Vehicle-mounted LNG cylinder outer pipeline pressure test device and test method

Abstract

The invention discloses a vehicle-mounted LNG cylinder outer pipeline pressure test device and test method. The device comprises a workbench, a gasifier, a buffer tank and a finned tube assembly, wherein the gasifier, the buffer tank and the finned tube assembly are arranged in a frame; one end of the pressurizing outer pipeline assembly is connected with the finned tube assembly, the other end of the pressurizing outer pipeline assembly is connected with one end of the first metal hose, one end of the filling port pipeline is screwed on a filling port of a side plate of the workbench, and the other end of the filling port pipeline is connected with the other end of the first metal hose. One end of the air return pipe assembly is screwed on the air return port of the workbench side plate; one end of the liquid inlet pipe is welded with an inlet of the gasifier, and the other end is connected with one end of the metal hose II; and the other end of the blow-down pipe is connected with the other end of the metal hose II. The outer pipeline is convenient to mount, the mounting efficiency of the outer pipeline is improved, and the levelness and perpendicularity of the construction condition of the pipeline can be inspected at any time; one-time pressure test verification is carried out on the outer pipeline, and the efficiency of pressure test verification of the outer pipeline is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure vessel valves and pipeline construction, and in particular relates to a vehicle-mounted LNG gas cylinder external pipeline pressure test device and a test method. Background Art

[0002] The vehicle LNG gas supply system is a system that provides fuel for LNG vehicles. Its function is to draw LNG from the LNG cylinder, gasify it through the vaporizer, and then supply it to the engine for combustion, thereby generating power. Structurally, the vehicle LNG gas supply system mainly includes LNG cylinders, vaporizers, buffer tanks, pressure regulating valves, safety valves, pressure gauges, filling devices, and external piping systems. In the traditional installation and construction of the external piping of LNG cylinders, the cylinders are first fixed to the frame with a drawstring before the welding and assembly of the external piping begins. There are shortcomings such as small space for pipeline installation and construction, difficulty in pipeline welding, and easy scratches on the bottle body. After the external piping system is installed, it is necessary to carry out pressure testing and verification on the cylinders and the external piping system together, which is time-consuming and labor-intensive, and the pipelines are difficult to repair, affecting the assembly efficiency of the LNG cylinders. Summary of the invention

[0003] The purpose of the present invention is to solve the above technical problems and to provide a vehicle-mounted LNG cylinder external pipeline pressure test device and test method that can improve both installation efficiency and pressure test verification efficiency.

[0004] To achieve the above-mentioned purpose, the present invention provides a vehicle-mounted LNG cylinder external pipeline pressure test device, comprising a workbench and a frame installed on the workbench, a vaporizer arranged on one side of the frame, a buffer tank arranged on the other side of the frame, a fin tube assembly and a connecting pipe arranged in the frame and located between the vaporizer and the buffer tank, one end of the connecting pipe is connected to the vaporizer outlet, and the other end is connected to the buffer tank inlet; it also includes a pressurized external pipeline assembly, a filling port pipeline, a return pipe assembly, a liquid inlet pipe, a vent pipe, an outlet pipe and a pressure gauge pipe arranged on the workbench; the pressurized external pipeline assembly is arranged on the workbench. One end of the filling port pipeline is screwed on the filling port of the workbench side panel, and the other end is connected to the other end of the metal hose one; one end of the return air pipe assembly is screwed on the return air port of the workbench side panel, and the other end is connected to the fin tube assembly; one end of the liquid inlet pipe is welded to the inlet of the vaporizer, and the other end is connected to one end of the metal hose two; one end of the vent pipe is connected to the return air pipe assembly, and the other end is connected to the other end of the metal hose two; one end of the pressure gauge pipe is connected to the pressure gauge on the workbench side panel, and the other end is connected to the outlet pipe.

[0005] Furthermore, the fin tube assembly includes two groups of fin tube units, each group of fin tube units includes two fin tubes, one end of the two fin tubes is connected through a first bend pipe, and the other end is connected through a third bend pipe, the two groups of fin tube units are connected through a second bend pipe, and the third bend pipes of the two groups of fin tube units are provided with connecting holes.

