CN108971710B - Connecting and processing technology of tube and tube plate - Google Patents
Connecting and processing technology of tube and tube plate Download PDFInfo
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- CN108971710B CN108971710B CN201810819964.7A CN201810819964A CN108971710B CN 108971710 B CN108971710 B CN 108971710B CN 201810819964 A CN201810819964 A CN 201810819964A CN 108971710 B CN108971710 B CN 108971710B
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- 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
- B23K9/00—Arc welding or cutting
- B23K9/16—Arc welding or cutting making use of shielding gas
- B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode
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- 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
- B23K9/00—Arc welding or cutting
- B23K9/32—Accessories
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Abstract
The invention discloses a connecting and processing technology of a tube and a tube plate, which comprises the following steps: overlaying the tube plate to form an overlaying layer; the pipe hole of the surfacing layer on the pipe plate is provided with a groove; penetrating the tube into the tube hole on the tube plate, wherein the end part of the tube is flush with the surfacing layer; expanding and connecting the welding area of the tube and the tube plate; welding the tube and the tube plate by adopting automatic pulse argon tungsten-arc welding filler wire; and expanding the non-welding area of the tube and the tube plate. According to the connection processing technology of the tube and the tube plate, the abrasion resistance and the corrosion resistance of the tube plate are improved by the surfacing layer, the clearance between the tube and the welding area of the tube plate is eliminated by the first expansion joint before welding, the welding quality is improved, the beveled filler wire welding is adopted, the leakage risk is reduced, the clearance between the tube and the non-welding area of the tube plate is eliminated by the second expansion joint after welding, the failure of the welding seam caused by the corrosion of liquid or impurities is prevented, and the connection quality between the tube and the tube plate is ensured by the two expansion joints before and after welding and the beveled filler wire welding.
Description
Technical Field
The invention relates to the field of heat exchangers, in particular to a connecting and processing technology of a tube and a tube plate.
Background
The heat exchanger with the tube plate structure is usually connected with a tube and a tube plate by adopting a welding or expansion or welding expansion combined process method. In a nuclear power system, the heat exchanger has high working temperature and pressure, the joint of a pipe and a pipe plate is easily damaged under the action of thermal deformation, thermal shock, thermal corrosion and fluid pressure, and the requirements on connection strength and tightness are difficult to ensure by adopting expansion joint or welding. At present, a method of welding and expanding is widely adopted, welding stress is considered to be far greater than expansion residual stress of sticking and expanding, and generally, a method of welding first and expanding second is adopted. The method is characterized in that welding is performed firstly and then expansion welding is performed, the main problem is to control the precision and matching of a pipe and a pipe hole on a pipe plate, when the expansion welding is performed after the welding is completed, the central line of the pipe must be overlapped with the central line of the pipe hole on the pipe plate, otherwise, excessive expansion welding deformation can damage a welding joint and even cause weld seam welding failure, and the control is difficult to achieve the requirements in the actual operation process.
Disclosure of Invention
The invention aims to provide a connecting and processing technology of a tube plate, which can ensure the connecting quality of the tube plate.
The technical scheme adopted by the invention is as follows:
a connecting and processing technology of tube and tube plates comprises the following steps:
a. overlaying the tube plate to form an overlaying layer;
b. the pipe hole of the surfacing layer on the pipe plate is beveled, the bevel angle is 45 degrees, and the depth is 2.5 mm;
c. penetrating the tube into the tube hole on the tube plate, wherein the end part of the tube is flush with the surfacing layer;
d. expanding and connecting the welding area of the tube and the tube plate;
e. welding the tube and the tube plate by argon arc welding filler wire;
f. and expanding the non-welding area of the tube and the tube plate.
Further as an improvement of the technical scheme, in the step e, automatic pulse argon tungsten-arc welding is adopted, the welding voltage is 8-14V, the pulse base value current is 30-190A, and the peak value current is 85-220A.
Further as an improvement of the technical scheme of the invention, in the step e, the welding speed is 50-80 mm/min.
And further as an improvement of the technical scheme of the invention, in the step e, the size of the throat is 2.01-2.61 mm, and the average size of the throat is 2.32 mm.
