CN115070244B - Sulfur-resistant chlorine-resistant high-temperature-resistant high-pressure-resistant heat exchange tube welding method - Google Patents
Sulfur-resistant chlorine-resistant high-temperature-resistant high-pressure-resistant heat exchange tube welding method Download PDFInfo
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- CN115070244B CN115070244B CN202210704064.4A CN202210704064A CN115070244B CN 115070244 B CN115070244 B CN 115070244B CN 202210704064 A CN202210704064 A CN 202210704064A CN 115070244 B CN115070244 B CN 115070244B
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- 238000003466 welding Methods 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 22
- 239000000460 chlorine Substances 0.000 title claims abstract description 15
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 229910052801 chlorine Inorganic materials 0.000 title claims abstract description 14
- 239000011593 sulfur Substances 0.000 title claims abstract description 14
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 14
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 239000002253 acid Substances 0.000 claims abstract description 31
- 238000002161 passivation Methods 0.000 claims abstract description 20
- 238000000137 annealing Methods 0.000 claims abstract description 19
- 238000005406 washing Methods 0.000 claims abstract description 15
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 238000001514 detection method Methods 0.000 claims description 8
- 238000005553 drilling Methods 0.000 claims description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 229910017604 nitric acid Inorganic materials 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 238000002791 soaking Methods 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 3
- 238000004321 preservation Methods 0.000 claims description 3
- 230000007797 corrosion Effects 0.000 abstract description 13
- 238000005260 corrosion Methods 0.000 abstract description 13
- 238000005452 bending Methods 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 5
- 238000007789 sealing Methods 0.000 abstract description 3
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 4
- 239000011651 chromium Substances 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000003137 locomotive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000037452 priming Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K37/00—Auxiliary devices or processes, not specially adapted to a procedure covered by only one of the preceding main groups
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
- B23K31/02—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to soldering or welding
- B23K31/027—Making tubes with soldering or welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/04—Tubular or hollow articles
- B23K2101/06—Tubes
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Details Of Heat-Exchange And Heat-Transfer (AREA)
Abstract
The invention relates to the technical field of welding, in particular to a method for welding a sulfur-resistant chlorine-resistant high-temperature-resistant high-pressure-resistant heat exchange tube. The heat exchange tube made of the N08800 material has high-temperature corrosion resistance; the thickness of the heat exchange tube wall is reduced to 2.5mm, so that the bending processability of the heat exchange tube is improved and the stress is reduced under the condition of ensuring the strength; according to the invention, solution annealing is carried out on the heat exchange tube, so that the residual stress of the heat exchange tube is reduced, and the plasticity, toughness and corrosion resistance of the heat exchange tube are improved; the heat exchange tube is subjected to acid washing passivation, so that a high-quality passivation film is formed, and the corrosion resistance stability of the heat exchange tube is improved; the invention increases the size of the small U-shaped bend to 190-210 mm, and can reduce the stress of the small U-shaped bend at the center of the heat exchanger; at least two strength welds are adopted, so that the sealing performance and strength of the welding of the heat exchange tube and the tube plate can be ensured. The welded heat exchange tube is not easy to damage under the working conditions of high temperature and high pressure containing sulfur and chlorine, and the service life is prolonged from 2 years to 10 years.
Description
Technical Field
The invention relates to the technical field of welding, in particular to a method for welding a sulfur-resistant chlorine-resistant high-temperature-resistant high-pressure-resistant heat exchange tube.
Background
Steam superheaters are devices that heat saturated steam to superheated steam having a certain temperature, and are widely used in power stations, locomotives and marine boilers.
The heat exchange tube material of the existing steam superheater adopts 321 (0 Cr18Ni10 Ti), and under the working condition of high temperature and high pressure containing sulfur and chloride ions, the stress corrosion is faster; and the heat exchange tube and the tube plate are connected in an expansion way, so that the heat exchange tube is easy to overstretch (too strong force) and damaged in the processing and manufacturing processes. Therefore, the heat exchange tube obtained by the preparation method is easy to damage and leak, and has short service life (generally 2 years).