[0006] Furthermore, the boost external pipeline assembly includes a boost elbow, a boost valve and a straight pipe, one end of the boost elbow is connected to a slip-on joint at one end of the boost valve through a boost valve welding square head, the other end of the boost valve is connected to one end of the straight pipe through a slip-on joint, the other end of the straight pipe is connected to a connecting hole of a third elbow in the fin tube assembly, and the straight pipe is parallel to the table top of the workbench, and the other end of the boost elbow is installed with a slip-on nut through a boost elbow welding square head; the boost valve is fixed to the side panel of the workbench through the boost valve welding square head, and the vertical center line of the boost valve coincides with the center line of the circular hole on the table top of the workbench.

[0007] Furthermore, the filling port pipeline includes a filling port elbow and a filling port welding square head arranged at both ends of the filling port elbow. The filling port welding square head at one end of the filling port elbow is tightened on the filling port through a slip-on nut 2, and the other end of the filling port elbow is vertically upward; the filling port welding square head at one end of the filling port elbow is connected to one end of a metal hose 1 through a slip-on nut 1, and the other end of the metal hose 1 is connected to the slip-on nut of the boost external pipeline.

[0008] Furthermore, the return air pipe assembly includes a return air elbow and a return air straight pipe, one end of the return air elbow is connected to one end of the return air straight pipe through a welding tee, and the welding tee coincides with the center line of the square hole on the workbench surface; the other end of the return air straight pipe is connected to the connecting hole of another third elbow in the fin tube assembly, and the return air straight pipe is arranged horizontally; the other end of the return air elbow is tightened on the return air port through a slip-on nut.

[0009] Furthermore, the liquid inlet pipe includes a liquid inlet elbow and a ferrule plug, one end of the liquid inlet elbow is connected to the ferrule plug, and the other end is welded to the inlet of the gasifier, and the liquid inlet elbow is fixed to the frame by a U-shaped pipe clamp.

[0010] Furthermore, the vent pipe includes a vent elbow and a threaded tee. One end of the vent elbow is connected to the external threaded end of one side of the threaded tee through a slip-on nut, and the other end is welded and fixed to the welding tee in the return air pipe assembly. When welding and fixing, one end of the vent elbow is vertically upward; the internal thread of the threaded tee is threadedly connected to the threaded plug to form a seal, and the external thread on the other side of the threaded tee is connected to one end of the metal hose two, and the other end of the metal hose two is connected to the ferrule plug ferrule.

[0011] Furthermore, the air outlet pipe includes an air outlet elbow, an air outlet joint welded to one end of the air outlet elbow, and an air outlet threaded plug. The air outlet threaded plug is connected to the air outlet joint by threads to seal the outlet of the air outlet elbow; the air outlet elbow has a prefabricated hole at the straight pipe end close to the air outlet joint; the other end of the air outlet elbow is welded to the outlet of the buffer tank, and the air outlet elbow is fixed to the frame by a U-shaped pipe clamp.

[0012] Furthermore, the pressure gauge tube includes a pressure gauge elbow and a straight joint. The straight joint and the pressure gauge elbow are connected by a ferrule. The other end of the straight joint is an internal thread structure, which is tightly connected to the pressure gauge through threads. The other end of the pressure gauge elbow is welded to the prefabricated hole of the outlet elbow.

[0013] A test method for the test device as described above is also provided as follows:

[0014] 1) Install external pipelines and check that all external pipelines have been installed;

[0015] 2) Introduce 0.1-0.2MPa dry air through the filling port for pressure test, apply foaming agent to the welds and joints of the external pipeline, and observe whether there are any leaks; if there is leakage at the joint or weld, first discharge the gas from the return air port, then tighten the joint or repair the weld leakage, and finally re-test the pressure for verification;

[0016] 3) After step 2) is normal, control the external gas source and slowly increase the pressure step by step. When the pressure rises to 0.5-0.7MPa, conduct a secondary inspection and apply a foaming agent to the welds and joints of the external pipeline to observe whether there are any leaks. At the same time, observe whether the reading of the pressure gauge changes within 1-2 minutes. A reading of ≤5% is normal, otherwise it is abnormal.

[0017] 4) When no abnormality or leakage occurs in step 3), continue to increase the pressure step by step by 0.1-0.2MPa, with each level of pressure stabilization time being 3-5min, until the test pressure of 1.0-1.5MPa is reached, and the pressure is maintained for 10-15min. Observe whether the pressure gauge changes. If the reading is ≤5%, it is normal, otherwise it is abnormal.

