively keep the inside of the pipeline clean.

[0031] (2) The carbon steel layer of the present invention has high hardness and strength, and serves as the outer wall support of the stainless steel layer. The resin layer is used to protect the carbon steel layer to prevent the carbon steel layer from being oxidized by oxygen and rusting, thereby shortening the life of the lined stainless steel composite three-way pipe fitting. The stainless steel layer used as the inner lining of the present application is not prone to cracks and has good sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The utility model relates to a lined stainless steel composite three-way pipe fitting of the present invention.

[0033] Figure 2 It is a schematic diagram of hydraulic expansion of the lined stainless steel composite tee pipe fitting of the present invention.

[0034] Among them, 1-stainless steel layer, 2-carbon steel layer, 3-resin layer. DETAILED DESCRIPTION

[0035] Embodiment 1:

[0036] like Figure 1 As shown, a crack-proof lined stainless steel composite three-way pipe fitting with enhanced sealing performance comprises a stainless steel layer 1, the outer layer of the stainless steel layer 1 is fixedly connected to a carbon steel layer 2, and the outer side of the carbon steel layer 2 is fixedly connected to a resin layer 3;

[0037] The stainless steel layer 1 is composed of the following components in mass percentage: Mn: 5.0%, Cr: 20.0%, Ni: 5.0%, Mo: 1.0%, Al: 0.1%, Sn: 0.08%, W: 1.0%, Co: 1.5%, Ti: 0.8%, and the balance is Fe; average Md value: 0.7830, area ratio of σ phase: 1.2%;

[0038] The carbon steel layer 2 is composed of the following components in mass percentage: Mn: 1.5%, Si: 0.2%, Cr: 0.1%, Ni: 0.5%, Mo: 0.1%, and the balance is Fe;

[0039] The resin layer 3 is composed of the following components in percentage by mass: 20% of boron trinitride ethylamine complex, 18% of alkylene glycidyl ether, 7% of fatty alcohol ethoxysiloxane, 3% of dimethyl tin, and the remainder is epoxy resin.

[0040] Embodiment 2:

[0041] like Figure 1 As shown, a crack-proof lined stainless steel composite three-way pipe fitting with enhanced sealing performance comprises a stainless steel layer 1, the outer layer of the stainless steel layer 1 is fixedly connected to a carbon steel layer 2, and the outer side of the carbon steel layer 2 is fixedly connected to a resin layer 3;

[0042] The stainless steel layer 1 is composed of the following components in mass percentage: Mn: 6.0%, Cr: 23.0%, Ni: 10.0%, Mo: 1.1%, Al: 0.8%, Sn: 0.07%, W: 2.0%, Co: 1.8%, Ti: 1.2%, and the balance is Fe; average Md value: 0.7732, area ratio of σ phase: 1.1%;

[0043] The carbon steel layer 2 is composed of the following components in mass percentage: Mn: 1.8%, Si: 0.5%, Cr: 0.3%, Ni: 0.9%, Mo: 0.3%, and the balance is Fe;

[0044] The resin layer 3 is composed of the following components in percentage by mass: 23.5% of boron trinitride ethylamine complex, 20% of alkylene glycidyl ether, 8.8% of fatty alcohol ethoxysiloxane, 3.2% of dimethyl tin, and the remainder is epoxy resin.

[0045] Embodiment 3:

[0046] like Figure 1 As shown, a crack-proof lined stainless steel composite three-way pipe fitting with enhanced sealing performance comprises a stainless steel layer 1, the outer layer of the stainless steel layer 1 is fixedly connected to a carbon steel layer 2, and the outer side of the carbon steel layer 2 is fixedly connected to a resin layer 3;

[0047] The stainless steel layer 1 is composed of the following components in mass percentage: Mn: 8.0%, Cr: 25.0%, Ni: 12.0%, Mo: 3.0%, Al: 1.0%, Sn: 0.02%, W: 3.0%, Co: 2.3%, Ti: 1.5%, and the balance is Fe; average Md value: 0.6503, area ratio of σ phase: 0.9%;

[0048] The carbon steel layer 2 is composed of the following components in mass percentage: Mn: 2.2%, Si: 0.8%, Cr: 0.5%, Ni: 1.5%, Mo: 0.4%, and the balance is Fe;

[0049] The resin layer 3 is composed of the following components in percentage by mass: 20-25.5% of boron trinitride ethylamine complex, 18-22% of alkylene glycidyl ether, 7-9.8% of fatty alcohol ethoxysiloxane, 3-5% of dimethyl tin, and the remainder is epoxy resin.

