Vacuum leakage test device for large-diameter rectangular expansion joint

Abstract

The utility model discloses a vacuum leakage test device for a large-caliber rectangular expansion joint, which comprises an expansion joint body and an external core cylinder, an evacuation volume is arranged in the external core cylinder, and the expansion joint body is positioned in the evacuation volume; the vacuumizing mechanism is communicated with the vacuumizing volume and is used for providing a vacuum environment; the leak detection mechanism is used for performing leak detection on the interior of the evacuated volume; according to the vacuum leakage test device for the large-caliber rectangular expansion joint provided by the utility model, the interior of the expansion joint body is not required to be vacuumized, but the vacuumizing volume between the expansion joint body and the external core cylinder is vacuumized, so that the volume of an area to be vacuumized is reduced, the requirement on vacuumizing equipment is reduced, and the production efficiency is improved. The area needing to be sealed is reduced, the efficiency of vacuum leak detection can be improved, and the cost of vacuum leak detection testing is reduced.

Description

Technical Field

[0001] The utility model relates to an expansion joint detection technology, in particular to a vacuum leakage testing device for a large-caliber rectangular expansion joint. Background Art

[0002] Rectangular expansion joints are an integral part of pipeline connections, buffering the expansion and contraction of pipes due to temperature fluctuations or fluid flow, thereby preventing cracking and leakage in the pipe joints. However, problems with the expansion joint itself, such as poor sealing or cracks, can seriously impact the safety and integrity of the pipeline system. Therefore, rectangular expansion joints require vacuum leak testing. A typical vacuum leak testing method involves evacuating the interior of the expansion joint and connecting it to a helium leak detector. Helium is then sprayed onto the exterior of the expansion joint where testing is required. The helium leak detector readings are then observed and recorded during the test to detect leaks.

[0003] For example, the utility model patent, entitled "A Gasbag Device for Detecting the Performance of an Expansion Joint Between a Steam Turbine and a Condenser," with authorization publication number CN202814664U and publication date March 20, 2013, includes an expansion joint connecting the low-pressure cylinder housing of the steam turbine and the condenser housing, and an airbag structure disposed around the expansion joint. The airbag structure, expansion joint, low-pressure cylinder housing, and condenser housing form a chamber with at least two openable and closable openings. This utility model avoids isolating a large number of valves and injecting large amounts of desalted water into the condenser steam chamber, circumventing many of the shortcomings of water injection and vacuum leak detection methods and ensuring the integrity of the main equipment. Helium leak detection can be performed immediately after the expansion joint is replaced, eliminating the need to remove temporary structures such as internal scaffolding. Helium leak detection is highly accurate, easily locates leaks, and detects and eliminates them immediately. Compared with water injection leak detection, vacuum leak detection significantly shortens the construction period.

[0004] Existing expansion joint products are small in size, regular in shape, and easy to detect. However, for large-diameter rectangular expansion joints, the area to be sealed is large and the circumference of the sealing line is long, making it difficult to seal. In addition, the volume to be evacuated is large. Using commonly used vacuum equipment, it is difficult to evacuate the product to be leak-tested to the vacuum level required for vacuum helium leak detection testing. Utility Model Content

[0005] The purpose of the utility model is to provide a vacuum leakage test device for large-diameter rectangular expansion joints to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] A vacuum leakage testing device for a large-diameter rectangular expansion joint comprises an expansion joint body and an external core barrel, wherein an evacuated volume is provided in the external core barrel, and the expansion joint body is located in the evacuated volume; a vacuum pumping mechanism, which is connected to the evacuated volume and is used to provide a vacuum environment; and a leak detection mechanism, which is used to detect leaks in the evacuated volume.

[0008] In the above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints, an annular plugging cover is fixedly provided at both upper and lower ends of the external core tube to form an evacuated volume.

[0009] The above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints has an upper evacuation port and a lower evacuation port opened on the external core tube. The upper and lower placement of the evacuation ports is conducive to improving gas replacement efficiency and evacuation efficiency.

[0010] The above-mentioned vacuum leakage testing device for large-diameter rectangular expansion joints comprises a vacuum pump connected to the upper vacuum port and a mechanical vacuum pump connected to the lower vacuum port.

[0011] The above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints comprises a leak detection mechanism comprising a leak detection port provided at the upper end of the external core barrel and connected to the evacuated volume, and the leak detection port is connected to an externally arranged helium detector.

[0012] In the above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints, a top annular plugging cover is screwed onto the upper end of the external core barrel, and a bottom annular plugging cover is fixedly provided at the lower end of the external core barrel.

[0013] In the above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints, vacuum sealing gaskets are provided on both the top annular plugging cover and the bottom annular plugging cover, and the vacuum sealing gaskets are used to seal the end pipe openings of the expansion joint body.