Disclosure of Invention
The invention aims to provide a welding method of a sulfur-resistant chlorine-resistant high-temperature high-pressure-resistant heat exchange tube, which solves the problems that the steam superheater heat exchange tube is easy to damage and has short service life under the working conditions of high temperature and high pressure containing sulfur and chlorine.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for welding a sulfur-resistant chlorine-resistant high-temperature high-pressure-resistant heat exchange tube, which comprises the following steps of:
sequentially carrying out solution annealing and acid washing passivation on the heat exchange tube to obtain a passivated heat exchange tube; the heat exchange tube is made of N08800; the wall thickness of the heat exchange tube is 2.5mm, and the thickness deviation is 0 to +0.20mm;
drilling holes on the tube plate according to pattern requirements, sequentially stringing the passivated heat exchange tubes into the tube plate according to the positions of the holes, adjusting the overhanging length of the tube bundle according to requirements, and positioning by spot welding to obtain a tube plate to be welded; when the hole is led, the minimum U-shaped bend corresponding to the center of the tube plate is 190-210 mm;
and performing strength welding on the pipe plate to be welded, wherein the strength welding comprises backing welding and strength cover welding in sequence.
Preferably, the outer diameter of the heat exchange tube is 38-39 mm, and the outer diameter deviation is-0.20- +0.10mm.
Preferably, the heat exchange tubes are not spliced.
Preferably, the temperature of the solution annealing is 680-700 ℃, and the heat preservation time is 110-120 minutes.
Preferably, the U-shaped bend section and at least 150mm straight section of the heat exchange tube are solution annealed.
Preferably, the width of the allowed hole bridge after the tube plate is drilled is 5.73-8.44 mm.
Preferably, the acid washing passivation comprises: soaking the heat exchange tube in acid liquor, taking out the heat exchange tube to wash to neutrality, and drying to form silvery white film on the surface of the heat exchange tube.
Preferably, the acid solution comprises 3 to 5 percent of compound acid, 0.1 to 0.3 percent of slow release agent and the balance of desalted water in percentage by mass; the complex acid includes nitric acid and hydrofluoric acid.
Preferably, the arc starting points of the backing welding and the strength cover welding are staggered by 115-125 degrees.
Preferably, after the backing welding, airtight leakage detection is carried out on the welding seam of the tube plate and the heat exchange tube by adopting shell side stamping, and after the welding seam is qualified, intensity cover surface welding is carried out.
The invention provides a method for welding a sulfur-resistant chlorine-resistant high-temperature high-pressure-resistant heat exchange tube, which comprises the following steps of: sequentially carrying out solution annealing and acid washing passivation on the heat exchange tube to obtain a passivated heat exchange tube; the heat exchange tube is made of N08800; the wall thickness of the heat exchange tube is 2.5mm, and the thickness deviation is 0 to +0.20mm; drilling holes on the tube plate according to pattern requirements, sequentially stringing the passivated heat exchange tubes into the tube plate according to the positions of the holes, adjusting the overhanging length of the tube bundle according to requirements, and positioning by spot welding to obtain a tube plate to be welded; when the hole is led, the minimum U-shaped bend corresponding to the center of the tube plate is 190-210 mm; and performing strength welding on the pipe plate to be welded, wherein the strength welding comprises backing welding and strength cover welding in sequence.
The invention changes the heat exchange tube made of N08800 material, which has higher chromium content and enough nickel content and higher high-temperature corrosion resistance; the wall thickness of the heat exchange tube is reduced to 2.5mm from the original 3mm, so that the bending processability of the heat exchange tube is improved and the stress is reduced under the condition of ensuring the strength; according to the invention, the solution annealing is carried out on the heat exchange tube, so that the residual stress of the heat exchange tube can be reduced, and the plasticity, toughness and corrosion resistance of the heat exchange tube are improved; the invention carries out acid washing passivation on the heat exchange tube, can remove various greasy dirt, rust, oxide skin, welding spots and other dirt, improves the corrosion resistance of the heat exchange tube, ensures that a high-quality passivation film is formed again, and can improve the corrosion resistance stability of the heat exchange tube; when the hole is led, the invention increases the size of the minimum U-shaped bend corresponding to the center of the tube plate from the current 104mm to 190-210 mm, and can reduce the stress of the small U-shaped bend at the center of the heat exchanger; finally, the invention adopts at least two strength welds to replace the existing expansion joint, can ensure the sealing performance and strength of the welding of the heat exchange tube and the tube plate, and prevent the occurrence of fracture at the fillet weld of the tube and the tube plate. The welded heat exchange tube is not easy to damage under the working conditions of high temperature and high pressure containing sulfur and chlorine, and the service life is prolonged from 2 years to 10 years.