[0050] Embodiment 4:

[0051] On the basis of Example 3, Example 4 provides a method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance, comprising the following steps:

[0052] S1. Cut the stainless steel pipe and the carbon steel pipe according to the production requirements, and obtain the carbon steel main pipe, the carbon steel branch pipe and the stainless steel pipe after cutting;

[0053] Stainless steel pipe is a seamless stainless steel pipe made by the perforation method. The perforation method is to heat the stainless steel billet to 850℃, then put the heated billet into the perforator for perforation to form a rough tube, and then the rough tube is rolled to reduce the tube wall thickness and increase the tube length. The rolled rough tube is sized by the sizing machine, and the sized rough tube is placed in the cooling tower for cooling to obtain the stainless steel pipe. The hydraulic expansion of stainless steel pipe has uniform internal structure and is not prone to cracks and uneven wall thickness.

[0054] S2. Drill holes in the side wall of the carbon steel main pipe. After the drilling is completed, weld the carbon steel branch pipe to the notch of the carbon steel main pipe. Then remove the welding slag at the welding place and remove the protruding part of the surface by a hand-held grinder to form a carbon steel tee pipe. Grind the inner wall of the carbon steel tee pipe to remove burrs.

[0055] S3, such as Figure 2As shown, the stainless steel pipe is heat treated, and then the heat-treated stainless steel pipe is inserted into the carbon steel tee pipe to form an assembly, and the assembly is placed in a hydraulic mold, and the stainless steel pipe is filled with emulsion through a hydraulic bulging device, and at the same time, the hydraulic rod is used to synchronously align and squeeze from both ends of the carbon steel main pipe, so that the stainless steel pipe is closely attached to the inner wall of the carbon steel tee pipe, and the stainless steel pipe is deformed to enter the carbon steel branch pipe and closely attached to the inner wall of the carbon steel branch pipe. After the hydraulic bulging is completed, a lined stainless steel tee blank is obtained;

[0056] The heat treatment method of stainless steel pipe is: heat the stainless steel pipe to 450℃, keep it warm for 1h, and cool it to room temperature with the furnace. Stainless steel pipe may generate internal stress during the manufacturing process, which is usually released during the heat treatment process. The heat treatment method mentioned above can reduce these internal stresses, thereby reducing cracks or deformation caused by stress concentration during the hydraulic bulging process;

[0057] The axial pressure of the hydraulic bulging equipment is 190Mpa and the bulging height is 30mm. The above axial pressure helps the material to be more evenly distributed in the mold, reduce material defects, and improve the surface finish and dimensional accuracy of the finished product;

[0058] The material filling ratio during hydraulic bulging is 4.5:1, the internal pressure of the stainless steel pipe is 150Mpa, the back pressure of the carbon steel pipe is 70Mpa, and the pressure holding time is 1min. The above pressure holding time can ensure that the pipe is fully solidified in the mold, improve the dimensional accuracy and shape stability of the product, and the above material filling ratio can fully compensate for the volume change of the pipe during the bulging process to avoid uneven wall thickness or cracks in the pipe;

[0059] The wall thickness of the stainless steel pipe is 5mm. If the wall thickness of the stainless steel pipe is too thin, it will be unfavorable for axial extrusion, resulting in a lower bulging height. If the wall thickness of the stainless steel pipe is too thick, the pressure required for deformation will be too large, increasing the difficulty of bulging.