As further improvement of the technical scheme of the invention, the welding voltage is 12V, the pulse base value current is 160A, and the peak value current is 190A.
Further as an improvement of the technical scheme of the invention, a mechanical tube expander is adopted for expanded connection in the step d, and a hydraulic tube expander is adopted for expanded connection in the step f.
And a further improvement of the technical scheme is that after the welding in the step e is finished, the welding seam is detected, the welding seam with the defects is repaired, the welding seam with the defects is cleaned, then the expansion joint and the welding are performed again, the improved tube expander is adopted for the re-expansion joint, and an arc transition surface or a 45-degree chamfer is arranged between an expansion shell and an expansion ball of the improved tube expander.
Further as an improvement of the technical scheme of the invention, manual argon arc welding is adopted when re-welding is carried out, and the welding current is 35-85A.
Further as an improvement of the technical scheme of the invention, in the step a, the surfacing layer is made of stainless steel, the tube is made of stainless steel, and the tube plate is made of low alloy steel.
As a further improvement of the technical scheme of the invention, the diameter of the tube is 20mm, the wall thickness is 2.5mm, the thickness of the tube plate is 170mm, and the thickness of the surfacing layer is 6 mm.
The invention has the beneficial effects that: the pipe and tube plate connecting and processing technology has the advantages that the wear resistance and corrosion resistance of the tube plate are improved through the surfacing layer, the gap between the welding area of the pipe and the tube plate is eliminated through first expansion joint before welding, the welding unevenness is prevented, the fatigue damage of a welded junction caused by vibration in the working process of a heat exchanger is prevented, the welding quality is improved, the beveled filler wire is adopted for welding, the welding penetration, the bearing section of a welding seam and the strength of the welding seam are large, the leakage risk is reduced, the second expansion joint after welding is realized, the gap between the pipe and a non-welding area of the tube plate is eliminated, the phenomenon that the welding seam fails due to corrosion caused by the liquid or impurities entering is prevented, the pipe and the tube plate are connected more tightly, and the connection quality of the.
Drawings
The invention will be further described with reference to the accompanying drawings in which:
FIG. 1 is a schematic structural view of a tube and tubesheet according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a conventional mechanical expander;
FIG. 3 is a schematic structural diagram of a chamfer modification of a modified expander according to an embodiment of the present invention;
fig. 4 is a structural schematic diagram of the circular arc transition surface modification of the modified tube expander according to the embodiment of the invention.
Detailed Description
Referring to fig. 1 to 4, the present invention is a process for connecting tube plates, preferably, the diameter of the tube 2 is 20mm, the wall thickness is 2.5mm, and the thickness of the tube plate 1 is 170mm, comprising the following steps:
a. the tube plate 1 is subjected to surfacing to form a surfacing layer 3, preferably, the thickness of the surfacing layer 3 is 6mm, the surfacing material is stainless steel, the tube 2 is made of stainless steel, and the tube plate 1 is made of low alloy steel.
b. The pipe hole of the surfacing layer 3 on the pipe plate 1 is provided with a bevel 4, the angle of the bevel 4 is 45 degrees, and the depth is 2.5 mm.
c. The tube 2 is inserted into the tube hole on the tube plate 1, the end of the tube 2 is flush with the overlaying layer 3, and the flush degree is-0.5 mm- +0.1 mm.
d. The welded area of the tubes 2 and the tube sheet 1 is expanded.
e. And (3) welding the tube 2 and the tube plate 1 by argon arc welding filler wire welding, wherein the welding wire is an ER308L welding wire with the diameter of 0.9mm, the welding position is vertical upward welding, and the number of welding layers is 1-2.
f. And expanding and connecting the non-welding areas of the tubes 2 and the tube plate 1.
