Special-shaped thin-wall pipeline pressure test connection method

Abstract

The invention relates to the technical field of pipeline pressure test, and discloses a special-shaped thin-wall pipeline pressure test connection method which is realized on the basis of a special tool comprising a [-shaped tool main body, a communicating joint and a sealing joint. The method comprises the steps of tool and pipeline cleaning pretreatment, precise positioning of a pipe joint through a conical positioning hole, limiting of the position of a rubber pad through an annular limiting table, threaded tightening of a communication / sealing joint to form a sealing cavity, segmented pressure boosting and maintaining detection and pressure relief ending. The problem of pressure test connection of the special-shaped thin-wall pipeline without the screwed pipe joint is solved, the pressure test effect of accurate positioning and reliable sealing is achieved through cooperation of the tool core structure and the method steps, the pipeline structure does not need to be damaged, operation is efficient, adaptability is high, the high-precision requirement for maintaining pressure for 120 minutes under the air pressure of 1.5 MPa can be met, and the application range is wide. The device is suitable for airtightness tests of similar pipelines in the fields of spaceflight, machinery and the like.

Description

Technical Field

[0001] This invention relates to the field of pipeline pressure testing technology, and specifically to a method for connecting irregularly shaped thin-walled pipelines for pressure testing. Background Technology

[0002] In aerospace, machinery manufacturing, and other fields, irregularly shaped thin-walled pipes are often used in critical systems such as cooling and media transportation due to their advantages of compact structure, light weight, and strong spatial adaptability. The airtightness of these pipes directly determines the operational safety and reliability of the entire equipment, so they must be tested through rigorous pressure tests. In some scenarios, a high-precision standard of maintaining pressure at 1.5 MPa for 120 minutes without leakage is even required.

[0003] Currently, the mainstream connection method for pipeline airtightness testing relies on the threaded structure of pipe fittings, achieving a sealed connection through the threaded engagement between the pipe fitting and the extension pipe of the pressure testing equipment. However, in practical applications, some irregularly shaped thin-walled pipelines are limited by structural design, installation space, or functional constraints, resulting in pipe fittings that cannot be threaded and are only smooth through-hole structures. This renders traditional threaded connection methods completely unsuitable. Existing technologies often use strong adhesive bonding for these unthreaded pipe fittings, fixing and sealing the extension pipe of the pressure testing equipment to the pipe fitting with glue. However, this method has significant drawbacks: cleaning the cured glue is extremely difficult, and the cleaning process easily scratches the surface of the pipe fitting and damages the integrity of the pipeline, affecting subsequent assembly and use; furthermore, the bonded connection structure cannot be reused, requiring reapplication of glue and waiting for curing after each test, making the operation cumbersome and the testing efficiency extremely low. Summary of the Invention

[0004] The present invention aims to provide a method for pressure testing and connection of irregularly shaped thin-walled pipes, in order to solve the technical problem that it is difficult to achieve an effective and reliable sealing connection between irregularly shaped thin-walled pipes without threaded pipe joints and the pressure testing equipment during airtightness testing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for pressure testing and connecting irregularly shaped thin-walled pipelines, implemented using a special tooling. The special tooling includes a C-shaped tooling body, a connecting joint, and a sealing joint. The upper and lower ends of the C-shaped tooling body are provided with coaxial through holes, including an upper through hole and a lower through hole. The lower through hole is a tapered positioning hole, the inner wall of which is adapted to the outer circumferential contour of the pipe joint of the irregularly shaped thin-walled pipeline. Both the connecting joint and the sealing joint are coaxially corresponding to the pipe joint. The connecting joint and the pipe joint are connected by a perforated rubber gasket, and the sealing joint and the pipe joint are sealed by a non-perforated rubber gasket. The bottom ends of both the connecting joint and the sealing joint are provided with an annular limiting platform. The method includes the following steps: Step 1: Pre-treatment, clean the main body of the C-shaped tooling, the connecting joint, the sealing joint, the perforated rubber gasket and the non-perforated rubber gasket, and at the same time clean the pipe joints of the irregular thin-walled pipeline, and confirm that there is no damage or impurity residue in each component; Step 2: Positioning and installation. Fix the two sets of the C-shaped tooling bodies to the test platform. Adjust the distance between the two sets of tooling according to the length of the irregular thin-walled pipe. Embed the pipe joints at both ends of the irregular thin-walled pipe into the corresponding conical positioning holes. Coaxial positioning is achieved by the fit between the inner wall of the conical positioning hole and the outer circumference of the pipe joint. Step 3: Sealing assembly. Place the perforated rubber gasket inside the annular limiting platform of the connecting joint, and place the non-perforated rubber gasket inside the annular limiting platform of the sealing joint. Screw the connecting joint and the sealing joint into the upper through hole of the C-shaped tool body through the threaded connection. Tighten until the perforated rubber gasket is tightly fitted to the end face of the pipe joint and the perforated rubber gasket conducts the connection between the pipe joint and the connecting joint. The non-perforated rubber gasket fully covers the end face of the pipe joint and fits tightly to form a closed sealing cavity. Step 4: Pressure test. Connect the air pipe of the pressure test equipment to the connecting joint, and pressurize the irregular thin-walled pipeline in sections to the preset test pressure, maintain the pressure for the preset time, and perform leak detection. Step 5: Depressurization and finishing. After depressurizing at the specified rate, disassemble the tooling and remove the irregular thin-walled pipeline. Clean all components and store them.

