A guide tube connection structure and connection method thereof

Abstract

The present invention provides a guide tube connection structure and a bellows expansion joint connection method. By using the connecting flange mother body to set a guide boss, and changing the connection method between the guide tube and the connecting flange from lap fillet welding to bottom-locking butt welding, the risk of scouring and thinning caused by high-velocity media can be effectively reduced while improving the quality of weld formation. By setting a plug welding structure that penetrates into the flange mother material matrix, the vibration cracking problem of the guide tube circumferential weld caused by the cantilever structure of the guide tube is further reduced, and the failure of equipment near the pipeline system caused by the falling off of the guide tube is avoided, thereby enhancing the safe service life of the metal bellows expansion joint as an important flexible compensation equipment of the pipeline system.

Description

Technical Field

[0001] The invention relates to a guide tube connection structure and a connection method thereof. Background Art

[0002] Metal bellows expansion joints are important flexible compensation equipment in cryogenic pipeline systems in the field of LNG transportation. At present, metal bellows expansion joints are mainly connected by flanges. Considering the high-velocity medium diversion inside the pipeline and the requirements of dual flow directions, expansion joints are often equipped with double guide tubes, and the guide tubes and flanges are connected by lap fillet welds. Figure 1 As shown in the figure. Since the tensile strength of the lap fillet weld is high in the axial direction, but the bending strength in the radial direction is low. The guide tube is a cantilever beam structure. When high-speed media continuously impacts the tail of the guide tube, it is easy to cause the tail of the guide tube to vibrate. The force generated by the vibration of the tail of the guide tube plus the length of the guide tube will generate a bending moment at the lap fillet weld position, which is easy to cause the circumferential weld of the guide tube to break and crack in the radial direction.

[0003] A Chinese patent with publication number CN110985800A discloses an anti-blocking and smooth-flow expansion joint. The patent provides a new type of flue gas turbine inlet and outlet expansion joint guide tube, which changes the flange of the guide tube into a flared structure and adds a gasket ring (the length must be ≥100mm).

[0004] A Chinese patent with publication number CN201462308U discloses a novel flue gas turbine inlet and outlet expansion joint guide tube, which provides a flexible combined guide tube, thereby providing an anti-blocking and smooth-flow expansion joint with larger axial, lateral and angular displacements.

[0005] The Chinese patent with publication number CN209800957U discloses a metal expansion joint that is resistant to strong airflow erosion. The conventional guide tube structure is improved by providing an inlet guide tube and an outlet guide tube. The inner diameter of the inlet guide tube is equal to the inner diameter of the inlet connecting pipe. The two are coplanar, which effectively increases the flow area of ​​the guide tube and greatly reduces the erosion of the guide tube by high-strength flow media. While maintaining the good compensation performance of the metal expansion joint, the safety and life of the metal expansion joint are improved.

[0006] The Chinese patent with publication number CN209800957U discloses a segmented flow guide sealing cylinder for high temperature expansion joints, including a flow guide cylinder A and a flow guide cylinder B. One end of the flow guide cylinder A and one end of the flow guide cylinder B are welded to the cylinder section of the expansion joint on the corresponding side, and the other end of the flow guide cylinder A and the other end of the flow guide cylinder B are staggered in the middle of the inner cavity of the expansion joint. The flow guide cylinder A includes a low thermal insulation cylinder and a segmented flow guide cylinder. One end of the low thermal insulation cylinder is welded to the inner wall of the cylinder section, and the other end is welded to the segmented flow guide cylinder. The cylinder surface is welded flush, one end of the segmented guide cylinder is welded to the inner wall of the cylinder segment, the space surrounded by the low thermal insulation cylinder, the inner wall of the cylinder segment and the segmented guide cylinder is filled with insulation material, and a sealing compensation bellows is provided at the staggered position of the segmented guide cylinder and the guide cylinder B to seal the gap to prevent the medium from entering the cavity between the guide cylinder and the bellows, generating coking and causing cracking of the guide cylinder; on the other hand, it can prevent the guide cylinder from being twisted and deformed due to high temperature thermal expansion, causing cracking of the weld at the connection between the guide cylinder and the cylinder segment.

