Automatic welding upside-down construction method for storage tank

Abstract

The invention discloses an automatic welding inverted construction method for a storage tank, which comprises the following steps of: firstly, mounting and welding a bottom plate, checking and accepting a foundation, drawing a center line, paving a middle plate, welding a middle plate welding seam, paving an edge plate, welding a 350mm welding seam on the outer side of the edge plate, assembling and welding a T-shaped seam between the edge plate and a wall plate, and assembling and welding a T-shaped seam between the edge plate and a wall plate; welding residual welding seams of the edge plate, and assembling and welding large angle seams between the center plate and the edge plate after the wall plate is mounted. Secondly, inversely installing and welding the tank body, firstly completing assembling and welding of a top ring wall plate of the storage tank, and installing a tank top ring beam rib plate, a reticulated shell structure and a skin; and hydraulic jacking equipment is installed, the installed tank body part is lifted upwards layer by layer through the hydraulic jacking equipment, plate surrounding work of each layer of strip plates is conducted, and longitudinal circular seams, vertical seams, outer side circular seams and inner side circular seams of the strip plates are welded in sequence. The welding quality is controlled by optimizing the welding process parameters, the storage tank construction efficiency is improved, and the construction period is shortened.

Description

Technical Field

[0001] The invention relates to a construction method for building vertical cylindrical atmospheric pressure or cryogenic storage tanks commonly used in industries such as petrochemicals, coal chemicals and fine chemicals for storing raw materials, intermediate products or finished products. Background Art

[0002] At present, the construction of large or super-large storage tanks, especially cryogenic, deep-cold and stainless steel storage tanks, is booming in China, and the construction technology is constantly iterating and updating. Storage tanks are generally made of carbon steel, low alloy steel, cryogenic steel, stainless steel, etc. In the original welding technology for storage tank construction, the welding process and welding parameters cannot adapt to the environment, material and other requirements of the storage tank, resulting in low construction efficiency and difficulty in unifying welding quality. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for automatic welding and inverted assembly of storage tanks, so as to achieve the purpose of improving the construction efficiency and welding quality of storage tanks.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for automatic welding and inverted assembly of a storage tank, comprising the following steps: Step 1: Bottom plate installation and welding After the foundation is inspected and accepted, the center line is marked and the middle pad is laid, then the middle plate is laid and the middle plate weld is welded, the edge plate is laid and the 350mm weld on the outer side of the edge plate is welded, the T-shaped seam between the edge plate and the wall plate is welded, and the remaining welds of the edge plate are welded. After the wall plate is installed, the large angle seam between the middle plate and the edge plate is welded; Step 2: Tank inversion and welding The tank is lifted by hydraulic jacking equipment, which includes an expansion ring, a hydraulic column and a hydraulic operation pump; the expansion ring is installed at the lower part of the top ring wall plate, and multiple vertical hydraulic columns are arranged at intervals. The bottom end of the hydraulic column is supported on the bottom plate of the storage tank, and the top end of the hydraulic column is fixed to the expansion ring; First, complete the assembly and welding of the tank top ring wall panel, install the tank top ring beam rib plate, lattice structure, and skin; install the hydraulic jacking equipment, use the hydraulic jacking equipment to lift the installed tank body layer by layer, carry out the enclosure work of each layer of the plate respectively, and weld the longitudinal circumferential seam, vertical seam, outer circumferential seam, and inner circumferential seam of the plate in turn; the vertical seam of the tank wall panel is welded by CO2 gas electric vertical welding, and the inner and outer circumferential seams of the tank body are welded by submerged arc automatic horizontal welding.

[0005] As a preferred implementation, in step one, when welding the middle width plate, first weld the short seam, then the long seam, and finally the full-length seam; the initial weld is made by manual arc welding, and the segmented back welding or skip welding method is adopted, and the filling and covering are made by submerged arc automatic flat / corner welding.

[0006] As a preferred embodiment, in step one, when welding the through-length seam and the short seam, the seam is welded from the center to both ends, and the weld is formed in one step by submerged arc automatic welding.

[0007] As a preferred embodiment, in step one, when welding the through-length seam, first weld the two longest through-length seams at the center of the base plate, and then weld the shorter long seams at both ends; when welding, first weld the through-length seam of 2.5 to 3.5 meters at the center, and then divide each weld from the center to both ends into several sections, and use the segmented back-welding method for welding. The overall welding direction is from the center to both ends, and one through-length weld is welded symmetrically using two welding machines.

