Pneumatic test questions [Daily Question 20090227]

Judging from the photos in the accident link provided by Fei Guo Hai Baozhu, it appears to be a fixed-pressure vessel. Therefore, this response is based on the \"Regulations for Safety Inspection of Fixed Pressure Vessels\" TSG_R0004-2008: 1. The main purpose is to check whether there are any leaks at the various connection points of the vessel. II. For pressure vessels that cannot be filled with liquid due to structural or support reasons, or those for which the operating conditions do not permit the retention of test liquid, a pneumatic test may be carried out in accordance with the provisions of the design drawings. III. Requirements: 1. The gas used in the experiment should be dry and clean air, nitrogen, or another inert gas. 2 The minimum temperature of the vessel wall metal during pneumatic testing for pressure vessels made of different materials shall be determined in accordance with the provisions of relevant standards. If factors such as plate thickness cause the material’s ductile transition temperature to rise, the metal temperature of the reactor wall must be increased accordingly. 3 During the pressure test, the safety department of the testing unit shall carry out on-site supervision. 4 The pressure should first be increased slowly to 10% of the specified test pressure, held at that level for a sufficient duration, and all welds and joints should be inspected initially. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If no abnormal phenomena occur, the pressure is then increased step by step to 10% of the specified test pressure, until the test pressure is reached, after which the pressure is maintained for a sufficient duration. Then it is reduced to the design pressure, and the pressure is held at that level for a sufficient amount of time for inspection; the pressure must remain constant during this inspection period. During the 5-bar pressure test, the pressure vessel should produce no abnormal noises; no leaks should be detected using soap solution or other leak detection fluids, and there should be no visible deformation, in which case it is considered qualified.

1. Purpose of the pressure test: The pressure test is used to determine the pressure resistance of pressure vessels; the pressure applied during this test is 1.15 times the design pressure. There is a difference between a pressure test and a leak test. 2. Conditions: Under normal circumstances, gas is not allowed to be used as the medium for pressure testing of pressure vessels. However, for those vessels in which it is not possible to safely fill them with liquid due to structural or support reasons, or where the operating conditions do not permit the retention of test liquid, pressure testing with gas may be employed in accordance with the specifications provided in the design drawings. If the container’s volume is too large, it cannot withstand the weight of water ； Or the casing is not suitable for media containing chloride ions, and the water used for the hydrostatic test contains a high amount of chloride ions ； Furthermore, in extreme cold, the liquid inside the container may freeze and cause the container to burst. A pneumatic test can be used. 3. Requirements: 1. For pressure vessels that, due to their structure or support conditions, cannot have liquids filled into them, or those for which the operating conditions do not permit the retention of test liquids, pneumatic testing may be employed in accordance with the specifications provided in the design drawings. 2. The gas used for pressure vessel testing should be dry and clean air, nitrogen, or other inert gases. 3. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 4. During the pressure test, the safety department of the testing unit shall conduct on-site supervision. 5. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased in stages by 10% of the specified test pressure until the test pressure is reached, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. 6. During the pressure test, if the pressure vessel produces no abnormal noises, shows no leaks when inspected with soapy water or other leak-detection fluids, and has no visible deformation, it is considered qualified.

It seems that a hydraulic pressure test must be carried out first, and only after passing that can a pneumatic pressure test be performed.

I would like to ask whether the safety technical supervision regulations for fixed pressure vessels, TSG R0004-2008, have been officially issued for the 2nd floor?

I. Purpose: To test the pressure resistance and sealing performance of pressure vessels. II. Pressure: 1.15 p/t. III. Conditions: Under normal circumstances, gases are not allowed to be used as the medium for pressure testing of pressure vessels. However, for those vessels for which it is not possible to safely fill them with liquid due to structural or supporting reasons, or where the operating conditions do not permit the retention of test liquid, pressure testing with gas may be carried out in accordance with the specifications provided in the design drawings. IV. Requirements: 1. The gas used for pressure vessel testing should be dry and clean air, nitrogen, or other inert gases. 2. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 3. During the pressure test, the safety department of the testing unit shall carry out on-site supervision. 4. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased in stages by 10% of the specified test pressure until the test pressure is reached, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. V. Qualification criteria: During the testing process, the pressure vessel shall show no abnormal noises; no air leakage shall be detected when inspected with soapy water or other leak detection fluids; and there shall be no visible deformation, in which case it is considered qualified.

On November 21, 2008, the General Administration of Quality Supervision, Inspection and Quarantine of China issued the \"Regulations on Safety Technical Inspection of Fixed Pressure Vessels\". 　　These regulations specify the mandatory basic safety requirements for the design, manufacturing, installation, repair, modification, inspection, and use of fixed pressure vessels. They apply to fixed pressure vessels that are used and manufactured within the People’s Republic of China and fall within the scope of application of the Regulations on the Safety Supervision of Special Equipment. These regulations are a revised version of the current \"Regulations on Safety Technical Inspection of Pressure Vessels\".