Drawings
FIG. 1 is a solder pattern of example 1;
FIGS. 2 to 9 show test reports of the raw materials used in example 1.
Detailed Description
The invention provides a method for welding a sulfur-resistant chlorine-resistant high-temperature high-pressure-resistant heat exchange tube, which comprises the following steps of:
sequentially carrying out solution annealing and acid washing passivation on the heat exchange tube to obtain a passivated heat exchange tube; the heat exchange tube is made of N08800; the wall thickness of the heat exchange tube is 2.5mm, and the thickness deviation is 0 to +0.20mm;
drilling holes on the tube plate according to pattern requirements, sequentially stringing the passivated heat exchange tubes into the tube plate according to the positions of the holes, adjusting the overhanging length of the tube bundle according to requirements, and positioning by spot welding to obtain a tube plate to be welded; when the hole is led, the minimum U-shaped bend corresponding to the center of the tube plate is 190-210 mm;
and performing strength welding on the pipe plate to be welded, wherein the strength welding comprises backing welding and strength cover welding in sequence.
According to the invention, the heat exchange tube is subjected to solution annealing and acid washing passivation in sequence, so that the passivated heat exchange tube is obtained.
In the invention, the heat exchange tube is made of N08800. The heat exchange tube comprises the following components in percentage by mass: less than or equal to 0.025 percent of C, 32 to 35 percent of Ni, 20 to 23 percent of Cr, 0.30 to 0.60 percent of Ti, 0.15 to 0.45 percent of Al, less than or equal to 0.50 percent of Cu and more than 15 percent of Ti/C; the grain size of the heat exchange tube is more than or equal to 5. The invention changes the heat exchange tube made of N08800 material, which has higher chromium content and enough nickel content and higher high-temperature corrosion resistance. In the invention, the heat exchange tube meets ASME SB-407 and the standard requirements of Heat exchanger tube ordering technical condition.
In the invention, the wall thickness of the heat exchange tube is 2.5mm, and the thickness deviation is 0 to +0.20mm. The wall thickness of the heat exchange tube is reduced to 2.5mm from the original 3mm, and the bending processability of the heat exchange tube is improved and the stress is reduced under the condition of ensuring the strength. In the invention, the outer diameter of the heat exchange tube is preferably 38-39 mm (in order to ensure the outer wall thickness and the flow area inside the tube at the U-shaped bent tube of the heat exchange tube, the heat exchange tube is solidIn the process of purchasing, the outer diameter is 38.45mm, and the outer diameter deviation is preferably-0.20 to +0.10mm. The heat exchange tube with the specification is selected, so that the heat exchange and strength requirements are met, the bending processability of the heat exchange tube is improved, and the stress is reduced. In the present invention, the yield strength (R) of a heat exchange tube of a phi 38mm by 2.5mm specification at 500 DEG C P 0.2 273 MPa). In the invention, the heat exchange tube is U-shaped, and the heat exchange tube is preferably made of a whole tube, and no splicing exists. The U-shaped pipe adopts cold bending.
In the present invention, the solution annealing temperature is preferably 680 to 700 ℃, more preferably 690 ℃; the incubation time is preferably 110 to 120 minutes, more preferably 115 minutes. The invention preferably performs solution annealing on the U-shaped bent pipe section and at least 150mm straight pipe section of the heat exchange pipe. The temperature is preferably increased from room temperature to the solution annealing temperature, and the heating rate is preferably 55-115 ℃/h; after the solution annealing is completed, the temperature is preferably reduced to 400 ℃ at a rate of 55-150 ℃/h, and then naturally reduced to room temperature. According to the invention, the solution annealing is carried out on the heat exchange tube, so that the residual stress of the heat exchange tube can be reduced, and the plasticity, toughness and corrosion resistance of the heat exchange tube are improved.
