A steel-lined high-silicon alloy structure and its welding method

Abstract

A steel-lined high-silicon alloy structure and a welding method thereof adopt a high-silicon screw connection + surfacing method, which makes the lining connection method more firm and reliable, and cleverly converts the welding between dissimilar steels of the carbon steel lining into welding between XDS high-silicon alloys of the same material as the lining, solving the problem of welding material selection between dissimilar steels. At the same time, argon arc welding is adopted, and the alloy elements in the weld pool will not be reduced during the welding process, and will not be mixed with the carbon steel base layer. The corrosion resistance of the weld area will not be reduced, and the corrosion resistance is strong, which greatly reduces the risk of corrosion at the welding point. The present invention adopts a bolt connection to tighten and a welding method between XDS high-silicon alloys of the same material, which can effectively prevent carburization and prevent intergranular corrosion of stainless steel, and solves the problem that direct welding of high-silicon steel and carbon steel will cause carburization of the carbon steel base layer into the high-silicon steel layer.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical equipment, and in particular to a steel-lined high-silicon alloy structure and a welding method thereof. Background Art

[0002] Sulfuric acid is a crucial basic chemical raw material, primarily used as a feedstock in the inorganic chemical industry. Known as the "mother of inorganic chemicals," it is widely used in the fertilizer, petroleum, nonferrous metallurgy, chemical fiber, plastics, and dye industries as a reaction medium and solvent in the production of a wide variety of chemical products. Therefore, it's no exaggeration to say that the annual output of sulfuric acid reflects the level of development of a country's national economy and industry.

[0003] In sulfuric acid production systems, atmospheric pressure corrosion protection equipment such as concentrated sulfuric acid dry absorption towers, concentrated sulfuric acid circulation tanks, and concentrated sulfuric acid storage tanks are commonly used and necessary. Traditional concentrated sulfuric acid dry absorption towers and other equipment typically utilize a carbon steel shell lined with acid-resistant ceramic tiles to prevent concentrated sulfuric acid from corroding the equipment cylinder. This brick lining structure places very strict demands on the lining material and its construction quality. In particular, the mortar joints between the acid-resistant ceramic tiles are prone to concentrated sulfuric acid leaking between the lining and the shell, corroding the outer shell steel plate. The resulting sulfate volume expansion can cause the steel plate shell to crack and cause production accidents. In addition, this brick lining structure has a thick lining layer, making the equipment heavy, the equipment foundation cost high, the lining construction complex, and the construction cycle long, making subsequent maintenance and repair more difficult.

[0004] In recent years, with the advancement of science and technology, research on high-silicon alloy materials resistant to concentrated sulfuric acid corrosion has emerged in China. This has greatly promoted the alloying of sulfuric acid production equipment, reducing or even avoiding production stoppages and overhauls, improving productivity and utilization. At the same time, equipment alloying can achieve the dual benefits of reliable, safe, and environmentally friendly operation. However, using all high-silicon alloys to build corrosion-resistant equipment for sulfuric acid production is expensive. The trend is to use more cost-effective carbon steel lined with high-silicon alloys. However, the current domestic lining method for carbon steel shells lined with high-silicon alloy steel plates is mainly based on plate welding. This mainly includes fixed welding between the alloy plate and the carbon steel substrate (including: full welding, intermittent welding, and plug welding methods), as well as sealing welding (including: lap welding sealing, plate fillet welding sealing, and butt welding sealing). The biggest drawback of this lining welding method is the direct welding of high-silicon alloy material to the carbon steel substrate, which is a case of welding between dissimilar steels. The selection of welding materials is difficult. Moreover, during the welding process, the alloy weld pool metal directly fuses with the carbon steel substrate, resulting in a decrease in alloying elements in the weld pool and an increase in impurities in the weld. This seriously affects the mechanical properties and corrosion resistance of the weld, and poses a significant risk of corrosion in the weld area. Therefore, it is urgent to develop a cost-effective, safe and reliable method for lining equipment with high-silicon alloys, which has important practical significance for the innovation of sulfuric acid production equipment. Summary of the Invention

[0005] In order to solve the technical defects of the prior art, the present invention provides a steel-lined high-silicon alloy structure and a welding method thereof.

