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

Abstract

The application discloses a kind of vehicle-mounted LNG cylinder outer pipeline pressure test device and test method, including workbench and be arranged in frame vaporizer, buffer tank and finned tube assembly;Boost outer pipeline assembly one end is connected with finned tube assembly, the other end is connected with the one end of metal hose one, filling opening pipeline one end is screwed on the filling opening of workbench side plate, the other end is connected with the other end of metal hose one;Gas return pipe assembly one end is screwed on the gas return port of workbench side plate;Liquid inlet pipe one end is welded with the inlet of vaporizer, the other end metal hose two one end is connected;Vent pipe one end is connected with gas return pipe assembly, the other end is connected with the other end of metal hose two.The outer pipeline of the application is convenient to install, improves the installation efficiency of outer pipeline, and can inspect the levelness and perpendicularity of pipeline construction situation at any time;Outer pipeline is verified by pressure test once, improves the efficiency of outer pipeline pressure test verification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pressure vessel valve and pipeline construction, and particularly relates to a vehicle-mounted LNG cylinder outer pipeline pressure test device and test method. BACKGROUND

[0002] The vehicle-mounted LNG gas supply system is a system for providing fuel for LNG vehicles, which functions to guide LNG from an LNG cylinder, gasify the LNG through a gasifier, and supply the gasified LNG to an engine for combustion to generate power. The vehicle-mounted LNG gas supply system, in terms of structure, mainly includes an LNG cylinder, a gasifier, a buffer tank, a pressure regulating valve, a safety valve, a pressure gauge, a filling device, and an outer pipeline system. In the traditional installation and construction of the LNG cylinder outer pipeline, the welding and assembly of the outer pipeline are performed after the LNG cylinder is fixed to a frame by a pull belt, which has the disadvantages of small pipeline installation and construction space, great pipeline welding difficulty, and easy scratching of the cylinder body. After the installation of the outer pipeline system is completed, pressure test verification of the LNG cylinder and the outer pipeline system together is required, which consumes time and effort, and makes pipeline repair difficult, thereby affecting the assembly efficiency of the LNG cylinder. SUMMARY

[0003] The present application aims to solve the above technical problems, and provides a vehicle-mounted LNG cylinder outer pipeline pressure test device and test method which can improve the installation efficiency and the pressure test verification efficiency.

[0004] To achieve the above-mentioned purpose, the present application provides a vehicle-mounted LNG cylinder outer pipeline pressure test device, which comprises a workbench, a frame mounted on the workbench, a gasifier arranged on one side of the frame, a buffer tank arranged on the other side of the frame, a finned tube assembly arranged between the gasifier and the buffer tank in the frame, and a connecting pipe, one end of the connecting pipe being in communication with the outlet of the gasifier and the other end being in communication with the inlet of the buffer tank; the device further comprises a pressurized outer pipeline assembly, a filling port pipeline, a gas return pipe assembly, a liquid inlet pipe, a vent pipe, a gas outlet pipe, and a pressure gauge pipe arranged on the workbench; one end of the pressurized outer pipeline assembly is connected with the finned tube assembly, and the other end is connected with one end of a metal hose I; one end of the filling port pipeline is screwed on a filling port of a side plate of the workbench, and the other end is connected with the other end of the metal hose I; one end of the gas return pipe assembly is screwed on a gas return port of the side plate of the workbench, and the other end is connected with the finned tube assembly; one end of the liquid inlet pipe is welded with the inlet of the gasifier, and the other end is connected with one end of a metal hose II; one end of the vent pipe is connected with the gas return pipe assembly, and the other end is connected with the other end of the metal hose II; one end of the pressure gauge pipe is connected with a pressure gauge of the side plate of the workbench, and the other end is connected with the gas outlet pipe.

[0005] Further, the finned tube assembly comprises two groups of finned tube units, each group of finned tube units comprising two finned tubes, one end of the two finned tubes being communicated through a first elbow pipe, the other end being communicated through a third elbow pipe, the two groups of finned tube units being communicated through a second elbow pipe, and each of the third elbow pipes of the two groups of finned tube units having a connecting hole.

