Machining method for steel cylinders with different plate thicknesses

Abstract

The invention discloses a method for machining steel cylinders with different plate thicknesses. The method comprises the steps that S1, parts are blanked and machined, specifically, the parts are cut through gas cutting or plasma cutting, and random spot check is conducted on site when the parts are blanked every time; s2, a cylinder pipe rolling and circle returning process which comprises the steps that S21, preparation work before cylinder rolling is conducted; step S22, rolling a cylinder; step S23, welding a longitudinal seam of the cylinder; step S24, secondary roundness correction of the cylinder; and S3, cylindrical pipe fitting assembly, specifically, S31, cylindrical pipe fitting assembly front requirements are met; step S32, carrying out a cylinder assembly construction process; s33, carrying out nondestructive testing on the cylinder welding seam; step S34, cylinder precision control; step S35, measuring the size of the cylinder; and S4, the cylinders are subjected to mark spraying treatment, and the cylinders are warehoused after being subjected to user inspection or final inspection. The manufacturing problem of large-diameter steel cylinders with different thicknesses is solved; the construction difficulty is reduced, and the manufacturing efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel cylinder manufacturing, in particular to a method for processing steel cylinders with different plate thicknesses. Background Art

[0002] In the wind power conduit rack project, the main body of the transition section is generally a large-diameter circular cylinder structure, which can be composed of multiple pipe sections with different wall thicknesses. The plate thickness is 65 to 90 mm, which is relatively thick, and the steel cylinder diameter is 7.5 meters, which is relatively large. The processing of the steel cylinder is difficult, costly, and time-consuming. In order to reduce the difficulty of construction, improve production efficiency and steel cylinder precision, it is necessary to provide a processing method for steel cylinders with different plate thicknesses to solve the problem of processing and manufacturing large-diameter steel cylinders with different plate thicknesses. Summary of the invention

[0003] The purpose of the present invention is to provide a method for processing steel cylinders with different plate thicknesses, which solves the difficulty in manufacturing steel cylinders with large diameters and different thicknesses; reduces the construction difficulty and improves the manufacturing efficiency.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for processing steel cylinders of different plate thicknesses, comprising the following steps:

[0006] Step S1, parts cutting and processing: using gas cutting or plasma cutting to cut parts, and performing random sampling on site each time parts are cut;

[0007] Step S2, the cylindrical tube winding and rounding process, respectively comprises:

[0008] Step S21, preparation work before cylinder rolling;

[0009] Step S22, cylinder rolling;

[0010] Step S23, welding the longitudinal seam of the cylinder;

[0011] Step S24, the cylinder is calibrated twice;

[0012] Step S3, assembling cylindrical pipe fittings, comprising:

[0013] Step S31, cylinder assembly pre-requisites;

[0014] Step S32, cylinder assembly construction process;

[0015] Step S33, nondestructive testing of the cylinder weld;

[0016] Step S34, cylinder precision control;

[0017] Step S35, measuring the cylinder size;

[0018] Step S4, spray marking the cylinders, and the cylinders are put into storage after user inspection or final inspection.

[0019] As a further improvement of the technical solution of the present invention, in step S1, the parts are measured, observed and inspected using a steel ruler or a tape measure, and the allowable deviations of such cut parts are: the allowable range of part width and length is ±1.5 mm; the cutting flatness is 0.05-2.0 mm; the cut depth is not more than 0.3 mm; and the local notch depth is not more than 1.0 mm.

[0020] As a further improvement of the technical solution of the present invention, in step S21, the preparatory work before cylinder rolling includes:

[0021] Step 211, make the inner arc template according to the designed arc size. Unless otherwise required, the chord length of the arc template at the large and small mouth ends shall not be less than 600mm; when the cylinder section diameter is greater than 4500mm, the chord length of the arc template at the large and small mouth ends shall not be less than 800mm;

[0022] Step 212, check the surface quality of the steel plate, clean up foreign matter, and ensure that the cutting slag on the cutting edge is clean;

[0023] Step 213, check the single section number and related marks to facilitate correct selection of the arc template;

[0024] Step 214, controlling the single section perimeter tolerance by strictly controlling the steel plate blanking size;

[0025] Step 215: Before the steel plate is rolled, the longitudinal seam bevel and edge must be polished for more than 25 mm to avoid affecting the welding quality.