After the solution annealing is completed, the heat exchange tube is subjected to acid washing passivation. In the present invention, the acid washing passivation preferably includes: soaking the heat exchange tube in acid liquor, taking out the heat exchange tube to wash to neutrality, and drying to obtain the passivated heat exchange tube. In the invention, the acid liquor preferably comprises 3-5% of compound acid, 0.1-0.3% of slow release agent and the balance of desalted water in percentage by mass; the complex acid comprises nitric acid and hydrofluoric acid; the mass concentration of the nitric acid is preferably 68%, and the mass concentration of the hydrofluoric acid is preferably 45%; the volume ratio of hydrofluoric acid to nitric acid is preferably 1:4. The invention has no special requirement on the preparation process of the acid liquor, and the compound acid and the slow release agent are directly added into desalted water. The invention has no special requirement on the dosage of the acid liquor, and can submerge the heat exchange tube. The invention has no special requirement on the neutrality of the washing, and can be washed by clean water. The invention can remove various greasy dirt, rust, oxide skin, welding spot and other dirt by carrying out acid cleaning passivation on the heat exchange tube, improve the corrosion resistance of the heat exchange tube, ensure the formation of a high-quality passivation film, and improve the corrosion resistance stability of the heat exchange tube.
After the pickling passivation is finished, the invention preferably carries out a water pressure test on the heat exchange tube, the test pressure is 6.95MPa, the U-shaped bent tube section of the heat exchange tube comprises a 50mm straight tube section for 100% PT detection, and the subsequent steps are carried out after the I grade is qualified.
The invention performs hole guiding on the tube plate according to pattern requirements, drills holes on the tube plate according to hole guiding positions, sequentially strings in the passivation heat exchange tubes, adjusts the extension length of the tube bundle according to requirements, and performs spot welding positioning to obtain the tube plate to be welded.
In the invention, the tube plate is preferably cleaned before the hole is led, and the tube plate is free from dirt and other harmful impurities.
In the invention, the minimum U-shaped bend corresponding to the center of the tube plate is 190-210 mm, more preferably 200mm (as shown in figure 1) when the hole is led. The invention increases the size of the minimum U-shaped bend corresponding to the center of the tube plate from the current 104mm to 190-210 mm, and can reduce the stress of the small U-shaped bend at the center of the heat exchanger. In the invention, the tube plate is preferably made of 15CrMo surfacing ENiCrMo.
After the holes are formed, the invention preferably checks whether each hole position meets the pattern requirement.
The present invention has no special requirements for the drilling process, and the drilling process well known in the art can be adopted. In the present invention, the width of the allowed hole bridge after the tube plate is drilled is preferably 5.73-8.44 mm. The invention controls the width of the hole bridge in the range, not only can prevent the hole bridge from being too narrow and the heat exchange pipes from being mutually influenced, but also can ensure that the house Kong Qiaotai is wide, the tube plate utilization rate is low, and the cost is high.
Before passing through the tube, the tube plate and the heat exchange tube are cleaned again preferably.
And after the pipe plate to be welded is obtained, carrying out strength welding on the pipe plate to be welded, wherein the strength welding comprises backing welding and strength cover welding in sequence.
The invention adopts backing welding firstly, after backing welding, shell side stamping is used for carrying out airtight leak detection on the weld joint of the tube plate and the heat exchange tube, and then intensity cover surface welding is carried out after the airtight leak detection is qualified. In the invention, the arc starting points of the backing welding and the strength cover welding are preferably staggered by 120 degrees so as to ensure the welding quality. The invention adopts at least two strength welds to replace the existing expansion joint, which not only can ensure the sealing performance and strength of the welding of the heat exchange tube and the tube plate, but also can prevent the fracture of the fillet weld of the tube and the tube plate. The invention has no special requirements on specific conditions of the backing welding and the strength cover welding, and the welding conditions well known in the art are adopted.
After the strength welding is finished, the invention preferably carries out 100% PT detection, and the steel is qualified according to grade I in NB/T47013.5-2015.
The following describes the method for welding the sulfur-resistant, chlorine-resistant and high-temperature-resistant heat exchange tube provided by the invention in detail by combining the examples, but the method is not to be interpreted as limiting the protection scope of the invention.