[0014] In the above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints, a connecting plate is formed on the outer side wall of the external core tube, and the connecting plate and the top annular plug cover are connected together by bolts.

[0015] In the above-mentioned vacuum leakage test device for large-diameter rectangular expansion joints, a rubber sealing ring is installed on the top annular plugging cover, and the rubber sealing ring is used to seal the contact portion between the connecting plate and the top annular plugging cover.

[0016] The above-mentioned vacuum leakage testing device for large-diameter rectangular expansion joints has a sealing rod screwed between the top annular plugging cover and the bottom annular plugging cover, and the connection between the expansion joint body and the top annular plugging cover is defined as the first connection position, and the connection between the expansion joint body and the bottom annular plugging cover is defined as the second connection position. When the expansion joint body is inserted into the external core barrel, the first connection position and the second connection position are tightened and sealed by the cooperation of the sealing rod and the vacuum sealing gasket.

[0017] In the above technical solution, the utility model provides a vacuum leakage testing device for large-diameter rectangular expansion joints. Instead of vacuuming the expansion joint body, the evacuated volume between the expansion joint body and the external core tube is vacuumed, so that the volume of the area to be vacuumed is reduced, and the requirements for the vacuuming equipment are reduced. The commonly used vacuuming equipment can be used to evacuate the expansion joint body to be tested for leaks to the vacuum degree required for the vacuum helium leak test, which reduces the area that needs to be sealed, improves the efficiency of vacuum leak detection, and reduces the cost of vacuum leak detection testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0019] Figure 1 A partial cross-sectional view of a vacuum leakage test device for a large-diameter rectangular expansion joint provided by an embodiment of the present utility model (without the expansion joint body).

[0020] Figure 2 A partial cross-sectional view of a vacuum leakage test device for a large-diameter rectangular expansion joint provided by an embodiment of the present utility model.

[0021] Figure 3 The present invention is an overall cross-sectional view of a vacuum leakage test device for a large-diameter rectangular expansion joint provided in one embodiment of the present invention.

[0022] Description of reference numerals:

[0023] 1. Expansion joint body; 2. External core tube; 21. Evacuation volume; 22. Upper evacuation port; 23. Lower evacuation port; 24. Top annular plug; 25. Bottom annular plug; 26. Vacuum gasket; 28. Rubber sealing ring; 29. ​​Sealing rod; 3. Vacuuming mechanism; 31. Molecular pump; 32. Mechanical vacuum pump; 4. Leak detection mechanism; 41. Leak detection port; 42. Helium detector. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1-3 As shown, an embodiment of the utility model provides a vacuum leakage testing device for a large-diameter rectangular expansion joint, comprising an expansion joint body 1, and an external core barrel 2, wherein an evacuated volume 21 is provided in the external core barrel 2, and the expansion joint body 1 is located in the evacuated volume 21; a vacuum pumping mechanism 3, which is connected to the evacuated volume 21 and is used to provide a vacuum environment; and a leak detection mechanism 4, which is used to detect leakage in the evacuated volume 21.

[0026] Specifically in the present embodiment, the expansion joint body 1 is a large-diameter rectangular expansion joint. The length, width and height of a general large-diameter rectangular expansion joint can reach 4*3.5*1.5 meters, and both ends are rectangular pipe openings for welding. The expansion joint body 1 is a prior art and will not be described in detail. The external core tube 2 can generally be consistent with the product appearance. The shape of the evacuated volume 21 corresponds to the expansion joint body 1, so that the expansion joint body 1 can be set into the evacuated volume 21. When the expansion joint body 1 is set into the evacuated volume 21, the evacuated volume 21 is a sealed space. The evacuated volume 21 refers to the space formed between the outer wall of the expansion joint body 1 and the inner wall of the external core tube 2 when vacuuming. The vacuuming mechanism 3 is a prior art and can evacuate the evacuated volume 21, which will not be described in detail here. The leak detection mechanism 4 is a prior art and can detect leaks in the evacuated volume 21, which will not be described in detail here. In the leakage experiment of the expansion joint body 1, the expansion joint body 1 is first The body 1 is mounted in the external core tube 2 so that the evacuated volume 21 is sealed, and then the evacuated volume 21 is evacuated by the vacuum mechanism 3, and then the evacuated volume 21 is detected for leakage by the leak detection mechanism 4, so as to detect the expansion joint body 1. In this way, there is no need to vacuum the internal volume of the expansion joint body 1, but to vacuum the evacuated volume 21 between the expansion joint body 1 and the external core tube 2, so that the volume of the area to be vacuumed is reduced. Compared with the original helium detection tooling, the volume of the vacuumed area is reduced from 20 cubic meters to 2 cubic meters, which can greatly reduce the volume that needs to be evacuated and reduce the requirements for the vacuum equipment. The expansion joint body 1 to be leak-tested can be evacuated to the vacuum degree required for the vacuum helium leak test using commonly used vacuum equipment, and there is no need to seal the inside of the ports at both ends of the expansion joint body 1, which reduces the area that needs to be sealed, improves the efficiency of vacuum leak detection, and reduces the cost of vacuum leak detection testing.