[0006] The technical solution adopted by the present invention is: a steel-lined high-silicon alloy structure, including an outer carbon steel base layer and an XDS high-silicon steel lining inside the carbon steel base layer, the carbon steel base layer and the XDS high-silicon steel lining layer are fitted together, the XDS high-silicon steel lining layer is provided with a conical through hole, and a tapped threaded hole is provided at a position corresponding to the conical through hole on the XDS high-silicon steel lining on the carbon steel base layer. The steel base layer and the XDS high-silicon steel lining are threadedly connected and fixed by screws passing through the conical through hole and the threaded hole. The screws are made of XDS high-silicon steel material, and the top of the screws is welded to the XDS high-silicon steel lining by XDS high-silicon steel welding material.

[0007] The thickness of the XDS high silicon steel lining is 4-6 mm.

[0008] The XDS high silicon steel lining is made of several high silicon steel lining plates. There is a 10mm gap between adjacent high silicon steel lining plates. A pressure strip is provided on the gap between adjacent high silicon steel lining plates. Both ends of the pressure strip are connected to the high silicon steel lining plates.

[0009] The distance between the screws is 200-300 mm, and the number of screw connection points on the steel-lined high-silicon alloy is 13-29 per square meter.

[0010] The XDS high silicon steel welding material is a Φ2.0 XDS high silicon welding wire.

[0011] The steel-lined high-silicon alloy structure is further provided with a connecting pipe, which is welded to the carbon steel base layer and the XDS high-silicon steel lining.

[0012] The diameter of the connecting pipe is DN<350, and the connecting pipe is made of pure XDS high silicon steel material.

[0013] The diameter of the connecting pipe is DN≥350, and the connecting pipe is made of steel-lined XDS high-silicon steel material.

[0014] A welding method for an acid distributor filter device comprises the following steps:

[0015] (1) Prepare the carbon steel cylinder of the equipment and grind the inner wall of the cylinder smooth as required to ensure the bonding strength of the subsequent lining. Cut and arrange the XDS lining layer sheets according to their size. Leave a 10mm gap between each XDS lining layer sheet when arranging the sheets, and make the sheet arrangement marks. At the same time, the XDS lining layer sheets need to be pre-bent to the same curvature according to the curvature of the carbon steel cylinder inner wall at the arrangement location.

[0016] (2) Determine the position of the screw connection point according to the position of the plate arrangement, drill threaded holes on the inner wall of the carbon steel base cylinder, process tapered through holes on the XDS lining layer, and grind off the burrs;

[0017] (3) Use a shearing machine to cut a 40mm wide layer for standby use. The material and thickness of the layer are consistent with the XDS high silicon lining layer;

[0018] (4) Stick the XDS lining layer to the inner wall of the carbon steel base cylinder according to the plate arrangement position and arc direction, and align it with the threaded holes at the connection points of the carbon steel base plate. Use manual compression or auxiliary equipment to make the XDS lining layer completely fit the carbon steel base. Screw the prepared XDS screws into the pre-processed threaded holes in sequence and tighten them;

[0019] (5) Check to ensure that all the screws at each connection point are screwed in and tightened. Use XDS high silicon welding wire to weld the top of the screw to the XDS lining layer by manual tungsten inert gas arc welding to ensure that the head of the screw hole at the connection point is fully filled with surfacing;

[0020] (6) Weld the connecting pipe to the steel-lined composite cylinder. The insertion depth of the connecting pipe should extend 6mm to 8mm beyond the inner lining of the equipment.

[0021] In the step (6), the diameter of the pipe is DN < 350, the pipe is made of pure XDS high silicon steel material, the diameter of the pipe is DN ≥ 350, the pipe is made of steel-lined XDS high silicon steel material, and the carbon steel pipe is first welded to the carbon steel base of the composite cylinder. After the steel pipe is welded, the lined XDS high silicon alloy pipe is inserted into the carbon steel pipe, and the insertion depth of the lined XDS high silicon alloy pipe extends out of the lining layer of the equipment by 6 mm to 8 mm.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a steel-lined high-silicon alloy structure and a welding method thereof, adopts a high-silicon screw connection + surfacing method, so that the lining connection method is more firm and reliable, and the welding between the dissimilar steels of the carbon steel lining is cleverly converted into welding between XDS high-silicon alloys of the same material as the lining, solving the problem of welding material selection between dissimilar steels. At the same time, argon arc welding is adopted, and the alloy elements in the weld pool will not be reduced during the welding process, and will not be mixed with the carbon steel base layer. The corrosion resistance of the weld area will not be reduced, and the corrosion resistance is strong, which greatly reduces the risk of corrosion at the welding point. The present invention adopts bolt connection to tighten, and the welding between XDS high-silicon alloys of the same material can effectively prevent carburization and prevent intergranular corrosion of stainless steel, and solves the problem that direct welding of high-silicon steel and carbon steel will cause carburization of the carbon steel base layer into the high-silicon steel layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] Figure 2 This is a schematic diagram of the steel-lined high-silicon alloy welding structure of the present invention.