[0007] The above-mentioned prior arts respectively propose solutions for preventing impact or vibration of the guide tube weld, but all of them require modification of the guide tube structure, and do not fundamentally solve the problem that the guide tube weld is directly eroded by the medium and vibrates off under the impact of high-velocity media. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a guide tube connection structure and a connection method thereof, which effectively eliminates the hidden danger of cracking of the circumferential weld of the guide tube due to high-speed medium scouring and vibration, avoids the failure of equipment near the pipeline system due to the falling off of the guide tube, and enhances the safe service period of the metal bellows expansion joint as an important flexible compensation equipment of the pipeline system.

[0009] The objective of the present invention is achieved through the following scheme: A guide tube connection structure comprises: a connecting flange, a bellows and a guide tube.

[0010] Among them, a weld impact prevention boss and a plug welding blind hole with the same wall thickness as the guide tube are arranged at the inner diameter of the connecting flange.

[0011] The guide tube is a straight section structure with end flanges and a plurality of drainage holes evenly distributed along the circumference.

[0012] A plurality of plug-welded through holes are arranged at intervals along the circumference of the guide tube, and the number of the plug-welded through holes is the same as that of the plug-welded blind holes.

[0013] Furthermore, the connecting flange is circumferentially welded to the guide tube, and the plug welding blind hole of the connecting flange and the plug welding through hole on the guide tube are connected by plug welding.

[0014] The connecting flange and the bellows are connected by circumferential welding.

[0015] Preferably, the circumferential welding method between the connecting flange and the guide tube is a bottom-lock butt welding.

[0016] Preferably, the circumferential welding method between the connecting flange and the bellows is a bottom-lock butt welding.

[0017] Preferably, the weld impact prevention boss is arranged within a range of 15 mm to 25 mm from the front end of the circumferential weld between the guide tube and the connecting flange.

[0018] Preferably, the width of the weld impact prevention boss is 10 mm-15 mm.

[0019] Preferably, the plug welding through hole on the guide tube is "V" shaped.

[0020] Preferably, the plug welding through holes are arranged at intervals of 200 mm to 250 mm in arc length along the circumference of the guide tube.

[0021] Preferably, the plug welding blind hole penetrates into the base of the connecting flange parent material by 3mm-5mm.

[0022] In addition to providing a guide tube connection structure, the present invention further provides a method for connecting a bellows expansion joint, which specifically includes the following steps:

[0023] Weld the connecting flange and guide tube, the plug welding through hole and the plug welding blind hole, and the connecting flange and the bellows into place to complete the connection of the bellows expansion joint.

[0024] Preferably, when the bellows expansion joint is a jacket type bellows expansion joint, the connection method is specifically as follows:

[0025] The first circumferential weld between the connecting flange and the guide tube is welded into place, and then the plug weld between the plug welding through hole and the plug welding blind hole is welded into place, and finally the second circumferential weld between the connecting flange and the bellows is welded into place to complete the connection of the guide tube connection structure that is resistant to impact and vibration from falling off on the jacket-type bellows expansion joint.

[0026] When the bellows expansion joint is an internal bellows expansion joint, the connection method is as follows:

[0027] The second circumferential weld between the connecting flange and the bellows is welded into place, and then the first circumferential weld between the connecting flange and the guide tube is welded into place, and finally the plug weld between the plug welding through hole and the plug welding blind hole is welded into place to complete the connection of the guide tube connection structure that is resistant to impact and vibration from falling off on the internal plug-in bellows expansion joint.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The present invention provides a guide tube connection structure and a connection method thereof. By setting a plug weld, the force generated by the vibration of the tail of the guide tube and the bending moment formed by the length of the guide tube will be first absorbed by the plug weld, so that the torque transmitted to the annular weld of the guide tube becomes smaller.

[0030] By setting up the anti-impact boss, the high-speed fluid medium will directly scour the boss body, which will have a certain shielding and buffering effect on the guide tube weld. Since the boss body is a forged flange or rolled steel plate, the material uniformity is good, and the overall mechanical properties are better than the weld body, which can solve the problem of erosion failure of the original lap fillet weld.

[0031] In addition, the impact-proof boss also changes the circumferential weld connecting the guide tube and the boss from the original fillet weld to a butt weld. The bending resistance of the butt weld is better than that of the fillet weld. Therefore, even in the extreme case where all the plug welds fail, the performance of the circumferential weld of the guide tube is still improved compared to the existing structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of a low temperature expansion joint in the background technology of the present invention;

[0033] Figure 2 It is a schematic diagram of the expansion joint connection of the guide tube connection structure that is resistant to shock and vibration shedding in the present invention;

[0034] Figure 3 It is a partial schematic diagram of the connecting flange in the present invention;

[0035] Figure 4 It is a schematic diagram of the local structure of the guide tube in the present invention;

[0036] Figure 5 It is a partial schematic diagram of the connection structure on the jacket-type bellows expansion joint in an embodiment of the present invention;

[0037] Figure 6 It is a partial schematic diagram of the connection structure on the internal plug-in bellows expansion joint in an embodiment of the present invention.