[0006] Further, the pressurizing outer pipe assembly comprises a pressurizing elbow pipe, a pressurizing valve and a straight pipe, one end of the pressurizing elbow pipe being connected with one end of the pressurizing valve through a pressurizing valve welding square head, the other end of the pressurizing valve being connected with one end of the straight pipe through a pressurizing valve live sleeve joint, the other end of the straight pipe being connected with the connecting hole of one of the third elbow pipes of the finned tube assembly, the straight pipe being parallel to the tabletop of the workbench, the other end of the pressurizing elbow pipe being provided with a live sleeve nut through a pressurizing elbow pipe welding square head; the pressurizing valve being fixed on the side plate of the workbench through a pressurizing valve welding square head, the vertical center line of the pressurizing valve coinciding with the center line of the circular hole on the tabletop of the workbench.

[0007] Further, the filling port pipe comprises a filling port elbow pipe and filling port welding square heads arranged at both ends of the filling port elbow pipe, the filling port welding square head at one end of the filling port elbow pipe being screwed on the filling port through a live sleeve nut two, the other end of the filling port elbow pipe being vertically upward; the filling port welding square head at one end of the filling port elbow pipe being connected with one end of a metal hose one through a live sleeve nut one, the other end of the metal hose one being connected with the live sleeve nut of the pressurizing outer pipe.

[0008] Further, the gas return pipe assembly comprises a gas return elbow pipe and a gas return straight pipe, one end of the gas return elbow pipe being communicated with one end of the gas return straight pipe through a welding tee, the welding tee coinciding with the center line of the square hole on the tabletop of the workbench; the other end of the gas return straight pipe being communicated with the connecting hole of the third elbow pipe of the other of the finned tube assemblies, the gas return straight pipe being horizontally arranged; the other end of the gas return elbow pipe being screwed on the gas return port through a live sleeve nut.

[0009] Further, the liquid inlet pipe comprises a liquid inlet elbow pipe and a clamping sleeve plug, one end of the liquid inlet elbow pipe being connected with the clamping sleeve plug, the other end being welded with the inlet of the gasifier, the liquid inlet elbow pipe being fixed on the frame through a U-shaped pipe clamp.

[0010] Further, the vent pipe comprises a vent elbow pipe and a threaded tee, one end of the vent elbow pipe being connected with one side of the outer threaded end of the threaded tee through a live sleeve nut, the other end being welded and fixed with the welding tee of the gas return pipe assembly, when being welded and fixed, the one end of the vent elbow pipe being vertically upward; the inner thread of the threaded tee being threadedly connected with a threaded plug to form a seal, the other side of the outer thread of the threaded tee being connected with one end of a metal hose two, the other end of the metal hose two being clamped with the clamping sleeve plug.

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

[0012] Further, the pressure gauge pipe comprises a pressure gauge elbow and a straight-through joint, the straight-through joint being connected with the pressure gauge elbow by a clamping sleeve, the other end of the straight-through joint being internally threaded to be tightly connected with the pressure gauge by threads, and the other end of the pressure gauge elbow being welded with the preformed hole of the air outlet elbow.

[0013] Further, the pressure gauge pipe comprises a pressure gauge elbow and a straight-through joint, the straight-through joint being connected with the pressure gauge elbow by a clamping sleeve, the other end of the straight-through joint being internally threaded to be tightly connected with the pressure gauge by threads, and the other end of the pressure gauge elbow being welded with the preformed hole of the air outlet elbow.

[0014] 1) Install the outer pipeline and check whether all the outer pipelines have been installed;

[0015] 2) Perform pressure test by introducing dry air at 0.1-0.2 MPa through the filling port, and observe whether there is any leakage point by applying foaming agent to the welds and joints of the outer pipeline; if there is any leakage at the joints or welds, first discharge the gas from the gas return port, then tighten the joints or repair the welds, and finally perform pressure test again;

[0016] 3) After step 2) is completed without any abnormality, control the external gas source to gradually increase the pressure, and when the pressure increases to 0.5-0.7 MPa, perform secondary inspection by applying foaming agent to the welds and joints of the outer pipeline to observe whether there is any leakage point; at the same time, observe whether the reading of the pressure gauge changes within 1-2 min, and if the reading is ≤5%, it is normal, otherwise it is abnormal;

[0017] 4) After step 3) is completed without any abnormality and leakage, continue to gradually increase the pressure by 0.1-0.2 MPa, and keep the pressure stable for 3-5 min at each level until the test pressure of 1.0-1.5 MPa is reached, keep the pressure for 10-15 min, and observe whether the reading of the pressure gauge changes, and 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 gas return port, and when the reading of the pressure gauge decreases to 0.7-0.9 MPa, keep the pressure for 3-5 min, recheck whether there is any leakage or abnormality in the pipeline system by applying foaming agent, and observe whether the reading of the pressure gauge changes, and if the reading is ≤5%, it is normal, otherwise it is abnormal;

[0019] 6) After step 5) is completed without any abnormality, gradually decrease the pressure by 0.1-0.2 MPa, and keep the pressure stable for 10-15 s at each level until the reading of the pressure gauge is 0, and the test is completed.