[0018] 5) After the test is completed, slowly discharge the gas from the return port. When the pressure gauge reading drops to 0.7-0.9MPa, maintain the pressure for 3-5 minutes, and use a foaming agent to recheck the pipeline system for leakage or abnormality. At the same time, observe whether the pressure gauge reading changes. A reading of ≤5% is normal, otherwise it is abnormal;

[0019] 6) After step 5) is normal, release the pressure step by step by 0.1-0.2MPa, with each pressure stabilization time being 10-15S, until the pressure gauge reading is 0 and the test is completed.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the vehicle-mounted LNG cylinder external pipeline pressure test device and test method of the present invention facilitates the installation of the external pipeline, improves the installation efficiency of the external pipeline, and can check the horizontality and verticality of the pipeline construction at any time to ensure the appearance quality; can perform a one-time pressure test verification on the external pipeline, thereby improving the efficiency of the external pipeline pressure test verification; in addition, since the volume of the external pipeline is small, the test verification time is short, and it is easy to repair the leakage problem, which greatly improves the efficiency of mass assembly of LNG cylinders. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the vehicle-mounted LNG cylinder external pipeline pressure test device of the present invention;

[0022] Figure 2 for Figure 1 Schematic diagram of the structure of the middle fin tube assembly;

[0023] Figure 3 for Figure 1 Schematic diagram of the structure of the middle boost external pipeline assembly;

[0024] Figure 4 for Figure 1 Schematic diagram of the pipeline structure of the middle filling port;

[0025] Figure 5 for Figure 1 Schematic diagram of the structure of the middle return air pipe assembly;

[0026] Figure 6 for Figure 1 Schematic diagram of the structure of the middle liquid inlet pipe;

[0027] Figure 7 for Figure 1 Schematic diagram of the middle vent pipe structure;

[0028] Figure 8 for Figure 1 Schematic diagram of the middle outlet pipe structure;

[0029] Fig. 9 for Figure 1 Schematic diagram of the pressure gauge tube structure;

[0030] Fig.10 for Figure 1 Schematic diagram of the workbench floor. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] like Figure 1The vehicle-mounted LNG cylinder external pipeline pressure test device shown comprises a workbench 1 and a frame 2 installed on the workbench 1, as well as a vaporizer 3 arranged on one side of the frame 2, a buffer tank 4 arranged on the other side of the frame 2, a fin tube assembly 5 and a connecting pipe arranged in the frame 2 and located between the vaporizer 3 and the buffer tank 4; one end of the connecting pipe 6 is connected to the outlet of the vaporizer 3 and the other end is connected to the inlet of the buffer tank 4, and the connecting pipe 6 is fixed to the frame 2 by a U-shaped pipe clamp. A limiting boss 1.1 is arranged on the table of the workbench 1, and the limiting boss 1.1 is a positioning device, and the left side of the bottom crossbeam of the frame 2 is completely in contact with the limiting boss 1.1; at the same time, a filling port 1.2, a return air port 1.3 and a pressure gauge 1.4 are installed on the side panel of the workbench 1.

[0033] Combination Figure 2 The fin tube assembly 5 shown includes two groups of fin tube units, each group of fin tube units includes two fin tubes 5.1, one end of the two fin tubes is connected through a first bend 5.3, and the other end is connected through a third bend 5.2, the two groups of fin tube units are connected through a second bend 5.4, and the third bends 5.2 of the two groups of fin tube units are provided with connecting holes 5.5.

[0034] Combination Figure 3 The boost external pipeline assembly 7 shown includes a boost elbow 7.1, a boost valve 7.2 and a straight pipe 7.3. One end of the boost elbow 7.1 is connected to a slip joint at one end of the boost valve 7.2 through a boost valve welding square head 7.4. The slip joint at the other end of the boost valve 7.2 is connected to one end of the straight pipe 7.3. The other end of the straight pipe 7.3 is connected to a connecting hole 5.5 of a third bend 5.2 in the fin tube assembly 5, ensuring that the straight pipe 7.3 is parallel to the table surface of the workbench 1. The other end of the boost elbow 7.1 is installed with a slip nut through the boost elbow welding square head 7.5. The boost valve 7.2 is connected to the side plate of the workbench 1 through the boost valve welding square head 7.4, ensuring that the vertical center line of the boost valve 7.2 coincides with the center line of the circular hole 1.5 on the table surface of the workbench 1 (such as Fig.10 shown).

