CN111015002A - Welding method for controlling welding restraint degree of floating head cover - Google Patents
Welding method for controlling welding restraint degree of floating head cover Download PDFInfo
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- CN111015002A CN111015002A CN201911368315.0A CN201911368315A CN111015002A CN 111015002 A CN111015002 A CN 111015002A CN 201911368315 A CN201911368315 A CN 201911368315A CN 111015002 A CN111015002 A CN 111015002A
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- welding
- floating head
- controlling
- head cover
- heat treatment
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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
- 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
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- Arc Welding In General (AREA)
Abstract
The invention relates to the technical field of welding, in particular to a welding method for controlling welding restraint of a floating head cover, which comprises the following steps of: firstly, heat treatment; secondly, testing hardness; thirdly, cleaning a weld bead; fourthly, preheating; fifthly, welding: the inner side is welded by adopting a U-shaped welding seam, the outer side is welded by adopting a fillet weld, the U-shaped welding seam is divided into A, B, C three welding areas from inside to outside, the fillet weld is divided into D, E two welding areas from inside to outside, and the welding is carried out by alternately overturning according to the sequence of A → D → B → E → C; sixthly, surfacing; seventh, cleaning after welding; and eighthly, checking the quality of the welding seam. The invention divides the inner side and the outer side of the welding area, adopts a method of alternately welding in divided areas, namely a symmetrical welding method, and is assisted by heat treatment, thereby reducing the restraint degree of the welding area of the floating flange and the arch cover, avoiding the cracks of the welding line and ensuring the welding quality.
Description
Technical Field
The invention relates to the technical field of welding, in particular to a welding method for controlling welding restraint of a floating head cover.
Background
The floating head cover is one of important parts in the floating head type heat exchanger, and if quality problems, particularly weld joints, are damaged inside the heat exchanger, equipment internal leakage can occur, and whether leakage occurs or not can be found difficultly at the first time. Therefore, the welding quality of the floating head cover is crucial.
Along with the large-scale of chemical devices in China, the floating head heat exchanger is gradually expanded towards the direction of large diameter and high pressure (DN is more than or equal to phi 1400mm, and P is more than or equal to 4.0 MPa). The specifications of two large parts in the floating head cover, namely a floating head flange and an arch cover, are gradually enlarged, for example: the thickness of the floating flange exceeds 250mm, and the thickness of the arch cover exceeds 30 mm.
Because the radial dimension of the floating head flange is thicker and the thickness of the arch cover is also thicker, the rigidity of a weldment is large, great welding stress is easy to generate during welding, and a welding seam is annular; as is well known, a girth weld has the greatest degree of constraint in various welding structures, and the degree of freedom of weld contraction is limited during welding of such a weld, which in turn increases welding stress further. In short, the higher the rigidity of the welded joint of the floating flange and the dome cover, the greater the value of the degree of constraint (the degree of constraint is a magnitude indicating the degree of constraint of the welded structure). The self-restraint conditions of the welding structure, such as the structural form, the position of a welding seam, the welding sequence, the self weight of the part, the shrinkage of other parts in the cooling process, the tightness degree of the clamping part and the like, can enable the welding joint to bear stress with different degrees, and cracks are generated in the weldment when the restraint value reaches a certain degree.
Disclosure of Invention
The invention mainly aims to overcome the problems of floating head cover welding in the prior art and provide a welding method for controlling the welding restraint of a floating head cover.
In order to achieve the above object, the welding method for controlling the welding constraint of the floating head cover of the invention comprises the following steps:
step one, heat treatment: carrying out heat treatment on the floating flange and the arch cover;
step two, hardness testing: carrying out hardness test after heat treatment;
thirdly, cleaning a weld bead: cleaning the welding bead and two sides of the welding bead to ensure the cleanness of the welding area;
step four, preheating: preheating a floating flange and an arch cover;
fifthly, welding: the inner side is welded by adopting a U-shaped welding seam, the outer side is welded by adopting a fillet weld, the U-shaped welding seam is divided into A, B, C three welding areas from inside to outside, the fillet weld is divided into D, E two welding areas from inside to outside, and the welding is carried out by alternately overturning according to the sequence of A → D → B → E → C;
sixthly, surfacing: surfacing is carried out on the inner side of the floating head flange;
seventh, cleaning after welding;
and eighthly, checking the quality of the welding seam.
Preferably, in a first step, the dome is subjected to a stress relief heat treatment.
Preferably, in a second step, it is ensured that the floating head flange has a hardness of not more than 150 HB.
Preferably, in the fourth step, the preheating temperature is 120-.
Preferably, in the fifth step, the temperature between the welding layers is 120-150 ℃.
Preferably, in the fifth step, 2-3 times of stress relief heat treatment are inserted in the welding process.
Preferably, after the surfacing welding in the sixth step is finished, the stress relief heat treatment is performed again.
Preferably, in the seventh step, the weld beading and the weld bead are ground by using a grinder.
Preferably, in the eighth step, 100% magnetic powder inspection is performed on the welding seams at the two sides.