[0020] Compared with the prior art, the vehicle-mounted LNG cylinder outer pipeline pressure test device and test method have the advantages that the outer pipeline is convenient to install, the installation efficiency of the outer pipeline is improved, the construction situation of the pipeline can be tested in terms of levelness and perpendicularity at any time, the appearance quality is ensured, the outer pipeline can be subjected to one-time pressure test verification, the efficiency of the outer pipeline pressure test verification is improved, in addition, due to the small volume of the outer pipeline, the test verification time is short, and the leakage problem can be easily repaired, so that the efficiency of the LNG cylinder large-batch assembly is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a vehicle-mounted LNG cylinder outer pipeline pressure test device structure schematic view.

[0022] Figure 2 It is Figure 1 It is a middle finned tube assembly structure schematic view.

[0023] Figure 3 It is Figure 1 It is a middle supercharged outer pipeline assembly structure schematic view.

[0024] Figure 4 It is Figure 1 It is a filling port pipeline structure schematic view.

[0025] Figure 5 It is Figure 1 It is a gas return pipe assembly structure schematic view.

[0026] Figure 6 It is Figure 1 It is a liquid inlet pipe structure schematic view.

[0027] Figure 7 It is Figure 1 It is a vent pipe structure schematic view.

[0028] Figure 8 It is Figure 1 It is a gas outlet pipe structure schematic view.

[0029] Figure 9 It is Figure 1 It is a pressure gauge pipe structure schematic view.

[0030] Figure 10 It is Figure 1 It is a workbench ground schematic view. DETAILED DESCRIPTION

[0031] The application will be further described below in combination with the drawings and specific embodiments.

[0032] As Figure 1The vehicle-mounted LNG cylinder outer pipeline pressure test device shown, including workbench 1 and the frame 2 installed on the workbench 1, and the arrangement in the frame 2 one side of the gasifier 3, the arrangement in the frame 2 the other side of the buffer tank 4, the arrangement in the frame 2 and between the gasifier 3 and the buffer tank 4 of the finned tube assembly 5 and the connecting pipe; the connecting pipe 6 one end with the gasifier 3 outlet communication, the other end with the buffer tank 4 inlet communication, and the connecting pipe 6 through the U-shaped pipe clamp fixed on the frame 2. The workbench 1 table top is arranged with the limiting boss 1.1, the limiting boss 1.1 is the positioning device, the frame 2 bottom beam left side and the limiting boss 1.1 completely fit; at the same time, the workbench 1 side plate is installed with the filling port 1.2, the back gas port 1.3 and the pressure gauge 1.4.

[0033] Combined Figure 2 The finned tube assembly 5 shown includes two groups of finned tube units, each group of finned tube unit includes two finned tubes 5.1, one end of the two finned tubes is communicated through the first elbow pipe 5.3, the other end is communicated through the third elbow pipe 5.2, the two groups of finned tube units are communicated through the second elbow pipe 5.4, and the third elbow pipe 5.2 of the two groups of finned tube units has a connecting hole 5.5.

[0034] Combined Figure 3 The booster outer pipeline assembly 7 shown includes a booster elbow pipe 7.1, a booster valve 7.2 and a straight pipe 7.3, one end of the booster elbow pipe 7.1 is connected with the one end of the booster valve 7.2 through the booster valve welding square head 7.4, the other end of the booster valve 7.2 is connected with the one end of the straight pipe 7.3 through the loose sleeve joint, the other end of the straight pipe 7.3 is connected with the connecting hole 5.5 of one of the third elbow pipes 5.2 in the finned tube assembly 5, which ensures that the straight pipe 7.3 is parallel to the table top of the workbench 1, and the other end of the booster elbow pipe 7.1 is installed with a loose sleeve nut through the booster elbow pipe welding square head 7.5; the booster valve 7.2 is installed on the side plate of the workbench 1 through the booster valve welding square head 7.4, which ensures that the vertical center line of the booster valve 7.2 coincides with the center line of the circular hole 1.5 on the table top of the workbench 1 (as shown in Figure 10 ).