Example 1
The pattern is shown in figure 1, the heat exchange tubes are 38.45mm multiplied by 2.5mm in size, N08800 in material, 200mm in size of the minimum U-shaped bend corresponding to the center of the tube plate, 1600mm in outer diameter of the tube plate, 15CrMo surfacing ENiCrMo in the tube plate, the number of the heat exchange tubes in each row on the right side in figure 1, 710 heat exchange tubes in the lower left corner, and the outer diameter and deviation requirements.
The specific welding steps are as follows:
s1, checking a heat exchange tube:
the heat exchange tube meets the standard requirements of ASME SB-407 and heat exchanger tube ordering technical conditions; the heat exchange tube is made of N08800; in addition to meeting ASME SB-407, the heat exchange tube should also meet the following requirements: less than or equal to 0.025 percent of C, 32 to 35 percent of Ni, 20 to 23 percent of Cr, 0.30 to 0.60 percent of Ti, 0.15 to 0.45 percent of Al, less than or equal to 0.50 percent of Cu and Ti/C>15; the grain size of the heat exchange tube is more than 5. The heat exchange tube is phi 38.45mm multiplied by 2.5mm, the wall thickness is reduced to 2.5mm from the original 3mm, the bending processability of the heat exchange tube is improved under the condition of ensuring the strength, the stress is reduced, and the yield strength (R P 0.2 273 MPa). The outer diameter deviation is-0.20 to +0.10mm, and the wall thickness deviation is 0 to +0.20mm; the two end surfaces of the heat exchange tube are perpendicular to the axis of the heat exchange tube, the U-shaped tube is made of the whole tube, and no splicing exists.
S2, solution annealing and acid washing passivation of the heat exchange tube: heating from room temperature to 690 ℃ at a heating rate of 85 ℃/h; incubating at 690 ℃ for 115 minutes; then cooling to 400 ℃ at the speed of 100 ℃/h, and then naturally cooling. Acid washing passivation: soaking the surface dirt with acid liquor (the composition is that 5% composite acid (hydrofluoric acid with the mass concentration of 45% and nitric acid with the mass concentration of 68% are mixed according to the volume ratio of 1:4) +0.2% corrosion inhibitor+desalted water) until the surface dirt is completely removed, forming even silvery white, forming even and compact passivation film, taking out after the treatment is completed, and washing the surface dirt with clear water.
S3, checking: after heat treatment, a water pressure test is carried out one by one, the test pressure is 6.95MPa, the U-shaped bent pipe section of the heat exchange pipe comprises a 50mm straight pipe section, 100% PT detection is carried out, and the grade I is qualified.
S4 cleaning (before hole introduction): cleaning the tube plate, and removing oil dirt and other harmful impurities.
S5, hole guiding: according to the heat exchange tube, the heat exchange tube holes are led in the tube plate according to the figure 1, and in order to reduce the stress of the small U-shaped bending part in the center of the heat exchanger, the small U-shaped bending size of the heat exchange tube is increased from 104mm to 200mm.
S6, checking: checking whether each lead position meets the pattern requirement.
S7, drilling: drilling is carried out according to the figure and the positions of the leading holes, and the minimum allowable hole bridge width is 5.73mm after the tube plate is drilled.
S8, pipe penetrating: and (3) removing burrs of the notch of the heat exchange tube before passing the tube, cleaning, removing oil dirt and other harmful impurities, sequentially stringing the heat exchange tube, adjusting the overhanging length of the tube bundle according to requirements, and positioning by spot welding.
S9, welding: the heat exchange tube and the tube plate are connected in a strength welding mode, at least two welding steps are adopted, after backing welding, shell side stamping is adopted to perform airtight leak detection on the tube plate and the heat exchange tube weld joint, then strength cover face welding is performed, and arcing points are staggered by 120 degrees.
S10, checking: and (5) detecting 100% PT after priming and welding, and qualifying according to class I in NB/T47013.5-2015. The pipe ends are flush, the welded joint is smooth, and the defects of cracks, air holes, slag inclusion, unfused, incomplete penetration and the like cannot be caused.
Fig. 2 to 9 are inspection reports of the raw materials used in example 1, showing that the heat exchange tubes and the tube sheets both meet the corresponding standard requirements.