[0006] Preferably, as an improvement, in step two, after the pipe fitting is placed into the tapered hole, it is positioned by fitting against the groove wall, and the fitting status between the pipe fitting and the sealing component is observed through the opening of the C-shaped tool body.

[0007] Preferably, as an improvement, in step three, a torque wrench is used to control the tightening of the positioning joint, with a tightening torque of 15-20N. m, the compression of the rubber pad is 1 / 3 to 1 / 2 of its own thickness.

[0008] Preferably, as an improvement, in step four, the preset test pressure is 1.5 MPa, the pressure holding time is 120 minutes, the segmented pressure increase rate does not exceed 0.3 MPa / min, and the pressure is stabilized for 3-5 minutes for each 0.3 MPa increase.

[0009] Preferably, as an improvement, in step four, the pressure relief rate does not exceed 0.2 MPa / min, and soap solution is applied to key sealing parts for leak detection during the pressure test.

[0010] The advantages of this solution are: 1. It accurately solves the pain points of connecting threadless pipe fittings without damaging the pipeline structure, avoiding problems such as cleaning difficulties and pipe joint scratches caused by glue bonding, and ensuring the subsequent use of the pipeline.

[0011] 2. Reliable sealing and suitable for high-precision pressure testing. The rubber gasket compression is stable and can meet the requirement of holding pressure at 1.5MPa for 120 minutes without leakage risk.

[0012] 3. It is highly efficient and adaptable, with interchangeable connectors, supports batch pressure testing, improves efficiency by more than 40%, and can adapt to different specifications of threadless pipe fittings.

[0013] 4. The tooling structure is simple to manufacture, the methods and steps are standardized, and the parts can be reused, reducing the testing cost and the operation threshold. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the assembly of tooling, pipelines, and pressure testing equipment in an embodiment of the present invention; Figure 2 This is a schematic diagram of the irregular thin-walled pipeline in an embodiment of the present invention; Figure 3 for Figure 1 Schematic diagram of the structure of the central connector; Figure 4 for Figure 1 Schematic diagram of the structure of the intermediate sealing joint; Figure 5 for Figure 3 A schematic diagram of the main body of the U-shaped tooling.

[0015] The reference numerals in the accompanying drawings include: 1. Connecting connector; 2. C-shaped tooling body; 201. Upper through hole; 202. Conical positioning hole; 3. Sealing connector; 4. Annular limiting platform; 5. Rubber pad; 501. Perforated rubber pad; 502. Non-perforated rubber pad; 6. Pipe connector; 7. Irregular thin-walled pipe. Detailed Implementation

[0016] The following detailed description illustrates the specific implementation method: This embodiment takes the airtightness test of an irregularly shaped thin-walled pipe 7 (wall thickness 0.5mm) in the aerospace field as an example. The pipe joint 6 is a threadless, smooth-hole structure with a hole diameter of Φ5mm. The test requirement is to maintain a pressure of 1.5MPa for 120 minutes, and the airtightness test should show no leakage. The pressure test operation is carried out based on the special tooling and method of this invention, as shown in the attached figure. Figure 1-5 As shown, the specific process is as follows: 1. Tooling and Equipment Preparation Special tooling: The main body 2 of the C-shaped tooling (with a tapered positioning hole 202 and a taper of 1:5, and an M8 mounting hole on the side wall) is made of 45 steel, the connecting joint 1, and the sealing joint 3 (the connecting joint 1 and the sealing joint 3 have the same shape, with an M20 external thread on the outer circumference and a ring-shaped limiting platform 4 at the bottom with a height of 2mm); the rubber pad 5 is made of nitrile rubber, and the rubber pad 5 is divided into a perforated rubber pad 501 (Φ14×3, with a center hole of Φ5) and a non-perforated rubber pad 502 (Φ14×3).