[0035] Combined Figure 4 The filling port pipeline 8 shown includes a filling port elbow pipe 8.1 and a filling port welding square head 8.2 arranged at both ends of the filling port elbow pipe 8.1, the filling port welding square head 8.2 at one end of the filling port elbow pipe 8.1 is tightened on the filling port 1.2 through the loose sleeve nut two 8.3, and the other end of the filling port elbow pipe 8.1 is ensured to be vertical upward, which completes the installation of the filling port; the filling port welding square head 8.2 at one end of the filling port elbow pipe 8.1 is connected with one end of the metal hose one 15 through the loose sleeve nut one 8.4, and the other end of the metal hose one 15 is connected with the loose sleeve nut of the booster outer pipeline 7.

[0036] Combined Figure 5The shown back gas pipe assembly 9 includes back gas elbow 9.1 and back gas straight pipe 9.2, one end of back gas elbow 9.1 communicates with one end of back gas straight pipe 9.2 through welded tee 9.3, the welded tee 9.3 coincides with the center line of the square hole 1.6 on the table 1 table (as shown Figure 10 The shown);The other end of the back gas straight pipe 9.2 communicates with the connecting hole 5.5 of the other third elbow 5.2 in the finned tube assembly 5 and ensures that the back gas straight pipe 9.2 is arranged horizontally;The other end of the back gas elbow 9.1 is screwed on the back gas port 1.3 through the loose sleeve nut to realize the installation of the back gas pipe assembly.

[0037] Combined Figure 6 The shown inlet pipe 10 includes inlet elbow 10.1 and sleeve plug 10.2, one end of inlet elbow 10.1 is connected with sleeve plug 10.2 and the other end is welded with the inlet of gasifier 3, inlet elbow 10.1 is fixed on frame 2 through U-shaped pipe clamp.

[0038] Combined Figure 7 The shown vent pipe 11 includes vent elbow 11.1 and threaded tee 11.2, one end of vent elbow 11.1 is connected with one side of external thread end of threaded tee 11.2 through loose sleeve nut and the other end is welded with welded tee 9.3 in back gas pipe assembly 9, when welded and fixed, the one end of vent elbow 11.1 is ensured to be vertical upward;The internal thread of threaded tee 11.2 is screwed with threaded plug 11.3 to form sealing, the other side of external thread of threaded tee 11.2 is connected with one end of metal hose two 14, the other end of metal hose two 14 is connected with sleeve plug 10.2.

[0039] Combined Figure 8 The shown outlet pipe 12 includes outlet elbow 12.1, outlet joint 12.2 welded on one end of outlet elbow 12.1 and outlet threaded plug 12.3, outlet threaded plug 12.3 is connected with outlet joint 12.2 through thread to seal the outlet of outlet elbow;Outlet elbow 12.1 has prefabricated hole 12.4 at the straight pipe end close to outlet joint 12.2;The other end of outlet elbow 12.1 is welded with the outlet of buffer tank 4, outlet elbow 12.1 is fixed on frame 2 through U-shaped pipe clamp to keep the whole horizontal arrangement.

[0040] Combined Figure 9 The shown pressure gauge pipe 13 includes pressure gauge elbow 13.1 and straight joint 13.2, the straight joint 13.2 is connected with the pressure gauge elbow 13.1 through sleeve, the other end of the straight joint 13.2 is internal thread structure, which is tightly connected with the pressure gauge 1.4 through thread, the other end of the pressure gauge elbow 13.1 is welded with 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 the outer pipeline and check that all the outer pipelines have been installed;

[0043] 2) Perform a pressure test by introducing dry air at 0.1-0.2 MPa through the filling port, and apply the foaming agent to the welds and joints of the outer pipeline to observe whether there are any leakage points; if there is leakage at the joints or the welds, first discharge the gas from the gas return port, then tighten the joints or repair the welds, and finally perform a pressure test again;

[0044] 3) After step 2) is normal, control the external gas source, and gradually increase the pressure, when the pressure increases to 0.5-0.7 MPa, perform a second check, apply the foaming agent to the welds and joints of the outer pipeline to observe whether there are any leakage points; at the same time, observe whether the reading of the pressure gauge changes within 1-2 min, and the reading ≤5% is normal, otherwise it is abnormal;