[0008] As a preferred embodiment, in step one, the initial weld of the shrinkage seam between the edge plate and the middle plate is carried out by segmented back-welding or skip welding, using submerged arc automatic flat / corner welding.

[0009] As a preferred embodiment, in step 1, when the middle plate, the edge plate and the T-shaped seam of the bottom plate are welded; For manual arc welding, when the diameter of the electrode or wire is 3.2 mm, the welding current is 125-165 A, the welding voltage is 23-27 V, and the welding line speed is 14.5-17.5 cm / min; when the diameter of the electrode or wire is 4.0 mm, the welding current is 145-185 A, the welding voltage is 25-30 V, and the welding line speed is 15-18.5 cm / min; For the submerged arc automatic flat / corner welding involved, when the diameter of the electrode or wire is 4.0 mm, the welding current is 380-500 A, the welding voltage is 35-40 V, and the welding line speed is 32-45 cm / min.

[0010] As a preferred embodiment, in step 1, when welding the large angle seam of the bottom plate; For manual arc welding, when the electrode or wire diameter is 4.0 mm, the welding current is 155-195 A, the welding voltage is 25-32 V, and the welding line speed is 15-17.5 cm / min; For the submerged arc automatic flat / corner welding involved, when the diameter of the electrode or wire is 2.4mm, the welding current is 350-450A, the welding voltage is 30-35V, and the welding line speed is 40-50cm / min.

[0011] As a preferred implementation, in step 2, when the tank wall thickness is ≤26mm, a single-sided groove is used, and when the tank wall thickness is >26mm, a double-sided asymmetric groove is used; for the butt joint of the circumferential submerged arc welding, when the tank wall thickness is ≤14mm, a single-sided groove is used, and when the tank wall thickness is >14mm, a double-sided asymmetric groove is used.

[0012] As a preferred embodiment, in step 2, when the tank body is welded vertically, the diameter of the welding rod or wire is 1.6 mm, the welding current is 360-380 A, the welding voltage is 38-42 V, and the welding line speed is 12-15 cm / min.

[0013] As a preferred embodiment, in step 2, when the tank body circumferential seam is welded, the diameter of the welding rod or welding wire is 3.2 mm, the welding current is 350-400 A, the welding voltage is 27-31 V, and the welding line speed is 35-55 cm / min.

[0014] The present invention adopts the wall panel inverted installation construction process and process, uses the hydraulic jacking process to lift the wall panel, optimizes the welding process parameters to control the welding quality, improves the tank construction efficiency, and shortens the construction period. In addition, the present invention also adopts full digital display automatic welding, which can master the welding process parameters throughout the process and monitor in real time, overcoming the defects of fragmentation and accidentality of manually collected data. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention provides a process flow chart of the automatic welding inversion construction method for storage tanks. DETAILED DESCRIPTION

[0016] This example uses a 30,000 m 3 Taking the welding inverted construction process of naphtha storage tanks as an example, this embodiment describes the automated welding process and parameter process for the construction of large or super-large storage tanks, especially low-temperature, deep-cold and stainless steel storage tanks.

[0017] The 30,000 m 3 The naphtha storage tank technical transformation project is built on a reserved space in the original production plant area. The potential safety hazard is high, so the inverted installation method is used to reduce the risk of high-altitude fire. The tank body number is TK-83101D, the diameter is 46300mm, the height is 26367mm, the main body material is Q345R / Q235B, the unit weight is 649 tons, the medium is naphtha, the structure is a fixed dome aluminum single (inner) floating plate, the working pressure is -30 / 150mmH2O column, the design temperature is -19.5 / 65℃, the nominal volume is 30000m 3 The construction content includes the prefabrication and installation of the tank bottom plate, wall plate, reinforcement ring, lattice shell, skin, inner floating plate and spiral ladder.

[0018] Figure 1This is the construction process flow of this embodiment. The tank construction of this embodiment adopts the inverted full digital display automatic welding technology, and the welding equipment preferably adopts the digital display welding equipment produced by Nanjing Leken Electromechanical Equipment Co., Ltd. The tank lifting adopts the matching CNC three-cylinder hydraulic jacking equipment. This set of equipment makes it possible to use automatic welding technology for the inner ring weld of the tank. The digital display part of the automatic welding machine can continuously detect parameters such as welding date, welding time, welding current, welding voltage, welding line speed, etc. in real time, and instantly display the welding line energy; data storage is up to more than one year. In particular, it provides strong technical support for the control of automated welding parameters of low-temperature, deep-cold and stainless steel storage tanks.