[0017] Auxiliary equipment: Pressure testing equipment (pressure display accuracy ±0.01MPa), torque wrench (range 0-50N) m), anhydrous ethanol, cleaning cloth, soap solution, brush, pressure recorder.

[0018] 2. Implementation Steps Step 1: Cleaning Pre-treatment Using a cleaning cloth soaked in anhydrous ethanol, wipe the conical positioning hole 202, horizontal observation groove, and threaded surface of the main body 2 of the C-shaped tooling, the threaded surface of the connecting joint 1 and the sealing joint 3, the annular limiting platform 4, the perforated rubber pad 501, and the non-perforated rubber pad 502 one by one to remove oil stains, iron filings and other impurities; at the same time, clean the end face and outer periphery of the pipe joints 6 at both ends of the pipeline, and check to confirm that there is no damage, deformation or scratches on each component, and that the rubber pad 5 is free from cracks or aging.

[0019] Step Two: Positioning and Installation Through the M8 mounting holes on the side wall of the C-shaped fixture body 2, the two sets of fixtures are symmetrically fixed to the test platform with bolts. The distance between the two sets of fixtures is adjusted to 620mm according to the length of the pipeline to be tested (600mm) to ensure that the pipeline is not subjected to pulling or squeezing stress after placement. The unthreaded pipe fittings 6 at both ends of the pipeline are respectively embedded into the conical positioning holes 202 of the two sets of fixtures. The position of the pipe fittings 6 is observed through one side of the opening of the C-shaped fixture body 2. The pipeline is adjusted so that the end face of the pipe fittings 6 is parallel and aligned with the annular limiting platform 4, with a coaxiality deviation ≤0.05mm.

[0020] Step 3: Sealing Assembly Place the perforated rubber gasket 501 smoothly into the annular limiting platform 4 of the connecting connector 1, ensuring that the opening of the perforated rubber gasket 501 is completely aligned with the internal channel of the pipe connector 6; place the non-perforated rubber gasket 502 into the annular limiting platform 4 of the sealing connector 3, ensuring that the rubber gasket 502 completely covers the bottom end face of the pipe connector 6; slowly screw the connecting connector 1 and the sealing connector 3 into the upper through hole 201 of the C-shaped tool body 2, and manually tighten them until the perforated rubber gasket 501 and the non-perforated rubber gasket 502 are in contact with the pipe connector 6. At this point, use a torque wrench to apply 18N. Tighten the torque in stages until the perforated rubber gasket 501 is tightly fitted to the end face of the pipe joint 6 and the perforated rubber gasket 501 connects the pipe joint 6 to the connecting joint 1. The non-perforated rubber gasket 502 fully covers the end face of the pipe joint 6 and fits tightly to form a closed sealing cavity.

[0021] Step 4: Pressure testing and airtightness recording Equipment connection: Fix the air pipe of the pressure testing equipment to the top of the connecting connector 1 with an M10 thread. After checking that the connection is not loose, start the pressure testing equipment for preheating and debugging for 5 minutes to confirm that the pressure gauges and valves are operating normally.

[0022] Segmented pressurization: Increase the pressure to 0.5 MPa at a rate of 0.28 MPa / min and stabilize for 5 minutes; then increase the pressure by 0.3 MPa and stabilize for 4 minutes at a rate of 4 minutes, successively increasing to 0.8 MPa, 1.1 MPa, and 1.4 MPa, and finally increasing to 1.5 MPa, then close the pressurization valve to enter the pressure holding stage.

[0023] Air tightness check: During the 120-minute pressure holding period, record the pressure value every 15 minutes. At the same time, use a brush dipped in soap solution to evenly apply soap solution to key areas such as pipe weld joints, the contact area between rubber gasket 5 and pipe fitting 6, and the threaded connection between the fitting and the tooling. Observe whether air bubbles are generated and record the leak detection results. The specific data is shown in the table below:

[0024] Step 5: Depressurize and finish After the pressure holding period, slowly release the pressure at a rate of 0.18 MPa / min until the pressure inside the irregular thin-walled pipeline 7 drops to atmospheric pressure. First, loosen the connection between the air pipe of the pressure testing equipment and the connecting joint 1. Then, use a wrench to loosen the connecting joint 1 and the sealing joint 3 of the two sets of fixtures in the opposite direction. Remove the perforated rubber gasket 501, the non-perforated rubber gasket 502, and the irregular thin-walled pipeline 7. Wipe the residual soap solution on each component with a cleaning cloth. Check that the perforated rubber gasket 501 and the non-perforated rubber gasket 502 are undamaged and can be kept for the next use. After cleaning the fixture components, store them properly and organize the pressure record data to form a pressure test report.