The connection processing technology of the tube and the tube plate, the surfacing layer 3 increases the wear resistance and the corrosion resistance of the tube plate 1, the gap of the welding area of the tube 2 and the tube plate 1 is eliminated by first expansion joint before welding, the welding is prevented from being uneven and the welded junction is prevented from being fatigue damaged due to vibration in the working process of a heat exchanger, the welding quality is improved, the beveled 4 filler wire welding is adopted, the welding penetration is realized, the bearing section of the welding seam and the strength of the welding seam are large, the leakage risk is reduced, the second expansion joint is realized after welding, the gap of the non-welding area of the tube 2 and the tube plate 1 is eliminated, the welding seam failure caused by the corrosion of liquid or impurities is prevented, the tube 2 and the tube plate 1 are connected more tightly, and the connection quality of the tube 2 and the tube plate 1.
The tube-plate welding technology of the C-shaped single-tube-pass vertical heat exchanger in the existing nuclear power system is a non-groove welding technology of a tube-plate welding seam of a tube without wire filling, the surfacing material of the tube plate is nickel-based, the material of the tube is also nickel-based, the diameters of the tube and a tube hole are small, namely phi 17.48mm, and the wall thickness of the tube is small, namely 1.01 mm. The nickel-based material is prone to microcrack during welding, and therefore leakage risks exist. The fusion depth of the welding seam of the tube plate without the groove is shallow, and the bearing section of the welding seam is correspondingly small, so that the strength of the welding seam is small. When the welding seam encounters slight friction or collision, the risk of welding seam leakage is easy to occur. The process adopts the tube 2 made of stainless steel and the tube plate 1 made of low alloy steel to ensure the strength of the tube 2 and the tube plate 1, adopts the tube 2 with larger diameter and wall thickness and welds the tube 2 and the tube plate 1 by filling wires with the groove 4, increases the strength of welding seams and reduces leakage risks.
The groove 4 is adopted for wire filling welding, the welding difficulty is greatly increased, and the size (the angle is 45 degrees and the side length is 2.5mm) of the groove 4 is set, so that great difficulty is brought to the selection of welding parameters. Because the groove 4 is small in size, the tungsten electrode cannot go deep into the root of the groove 4, welding heat input is limited to be large enough to be melted through the root to meet requirements of a throat, and the tube 2 is collapsed and contracted due to overlarge welding heat input. Meanwhile, the tungsten electrode cannot go deep into the root of the groove 4, and the electric arc can also melt the metal on the side walls of the tube 2 and the tube plate 1 firstly, molten iron after melting forms a molten pool floating above the root under the action of the surface tension of the liquid, so that the electric arc is prevented from reaching the root, a sealed cavity is formed between the electric arc and the root of the welding line, and the poor fusion of the root is caused, and therefore the quality of the welding line of the root can be ensured only by selecting proper welding parameters. Through a large number of process tests and adjustment of process parameters, optimal welding process parameters and repair process parameters are obtained.
In the preferred embodiment of the invention, in the step e, automatic pulse argon tungsten-arc welding is adopted, the welding voltage is 8-14V, the pulse base value current is 30-190A, and the peak current is 85-220A.
In a preferred embodiment of the present invention, in the step e, the welding speed is 50 to 80 mm/min.
In a preferred embodiment of the invention, in step e, the throat size is 2.01-2.61 mm, and the average throat size is 2.32 mm.
The open groove 4 wire filling welding in the process adopts the parameters, so that a well-formed welding seam can be obtained, the number of discontinuous unqualified points at the root of the welding seam is 0, and the pores of the welding seam are eliminated. Preferably, a larger welding voltage and welding current are adopted, the welding voltage is 12V, the pulse base value current is 160A, the peak current is 190A, the welding speed is 60mm/min, the welding heat can be ensured to be large enough, the penetration root meets the requirement of the throat, and the tube 2 cannot be collapsed and shrunk.
In a preferred embodiment of the present invention, a mechanical expander is used for the expansion in step d, and a hydraulic expander is used for the expansion in step f. The depth of the mechanical tube expander is a welding area, the depth of the hydraulic tube expander is a non-welding area, namely the thickness of the tube plate 1 minus the depth of the mechanical tube expander, and the depth of the hydraulic tube expander is larger than the depth of the mechanical tube expander.