[0045] 4) When step 3) is normal and no leakage occurs, continue to gradually increase the pressure by 0.1-0.2 MPa, and the pressure stabilizing time of each step is 3-5 min, until the test pressure reaches 1.0-1.5 MPa, and the pressure is maintained for 10-15 min, and observe whether the reading of the pressure gauge changes, and the reading ≤5% is normal, otherwise it is abnormal;

[0046] 5) After the test is completed, slowly discharge the gas from the gas return port, when the reading of the pressure gauge decreases to 0.7-0.9 MPa, maintain the pressure for 3-5 min, and recheck the pipeline system for leakage or abnormality by using the foaming agent, and observe whether the reading of the pressure gauge changes, and the reading ≤5% is normal, otherwise it is abnormal;

[0047] 6) After step 5) is normal, gradually reduce the pressure by 0.1-0.2 MPa, and the pressure stabilizing time of each step is 10-15 s, until the reading of the pressure gauge is 0, and the test is completed.

[0048] The external test gas source fills the gas through the filling port, and the test gas passes through the filling port, the filling port pipeline, the metal hose one, the booster outer pipeline, the finned tube assembly, the gas return tube assembly, the vent pipe, the metal hose two, the liquid inlet pipe, the gasifier, the connecting pipe, the buffer tank, the gas outlet pipe and the pressure gauge pipe in turn. Since the entire outer pipeline is a closed system, the pressure test of the entire outer pipeline can be performed once by filling the gas through the filling port, and the value of the test pressure is observed through the pressure gauge, so that the installation and pressure test verification of the outer pipeline are completed. After the pressure test verification is passed, the metal hose one and the metal hose two are removed after the pressure is released, 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 by: The workbench comprises a workbench and a frame mounted 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; the workbench also comprises a pressurized external pipeline assembly, a filling port pipeline, a return air pipe assembly, a liquid inlet pipe, a vent pipe, an air outlet pipe and a pressure gauge pipe; one end of the pressurized external pipeline assembly is connected to the fin tube assembly and the other end is connected to the buffer tank inlet. Connected to one end of metal hose 1, one end of the filling port pipeline is screwed to the filling port on the workbench side panel, and the other end is connected to the other end of metal hose 1; one end of the return air pipe assembly is screwed to the return air port on the workbench side panel, and the other end is connected to the finned 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 2; 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 2; 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; The entire external pipeline is a closed system. After the pressure test is passed, remove the metal hose 1 and metal hose 2 after pressure relief, and replace the gas cylinder to complete the installation of the LNG gas supply system.

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 joint at one end of the boost valve through a boost valve welding square head. The slip joint at the other end of the boost valve is connected to one end of the straight pipe. The other end of the straight pipe is connected to a connecting hole of a third elbow in the fin tube assembly. The straight pipe is parallel to the table top of the workbench. The other end of the boost elbow is installed with a slip 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. The vertical center line of the boost valve coincides with the center line of the circular hole on the workbench table.

4. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 3 is characterized by: 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 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. 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 threaded end of the threaded tee on one side 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 2, and the other end of the metal hose 2 is connected to the ferrule plug.

8. The vehicle-mounted LNG cylinder external pipeline pressure test device according to claim 6 is characterized by: 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 near 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, 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 sleeve. 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.

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 piping and check that all external piping has 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 leaking weld, and finally re-test the pressure for verification; 3) After step 2) is complete, control the external gas source and slowly increase the pressure step by step. When the pressure reaches 0.5-0.7 MPa, perform a secondary inspection by applying a foaming agent to the welds and joints of the external pipeline to observe for leaks. At the same time, observe the pressure gauge reading for changes within 1-2 minutes. A reading of ≤5% is normal, otherwise it is abnormal. 4) If no abnormality or leakage occurs in step 3), continue to increase the pressure step by step by 0.1-0.2 MPa, with each level maintaining pressure for 3-5 minutes, until the test pressure of 1.0-1.5 MPa is reached. Maintain the pressure for 10-15 minutes and observe whether the pressure gauge reading changes. A reading of ≤5% 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 0.7-0.9 MPa, maintain the pressure for 3-5 minutes. Use a foaming agent to recheck the piping system for leaks or abnormalities. 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 completed without any abnormality, release the pressure step by step by 0.1-0.2 MPa, with the pressure stabilization time for each step being 10-15 seconds, until the pressure gauge reads 0 and the test is completed.

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