[0060] S4, fix the lined stainless steel tee blank, drill a hole from the carbon steel branch pipe, remove the deformed stainless steel closed section, and then grind the drilled part to obtain a lined stainless steel composite pipe;

[0061] S5. Use the sealing cover to seal the three pipe openings of the lined stainless steel composite pipe, and then put it into the resin liquid tank for immersion treatment. The temperature of the liquid inlet tank is 20°C. After the immersion treatment is completed, it is dried at an ambient temperature of 100°C for 10 minutes. After the drying is completed, the sealing cover is removed to obtain a lined stainless steel composite three-way pipe fitting. The stainless steel pipe is used as the inner lining and is formed into a composite metal pipe with a carbon steel pipe. The lined stainless steel composite pipe has excellent corrosion resistance and can resist corrosion from water and air, as well as corrosion from weak acids and weak alkalis. It is suitable for the transportation of a variety of chemical media. The lined stainless steel composite pipe will not produce scaling or nodules, keeping the pipe clean, and is suitable for drinking water systems and other occasions with high hygiene requirements.

[0062] The emulsion is composed of the following components in percentage by mass: 15% base oil, 6.5% sodium petroleum sulfonate emulsifier, 4.3% zinc naphthenate rust inhibitor, 5.5% sodium dithiohyaluronic acid extreme pressure additive, 2.8% polyglycerol fatty acid ester stabilizer, and the balance is water. As a hydraulic medium, the emulsion can evenly transmit pressure to the inner wall of the pipe, helping the pipe to undergo plastic deformation in the mold, thereby achieving bulging of the pipe.

[0063] Embodiment 5:

[0064] On the basis of Example 3, Example 5 provides a method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance, comprising the following steps:

[0065] S1. Cut the stainless steel pipe and the carbon steel pipe according to the production requirements, and obtain the carbon steel main pipe, the carbon steel branch pipe and the stainless steel pipe after cutting;

[0066] Stainless steel pipe is a seamless stainless steel pipe made by the perforation method. The perforation method is to heat the stainless steel billet to 880℃, then put the heated billet into the perforator for perforation to form a rough tube, and then the rough tube is rolled to reduce the tube wall thickness and increase the tube length. The rolled rough tube is sized by the sizing machine, and the sized rough tube is placed in the cooling tower for cooling to obtain the stainless steel pipe. The hydraulic expansion of stainless steel pipe has uniform internal structure and is not prone to cracks and uneven wall thickness.

[0067] S2. Drill holes in the side wall of the carbon steel main pipe. After the drilling is completed, weld the carbon steel branch pipe to the notch of the carbon steel main pipe. Then remove the welding slag at the welding place and remove the protruding part of the surface by a hand-held grinder to form a carbon steel tee pipe. Grind the inner wall of the carbon steel tee pipe to remove burrs.

[0068] S3, such as Figure 2As shown, the stainless steel pipe is heat treated, and then the heat-treated stainless steel pipe is inserted into the carbon steel tee pipe to form an assembly, and the assembly is placed in a hydraulic mold, and the stainless steel pipe is filled with emulsion through a hydraulic bulging device, and at the same time, the hydraulic rod is used to synchronously align and squeeze from both ends of the carbon steel main pipe, so that the stainless steel pipe is closely attached to the inner wall of the carbon steel tee pipe, and the stainless steel pipe is deformed to enter the carbon steel branch pipe and closely attached to the inner wall of the carbon steel branch pipe. After the hydraulic bulging is completed, a lined stainless steel tee blank is obtained;

[0069] The heat treatment method for stainless steel pipes is: heat the stainless steel pipes to 500℃, keep them warm for 1.2 hours, and cool them to room temperature with the furnace. Stainless steel pipes may generate internal stresses during the manufacturing process, which are usually released during the heat treatment process. Heat treatment by the above method can reduce these internal stresses, thereby reducing cracks or deformations caused by stress concentration during the hydraulic bulging process;

[0070] The axial pressure of the hydraulic bulging equipment is 194Mpa and the bulging height is 45mm. The above axial pressure helps the material to be more evenly distributed in the mold, reduce material defects, and improve the surface finish and dimensional accuracy of the finished product;

[0071] The material filling ratio during hydraulic bulging is 4.5:1, the internal pressure of the stainless steel pipe is 155Mpa, the back pressure of the carbon steel pipe is 77Mpa, and the pressure holding time is 1.5min. The above pressure holding time can ensure that the pipe is fully solidified in the mold, improve the dimensional accuracy and shape stability of the product, and the above material filling ratio can fully compensate for the volume change of the pipe during the bulging process to avoid uneven wall thickness or cracks in the pipe;

[0072] The wall thickness of the stainless steel pipe is 6mm. If the wall thickness of the stainless steel pipe is too thin, it will be unfavorable for axial extrusion, resulting in a lower bulging height. If the wall thickness of the stainless steel pipe is too thick, the pressure required for deformation will be too large, increasing the difficulty of bulging.