[0038] In the figure, 1 is a connecting flange; 2 is a bellows; 3 is a guide tube; 4 is a weld impact prevention boss; 5 is a plug weld blind hole; 6 is a plug weld through hole; 7 is a first ring weld; 8 is a plug weld; and 9 is a second ring weld. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0040] like Figures 2 to 4 As shown, the technical solution of the present invention provides a guide tube connection structure, including: a connecting flange 1, a bellows 2 and a guide tube 3.

[0041] Among them, a weld impact prevention boss 4 and a plug welding blind hole 5 with the same wall thickness as the guide tube 3 are arranged at the inner diameter of the connecting flange 1.

[0042] The guide tube 3 is a straight section structure with a flanged end and has a plurality of drainage holes evenly distributed along the circumference.

[0043] A plurality of plug-weld through holes 6 are arranged at intervals along the circumference of the guide tube 3 , and the number of the plug-weld through holes 6 is the same as that of the plug-weld blind holes 5 .

[0044] Furthermore, the connecting flange 1 is circumferentially welded to the guide tube 3 , and the plug welding blind hole 5 of the connecting flange 1 and the plug welding through hole 6 on the guide tube 3 are connected by plug welding.

[0045] The connecting flange 1 and the bellows 2 are connected by circumferential welding.

[0046] In some embodiments of the present invention, the circumferential welding method between the connecting flange 1 and the guide tube 3 is a bottom-locking butt welding, and the circumferential welding method between the connecting flange 1 and the bellows 2 is a bottom-locking butt welding.

[0047] In these embodiments, a bottom-lock butt welding method is used to replace the traditional lap fillet weld, which can effectively reduce the risk of erosion and thinning caused by high-flow medium while improving the forming quality of the weld.

[0048] In some embodiments of the present invention, the weld impact prevention boss 4 is arranged within the range of 15mm-25mm from the front end of the circumferential weld between the guide tube 3 and the connecting flange 1, and the width of the weld impact prevention boss 4 is 10mm-15mm.

[0049] In some embodiments of the present invention, the plug welding through hole 6 on the guide tube 3 is "V" shaped.

[0050] In some embodiments of the present invention, the plug welding through holes 6 are arranged at intervals of 200mm-250mm along the circumference of the guide tube 3, and the plug welding blind holes 5 penetrate 3mm-5mm into the base material of the connecting flange 1. In these embodiments, the plug welding structure that penetrates into the base material of the connecting flange 1 can further reduce the vibration cracking problem caused by the cantilever structure of the guide tube 3.

[0051] In the technical solution of the present invention, in addition to providing a guide tube connection structure, a connection method of a bellows expansion joint is further provided, which specifically includes the following steps:

[0052] Weld the connecting flange 1 and the guide tube 3, the plug welding through hole 6 and the plug welding blind hole 5, and the connecting flange 1 and the bellows 2 into place to complete the connection of the bellows expansion joint.

[0053] like Figure 5 As shown, in some embodiments of the present invention, when the bellows expansion joint is a jacket type bellows expansion joint, the connection method is specifically as follows:

[0054] The weld impact prevention boss 4 is set 15mm from the front end of the circumferential weld between the guide tube 3 and the connecting flange 1, and the width of the weld impact prevention boss 4 is 10mm. The plug welding through holes 6 are set at intervals of 200mm along the circumference of the guide tube 3, and the plug welding blind holes 5 penetrate 3mm into the base material of the connecting flange 1.

[0055] The first circumferential weld 7 between the connecting flange 1 and the guide tube 3 is welded in place, and then the plug weld 8 between the plug welding through hole 6 and the plug welding blind hole 5 is welded in place, and finally the second circumferential weld 9 between the connecting flange 1 and the bellows 2 is welded in place to complete the connection of the guide tube connection structure that is resistant to impact and vibration from falling off on the jacket-type bellows expansion joint.