[0019] The welding of the inside and outside welds of the tank bottom plate and the large angle seams of the bottom plate / wall plate are all carried out with a fully digital display automated submerged arc flat / angle welding trolley; the inside and outside longitudinal welds of the tank wall plate are welded with a fully digital display automated inverted / upright gas-electric vertical welding machine; the inside and outside circumferential welds of the tank wall plate are welded with a fully digital display automated inverted single-sided submerged arc automatic horizontal welding machine.

[0020] Specifically, the full digital display flip chip single-sided submerged arc automatic horizontal welding machine model specification MSHW-1000 / D, quantity 6 sets. Full digital display flip chip gas electric vertical welding machine model specification MEGW-1000 / D, quantity 2 sets. Full digital display submerged arc automatic flat / angle welding trolley model specification MLTW-P / J, quantity 2 sets.

[0021] The CNC three-cylinder hydraulic jacking equipment can accurately distribute the jacking load of each cylinder through the instrument control device to achieve the best safe lifting state.

[0022] 1. Welding parameters According to the wall thickness of different parts of the tank body to be welded, welding position, and welding method, the welding process parameters of this embodiment are shown in Table 1, and the technical standards of welding materials, welding wires, and flux are shown in Table 2.

[0023] Table 1

[0024] Table 2

[0025] 2. Bottom plate installation and welding process After the foundation is accepted, mark the center line and lay the middle pad, then lay the middle plate and weld the middle plate weld, lay the edge plate and weld the 300mm weld on the outside of the edge plate, assemble and weld the T-shaped seam between the edge plate and the wall plate, weld the remaining welds of the edge plate, and after the wall plate is installed, assemble and weld the large angle seam between the middle plate and the edge plate.

[0026] A base plate construction layout drawing should be drawn before construction, and the diameter of the layout drawing should be enlarged by 0.1% to 0.15% according to the design requirements.

[0027] When laying the middle plate, the middle plates that have been cut, cut, anti-corroded and numbered according to the layout diagram are hoisted into the center of the foundation in sequence, and the middle plates are laid from the center to the outside. After the middle plates are laid, the gaps, staggered amounts and other deviations at the weld joints are checked and adjusted, and spot welded to meet the requirements of automated welding.

[0028] When laying edge plates, the outer circumference of the edge plates and the center line of the butt weld are used as the reference lines to spread out the plates, and the outer circle size is ensured during laying. The laying of the edge plates of the tank bottom is carried out after the laying of the middle plates of the tank. When the bottom plate and the pad are spot welded and positioned, the adjacent two sides of each steel plate are spot welded and fixed to the pad, and the other two sides are free to shrink.

[0029] The welding sequence of the tank bottom plate is: welding the middle plate, welding the butt weld of the outer edge plate, welding the T-shaped seam between the edge plate and the wall plate, welding the butt weld of the remaining edge plates, and welding the large angle seam between the middle plate and the edge plate.

[0030] Among them, when welding the middle plate, the short seam is welded first, then the long seam, and finally the full-length seam; the initial layer of welds is primed with manual arc welding, and the segmented back welding or skip welding method is adopted, and submerged arc automatic flat / corner welding is used for filling and covering.

[0031] When welding short seams of full-length seams, the seams are welded from the center to both ends in a skipped manner, and the welds are formed in one step using submerged arc automatic welding.

[0032] When welding the long seam of a medium-width plate, welding is performed from the center to both ends using two plate units.

[0033] When welding the full-length seam, first weld the two longest full-length seams at the center of the bottom plate, and then weld the shorter long seams at both ends. When welding, first weld the full-length seam at the center for 2.5 to 3.5 meters, and then divide each weld from the center to both ends into several sections, and use the segmented back-welding method for welding. The overall welding direction is from the center to both ends. Two welding machines are used for symmetrical welding of a full-length weld.

[0034] When welding the annular edge plate of the tank bottom, first weld the weld on the outer edge of the edge plate, and then complete the welding of the remaining welds of the edge plate and the remaining welds of the middle plate after the T-shaped fillet welding connecting the tank bottom and the wall plate is completed and before the large fillet welding between the edge plate and the middle plate.