[0035] Combination Figure 4 The filling port pipeline 8 shown includes a filling port elbow 8.1 and a filling port welding square head 8.2 arranged at both ends of the filling port elbow 8.1. The filling port welding square head 8.2 at one end of the filling port elbow 8.1 is tightened on the filling port 1.2 through a slip-on nut 8.3, and the other end of the filling port elbow 8.1 is ensured to be vertically upward to complete the installation of the filling port; the filling port welding square head 8.2 at one end of the filling port elbow 8.1 is connected to one end of a metal hose 15 through a slip-on nut 8.4, and the other end of the metal hose 15 is connected to the slip-on nut of the boost external pipeline 7.

[0036] Combination Figure 5The return air pipe assembly 9 shown in the figure includes a return air elbow 9.1 and a return air straight pipe 9.2. One end of the return air elbow 9.1 is connected to one end of the return air straight pipe 9.2 through a welding tee 9.3. The welding tee 9.3 coincides with the center line of the square hole 1.6 on the workbench 1 (as shown in FIG. Fig.10 The other end of the return air straight pipe 9.2 is connected to the connecting hole 5.5 of another third bend pipe 5.2 in the fin tube assembly 5, and ensures that the return air straight pipe 9.2 is arranged horizontally; the other end of the return air bend pipe 9.1 is tightened on the return air port 1.3 through a slip-on nut to realize the installation of the return air pipe assembly.

[0037] Combination Figure 6 The liquid inlet pipe 10 shown includes a liquid inlet elbow 10.1 and a ferrule plug 10.2. One end of the liquid inlet elbow 10.1 is connected to the ferrule plug 10.2 and the other end is welded to the inlet of the gasifier 3. The liquid inlet elbow 10.1 is fixed to the frame 2 by a U-shaped pipe clamp.

[0038] Combination Figure 7 The vent pipe 11 shown includes a vent elbow 11.1 and a threaded tee 11.2. One end of the vent elbow 11.1 is connected to the external thread end of one side of the threaded tee 11.2 through a slip-on nut, and the other end is welded and fixed to the welding tee 9.3 in the return air pipe assembly 9. When welding and fixing, ensure that one end of the vent elbow 11.1 is vertically upward; the internal thread of the threaded tee 11.2 is threadedly connected to the threaded plug 11.3 to form a seal, and the external thread on the other side of the threaded tee 11.2 is connected to one end of the metal hose 14, and the other end of the metal hose 14 is connected to the ferrule plug 10.2.

[0039] Combination Figure 8 The air outlet pipe 12 shown includes an air outlet elbow 12.1, an air outlet joint 12.2 welded to one end of the air outlet elbow 12.1, and an air outlet threaded plug 12.3. The air outlet threaded plug 12.3 is threadedly connected to the air outlet joint 12.2 to seal the outlet of the air outlet elbow; the air outlet elbow 12.1 has a prefabricated hole 12.4 at the straight pipe end close to the air outlet joint 12.2; the other end of the air outlet elbow 12.1 is welded to the outlet of the buffer tank 4, and the air outlet elbow 12.1 is fixed to the frame 2 by a U-shaped pipe clamp to maintain the overall horizontal arrangement.

[0040] Combination Fig. 9 The pressure gauge tube 13 shown includes a pressure gauge elbow 13.1 and a straight joint 13.2. The straight joint 13.2 and the pressure gauge elbow 13.1 are connected by a ferrule. The other end of the straight joint 13.2 is an internal thread structure and is tightly connected to the pressure gauge 1.4 through threads. The other end of the pressure gauge elbow 13.1 is welded to the prefabricated hole 12.4 of the outlet elbow 12.1.

[0041] The test process of the above-mentioned vehicle-mounted LNG cylinder external pipeline pressure test device is as follows:

[0042] 1) Install external pipelines and check that all external pipelines have been installed;

[0043] 2) Introduce 0.1-0.2MPa dry air through the filling port for pressure test, apply foaming agent to the welds and joints of the external pipeline, and observe whether there are any leaks; if there is leakage at the joint or weld, first discharge the gas from the return air port, then tighten the joint or repair the weld leakage, and finally re-test the pressure for verification;

[0044] 3) After step 2) is normal, control the external gas source and slowly increase the pressure step by step. When the pressure rises to 0.5-0.7MPa, conduct a secondary inspection and apply a foaming agent to the welds and joints of the external pipeline to observe whether there are any leaks. At the same time, observe whether the reading of the pressure gauge changes within 1-2 minutes. A reading of ≤5% is normal, otherwise it is abnormal.