[0026] As a further improvement of the technical solution of the present invention, in step S22, the cylinder rolling includes:

[0027] Step S221: When loading, the middle roller should be used to align the ends of the steel plate conveyor bed to prevent corner deviation;

[0028] Step S222, keep the upper roller at a certain inclination, pre-bend one end of the head into an arc within a range of about 200 to 300 mm, and use a sample to check the large and small ends. Only after passing the test can continuous rolling be carried out; if necessary, draw 5 to 7 plain lines on the sheet;

[0029] Step S223, during the rolling process, the peeled oxide scale should be cleaned at any time, and the forming condition should be observed. At the same time, the arcs of the large and small mouth ends should be checked at any time with the corresponding inner arc template. The local concave and convex should meet the requirements of the specification, and a certain amount of springback should be considered after the steel plate is rolled;

[0030] Step S224: When rolling a large diameter cylinder section, a crane or an auxiliary frame of the plate rolling machine must be used to prevent the rolled workpiece from being deformed due to the deadweight of the steel plate. However, it should be noted that the crane or the auxiliary device cannot be lifted too high to cause permanent deformation of the formed arc segment.

[0031] Step S225: The cylinder section with pre-bends must be accurate in size during secondary cutting, and the cutting surface in the thickness direction must be perpendicular to the surface of the steel plate.

[0032] As a further improvement of the technical solution of the present invention, in step S23, the cylindrical longitudinal seam welding includes:

[0033] Step S231, firstly, thoroughly clean the oil stains and rust within the range of 20 to 30 mm on both sides of the longitudinal seam;

[0034] Step S232: Using CO 2 Gas shielded welding is used for pre-welding; the pre-welding seam must be highly uniform and have a smooth surface;

[0035] Step S233, when the cylinder section is lifted from the plate rolling machine and transported to the specified area, a special U-shaped lifting device or chain hook should be used. During the transportation process, shaking, rubbing and collision should be prevented. The contact part between the cylinder section and the ground should be flat, free of sharp objects, and prevented from rolling. The cylinder section should be placed neatly and regularly; the electric crane should be operated according to the operating specifications.

[0036] As a further improvement of the technical solution of the present invention, in step S24, the secondary rounding of the cylinder includes:

[0037] Step S241, after the longitudinal seam welding is completed, a secondary rounding is performed before NDT, and it is ensured that the welding groove and the lack of meat in this part are not damaged; the arc-starting plate should be removed before rounding; the arc-starting plate is removed by air gouging and hammering is prohibited;

[0038] Step S242: The secondary rounding is performed using a three-roll plate rolling machine. After rounding, the arc of the cylinder section should have a natural transition and be evenly smooth, especially the local concave-convex value E at the longitudinal seam should be <(0.1t+1)mm;

[0039] Step S243: After rounding, the surface damage caused during the rolling process is repaired, patched, and ground. The cylinder section mark after rounding should still be clearly legible, otherwise it should be rewritten.

[0040] As a further improvement of the technical solution of the present invention, in step S31, the cylinder assembly is required to include:

[0041] Step S311, using a CNC cutting machine to ensure the precision of thinning and surface flatness;

[0042] Step S312, strictly control the misalignment: use the hydraulic roller frame to adjust the position of the single section. If the misalignment exceeds the specification requirements, use the hydraulic jack to handle the misalignment until it meets the requirements, and then spot weld it.