[0035] The base welding of the annular edge plate butt weld is done by manual arc welding, and the welder should weld evenly and symmetrically. The initial weld of the shrinkage seam between the edge plate and the middle plate is done by segmented back-welding (or skip welding), and the welding is done by a fully digital submerged arc automatic flat / angle welding trolley.

[0036] For the T-shaped corner seam between the tank bottom and the tank wall, after the vertical seam welding of the bottom ring wall plate is completed, the inside corner weld of the tank is welded first, and the welding is evenly distributed by pairs of manual welders. Then the outside corner weld of the tank is welded, and a fully digital submerged arc automatic flat / corner welding trolley is used.

[0037] 3. Tank inverted installation and welding process Before the second ring of wall panels are installed upside down, the welding of the tank top ring wall panels, installation of the tank top ring beam reinforcement plates, lattice shell structure and skin are completed first.

[0038] The wall panel installation adopts the CNC hydraulic jacking and inverted installation method. The tank body is lifted by hydraulic jacking equipment, which includes an expansion ring, a hydraulic column and a hydraulic operation pump; the expansion ring is installed at the bottom of the top ring wall panel, and multiple vertical hydraulic columns are arranged at intervals. The bottom end of the hydraulic column is supported on the bottom plate of the tank, and the top end of the hydraulic column is fixed to the expansion ring.

[0039] The hydraulic jacking equipment includes 30 three-cylinder hydraulic columns, 10 hydraulic operating pumps (one-to-three oil supply mode), a CNC operating table, and hydraulic systems, power supply systems, automatic control systems, etc. A set of expansion rings should be installed in advance at the bottom of the top ring wall plate, and the automatic welding machine running track and other preparations should be installed.

[0040] The overall installation concept of the tank body is: first install the hydraulic jacking equipment and the expansion ring, use the hydraulic jacking equipment to lift the installed tank body layer by layer, carry out the enclosure work of each layer of the plate respectively, and weld the longitudinal circumferential seam, vertical seam, outer circumferential seam, inner root cleaning of the circumferential seam, and inner circumferential seam of the plate in turn, and finally grind and inspect the welds.

[0041] After all installation preparations are completed, lift the tank body, first conduct a trial lift, and after confirmation, lift the pipe wall to the required height and hydraulically lock the cylinder.

[0042] When installing the enclosure, first draw a circle line on the bottom of the tank according to the inner diameter of the tank to be installed, and draw a check circle line at 100mm of the inner diameter of the tank, and punch out a mark, or weld a positioning block. After the enclosure of the enclosure, before and after spot welding, the geometric dimensions of the cylinder and the weld groove (horizontality, verticality, ovality, groove gap, edge angle, local convexity, etc.) must be checked at any time to ensure accuracy.

[0043] The order of wall panel welding is to weld the longitudinal seam first and then the circumferential weld. Before welding the longitudinal seam, first weld the gantry plate to prevent deformation. The vertical weld is welded from bottom to top by two gas-electric vertical welders and formed in one time. The circumferential seam adopts the submerged arc welding automatic welding method, first weld the outer part of the circumferential seam, then weld the inner part of the circumferential seam. After the outer side is welded, the inner side is ground and cleaned by carbon arc gouging or angle grinder. The inner circumferential weld can be welded only after passing the inspection.

[0044] When welding the circumferential seam on the outer side of the wall panel, four horizontal welding machines are evenly arranged along the weld and welded simultaneously in the same direction. When welding the circumferential seam on the inner side of the wall panel, two horizontal welding machines are evenly and symmetrically distributed and welded simultaneously in the same direction.

[0045] During automatic submerged arc welding, special attention should be paid to the flux being fully dried before use, and the flux accumulation height should not be too high. After the welding primer is completed, if the automatic welding is carried out after a long interval, the floating rust, paint and debris within the groove and within 100mm on both sides should be carefully cleaned before welding. The automatic welding track should be kept parallel to the groove to prevent deviation from the welding position. Before automatic welding, the appropriate welding current, voltage and driving speed should be selected according to the gap size of the weld, and they should remain unchanged during the welding process.