[0027] Moreover, the pressure-bearing welds of the expansion joint body 1 are all internal welds (exposed inside the expansion joint body 1). By evacuating the outside of the expansion joint body 1, the parts of the expansion joint body 1 to be leak-checked (welds) are exposed. Before the overall leak detection, helium can be sprayed on the exposed welds inside the expansion joint body 1 for pre-leak detection, so as to quickly locate and repair larger leaks. Compared with evacuating the inside of the expansion joint body 1, if there is a larger leak. Because the welds of the expansion joint body 1 are not exposed, only the approximate position can be located, and the repair can only be carried out after the leak detection tooling is removed. By adopting the external evacuation method, the leak point can be located quickly and relatively accurately, and it can be repaired without removing the vacuum leak detection tooling.

[0028] In another embodiment provided by the present invention, an annular plugging cover is detachably fixed at both upper and lower ends of the external core barrel 2 to form an evacuated volume 21. That is to say, a detachable tooling is used instead of a welding baffle sealing method to improve the efficiency of leak detection and repair, while reducing the cost of vacuum helium leak detection.

[0029] In another embodiment provided by the present invention, an upper evacuation port 22 and a lower evacuation port 23 are provided on the external core barrel 2, and the upper evacuation port 22 is located above the lower evacuation port 23 to improve the gas replacement efficiency and the evacuation efficiency. The lower evacuation port 23 is connected to a first evacuation device in a low vacuum state, and the upper evacuation port 22 is connected to a second evacuation device in a high vacuum state. The first evacuation device and the second evacuation device are collectively referred to as a vacuum mechanism 3. The upper evacuation port 22 and the lower evacuation port 23 are arranged one high and one low. Taking advantage of the fact that nitrogen is lighter than air, pure nitrogen is filled into the upper evacuation port 22 before evacuation, and air is discharged from the lower evacuation port 23, which can effectively improve the air replacement speed and replacement efficiency of the evacuated volume 21.

[0030] In another embodiment provided by the present invention, the vacuum pumping mechanism 3 includes a molecular pump 31 (second vacuuming device) connected to the upper vacuum port 22. The molecular pump 31 is a prior art and is mainly used to further reduce the pressure in the vacuum volume 21 to achieve a high vacuum state. It also includes a mechanical vacuum pump 32 (first vacuuming device) connected to the lower vacuum port 23. The mechanical vacuum pump 32 is preferably a Roots pump with a high pumping speed, which can quickly pump the vacuum volume 21 to the vacuum degree required for the vacuum helium leak test. The mechanical vacuum pump 32 is mainly used to reduce the gas pressure in the vacuum volume 21. Low enough to fit the molecular pump 31. During operation, when the expansion joint body 1 is mounted within the external core barrel 2, the mechanical vacuum pump 32 begins operating, reducing the gas pressure within the evacuated volume 21 to a certain level. When the mechanical vacuum pump 32 reduces the pressure within the evacuated volume 21 to a level within which the molecular pump 31 can begin operating, the molecular pump 31 starts, using its high-speed rotating blades to expel gas molecules and further reduce the gas pressure. During leak detection, the valves of the upper and lower evacuation ports 22 and 23 are generally closed, relying solely on the vacuum pump within the helium leak detector to maintain pressure. If it is indeed necessary to activate the pump group of the evacuation system 3 to maintain pressure, the impact of activating the evacuation system will be eliminated from the final calculation of the results.

[0031] In another embodiment provided by the present invention, the leak detection mechanism 4 includes a leak detection port 41 opened at the upper end of the external core tube 2 and connected to the evacuated volume 21, and the leak detection port 41 is connected to an externally arranged helium detector 42, and the helium detector 42 is a prior art and is used to detect helium leakage; it should be noted that during the pre-leak detection, helium needs to be sprayed on the exposed pressure weld inside the expansion joint body 1 from top to bottom, so as to quickly locate and repair larger leaks; during the overall leak detection, the exposed weld inside the expansion joint body 1 is covered with a plastic film, and helium is filled in the film to perform an overall leak detection.

[0032] In another embodiment provided by the present invention, a top annular plug 24 is screwed onto the upper end of the external core barrel 2, and a bottom annular plug 25 is fixedly provided at the lower end of the external core barrel 2, so that an evacuated volume 21 is formed between the external core barrel 2, so that the expansion joint body 1 can be installed in the external core barrel 2, and the top annular plug 24 adopts a detachable design, which can improve the reuse rate of tooling and reduce the time and cost of vacuum helium leak detection testing and product processing after leak detection.