As a preferred embodiment of the present invention, after the welding in step e is completed, the weld is detected, the weld with defects is repaired, the weld with defects is cleaned, then expanded and welded again, a modified tube expander is used for the re-expanded welding, as shown in fig. 2, a conventional mechanical tube expander is used, when the weld is repaired, the weld is cleaned, due to the existence of the groove 4, the effective expanded joint length of the expanded bead 6 is reduced and the expanded joint strength is reduced, which affects the expanded joint effect, as shown in fig. 3 and 4, an arc transition surface or a 45-degree chamfer is arranged between the expansion shell 5 and the expanded bead 6 of the modified tube expander, and the arc transition surface or the chamfer surface is in contact with the groove 4, so as to ensure that the expanded joint length is the length of the expanded bead 6, and improve the expanded joint effect.
Preferably, manual argon arc welding is adopted during re-welding, the welding current is 35-85A, and the number of welding layers is 1-3.
The invention is not limited to the above embodiments, and those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the invention, and such equivalent modifications or substitutions are included in the scope defined by the claims of the present application.
Claims (10)
1. The connecting and processing technology of the tube and the tube plate is characterized by comprising the following steps:
a. overlaying the tube plate (1) to form an overlaying layer (3);
b. a groove (4) is formed in the tube hole of the surfacing layer (3) on the tube plate (1), the angle of the groove (4) is 45 degrees, and the depth is 2.5 mm;
c. the tube (2) is inserted into the tube hole on the tube plate (1), and the end part of the tube (2) is flush with the surfacing layer (3);
d. expanding and connecting the welding area of the tube (2) and the tube plate (1);
e. welding the tube (2) and the tube plate (1) by adopting argon arc welding filler wire;
f. and expanding and connecting the non-welding area of the tube (2) and the tube plate (1).
2. A process of joining tube and tube sheets according to claim 1, wherein: in the step e, automatic pulse argon tungsten-arc welding is adopted, the welding voltage is 8-14V, the pulse base value current is 30-190A, and the peak value current is 85-220A.
3. A process of joining tube and tube sheets according to claim 1, wherein: in the step e, the welding speed is 50-80 mm/min.
4. A process of joining tube and tube sheets according to claim 1, wherein: in the step e, the size of the throat is 2.01-2.61 mm, and the average size of the throat is 2.32 mm.
5. A process of joining tube sheets according to claim 2, wherein: the welding voltage was 12V, the pulse base current was 160A, and the peak current was 190A.
6. A process of joining tube and tube sheets according to claim 1, wherein: and d, performing expansion joint in the step d by using a mechanical pipe expander, and performing expansion joint in the step f by using a hydraulic pipe expander.
7. A process of joining tube and tube sheets according to claim 1, wherein: and e, after the welding in the step e is finished, detecting the welding line, repairing the welding line with the defects, cleaning the welding line with the defects, then performing expanded welding and welding again, wherein a modified tube expander is adopted for the re-expanded welding, and an arc transition surface or a 45-degree chamfer is arranged between an expansion shell (5) and an expansion bead (6) of the modified tube expander.
8. A process of joining tube and tube sheets according to claim 7, wherein: and manual argon arc welding is adopted during re-welding, and the welding current is 35-85A.
9. A process of joining tube and tube sheets according to claim 1, wherein: in the step a, the surfacing layer (3) is made of stainless steel, the tube (2) is made of stainless steel, and the tube plate (1) is made of low alloy steel.
10. The connection processing technology of the tube and the tube plate according to any one of claims 1 to 9, characterized in that: the diameter of the tube (2) is 20mm, the wall thickness is 2.5mm, the thickness of the tube plate (1) is 170mm, and the thickness of the surfacing layer (3) is 6 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810819964.7A CN108971710B (en) | 2018-07-24 | 2018-07-24 | Connecting and processing technology of tube and tube plate |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810819964.7A CN108971710B (en) | 2018-07-24 | 2018-07-24 | Connecting and processing technology of tube and tube plate |
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| CN108971710A CN108971710A (en) | 2018-12-11 |
| CN108971710B true CN108971710B (en) | 2021-03-12 |
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| CN108971710A (en) | 2018-12-11 |
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