[0043] As a further improvement of the technical solution of the present invention, in step S32, the cylinder assembly construction process includes:

[0044] Step S321, after the single segment is manufactured, it is hoisted onto a roller frame for assembly, and the process is as follows: segment rolling → inspection → assembly → circumferential welding → precision inspection;

[0045] Step S322, the butt welds of the cylinder wall are aligned outside, and the butt welds of the web are aligned outside. When the thickness difference between the butt plates is greater than 5 mm, a thickness transition is required in the wall thickness change section. The thick plate is beveled to the same thickness as the thin plate. The transition slope is 1:4, and the bevel length is 4 times the thickness difference. When the thickness difference is less than or equal to 5 mm, no bevel treatment is performed.

[0046] As a further improvement of the technical solution of the present invention, in step S33, the nondestructive testing of the cylinder weld includes: the steel plate splicing seam is a double-sided groove weld, the weld grade is level 1, full penetration is required, and 100% UT testing is required 24 hours after welding. Only after the test is qualified can the next process be entered; the rolled butt longitudinal seam is a double-sided groove weld, the weld grade is level 1, full penetration is required, and 100% UT and 100% MT testing are required 24 hours after welding.

[0047] As a further improvement of the technical solution of the present invention, in step S34, the rolled steel pipe should meet the requirements of the specification, should be strictly measured at intervals of 1m along the pipeline, and the butt welding between steel pipes should meet the following requirements:

[0048] (1) Three or more girth welds are not allowed within any 3.0m range of the steel pipe;

[0049] (2) The warping deviation of the longitudinal steel plate of the shell joint shall not exceed 3mm within a range of 600mm; the misalignment deviation of the shell joint shall be 1 / 10 of the plate thickness and shall not exceed 3mm;

[0050] (3) The minimum longitudinal weld spacing between cylinder segments is 500 mm.

[0051] In step S35, each section of the cylinder is rolled from 2 to 4 sheets according to the cylinder diameter and the design requirements of the plate thickness at different positions; the cylinder should be rounded after rolling and welding, and the local unevenness and overall size should be handled to meet the following requirements:

[0052] (1) Cylinder straightness: ≤10mm;

[0053] (2) The ovality of the upper mouth D1≤3mm;

[0054] (3) Ellipticity at other positions: ±1% of diameter, and not more than 6 mm;

[0055] (4) End face verticality: less than 2mm

[0056] Compared with the prior art, the invention has the following beneficial effects:

[0057] The present invention first cuts the plate to be rolled, then rolls it, and then calibrates the roundness after the longitudinal seam is welded. After the processing of each section of the cylinder is completed, the overall assembly is butt-jointed, and the butt welds of different plate thicknesses are welded by transition groove welding. After the overall assembly is completed, flaw detection and size inspection are performed. This solves the manufacturing problem of large-diameter steel cylinders with different thicknesses; reduces the construction difficulty and improves the manufacturing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a schematic diagram of a cylindrical rolling process according to an embodiment of the present invention;

[0059] Figure 2 This is a schematic diagram of longitudinal seam welding according to an embodiment of the present invention;

[0060] Figure 3 This is a schematic diagram of a rounding and rounding process according to an embodiment of the present invention;

[0061] Figure 4 This is a schematic diagram of steel cylinder splicing according to an embodiment of the present invention;

[0062] Figure 5 This is a schematic diagram of the steel cylinder measurement arrangement according to an embodiment of the present invention;

[0063] Figure 6 This is a process flow chart of the cylinder manufacturing process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0065] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, upper end, lower end, top, bottom...) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0066] In the present invention, unless otherwise clearly defined and limited, the term "connection" should be understood in a broad sense, for example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features; in addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0068] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0069] Reference Figures 1 to 6 The present invention provides a method for processing steel cylinders with different plate thicknesses, which realizes the rolling of large-diameter steel cylinders with different thicknesses and the butt connection of steel cylinders with different plate thicknesses, wherein the method comprises the following steps:

[0070] 1. Parts cutting and processing:

[0071] For parts cut by gas cutting or plasma cutting, random sampling is carried out on site each time the parts are cut. The parts are measured and inspected by steel ruler or tape measure. The allowable deviations of such cut parts are as follows:

[0072] Table 1 Gas cutting allowable deviation Unit: mm

[0073]

[0074] 2. Cylindrical tube winding and rounding process:

[0075] 2.1 Preparation before rolling:

[0076] (1) Make inner arc templates (if necessary, outer arc templates should be made) according to the designed arc size. Unless otherwise required, the chord length of the arc templates at the large and small ends shall not be less than 600mm. When the diameter of the cylinder section is greater than 4500mm, the chord length of the arc templates at the large and small ends shall not be less than 800mm;

[0077] (2) Check the surface quality of the steel plate and clean up foreign matter, especially whether the cutting slag on the cutting edge is clean;

[0078] (3) Check the section number and related marks to select the correct arc template;

[0079] (4) Control the single section circumference tolerance by strictly controlling the steel plate cutting size;

[0080] (5) Before the steel plate is rolled, the longitudinal seam bevel and edge must be polished by more than 25 mm to avoid affecting the welding quality.

[0081] 2.2 Rolling:

[0082] (1) When loading, the middle roller should be used to align the ends of the steel plate conveyor bed to prevent corner deviation;

[0083] (2) Keep the upper roller at a certain inclination, pre-bend one end of the head about 200-300mm to the required arc, and use a sample to check the large and small ends. Only after passing the test can continuous rolling be carried out. If necessary, draw 5-7 plain lines on the sheet;

[0084] (3) During the rolling process, the peeled oxide scale should be cleaned at any time, and the forming condition should be observed. At the same time, the arc of the large and small mouth ends should be checked at any time with the corresponding inner arc template. The local concave and convex should meet the requirements of the specification. A certain amount of springback should be considered after the steel plate is rolled;

[0085] (4) When rolling large diameter cylinder sections, a crane or an auxiliary frame of the plate rolling machine must be used to prevent the rolled workpiece from being deformed due to the deadweight of the steel plate. However, it should be noted that the crane or auxiliary device should not be lifted too high, which may cause permanent deformation of the formed arc segment.

[0086] (5) For cylinder sections with pre-bends, the secondary cutting requires accurate dimensions and the cutting surface in the thickness direction should be perpendicular to the surface of the steel plate. Figure 1 .

[0087] 2.3 Longitudinal seam welding:

[0088] (1) First, thoroughly clean the oil and rust within 20 to 30 mm on both sides of the longitudinal seam;

[0089] (2) Use CO2 gas shielded welding for pre-welding. The pre-welding weld must be highly uniform and have a smooth surface;

[0090] (3) When the cylinder section is lifted from the plate rolling machine and transported to the specified area, a special U-shaped lifting device or chain hook should be used. During the transportation process, shaking, rubbing and collision should be prevented. The contact part between the cylinder section and the ground should be flat, without sharp objects, and prevented from rolling. The cylinder section should be placed neatly and regularly. The operation of the electric crane should be in accordance with the operating specifications. Figure 2 .

[0091] 2.4 Secondary calibration:

[0092] (1) After the longitudinal seam welding is completed, a second rounding shall be carried out before NDT to ensure that the welding groove and the gap in this part are not damaged; the arc-starting plate shall be removed before rounding. The arc-starting plate shall be removed by air gouging and hammering is prohibited.

[0093] (2) The secondary rounding shall be conducted by a three-roll plate rolling machine. After rounding, the arc of the cylinder section shall be naturally transitioned and evenly smooth. In particular, the local concavity (angle) at the longitudinal seam shall meet the following requirements (if there are additional requirements in the design specification, follow the design specification): E value shall be < (0.1t+1) mm (see Figure 2 ).

[0094] (3) After rounding, the surface damage caused during the rolling process should be repaired, patched, and ground. The cylinder segment markings should still be clearly legible after rounding. Otherwise, they should be rewritten. Figure 3 .