[0045] 4) When no abnormality or leakage occurs in step 3), continue to increase the pressure step by step by 0.1-0.2MPa, with each level of pressure stabilization time being 3-5min, until the test pressure of 1.0-1.5MPa is reached, and the pressure is maintained for 10-15min. Observe whether the pressure gauge changes. If the reading is ≤5%, it is normal, otherwise it is abnormal.

[0046] 5) After the test is completed, slowly discharge the gas from the return port. When the pressure gauge reading drops to 0.7-0.9MPa, maintain the pressure for 3-5 minutes, and use a foaming agent to recheck the pipeline system for leakage or abnormality. At the same time, observe whether the pressure gauge reading changes. A reading of ≤5% is normal, otherwise it is abnormal;

[0047] 6) After step 5) is normal, release the pressure step by step by 0.1-0.2MPa, with each pressure stabilization time being 10-15S, until the pressure gauge reading is 0 and the test is completed.

[0048] The external test gas source of the present invention is inflated through the filling port, and the test gas passes through the filling port, the filling port pipeline, the first metal hose, the pressurized external pipeline, the fin tube assembly, the return pipe assembly, the vent pipe, the second metal hose, the liquid inlet pipe, the vaporizer, the connecting pipe, the buffer tank, the gas outlet pipe, and the pressure gauge tube in sequence. Since the entire external pipeline is a closed system, a one-time pressure test can be performed on the entire external pipeline by inflating from the filling port. The value of the test pressure is observed by the pressure gauge, thereby completing the installation of the external pipeline and the pressure test verification. After the pressure test verification is passed, the metal hose one and the metal hose two are removed after the pressure is relieved, and the gas cylinder is placed to complete the installation of the LNG gas supply system, thereby improving the construction and installation efficiency.

Claims

1. A vehicle-mounted LNG cylinder external pipeline pressure test device, characterized in that: The invention comprises a workbench and a frame installed on the workbench, a vaporizer arranged on one side of the frame, a buffer tank arranged on the other side of the frame, a fin tube assembly and a connecting pipe arranged in the frame and located between the vaporizer and the buffer tank, one end of the connecting pipe is connected to the vaporizer outlet, and the other end is connected to the buffer tank inlet; it also comprises a pressurized external pipeline assembly, a filling port pipeline, a return pipe assembly, a liquid inlet pipe, a vent pipe, an air outlet pipe and a pressure gauge pipe arranged on the workbench; one end of the pressurized external pipeline assembly is connected to the fin tube assembly, and the other end is connected to the fin tube assembly. One end is connected to one end of metal hose one, one end of the filling port pipeline is screwed on the filling port of the workbench side panel, and the other end is connected to the other end of metal hose one; one end of the return air pipe assembly is screwed on the return air port of the workbench side panel, and the other end is connected to the fin tube assembly; one end of the liquid inlet pipe is welded to the inlet of the vaporizer, and the other end is connected to one end of metal hose two; one end of the vent pipe is connected to the return air pipe assembly, and the other end is connected to the other end of metal hose two; one end of the pressure gauge tube is connected to the pressure gauge on the workbench side panel, and the other end is connected to the outlet pipe.

2. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 1 is characterized in that: The fin tube assembly includes two groups of fin tube units, each group of fin tube units includes two fin tubes, one end of the two fin tubes is connected through a first bend pipe, and the other end is connected through a third bend pipe. The two groups of fin tube units are connected through a second bend pipe, and the third bend pipes of the two groups of fin tube units are both provided with connecting holes.

3. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 2 is characterized in that: The boost external pipeline assembly includes a boost elbow, a boost valve and a straight pipe, one end of the boost elbow is connected to a slip-on joint at one end of the boost valve through a boost valve welding square head, the other end of the boost valve is connected to one end of the straight pipe through a slip-on joint, the other end of the straight pipe is connected to a connecting hole of a third elbow in the fin tube assembly, and the straight pipe is parallel to the table top of the workbench, and the other end of the boost elbow is installed with a slip-on nut through a boost elbow welding square head; the boost valve is fixed to the side panel of the workbench through the boost valve welding square head, and the vertical center line of the boost valve coincides with the center line of the circular hole on the table top of the workbench.

4. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 3 is characterized in that: The filling port pipeline includes a filling port elbow and a filling port welding square head arranged at both ends of the filling port elbow. The filling port welding square head at one end of the filling port elbow is tightened on the filling port through a slip-on nut 2, and the other end of the filling port elbow is vertically upward; the filling port welding square head at one end of the filling port elbow is connected to one end of a metal hose 1 through a slip-on nut 1, and the other end of the metal hose 1 is connected to the slip-on nut of the boost external pipeline.

5. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 2 is characterized in that: The return air pipe assembly includes a return air elbow and a return air straight pipe. One end of the return air elbow is connected to one end of the return air straight pipe through a welding tee, and the welding tee coincides with the center line of the square hole on the workbench surface; the other end of the return air straight pipe is connected to the connecting hole of another third elbow in the fin tube assembly, and the return air straight pipe is arranged horizontally; the other end of the return air elbow is tightened on the return air port through a slip-on nut.

6. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 1 is characterized in that: The liquid inlet pipe comprises a liquid inlet elbow and a ferrule plug, one end of the liquid inlet elbow is connected to the ferrule plug, and the other end is welded to the inlet of the gasifier, and the liquid inlet elbow is fixed to the frame by a U-shaped pipe clamp.

7. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 6 is characterized in that: The vent pipe includes a vent elbow and a threaded tee. One end of the vent elbow is connected to the external thread end of one side of the threaded tee through a slip-on nut, and the other end is welded and fixed to the welding tee in the return air pipe assembly. When welding and fixing, one end of the vent elbow is vertically upward; the internal thread of the threaded tee is threadedly connected to the threaded plug to form a seal, and the external thread on the other side of the threaded tee is connected to one end of the metal hose two, and the other end of the metal hose two is connected to the ferrule plug ferrule.

8. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 6 is characterized in that: The air outlet pipe includes an air outlet elbow, an air outlet joint welded to one end of the air outlet elbow, and an air outlet threaded plug. The air outlet threaded plug is connected to the air outlet joint by threads to seal the outlet of the air outlet elbow. The air outlet elbow has a prefabricated hole at the straight pipe end close to the air outlet joint. The other end of the air outlet elbow is welded to the outlet of the buffer tank, and the air outlet elbow is fixed to the frame by a U-shaped pipe clamp.

9. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 8 is characterized in that: The pressure gauge tube includes a pressure gauge elbow and a straight joint. The straight joint and the pressure gauge elbow are connected by a ferrule. The other end of the straight joint is an internal thread structure and is tightly connected to the pressure gauge through threads. The other end of the pressure gauge elbow is welded to the prefabricated hole of the outlet elbow.

10. A test method according to any one of claims 1 to 9, characterized in that: The test method is as follows: 1) Install external pipelines and check that all external pipelines have been installed; 2) Introduce 0.1-0.2MPa dry air through the filling port for pressure test, apply foaming agent to the welds and joints of the external pipeline, and observe whether there are any leaks; if there is leakage at the joint or weld, first discharge the gas from the return air port, then tighten the joint or repair the weld leakage, and finally re-test the pressure for verification; 3) After step 2) is normal, control the external gas source and slowly increase the pressure step by step. When the pressure rises to 0.5-0.7MPa, conduct a secondary inspection and apply a foaming agent to the welds and joints of the external pipeline to observe whether there are any leaks. At the same time, observe whether the reading of the pressure gauge changes within 1-2 minutes. A reading of ≤5% is normal, otherwise it is abnormal. 4) When no abnormality or leakage occurs in step 3), continue to increase the pressure step by step by 0.1-0.2MPa, with each level of pressure stabilization time being 3-5min, until the test pressure of 1.0-1.5MPa is reached, and the pressure is maintained for 10-15min. Observe whether the pressure gauge changes. If the reading is ≤5%, it is normal, otherwise it is abnormal. 5) After the test is completed, slowly discharge the gas from the return port. When the pressure gauge reading drops to 0.7-0.9MPa, maintain the pressure for 3-5 minutes, and use a foaming agent to recheck the pipeline system for leakage or abnormality. At the same time, observe whether the pressure gauge reading changes. A reading of ≤5% is normal, otherwise it is abnormal; 6) After step 5) is normal, release the pressure step by step by 0.1-0.2MPa, with each pressure stabilizing time being 10-15S, until the pressure gauge reads.

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