[0025] During the test, the conical positioning hole 202 of the tooling achieved precise coaxial positioning of the pipe joint 6, the annular limiting platform 4 and torque control ensured uniform compression of the rubber pad 5, and the differentiated design of the perforated rubber pad 501 and the non-perforated rubber pad 502 met the requirements for media flow and sealing. The combination of segmented pressure increase and pressure holding test effectively avoided damage to the irregular thin-walled pipeline 7 caused by pressure shock. From the airtightness test data, during the 120-minute pressure holding period, the pipeline pressure fluctuation was always controlled within ±0.03MPa, and no bubbles were generated in the key sealing parts, and the sealing reliability met the design requirements. At the same time, the entire test process did not require damage to the original pipeline structure, the tooling was easy to disassemble and assemble, and the joints were interchangeable. Compared with the traditional glue bonding method, the test efficiency was improved by more than 40%, and the pipeline structure remained intact and undamaged, fully verifying the practicality, reliability and efficiency of the invention, and fully meeting the stringent requirements of the aerospace field for the airtightness test of the irregular thin-walled pipeline 7.

[0026] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for pressure testing and connecting irregularly shaped thin-walled pipelines, characterized in that, The method employs specialized tooling, comprising a C-shaped tooling body, a connecting joint, and a sealing joint. The C-shaped tooling body has coaxial through holes at both its upper and lower ends, including an upper through hole and a lower through hole. The lower through hole is a tapered positioning hole, the inner wall of which is adapted to the outer contour of the pipe joint of the irregularly shaped thin-walled pipeline. Both the connecting joint and the sealing joint are coaxially corresponding to the pipe joint. The connecting joint and the pipe joint are connected by a perforated rubber gasket, and the sealing joint and the pipe joint are sealed by a non-perforated rubber gasket. Both the connecting joint and the sealing joint have an annular limiting platform at their bottom ends. The method includes the following steps: Step 1: Pre-treatment, clean the main body of the C-shaped tooling, the connecting joint, the sealing joint, the perforated rubber gasket and the non-perforated rubber gasket, and at the same time clean the pipe joints of the irregular thin-walled pipeline, and confirm that there is no damage or impurity residue in each component; Step 2: Positioning and installation. Fix the two sets of the C-shaped tooling bodies to the test platform. Adjust the distance between the two sets of tooling according to the length of the irregular thin-walled pipe. Embed the pipe joints at both ends of the irregular thin-walled pipe into the corresponding conical positioning holes. Coaxial positioning is achieved by the fit between the inner wall of the conical positioning hole and the outer circumference of the pipe joint. Step 3: Sealing assembly. Place the perforated rubber gasket inside the annular limiting platform of the connecting joint, and place the non-perforated rubber gasket inside the annular limiting platform of the sealing joint. Screw the connecting joint and the sealing joint into the upper through hole of the C-shaped tool body through the threaded connection. Tighten until the perforated rubber gasket is tightly fitted to the end face of the pipe joint and the perforated rubber gasket conducts the connection between the pipe joint and the connecting joint. The non-perforated rubber gasket fully covers the end face of the pipe joint and fits tightly to form a closed sealing cavity. Step 4: Pressure test. Connect the air pipe of the pressure test equipment to the connecting joint, and pressurize the irregular thin-walled pipeline in sections to the preset test pressure, maintain the pressure for the preset time, and perform leak detection. Step 5: Depressurization and finishing. After depressurizing at the specified rate, disassemble the tooling and remove the irregular thin-walled pipeline. Clean all components and store them.

2. The method for pressure testing and connection of irregularly shaped thin-walled pipelines according to claim 1, characterized in that: In step two, after the pipe fitting is placed into the tapered hole, it is positioned by fitting against the groove wall, and the fitting status between the pipe fitting and the sealing component is observed through the opening of the C-shaped tool body.

3. The method for pressure testing and connection of irregularly shaped thin-walled pipelines according to claim 2, characterized in that: In step three, a torque wrench is used to control the tightening of the positioning connector, with a tightening torque of 15-20N. m, the compression of the rubber pad is 1 / 3 to 1 / 2 of its own thickness.

4. The method for pressure testing and connection of irregularly shaped thin-walled pipelines according to claim 3, characterized in that: In step four, the preset test pressure is 1.5 MPa, and the pressure holding time is 120 minutes; the segmented pressure increase rate does not exceed 0.3 MPa / min, and the pressure is stabilized for 3-5 minutes for each 0.3 MPa increase.

5. The method for pressure testing and connection of irregularly shaped thin-walled pipelines according to claim 4, characterized in that: In step four, the pressure relief rate shall not exceed 0.2 MPa / min, and soap solution shall be applied to key sealing parts for leak detection during the pressure test.

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