The invention has the following beneficial effects:
(1) according to the invention, the inner side and the outer side of the welding area are partitioned, a partition alternate welding method, namely a symmetrical welding method, is adopted, and heat treatment is assisted, so that the restraint degree of the welding area of the floating flange and the arch cover is reduced, cracks are prevented from occurring in the welding line, and the welding quality is ensured;
(2) the surfacing layer of the floating head flange is arranged in the last step for operation, so that the component with higher rigidity is prevented from further increasing the rigidity, and better construction conditions are strived for in the welding area between the floating head flange and the arch cover.
Drawings
FIG. 1 is a schematic view of the weld of the floating head cover of the present invention;
wherein the figures include the following reference numerals: 1. a floating head flange; 2. and (4) an arch cover.
Detailed Description
The invention will be further explained with reference to the drawings.
The invention discloses a welding method for controlling welding restraint of a floating head cover, which comprises the following steps:
step one, heat treatment: stress relief heat treatment is carried out on the floating head flange 1 and the arch cover 2;
step two, hardness testing: performing a hardness test after heat treatment, wherein the floating head flange 1 is qualified when the hardness is not more than 150 HB;
thirdly, cleaning a weld bead: cleaning up the welding bead and oil stain, rust and other sundries in the range of 30mm on the two sides of the welding bead to ensure the cleanness of the welding zone;
step four, preheating: preheating the floating head flange 1 and the arch cover 2 to 120-130 ℃;
fifthly, welding: as shown in fig. 1, the inner side is welded by a U-shaped welding seam, the outer side is welded by a fillet welding seam, the U-shaped welding seam is divided into A, B, C three welding areas from inside to outside, the fillet welding seam is divided into D, E two welding areas from inside to outside, the welding is carried out by turning and alternately welding according to the sequence of A → D → B → E → C, before the welding of the D welding area, carbon arc gouging is carried out on the blunt edge, the temperature between the welding layers is controlled within the range of 150 degrees, and stress-relieving heat treatment is carried out for 2-3 times in the welding process;
sixthly, surfacing: after welding, surfacing is carried out on the inner side of the floating head flange 1, namely an F area on a welding area C, and after surfacing is finished, stress relief heat treatment is carried out again;
seventhly, cleaning after welding, and polishing welding beading and a welding bead by adopting a grinding wheel machine to ensure that the surface quality of the welding bead meets the requirements of the weld reinforcement height and the like of GB/T150.4-2014;
and eighthly, inspecting the quality of the welding line, and performing 100% magnetic powder inspection on the welding lines at two sides to ensure that the welding line meets the I-level qualified requirement in NB/T47013.4-2015.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A welding method for controlling welding restraint of a floating head cover is characterized by comprising the following steps:
step one, heat treatment: carrying out heat treatment on the floating flange (1) and the arch cover (2);
step two, hardness testing: carrying out hardness test after heat treatment;
thirdly, cleaning a weld bead: cleaning the welding bead and two sides of the welding bead to ensure the cleanness of the welding area;
step four, preheating: preheating the floating flange (1) and the arch cover (2);
fifthly, welding: the inner side is welded by adopting a U-shaped welding seam, the outer side is welded by adopting a fillet weld, the U-shaped welding seam is divided into A, B, C three welding areas from inside to outside, the fillet weld is divided into D, E two welding areas from inside to outside, and the welding is carried out by alternately overturning according to the sequence of A → D → B → E → C;
sixthly, surfacing: surfacing is carried out on the inner side of the floating head flange (1);
seventh, cleaning after welding;
and eighthly, checking the quality of the welding seam.
2. Welding method for controlling the confinement of welding of a floating head cover according to claim 1, characterized in that in the first step the dome (2) is subjected to a stress-relief heat treatment.
3. Welding method for controlling the confinement of welding of a floating head cover according to claim 1, characterized in that in the second step it is ensured that the floating head flange (1) has a hardness not exceeding 150 HB.
4. The method as claimed in claim 1, wherein the preheating temperature is 120-130 degrees in the fourth step.
5. The welding method for controlling the constraint of welding the floating head cover as recited in claim 1, wherein in the fifth step, the temperature between the welding layers is 120-150 ℃.
6. The welding method for controlling the constraint of welding the floating head cover according to claim 1, wherein in the fifth step, 2-3 times of stress relief heat treatment are inserted in the welding process.
7. A welding method for controlling the weld restraint of a floating head cover according to claim 1, wherein the stress relief heat treatment is performed again after the overlaying welding of the sixth step is completed.
8. The welding method for controlling the constraint of welding the floating head cover according to claim 1, wherein in the seventh step, the beading and the bead are ground by using a grinder.
9. The welding method for controlling the welding restraint of the floating head cover according to claim 1, wherein in the eighth step, 100% magnetic powder inspection is performed on the welding seams at both sides.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911368315.0A CN111015002A (en) | 2019-12-26 | 2019-12-26 | Welding method for controlling welding restraint degree of floating head cover |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911368315.0A CN111015002A (en) | 2019-12-26 | 2019-12-26 | Welding method for controlling welding restraint degree of floating head cover |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111015002A true CN111015002A (en) | 2020-04-17 |
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ID=70214732
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911368315.0A Withdrawn CN111015002A (en) | 2019-12-26 | 2019-12-26 | Welding method for controlling welding restraint degree of floating head cover |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111015002A (en) |
-
2019
- 2019-12-26 CN CN201911368315.0A patent/CN111015002A/en not_active Withdrawn
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| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20200417 |