[0095] 3. Cylindrical tube segment assembly process:

[0096] 3.1 Requirements before assembling steel cylinders:

[0097] (1) Use CNC cutting machine to ensure the precision of thinning and surface flatness;

[0098] (2) Strictly control the amount of misalignment: Use a hydraulic roller frame to adjust the position of the single section. If the amount of misalignment exceeds the specification requirements, use a hydraulic jack to fix the misalignment until it meets the requirements, and then spot weld it.

[0099] 3.2 Group construction process:

[0100] After the production of a single segment is completed, it is hoisted onto a roller frame for assembly, following the steps of segment rolling back into a circle → inspection → assembly → circumferential seam welding → precision inspection.

[0101] The butt welds of the cylinder wall are aligned outside, and the butt welds of the web are aligned outside. When the thickness difference between the butt plates is greater than 5mm, the wall thickness change section needs to be made into a thickness transition, and the thick plate is beveled to the same thickness as the thin plate. The transition slope is 1:4, and the bevel length is 4 times the thickness difference. For details, please refer to the butt weld welding details in this book. When the thickness difference is less than or equal to 5mm, no bevel treatment is performed. Figure 4 .

[0102] 3.3 Nondestructive testing of welds:

[0103] The steel plate joint seam is double-sided groove welding, the weld grade is level 1, full penetration is required, and 100% UT testing is required 24 hours after welding. Only after passing the test can the next process be entered. The rolled butt longitudinal seam is double-sided groove welding, the weld grade is level 1, full penetration is required, and 100% UT and 100% MT testing are required 24 hours after welding. The UT testing standard is implemented in accordance with the industry standard "Non-destructive Testing of Pressure Equipment Part 3: Ultrasonic Testing" No. 1 Amendment (NB / T47013.3-2015 / XG1-2018), and the acceptance level is level I.

[0104] 3.4 Precision control:

[0105] Rolled steel pipes shall comply with the requirements of SY / Y 10002-2000 specification and shall be strictly measured at 1m intervals along the pipeline. The butt welding between steel pipes shall meet the following requirements:

[0106] (1) Three or more circumferential welds are not allowed within any 3.0 m range of the steel pipe.

[0107] (2) The warping deviation of the longitudinal steel plate of the tube joint shall not exceed 3mm within a range of 600mm. The misalignment deviation of the tube joint shall be 1 / 10 of the plate thickness and shall not exceed 3mm.

[0108] (3) The minimum longitudinal weld spacing between cylinder segments is 500 mm.

[0109] 3.5 Dimensional Measurement:

[0110] According to the design requirements of the cylinder diameter and the plate thickness at different positions, each section of the cylinder can be rolled from 2 to 4 plates. After the cylinder is rolled and welded, it should be rounded, and the local unevenness (especially the longitudinal seam position of the spliced ​​plate) and the overall size should be handled well, and the following requirements should be met:

[0111] (1) Cylinder straightness: ≤10mm.

[0112] (2) Upper mouth ovality D1 (with flange connection end): ≤3mm (mutually perpendicular outer diameter difference);

[0113] (3) Ellipticity at other positions: ±1% of the diameter, and not more than 6 mm (the difference between mutually perpendicular diameters).

[0114] (4) End face verticality: less than 2 mm;

[0115] (5) Circumference deviation: The circumference of any position of the pipe section should be less than 0.1% of the nominal circumference or 10mm, whichever is smaller. Figure 5 .

[0116] Compared with the existing technology, the present invention has the following beneficial effects:

[0117] The present invention first cuts the plate to be rolled, then rolls it, and then calibrates the roundness after the longitudinal seam is welded. After the processing of each section of the cylinder is completed, the overall assembly is butt-jointed, and the butt welds of different plate thicknesses are welded by transition groove welding. After the overall assembly is completed, flaw detection and size inspection are performed. This solves the manufacturing problem of large-diameter steel cylinders with different thicknesses; reduces the construction difficulty and improves the manufacturing efficiency.