[0073] S4, fix the lined stainless steel tee blank, drill a hole from the carbon steel branch pipe, remove the deformed stainless steel closed section, and then grind the drilled part to obtain a lined stainless steel composite pipe;

[0074] S5. The three pipe openings of the lined stainless steel composite pipe are sealed with a sealing cover, and then placed in a resin tank for immersion treatment. The temperature of the inlet tank is 23°C. After the immersion treatment is completed, it is dried at an ambient temperature of 110°C for 13 minutes. After the drying is completed, the sealing cover is removed to obtain a lined stainless steel composite three-way pipe fitting. The stainless steel pipe is used as the inner lining and is formed into a composite metal pipe with a carbon steel pipe. The lined stainless steel composite pipe has excellent corrosion resistance and can resist corrosion from water and air, as well as corrosion from weak acids and alkalis. It is suitable for the transportation of a variety of chemical media. The lined stainless steel composite pipe will not produce scaling or nodules, and the pipe will be kept clean. It is suitable for drinking water systems and other occasions with high hygiene requirements.

[0075] The emulsion is composed of the following components in percentage by mass: 18% base oil, 7.3% sodium petroleum sulfonate emulsifier, 5.5% zinc naphthenate rust inhibitor, 7.3% sodium dithiohyaluronic acid extreme pressure additive, 3.2% polyglycerol fatty acid ester stabilizer, and the balance is water. As a hydraulic medium, the emulsion can evenly transmit pressure to the inner wall of the pipe, helping the pipe to undergo plastic deformation in the mold, thereby achieving bulging of the pipe.

[0076] Embodiment 6:

[0077] On the basis of Example 3, Example 6 provides a method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance, comprising the following steps:

[0078] S1. Cut the stainless steel pipe and the carbon steel pipe according to the production requirements, and obtain the carbon steel main pipe, the carbon steel branch pipe and the stainless steel pipe after cutting;

[0079] Stainless steel pipe is a seamless stainless steel pipe made by the perforation method. The perforation method is to heat the stainless steel billet to 900℃, then put the heated billet into the perforator for perforation to form a rough tube, and then the rough tube is rolled to reduce the tube wall thickness and increase the tube length. The rolled rough tube is sized by the sizing machine, and the sized rough tube is placed in the cooling tower for cooling to obtain the stainless steel pipe. The hydraulic expansion of stainless steel pipe has uniform internal structure and is not prone to cracks and uneven wall thickness.

[0080] S2. Drill holes in the side wall of the carbon steel main pipe. After the drilling is completed, weld the carbon steel branch pipe to the notch of the carbon steel main pipe. Then remove the welding slag at the welding place and remove the protruding part of the surface by a hand-held grinder to form a carbon steel tee pipe. Grind the inner wall of the carbon steel tee pipe to remove burrs.

[0081] S3, such as Figure 2As shown, the stainless steel pipe is heat treated, and then the heat-treated stainless steel pipe is inserted into the carbon steel tee pipe to form an assembly, and the assembly is placed in a hydraulic mold, and the stainless steel pipe is filled with emulsion through a hydraulic bulging device, and at the same time, the hydraulic rod is used to synchronously align and squeeze from both ends of the carbon steel main pipe, so that the stainless steel pipe is closely attached to the inner wall of the carbon steel tee pipe, and the stainless steel pipe is deformed to enter the carbon steel branch pipe and closely attached to the inner wall of the carbon steel branch pipe. After the hydraulic bulging is completed, a lined stainless steel tee blank is obtained;