Claims

1. A method for automatic welding and inverted assembly of storage tanks, characterized in that: The following steps are involved: Step 1: Bottom plate installation and welding After the foundation is inspected and accepted, the center line is marked and the middle pad is laid, then the middle plate is laid and the middle plate weld is welded, the edge plate is laid and the 350mm weld on the outer side of the edge plate is welded, the T-shaped seam between the edge plate and the wall plate is welded, and the remaining welds of the edge plate are welded. After the wall plate is installed, the large angle seam between the middle plate and the edge plate is welded; Step 2: Tank inversion and welding The tank is lifted by hydraulic jacking equipment, which includes an expansion ring, a hydraulic column and a hydraulic operation pump; the expansion ring is installed at the lower part of the top ring wall plate, and multiple vertical hydraulic columns are arranged at intervals. The bottom end of the hydraulic column is supported on the bottom plate of the storage tank, and the top end of the hydraulic column is fixed to the expansion ring; First, complete the assembly and welding of the tank top ring wall panel, install the tank top ring beam rib plate, lattice structure, and skin; install the hydraulic jacking equipment, use the hydraulic jacking equipment to lift the installed tank body layer by layer, carry out the enclosure work of each layer of the plate respectively, and weld the longitudinal circumferential seam, vertical seam, outer circumferential seam, and inner circumferential seam of the plate in turn; the vertical seam of the tank wall panel is welded by CO2 gas electric vertical welding, and the inner and outer circumferential seams of the tank body are welded by submerged arc automatic horizontal welding.

2. The method according to claim 1, characterized in that: In step one, when welding the middle plate, first weld the short seam, then the long seam, and finally the full-length seam; the initial weld is primed with manual arc welding, and the segmented back welding or skip welding method is used, and submerged arc automatic flat / angle welding is used for filling and covering.

3. The method according to claim 2, characterized in that: In step one, when welding the full-length seam and short seam, the seam is welded from the center to both ends, and the weld is formed in one step by submerged arc automatic welding.

4. The method according to claim 2, characterized in that: In step one, when welding the full-length seam, first weld the two longest full-length seams at the center of the bottom plate, and then weld the shorter long seams at both ends; when welding, first weld the full-length seam of 2.5 to 3.5 meters at the center, and then divide each weld from the center to both ends into several sections, and use the segmented back-welding method for welding. The overall welding direction is from the center to both ends, and one full-length weld is welded symmetrically using two welding machines.

5. The method according to claim 2, 3 or 4, characterized in that: In step 1, the initial weld of the shrinkage seam between the edge plate and the middle plate is carried out by segmented back-welding or skip welding, and submerged arc automatic flat / corner welding is adopted.

6. The method according to claim 5, characterized in that: In step 1, when welding the middle plate, edge plate and T-seam of the bottom plate; For manual arc welding, when the diameter of the electrode or wire is 3.2 mm, the welding current is 125-165 A, the welding voltage is 23-27 V, and the welding line speed is 14.5-17.5 cm / min; when the diameter of the electrode or wire is 4.0 mm, the welding current is 145-185 A, the welding voltage is 25-30 V, and the welding line speed is 15-18.5 cm / min; For the submerged arc automatic flat / corner welding involved, when the diameter of the electrode or wire is 4.0 mm, the welding current is 380-500 A, the welding voltage is 35-40 V, and the welding line speed is 32-45 cm / min.

7. The method according to claim 6, characterized in that: In step 1, when welding the large angle seam of the bottom plate; For manual arc welding, when the electrode or wire diameter is 4.0 mm, the welding current is 155-195 A, the welding voltage is 25-32 V, and the welding line speed is 15-17.5 cm / min; For the submerged arc automatic flat / corner welding involved, when the diameter of the electrode or wire is 2.4mm, the welding current is 350-450A, the welding voltage is 30-35V, and the welding line speed is 40-50cm / min.

8. The method according to claim 1 or 7, characterized in that: In step 2, when the tank wall thickness is ≤26mm, a single-sided groove is used, and when the tank wall thickness is >26mm, a double-sided asymmetric groove is used; for the butt joint of the circumferential submerged arc welding, when the tank wall thickness is ≤14mm, a single-sided groove is used, and when the tank wall thickness is >14mm, a double-sided asymmetric groove is used.

9. The method according to claim 8, characterized in that: In step 2, when the tank body is welded vertically, the diameter of the welding rod or wire is 1.6 mm, the welding current is 360-380 A, the welding voltage is 38-42 V, and the welding line speed is 12-15 cm / min.

10. The method according to claim 9, characterized in that: In step 2, when welding the annular seam of the tank body, the diameter of the welding rod or welding wire is 3.2 mm, the welding current is 350-400 A, the welding voltage is 27-31 V, and the welding line speed is 35-55 cm / min.

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