[0118] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for processing steel cylinders with different plate thicknesses, characterized in that: The following steps are involved: Step S1, parts cutting and processing: using gas cutting or plasma cutting to cut parts, and performing random sampling on site each time parts are cut; Step S2, the cylindrical tube winding and rounding process, respectively comprises: Step S21, preparation work before cylinder rolling; Step S22, cylinder rolling; Step S23, welding the longitudinal seam of the cylinder; Step S24, the cylinder is calibrated twice; Step S3, assembling cylindrical pipe fittings, comprising: Step S31, cylinder assembly pre-requisites; Step S32, cylinder assembly construction process; Step S33, nondestructive testing of the cylinder weld; Step S34, cylinder precision control; Step S35, measuring the cylinder size; Step S4, spray marking the cylinders, and the cylinders are put into storage after user inspection or final inspection.

2. The method for processing steel cylinders with different plate thicknesses according to claim 1, characterized in that: In step S1, the parts are measured and inspected by a steel ruler or a tape measure, and the allowable deviations of such cut parts are as follows: the allowable range of the width and length of the parts is ±1.5 mm; the cutting flatness is 0.05-2.0 mm; the cutting depth is not more than 0.3 mm; and the local notch depth is not more than 1.0 mm.

3. The method for processing steel cylinders with different plate thicknesses according to claim 1, characterized in that: In step S21, the preparation work before cylinder rolling includes: Step 211, make the inner arc template according to the designed arc size. Unless otherwise required, the chord length of the arc template at the large and small mouth ends shall not be less than 600mm; when the cylinder section diameter is greater than 4500mm, the chord length of the arc template at the large and small mouth ends shall not be less than 800mm; Step 212, check the surface quality of the steel plate, clean up foreign matter, and ensure that the cutting slag on the cutting edge is clean; Step 213, check the single section number and related marks to facilitate correct selection of the arc template; Step 214, controlling the single section perimeter tolerance by strictly controlling the steel plate blanking size; Step 215: Before the steel plate is rolled, the longitudinal seam bevel and edge must be polished for more than 25 mm to avoid affecting the welding quality.

4. The method for processing steel cylinders of different plate thicknesses according to claim 1, characterized in that: In the step S22, the cylinder rolling includes: Step S221: When loading, the middle roller should be used to align the ends of the steel plate conveyor bed to prevent corner deviation; Step S222, keep the upper roller at a certain inclination, pre-bend one end of the head into an arc within a range of about 200 to 300 mm, and use a sample to check the large and small ends. Only after passing the test can continuous rolling be carried out; if necessary, draw 5 to 7 plain lines on the sheet; Step S223, during the rolling process, the peeled oxide scale should be cleaned at any time, and the forming condition should be observed. At the same time, the arcs of the large and small mouth ends should be checked at any time with the corresponding inner arc template. The local concave and convex should meet the requirements of the specification, and a certain amount of springback should be considered after the steel plate is rolled; Step S224: When rolling a large diameter cylinder section, a crane or an auxiliary frame of the plate rolling machine must be used to prevent the rolled workpiece from being deformed due to the deadweight of the steel plate. However, it should be noted that the crane or the auxiliary device cannot be lifted too high to cause permanent deformation of the formed arc segment. Step S225: The cylinder section with pre-bends must be accurate in size during secondary cutting, and the cutting surface in the thickness direction must be perpendicular to the surface of the steel plate.

5. The method for processing steel cylinders of different plate thicknesses according to claim 1, characterized in that: In the step S23, the longitudinal seam welding of the cylinder includes: Step S231, firstly, thoroughly clean the oil stains and rust within the range of 20 to 30 mm on both sides of the longitudinal seam; Step S232, pre-welding is performed using CO2 gas shielded welding; the pre-welding weld is required to be highly uniform and have a smooth surface; Step S233, when the cylinder section is lifted from the plate rolling machine and transported to the specified area, a special U-shaped lifting device or chain hook should be used. During the transportation process, shaking, rubbing and collision should be prevented. The contact part between the cylinder section and the ground should be flat, free of sharp objects, and prevented from rolling. The cylinder section should be placed neatly and regularly; the electric crane should be operated according to the operating specifications.