[0082] The heat treatment method for stainless steel pipes is: heat the stainless steel pipes to 600℃, keep them warm for 2 hours, and cool them to room temperature with the furnace. Stainless steel pipes may generate internal stresses during the manufacturing process, which are usually released during the heat treatment process. Heat treatment by the above method can reduce these internal stresses, thereby reducing cracks or deformations caused by stress concentration during the hydraulic bulging process;

[0083] The axial pressure of the hydraulic bulging equipment is 200Mpa and the bulging height is 50mm. The above axial pressure helps the material to be more evenly distributed in the mold, reduce material defects, and improve the surface finish and dimensional accuracy of the finished product;

[0084] The material filling ratio during hydraulic bulging is 4.5:1, the internal pressure of the stainless steel pipe is 160Mpa, the back pressure of the carbon steel pipe is 80Mpa, and the pressure holding time is 2 minutes. The above pressure holding time can ensure that the pipe is fully solidified in the mold, improve the dimensional accuracy and shape stability of the product, and the above material filling ratio can fully compensate for the volume change of the pipe during the bulging process to avoid uneven wall thickness or cracks in the pipe;

[0085] The wall thickness of the stainless steel pipe is 10mm. If the wall thickness of the stainless steel pipe is too thin, it will be unfavorable for axial extrusion, resulting in a lower bulging height. If the wall thickness of the stainless steel pipe is too thick, the pressure required for deformation will be too large, increasing the difficulty of bulging.

[0086] S4, fix the lined stainless steel tee blank, drill a hole from the carbon steel branch pipe, remove the deformed stainless steel closed section, and then grind the drilled part to obtain a lined stainless steel composite pipe;

[0087] S5. The three pipe openings of the lined stainless steel composite pipe are sealed with a sealing cover, and then placed in a resin liquid tank for immersion treatment. The temperature of the liquid inlet tank is 30°C. After the immersion treatment is completed, it is dried at an ambient temperature of 120°C for 15 minutes. After the drying is completed, the sealing cover is removed to obtain a lined stainless steel composite three-way pipe fitting. The stainless steel pipe is used as the inner lining and is formed into a composite metal pipe with a carbon steel pipe. The lined stainless steel composite pipe has excellent corrosion resistance and can resist corrosion from water and air, as well as corrosion from weak acids and weak alkalis. It is suitable for the transportation of a variety of chemical media. The lined stainless steel composite pipe will not produce scaling or nodules, and the pipe will be kept clean. It is suitable for drinking water systems and other occasions with high hygiene requirements.

[0088] The emulsion is composed of the following components by mass percentage: 20% base oil, 8.3% sodium petroleum sulfonate emulsifier, 6.5% zinc naphthenate rust inhibitor, 9% sodium dithiohyaluronic acid extreme pressure additive, 7.2% polyglycerol fatty acid ester stabilizer, and the balance is water. As a hydraulic medium, the emulsion can evenly transmit pressure to the inner wall of the pipe, helping the pipe to undergo plastic deformation in the mold, thereby achieving bulging of the pipe.

[0089] The performance comparison of the lined stainless steel composite pipes of implementation 1 to implementation 6 is shown in Table 1;

[0090] Table 1: Performance comparison of stainless steel lined composite pipes from Example 1 to Example 6;

[0091]

[0092]

[0093] Comparing Examples 1 to 6, the lined stainless steel composite tee pipe fitting prepared in Example 6 has the highest yield strength and tensile strength and the best elongation. It can be seen from the comparison that Example 6 is the best example.

Claims

1. A crack-proof lined stainless steel composite three-way pipe fitting with enhanced sealing performance, characterized in that: It comprises a stainless steel layer (1), the outer layer of the stainless steel layer (1) is fixedly connected to a carbon steel layer (2), and the outer side of the carbon steel layer (2) is fixedly connected to a resin layer (3); The stainless steel layer (1) is composed of the following components in percentage by weight: Composition: Mn: 5.0-8.0%, Cr: 20.0-25.0%, Ni: 5.0-12.0%, Mo: 1.0-3.0%, Al: 0.1-1.0%, Sn<1.0%, W: 1.0-3.0%, Co: 1.5-2.3%, Ti: 0.8-1.5%, the balance is Fe; average Md value<0.7840, area ratio of σ phase<1.5%; The carbon steel layer (2) is composed of the following components in percentage by mass: Composition: Mn: 1.5-2.2%, Si: 0.2-0.8%, Cr: 0.1-0.5%, Ni: 0.5-1.5%, Mo: 0.1-0.4%, the balance is Fe; The resin layer (3) is composed of the following components in percentage by mass: 20-25.5% of boron trinitride ethylamine complex, 18-22% of alkylene glycidyl ether, 7-9.8% of fatty alcohol ethoxysiloxane, 3-5% of dimethyl tin, and the remainder is epoxy resin.

2. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 1, characterized in that: The following steps are involved: S1. Cut the stainless steel pipe and the carbon steel pipe according to the production requirements, and obtain the carbon steel main pipe, the carbon steel branch pipe and the stainless steel pipe after cutting; S2. Drill holes in the side wall of the carbon steel main pipe. After the drilling is completed, weld the carbon steel branch pipe to the notch of the carbon steel main pipe. Then remove the welding slag at the welding place and remove the protruding part of the surface by a hand-held grinder to form a carbon steel tee pipe. Grind the inner wall of the carbon steel tee pipe to remove burrs. S3, heat-treating the stainless steel pipe, and then inserting the heat-treated stainless steel pipe into the carbon steel tee pipe to form an assembly, placing the assembly into a hydraulic mold, filling the stainless steel pipe with emulsion through a hydraulic bulging device, and synchronously squeezing the stainless steel pipe from both ends of the carbon steel main pipe through a hydraulic rod, so that the stainless steel pipe is closely attached to the inner wall of the carbon steel tee pipe, and the stainless steel pipe is deformed to enter the carbon steel branch pipe and closely attached to the inner wall of the carbon steel branch pipe. After the hydraulic bulging is completed, a lined stainless steel tee blank is obtained; S4, fix the lined stainless steel tee blank, drill a hole from the carbon steel branch pipe, remove the deformed stainless steel closed section, and then grind the drilled part to obtain a lined stainless steel composite pipe; S5. The three pipe openings of the lined stainless steel composite pipe are sealed by a sealing cover, and then placed in a resin liquid tank for immersion treatment. The temperature of the liquid inlet tank is 20-30°C. After the immersion treatment is completed, it is dried at an ambient temperature of 100-120°C for 10-15 minutes. After the drying is completed, the sealing cover is removed to obtain a lined stainless steel composite three-way pipe fitting.

3. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 2, characterized in that: The emulsion is composed of the following components in percentage by mass: 15-20% base oil, 6.5-8.3% petroleum sodium sulfonate emulsifier, 4.3-6.5% zinc cyclohexaneate rust inhibitor, 5.5-9% sodium dithiohyaluronic acid extreme pressure additive, 2.8-7.2% polyglycerol fatty acid ester stabilizer, and the balance is water.

4. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 2, characterized in that: The axial pressure of the hydraulic bulging equipment is 190-200Mpa, and the bulging height is 30-50mm.

5. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 2, characterized in that: The heat treatment method of the stainless steel pipe is: heating the stainless steel pipe to 450-600° C., keeping the temperature for 1-2 hours, and cooling the stainless steel pipe to room temperature along with the furnace.

6. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 2, characterized in that: The feed ratio during hydraulic bulging is 4.5:1, the internal pressure of the stainless steel pipe is 150-160 MPa, the back pressure of the carbon steel pipe is 70-80 MPa, and the pressure holding time is 1-2 minutes.

7. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 2, characterized in that: The wall thickness of the stainless steel pipe is 5-10 mm.

8. The method for preparing a crack-resistant lined stainless steel composite three-way pipe fitting with enhanced sealing performance as claimed in claim 2, characterized in that: The stainless steel pipe is a seamless stainless steel pipe prepared by a perforation method, wherein the stainless steel billet is heated to 850-900°C, and then the heated billet is placed in a perforator for perforation to form a rough tube, and then the rough tube is subjected to a rolling process to reduce the tube wall thickness and increase the tube length, and the rolled rough tube is sizing processed by a sizing machine, and the sizing rough tube is placed in a cooling tower for cooling to obtain a stainless steel pipe.

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