Comparative example 1
Comparative example 1 a steam superheater of a conversion device of Yunnan Tianan chemical industry Co., ltd was welded by a conventional method, the heat exchange tube was made of 321 (0 Cr18Ni10 Ti), the wall thickness was 3mm, the minimum U-bend corresponding to the center of the tube sheet was 104mm, and the heat exchange tube and the tube sheet were expansion-jointed.
Example 1 welded heat exchange tubes have been currently implemented in the Yunnan Tianan chemical industry Co., ltd. The steam superheater of the conversion device has the shell side steam of 255-440 ℃ and 4.0-4.8 MPa; tube side synthesis gas: 350-500 deg.C, 3.8-4.5 MPa, CO and H 2 、CO 2 、H 2 S、Cl - Such as various components, especially H 2 S(2000～4000ppm)、Cl - (500-700 ppm) is highly corrosive to equipment. By the invention, the service life of the heat exchange tube can reach 10 years, and the service life of the previous heat exchanger (comparative example 1) is only 2 years.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (9)
1. The welding method of the sulfur-resistant chlorine-resistant high-temperature-resistant high-pressure-resistant heat exchange tube is characterized by comprising the following steps of:
sequentially carrying out solution annealing and acid washing passivation on the heat exchange tube to obtain a passivated heat exchange tube; the heat exchange tube is made of N08800; the wall thickness of the heat exchange tube is 2.5mm, and the thickness deviation is 0 to +0.20mm;
drilling holes on the tube plate according to pattern requirements, sequentially stringing the passivated heat exchange tubes into the tube plate according to the positions of the holes, adjusting the overhanging length of the tube bundle according to requirements, and positioning by spot welding to obtain a tube plate to be welded; when the hole is led, the minimum U-shaped bend corresponding to the center of the tube plate is 190-210 mm in size;
performing strength welding on the pipe plate to be welded, wherein the strength welding comprises backing welding and strength cover welding in sequence;
the temperature of the solution annealing is 680-700 ℃, and the heat preservation time is 110-120 minutes; heating from room temperature to the solution annealing temperature, wherein the heating rate is 55-115 ℃/h; and after the solution annealing heat preservation is finished, cooling to 400 ℃ at a speed of 55-150 ℃/h, and naturally cooling to room temperature.
2. The heat exchange tube welding method according to claim 1, wherein the outer diameter of the heat exchange tube is 38-39 mm, and the outer diameter deviation is-0.20 to +0.10mm.
3. The heat exchange tube welding method of claim 1, wherein there is no splice of the heat exchange tubes.
4. The heat exchange tube welding method according to claim 1, wherein the solution annealing is performed on the U-bend tube section and at least 150mm straight tube section of the heat exchange tube.
5. The heat exchange tube welding method according to claim 1, wherein the allowable width of the hole bridge after the tube plate is drilled is 5.73-8.44 mm.
6. The heat exchange tube welding method according to claim 1, wherein the acid washing passivation comprises: soaking the heat exchange tube in acid liquor, taking out the heat exchange tube to wash to neutrality, and drying to form silvery white film on the surface of the heat exchange tube.
7. The heat exchange tube welding method according to claim 6, wherein the acid solution comprises 3-5% of compound acid, 0.1-0.3% of slow release agent and the balance of desalted water in percentage by mass; the complex acid includes nitric acid and hydrofluoric acid.
8. The heat exchange tube welding method according to claim 1, wherein the arc starting points of the backing weld and the strength cover weld are staggered by 115-125 °.
9. The method for welding heat exchange tubes according to claim 1, wherein after the backing welding, the tube plate and the heat exchange tube weld joint are subjected to airtight leak detection by adopting shell side stamping, and after the tube plate and the heat exchange tube weld joint are qualified, the tube plate and the heat exchange tube weld joint are subjected to strength cover face welding.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210704064.4A CN115070244B (en) | 2022-06-21 | 2022-06-21 | Sulfur-resistant chlorine-resistant high-temperature-resistant high-pressure-resistant heat exchange tube welding method |
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| JP2011038655A (en) * | 2009-08-07 | 2011-02-24 | T Rad Co Ltd | Reinforcement structure of heat exchanger |
| CN102240898A (en) * | 2010-05-12 | 2011-11-16 | 杨铁君 | Preparation method for heat exchange tube used for extracting temperature of sewage |
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