6. The method for processing steel cylinders with different plate thicknesses according to claim 1, characterized in that: In step S24, the secondary rounding of the cylinder includes: Step S241, after the longitudinal seam welding is completed, a secondary rounding is performed before NDT, and it is ensured that the welding groove and the lack of meat in this part are not damaged; the arc-starting plate should be removed before rounding; the arc-starting plate is removed by air gouging and hammering is prohibited; Step S242: The secondary rounding is performed using a three-roll plate rolling machine. After rounding, the arc of the cylinder section should have a natural transition and be evenly smooth, especially the local concave-convex value E at the longitudinal seam should be <(0.1t+1)mm; Step S243: After rounding, the surface damage caused during the rolling process is repaired, patched, and ground. The cylinder section mark after rounding should still be clearly legible, otherwise it should be rewritten.

7. The method for processing steel cylinders of different plate thicknesses according to claim 1, characterized in that: In step S31, the cylinder assembly requirements include: Step S311, using a CNC cutting machine to ensure the precision of thinning and surface flatness; Step S312, strictly control the misalignment: use the hydraulic roller frame to adjust the position of the single section. If the misalignment exceeds the specification requirements, use the hydraulic jack to handle the misalignment until it meets the requirements, and then spot weld it.

8. The method for processing steel cylinders with different plate thicknesses according to claim 1, characterized in that: In step S32, the cylinder assembly construction process includes: Step S321, after the single segment is manufactured, it is hoisted onto a roller frame for assembly, and the process is as follows: segment rolling → inspection → assembly → circumferential welding → precision inspection; Step S322, the butt welds of the cylinder wall are aligned outside, and the butt welds of the web are aligned outside. When the thickness difference between the butt plates is greater than 5 mm, a thickness transition is required in the wall thickness change section. The thick plate is beveled to the same thickness as the thin plate. The transition slope is 1:4, and the bevel length is 4 times the thickness difference. When the thickness difference is less than or equal to 5 mm, no bevel treatment is performed.

9. The method for processing steel cylinders with different plate thicknesses according to claim 1, characterized in that: In step S33, the nondestructive testing of the cylinder weld includes: the steel plate joint seam is a double-sided groove weld, the weld grade is level 1, full penetration is required, and 100% UT testing is required 24 hours after welding. Only after the test is qualified can the next process be entered; the rolled butt longitudinal seam is a double-sided groove weld, the weld grade is level 1, full penetration is required, and 100% UT and 100% MT testing are required 24 hours after welding.

10. The method for processing steel cylinders with different plate thicknesses according to claim 1, characterized in that: In step S34, the rolled steel pipe should meet the requirements of the specification, and should be strictly measured at intervals of 1m along the pipeline. The butt welding between steel pipes should meet the following requirements: (1) Three or more girth welds are not allowed within any 3.0m range of the steel pipe; (2) The warping deviation of the longitudinal steel plate of the shell joint shall not exceed 3mm within a range of 600mm; the misalignment deviation of the shell joint shall be 1 / 10 of the plate thickness and shall not exceed 3mm; (3) The minimum longitudinal weld spacing between cylinder segments is 500 mm. In step S35, each section of the cylinder is rolled from 2 to 4 sheets according to the cylinder diameter and the design requirements of the plate thickness at different positions; the cylinder should be rounded after rolling and welding, and the local unevenness and overall size should be handled to meet the following requirements: (1) Cylinder straightness: ≤10mm; (2) The ovality of the upper mouth D1≤3mm; (3) Ellipticity at other positions: ±1% of diameter, and not more than 6 mm; (4) End face verticality: less than 2 mm.

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