[0033] In another embodiment provided by the present invention, vacuum sealing pads 26 are provided on both the top annular plug cover 24 and the bottom annular plug cover 25. The vacuum sealing pads 26 are used to seal the end pipe openings of the expansion joint body. When the expansion joint body 1 is inserted into the external core tube 2, the end of the expansion joint body 1 is squeezed onto the two vacuum rubber pads 26 to form a sealed environment.

[0034] In another embodiment provided by the present invention, a connecting plate is formed on the outer side wall of the external core barrel 2, and the connecting plate and the top annular plugging cover 24 are connected together by bolts, so as to avoid the side wall of the external core barrel 2 and the top annular plugging cover 24 being connected together by bolts, thereby increasing the contact area between the external core barrel 2 and the top annular plugging cover 24, so that the sealing effect is better.

[0035] In another embodiment provided by the present invention, a rubber sealing ring 28 is installed on the top annular plug cover 24 , and the rubber sealing ring 28 is used to further seal the contact portion between the connecting plate and the top annular plug cover 24 .

[0036] In another embodiment provided by the present invention, a sealing rod 29 is screwed between the top annular plugging cover 24 and the bottom annular plugging cover 25, and the connection between the expansion joint body and the top annular plugging cover 24 is defined as the first connection position, and the connection between the expansion joint body and the bottom annular plugging cover 25 is defined as the second connection position. When the expansion joint body 1 is inserted into the external core tube 2, the first connection position and the second connection position are tightened and sealed by the cooperation of the sealing rod 29 and the vacuum sealing gasket 26, and the rigidity of the expansion joint body 1 is relied upon to make the end pipe mouth of the expansion joint body 1 and the vacuum sealing gasket 26 pressed and sealed.

[0037] In addition, a vacuum gauge and a standard leak hole are provided at the upper end of the top annular plug 24. The vacuum gauge is used to measure the vacuum degree of the evacuated volume 21, and the standard leak hole is used to calibrate the helium leak detector and the entire vacuum system during the measurement or calibration process. The vacuum gauge and the standard leak hole are both existing technologies and will not be described in detail here.

[0038] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A vacuum leakage test device for a large-diameter rectangular expansion joint, comprising an expansion joint body, characterized in that: It also includes an external core barrel, wherein the external core barrel is provided with an evacuated volume, and the expansion joint body is located in the evacuated volume; a vacuum pumping mechanism, the vacuum pumping mechanism being in communication with the evacuated volume and being used to provide a vacuum environment; A leak detection mechanism is used to detect leaks in the evacuated volume.

2. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 1, characterized in that: An annular blocking cover is fixedly provided at both the upper and lower ends of the external core barrel to form an evacuated volume.

3. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 1, characterized in that: The external core barrel is provided with an upper evacuation port and a lower evacuation port. The upper and lower placement of the evacuation ports is beneficial to improving the gas replacement efficiency and the evacuation efficiency.

4. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 3, characterized in that: The vacuum pumping mechanism includes a molecular pump connected to the upper vacuum port, and also includes a mechanical vacuum pump connected to the lower vacuum port.

5. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 1, characterized in that: The leak detection mechanism comprises a leak detection port which is arranged at the upper end of the external core barrel and communicates with the evacuated volume, and the leak detection port is communicated with an externally arranged helium detector.

6. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 2, characterized in that: A top annular plugging cover is screwed onto the upper end of the external core barrel, and a bottom annular plugging cover is fixedly disposed on the lower end of the external core barrel.

7. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 6, characterized in that: The top annular plugging cover and the bottom annular plugging cover are both provided with vacuum sealing gaskets, and the vacuum sealing gaskets are used to seal the end pipe openings of the expansion joint body.

8. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 6, characterized in that: A connecting plate is formed on the outer side wall of the external core barrel, and the connecting plate is connected to the top annular blocking cover by bolts.

9. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 8, characterized in that: A rubber sealing ring is installed on the top annular plugging cover, and the rubber sealing ring is used to seal the contact portion between the connecting plate and the top annular plugging cover.

10. A vacuum leakage test device for large-diameter rectangular expansion joints according to claim 6, characterized in that: A sealing rod is screwed between the top annular plug cover and the bottom annular plug cover, and the connection between the expansion joint body and the top annular plug cover is defined as the first connection position, and the connection between the expansion joint body and the bottom annular plug cover is defined as the second connection position. When the expansion joint body is inserted into the external core barrel, the first connection position and the second connection position are tightened and sealed by the cooperation of the sealing rod and the vacuum sealing gasket.

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