[0025] Figure 3 This is a schematic diagram of the splicing structure of the high silicon steel liner of the present invention.

[0026] Figure 4 It is a schematic diagram of the screw structure of the present invention.

[0027] Figure 5 This is a schematic diagram of the connection structure of the connecting pipe with a diameter of DN < 350 according to the present invention.

[0028] Figure 6 This is a schematic diagram of the connection structure of the connecting pipe with a diameter of DN≥350 according to the present invention.

[0029] Among them, 1-carbon steel base, 2-XDS high silicon steel lining, 3-screws, 4-layering strips, 5-connecting pipes. DETAILED DESCRIPTION

[0030] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] A steel-lined high-silicon alloy structure comprises an outer carbon steel base layer 1 and an XDS high-silicon steel lining layer 2 within the carbon steel base layer 1. The XDS high-silicon steel lining layer 2 has a thickness of 4-6 mm. The carbon steel base layer 1 and the XDS high-silicon steel lining layer 2 are bonded together. The XDS high-silicon steel lining layer 2 is provided with a tapered through-hole. Tapped threaded holes are provided on the carbon steel base layer 1 at positions corresponding to the tapered through-holes in the XDS high-silicon steel lining layer 2. The steel base layer and the XDS high-silicon steel lining layer 2 are secured together by screws 3 threaded through the tapered through-holes and threaded into the threaded holes. The screws 3 are made of XDS high-silicon steel, and the tops of the screws 3 are welded to the XDS high-silicon steel lining layer 2 using XDS high-silicon steel welding consumables. The XDS high-silicon steel lining layer and the carbon steel base layer are bonded together using screws, which are then welded to the inner layer using solid welding wire made of the same material as the lining layer. Argon arc welding is used to isolate the dielectric side of the lining layer from the base layer to prevent dielectric corrosion. The strength and rigidity of the equipment are mainly borne by the carbon steel base layer. The XDS high-silicon lining layer mainly plays an anti-corrosion role, protecting the equipment from corrosion by corrosive media such as concentrated sulfuric acid. At the same time, it also plays a certain auxiliary strengthening role in the strength of the equipment.

[0032] The XDS high-silicon steel lining 2 is composed of several high-silicon steel lining plates, with a 10mm gap between adjacent plates. A pressure strip 4 is installed in the gaps between adjacent plates, with both ends of the pressure strip 4 connected to the high-silicon steel lining plates. The spacing between the screws 3 is 200-300mm, and the number of screw connection points per square meter of the high-silicon alloy steel lining is 13-29.

[0033] The XDS high silicon steel welding material is a Φ2.0 XDS high silicon welding wire.

[0034] The steel-lined high-silicon alloy structure also features a pipe 5, which is welded to the carbon steel base layer 1 and the XDS high-silicon steel lining 2. The pipe 5 has a DN diameter less than 350 mm and is made of pure XDS high-silicon steel. The pipe 5 has a DN diameter greater than or equal to 350 mm and is made of steel-lined XDS high-silicon steel. The outer diameter of the XDS alloy pipe is tailored to the inner diameter of the carbon steel pipe, with a 1mm gap to ensure smooth insertion.

[0035] The connection method of this invention is more solid and reliable; this invention uses XDS high-silicon alloy screws made of the same material as the lining to fasten the carbon steel base layer, and the top of the XDS screw is welded to the lining layer, which avoids the difficulties caused by welding between dissimilar steels. The welding between the top of the screw and the XDS lining is welding between the same steels. The welding material is XDS high-silicon steel solid welding wire made of the same material as the lining, which solves the problem of welding material selection. Argon arc welding is used for welding. The alloy elements in the weld pool will not be reduced during the welding process, and will not be mixed with the carbon steel base layer. The corrosion resistance of the weld area will not be reduced, and the corrosion resistance is strong, which greatly reduces the risk of corrosion at the welding point.