[0056] like Figure 6 As shown, in some embodiments of the present invention, when the bellows expansion joint is an internal bellows expansion joint, the connection method is specifically as follows:

[0057] The weld impact prevention boss 4 is arranged within the range of 25mm of the front end of the circumferential weld between the guide tube 3 and the connecting flange 1, and the width of the weld impact prevention boss 4 is 15mm. The plug welding through holes 6 are arranged at intervals of 250mm along the circumference of the guide tube 3, and the plug welding blind holes 5 penetrate 5mm into the base material of the connecting flange 1.

[0058] The second circumferential weld 9 between the connecting flange 1 and the bellows 2 is welded in place, and then the first circumferential weld 7 between the connecting flange 1 and the guide tube 3 is welded in place, and finally the plug weld 8 between the plug welding through hole 6 and the plug welding blind hole 5 is welded in place to complete the connection of the guide tube connection structure that is resistant to impact and vibration from falling off on the internal plug-in bellows expansion joint.

[0059] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A guide tube connection structure, characterized in that: The guide tube connection structure comprises: a connection flange (1), a bellows (2) and a guide tube (3); Wherein, a weld impact prevention boss (4) and a plug welding blind hole (5) having the same wall thickness as the guide tube (3) are arranged at the inner diameter of the connecting flange (1); The anti-weld impact boss (4) is circumferentially welded to the guide tube (3), and the circumferential welding method is bottom-lock butt welding; The guide tube (3) is a straight section structure with an end flange and has a plurality of drainage holes evenly distributed along the circumference; A plurality of plug-welded through holes (6) are arranged at intervals along the circumference of the guide tube (3), and the number of the plug-welded through holes (6) is the same as the number of the plug-welded blind holes (5); The connecting flange (1) is circumferentially welded to the guide tube (3), and the plug welding blind hole (5) of the connecting flange (1) and the plug welding through hole (6) on the guide tube (3) are connected by plug welding; The connecting flange (1) and the corrugated pipe (2) are connected by circumferential welding.

2. A guide tube connection structure according to claim 1, characterized in that: The circumferential welding method between the connecting flange (1) and the corrugated pipe (2) is bottom-lock butt welding.

3. A guide tube connection structure according to claim 1, characterized in that: The weld impact prevention boss (4) is arranged within a range of 15 mm to 25 mm from the front end of the weld plug between the guide tube (3) and the connecting flange (1).

4. A guide tube connection structure according to claim 1, characterized in that: The width of the weld seam impact prevention boss (4) is 10 mm to 15 mm.

5. The guide tube connection structure according to claim 1, characterized in that: The plug welding through hole (6) on the guide tube (3) is in a "V" shape.

6. A guide tube connection structure according to claim 1, characterized in that: The plug welding through holes (6) are arranged at intervals of 200 mm to 250 mm in arc length along the circumference of the guide tube (3).

7. The guide tube connection structure according to claim 1, characterized in that: The plug welding blind hole (5) penetrates into the base material of the connecting flange (1) by 3 mm to 5 mm.

8. A method for connecting a bellows expansion joint, characterized in that: The connection is performed using the connection structure according to any one of claims 1 to 7, specifically comprising the following steps: The weld seam impact prevention boss (4) (1) and the guide tube (3), the plug welding through hole (6) and the plug welding blind hole (5), and the connecting flange (1) and the bellows (2) are welded in place to complete the connection of the bellows expansion joint.

9. A method for connecting a bellows expansion joint according to claim 8, characterized in that: When the bellows expansion joint is a jacket-type bellows expansion joint, the connection method is specifically as follows: the first circumferential weld (7) of the anti-weld impact boss (4) and the guide tube (3) is welded in place, the plug weld (8) of the plug weld through hole (6) and the plug weld blind hole (5) is welded in place, and finally the second circumferential weld (9) of the connecting flange (1) and the bellows (2) is welded in place, thereby completing the connection of the guide tube connection structure that is anti-impact and vibration-detached on the jacket-type bellows expansion joint; When the bellows expansion joint is an internal bellows expansion joint, the connection method is specifically as follows: The second annular weld (9) of the connecting flange (1) and the bellows (2) is welded in place, and then the first annular weld (7) of the anti-weld impact boss (4) and the guide tube (3) is welded in place, and finally the plug weld (8) of the plug welding through hole (6) and the plug welding blind hole (5) is welded in place, thereby completing the connection of the guide tube connection structure that is resistant to impact and vibration from falling off on the internal plug-in bellows expansion joint.

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