[0036] The screws are made of XDS high-silicon alloy, and the top of the screw contains a cross groove. The function of the cross groove is, on the one hand, to make it convenient to use a screwdriver to screw the screw in during installation, and secondly, when the screw is screwed into place and the top of the screw is fully welded, it is more conducive to the welding pool of molten steel, making the welding stronger; the screw head is designed to be a conical surface. When the screw head is in close contact with the conical surface of the lining, the load-bearing value is large and the stability is good, which can prevent loosening during connection and ensure that the threaded connection remains tight after the XDS high-silicon alloy is welded on the top of the screw.

[0037] The inner lining is made of 4~6mm XDS high-silicon alloy material, a special high-silicon alloy with good internal corrosion resistance, mechanical properties, and excellent welding performance. The 4~6mm inner lining layer is selected based on the principle that if it is too thin, on the one hand, the corrosion margin of the lining layer is too small, and on the other hand, the XDS high-silicon plate is easily burned during surfacing welding, resulting in lining failure. If it is too thick, it will greatly increase the cost of the equipment high-silicon alloy material and increase the difficulty of lining, which is not cost-effective. The XDS high-silicon alloy lining material includes the following components and the content of each component (by mass percentage) is: C≤0.03%, 5.00%≤Si≤7.00%, Mn≤2.00%, S≤0.03%, P≤0.045%, 11.50%≤Cr≤18.50%, 14.50%≤Ni≤19.50%, 0.30%≤Mo≤3.00%, 0.30%≤Cu≤3.00%, Al≤0.50%, Re≤0.50%, Fe and other

[0038]

[0039] (1) The inventors determined and provided the spacing between connection points and the specifications of XDS screws at the connection points by combining theoretical calculations with experimental research. The comparison table for the spacing between connection points and the specifications of screws is as follows:

[0040]

[0041] Preparation before lining

[0042] (1) Make the carbon steel cylinder of the equipment and polish the inner wall of the cylinder smooth as required to ensure the bonding strength of the subsequent lining;

[0043] (2) Use XDS high-silicon rods made of the same material as the lining to process screws (the size of the screws is determined by the diameter and wall thickness of the lining equipment, generally M8 to M12 (see the table for details), the top of the screw contains a cross slot, and the taper of the screw head is 100° to 120°);

[0044] (3) Cut and arrange the qualified XDS lining sheets according to their sizes. When arranging the sheets, pay attention to leaving a 10mm gap between each XDS lining sheet (the gap has the following three functions: ① It serves as an exhaust groove when welding the bead, ② It facilitates thermal expansion and contraction during the normal operation of the equipment, and ③ It serves as an ammonia flow groove when the ammonia leakage test is done after the equipment is lined). And make good arrangement marks. At the same time, the XDS lining sheet should be pre-bent to a consistent curvature according to the curvature of the carbon steel cylinder inner wall at the arrangement position for standby use;

[0045] (4) Determine the position of the screw connection point according to the position of the plate arrangement, drill threaded holes on the inner wall of the carbon steel base cylinder (the size and depth of the threaded holes are determined according to the thickness of the carbon steel base, and the threaded hole size is generally M8~M12, see the table for details), and process tapered through holes on the XDS lining layer, and grind off the burrs;

[0046] (5) Use a shearing machine to cut a 40mm wide layer for standby use. The material and thickness of the layer are consistent with the XDS high silicon lining layer;

[0047] (6) Prepare Φ2.0 XDS high silicon welding wire for standby use;

[0048] (7) Clean the lining surface and the screw surface with a cleaning agent or anhydrous ethanol;

[0049] Lining process (pressing the plate, tightening the threaded holes with screws, welding)

[0050] (1) Stick the XDS lining layer to the inner wall of the carbon steel base cylinder according to the plate position and arc direction, and align it with the threaded holes of the carbon steel base plate connection points. Pay attention to controlling the reserved gap of 10mm between each plate. Use manual pressing or auxiliary equipment to make the XDS lining layer completely fit the carbon steel base. During the plate sticking process, the surface of the XDS lining layer must be well protected and scratches should be avoided as much as possible (it is best to use wooden boards or rubber pads for operating scaffolding or auxiliary tools) to avoid affecting the PT detection effect.

[0051] (2) Screw in the screws. Screw the prepared XDS screws into the pre-processed threaded holes in sequence and tighten them with a screwdriver;

[0052] (3) Check to ensure that all the screws at each connection point are screwed in and tightened. Use XDS high silicon welding wire to weld the top of the screw to the XDS lining layer by manual tungsten inert gas arc welding to ensure that the head of the screw hole at the connection point is filled with surfacing. During welding, the welding current needs to be strictly controlled according to the welding process documents prepared in the early stage to avoid excessive current burning through the XDS lining layer and causing carburization;

[0053] (4) The quality of the welding seams at the connection points shall be tested by PT according to the method in NB / T47013.5-2015, and the level I test shall be qualified. The purpose is to ensure that there are no defects on the surface of the cladding welds.

[0054] Welding method between the nozzle and the steel-lined XDS high-silicon alloy composite cylinder

[0055] A complete equipment requires various process nozzles and instrument interfaces on the cylinder. After experimental verification, the inventors have provided two welding methods between the nozzle and the steel-lined composite cylinder:

[0056] a. For pipes with a diameter less than DN350, XDS high-silicon alloy steel pipes shall be used. When welded to the steel-lined composite cylinder, the pipe insertion depth shall extend 6mm to 8mm beyond the inner lining of the equipment (see node diagram a). This is to convert the fillet weld where the pipe extends into the cylinder into a weld between XDS high-silicon alloys, thus avoiding the disadvantage of reduced alloy elements in the weld caused by welding between XDS alloy pipes and carbon steel dissimilar steels, ensuring the quality of the high-silicon alloy in the weld to the greatest extent and reducing the risk of corrosion. The fillet welds between the outer wall of the XDS alloy pipe and the outer wall of the composite cylinder shall be firmly welded.

[0057] b. For pipes with a diameter greater than or equal to DN350, considering the high price and cost-effectiveness of XDS high-silicon pure alloy steel pipes, the inventors have also proposed a method of lining carbon steel pipes with XDS alloy pipes, which are then welded to the composite cylinder of the equipment. The specific implementation method is to first determine the specifications and length of the carbon steel pipe, calculate the outer diameter of the alloy pipe based on the inner diameter of the carbon steel pipe (1mm smaller than the inner diameter of the carbon steel base steel pipe), first weld the carbon steel pipe to the carbon steel base of the composite cylinder, and perform the welding joint type according to G2 in HG / T20583-2020 (see node diagram b). After the carbon steel pipe is welded, the lined XDS high-silicon alloy pipe is inserted into the carbon steel pipe. The insertion depth should also extend 6mm to 8mm beyond the inner lining of the equipment. This makes the fillet weld here become a weld between XDS high-silicon alloys, which is a weld between the same type of steel, avoiding the safety hazards of the weld.

[0058] Ammonia leakage test of XDS high silicon alloy lining layer of steel

[0059] (1) Open a detection process hole on the carbon steel layer on the surface of the composite cylinder of the equipment. The detection hole size can be M8 or M10. The detection hole needs to be opened at the bottom of the composite cylinder to facilitate the input flow of ammonia during detection.

[0060] (2) Thoroughly clean the surface of the equipment lining, including the welding slag at the screws of the lining construction connection points, and the stains left during the PT inspection after welding.

[0061] (3) Clean the inner wall of the steel-lined XDS equipment and dry it in the air or in the oven for inspection.

[0062] (4) Continuously introduce ammonia gas from the detection process hole to fill the entire gap reserved between the carbon steel base layer and the XDS lining layer.

[0063] (5) Put the phenolphthalein test solution into a spray bottle and spray it evenly onto the welds of the XDS lining laminate strips through the nozzle of the spray bottle. All welds must be sprayed. Based on the principle that the phenolphthalein test solution turns red when it encounters alkalinity, carefully observe the color change of the welds. If the welds are red, it indicates that there is an ammonia leak, indicating that the welding is defective. Otherwise, the welds are intact and the defective welds should be polished and repaired.

[0064] Technical personnel should note: Although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention. Any modification using the inventive concept will be included in the scope of protection of this patent.

[0065] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A steel-lined high-silicon alloy structure, comprising an outer carbon steel base layer (1) and an XDS high-silicon steel lining layer (2) within the carbon steel base layer (1), characterized in that: The carbon steel base layer (1) and the XDS high silicon steel lining layer (2) are fitted and connected, the XDS high silicon steel lining layer (2) is provided with a tapered through hole, and a tapped threaded hole is provided at a position corresponding to the tapered through hole on the carbon steel base layer (1) and the XDS high silicon steel lining layer (2), and the steel base layer and the XDS high silicon steel lining layer (2) are fixed by screws (3) passing through the tapered through hole and the threaded hole, and the screws (3) are made of XDS high silicon steel material, and the top of the screws (3) and the XDS high silicon steel lining layer (2) are connected by XDS The high silicon steel welding material is welded and connected. The thickness of the XDS high silicon steel lining (2) is 4-6 mm. The XDS high silicon steel lining (2) is formed by splicing a plurality of high silicon steel lining plates. There is a gap of 10 mm between adjacent high silicon steel lining plates. A pressure strip (4) is provided on the gap between adjacent high silicon steel lining plates. Both ends of the pressure strip (4) are also connected to the high silicon steel lining plates. The spacing between the screws (3) and the screws (3) is 200-300 mm. The number of screw (3) connection points on each square meter of the steel lining high silicon alloy is 13-29.

2. A steel-lined high silicon alloy structure according to claim 1, characterized in that: The XDS high silicon steel welding material is a Φ2.0 XDS high silicon welding wire.

3. The steel-lined high-silicon alloy structure according to claim 1, characterized in that: The steel-lined high-silicon alloy structure is further provided with a connecting pipe (5), and the connecting pipe (5) is welded to the carbon steel base layer (1) and the XDS high-silicon steel lining layer (2).

4. A steel-lined high silicon alloy structure according to claim 3, characterized in that: The diameter of the connecting pipe (5) is DN<350, and the connecting pipe (5) is made of pure XDS high silicon steel material.

5. The steel-lined high-silicon alloy structure according to claim 3, characterized in that: The diameter of the connecting pipe (5) is DN≥350, and the connecting pipe (5) is made of steel-lined XDS high-silicon steel material.

6. A welding method for a steel-lined high-silicon alloy structure according to claim 3, characterized in that: The following steps are involved: (1) Prepare the carbon steel cylinder of the equipment and grind the inner wall of the cylinder smooth as required to ensure the bonding strength of the subsequent lining. Cut and arrange the XDS lining layer sheets according to their size. Leave a 10mm gap between each XDS lining layer sheet when arranging the sheets, and make the sheet arrangement marks. At the same time, the XDS lining layer sheets need to be pre-bent to the same curvature according to the curvature of the carbon steel cylinder inner wall at the arrangement location. (2) Determine the position of the screw connection point according to the position of the plate arrangement, drill threaded holes on the inner wall of the carbon steel base cylinder, process tapered through holes on the XDS lining layer, and grind off the burrs; (3) Use a shearing machine to cut a 40mm wide layer for standby use. The material and thickness of the layer are consistent with the XDS high silicon lining layer; (4) Stick the XDS lining layer to the inner wall of the carbon steel base cylinder according to the plate arrangement position and arc direction, and align it with the threaded holes at the connection points of the carbon steel base plate. Use manual compression or auxiliary equipment to make the XDS lining layer completely fit the carbon steel base. Screw the prepared XDS screws into the pre-processed threaded holes in sequence and tighten them; (5) Check to ensure that all the screws at each connection point are screwed in and tightened. Use XDS high silicon welding wire to weld the top of the screw to the XDS lining layer by manual tungsten inert gas arc welding to ensure that the head of the screw hole at the connection point is fully filled with surfacing; (6) Weld the connecting pipe to the steel-lined composite cylinder. The insertion depth of the connecting pipe should extend 6mm to 8mm beyond the inner lining of the equipment.

7. The welding method according to claim 6, characterized in that: In the step (6), the diameter of the pipe is DN < 350, the pipe is made of pure XDS high silicon steel material, the diameter of the pipe is DN ≥ 350, the pipe is made of steel-lined XDS high silicon steel material, and the carbon steel pipe is first welded to the carbon steel base of the composite cylinder. After the steel pipe is welded, the lined XDS high silicon alloy pipe is inserted into the carbon steel pipe, and the insertion depth of the lined XDS high silicon alloy pipe extends out of the lining layer of the equipment by 6 mm to 8 mm.

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