Pressure vessels are generally subjected to hydraulic testing in the manufacturing plant, while pneumatic testing is often carried out during on-site installation and alignment. In accordance with the requirements of the standards \"Construction Technology Standards for On-site Welding of Steel Towers and Vessels in Petrochemical Industries (SH/T3524‑1999)\” and \"Construction and Acceptance Standards for Medium and Low Pressure Chemical Equipment (HGJ209-83)\”, the method for pressure testing is as follows: 1. The gas used for testing should be dry and clean air, nitrogen, or some other inert gas. 2. Seal all openings of the closed container, and use an air compressor to fill the equipment with dry and clean air, at a temperature of not less than 150°C. Slowly increase the pressure to 10% of the test pressure and maintain it for 10 minutes, while conducting a preliminary inspection of all welds on the equipment itself as well as those on the connecting pipes ； After passing the test, the pressure is increased further to 50% of the test pressure; thereafter, it is raised in steps of 10% of each test pressure level until reaching the test pressure, and held at that level for 10 minutes. After that, the pressure is reduced to the design pressure and held there for at least 30 minutes, during which inspections are carried out. 3 During the pressure test, the pressure vessel should produce no abnormal noises; no leaks should be detected using soap solution or other leak detection fluids, and there should be no visible deformation, in which case it is considered qualified. What needs to be noted during the pressure test is that the test pressure is usually 1.15 times the design pressure ； In principle, a pressure test is not carried out when the pressure for the pressure test exceeds 0.6 Mpa ； The container must not be struck during the pressure test ； Proper safety measures must be taken during pressure tests, as pressure differs from hydraulic pressure, and this matter requires sufficient attention!

1. Purpose: To test the pressure resistance and sealing performance of pressure vessels. 2. Pressure: 1.15 p/t. 3. Conditions: Under normal circumstances, gases are not allowed to be used as the medium for pressure testing of pressure vessels. However, for those vessels where it is not possible to safely fill them with liquid due to structural or supporting reasons, or where the operating conditions do not permit the retention of test liquid, gas testing may be employed in accordance with the specifications provided in the design drawings. Four requirements: 1. The gas used for pressure vessel testing should be dry and clean air, nitrogen, or other inert gases. 2. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 3. During the pressure test, the safety department of the testing unit shall carry out on-site supervision. 4. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased in stages by 10% of the specified test pressure until the test pressure is reached, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. V. Qualification criteria: During the testing process, the pressure vessel shall show no abnormal noises; no air leakage shall be detected when inspected with soapy water or other leak detection fluids; and there shall be no visible deformation, in which case it is considered qualified.

It should be said that the explosion of the LNG pipeline in Xiaoyangshan, Shanghai, was an explosion of a pressure pipeline; therefore, I believe the relevant standards for pressure pipelines, namely the \"GB50235-1997 Code for Construction and Acceptance of Industrial Metal Piping Projects\", should be applied. I’ll try to reply too! Pneumatic testing of pressure pipelines: 1. Pneumatic testing is primarily used to determine whether the pressure resistance of the pressure pipelines meets the specified standards. 2. What are the requirements for the barometric test? According to the standard GB50235-1997 Code for Construction and Acceptance of Industrial Metal Piping Projects: 7.5.1.1 The pressure test shall use liquid as the testing medium. When the design pressure of the pipeline is less than or equal to 0.6 MPa, gas can also be used as the testing medium, but effective safety measures must be taken. Gas pressure testing is strictly prohibited for brittle materials. . . . . 7.5.1.3 When conducting a pressure test, a no-entry zone shall be established, and unauthorized personnel must not enter. 7.5.1.4 No repairs shall be made on the pipeline after the pressure test is completed. 7.5.1.5 The project owner shall participate in the pressure test. After the pressure test is successful, the “Pipeline System Pressure Test Record” shall be filled out together with the construction unit in the format specified in Article A.0.8 of Appendix A to these specifications. 7.5.2 The following conditions must be met prior to the pressure test: 7.5.2.1 The pipeline installation work within the scope of the test, excluding painting and insulation, shall have been fully completed in accordance with the design drawings and relevant provisions on installation quality standards. 7.5.2.2 The welds and other areas to be inspected have not yet been painted or insulated. 7.5.2.3 Temporary restraining devices have been installed on the expansion joints of the pipeline. 7.5.2.4 The pressure gauges used for testing have been calibrated and are within their weekly inspection period; their accuracy must be at least 1.5 grade. The full scale value of the gauges should be 1.5 to 2 times the maximum pressure to be measured, and no fewer than two pressure gauges shall be used. 7.5.2.5 Liquids or gases that meet the pressure test requirements are available. 7.5.2.6 The pipeline has been reinforced as required by the test. 7.5.2.7 For pipelines transporting highly toxic fluids and pipelines with a design pressure of 10 MPa or higher, prior to the pressure test, the following documents must have been rechecked by the project owner: (1) Quality certificates for the pipeline components. ⑵ Records of inspection or testing of pipeline components. ⑶ Pipe processing record. ⑷ Welding inspection and heat treatment records. ⑸ Documents for design modifications and material substitutions. 7.5.2.8 The test pipeline and unrelated systems have been separated using blind flanges or other measures. 7.5.2.9 The safety valves, rupture discs, and instrumentation components on the pipeline to be tested have been removed or isolated. 7.5.2.10 The test plan has been approved, and technical briefings have been conducted. . . . . . 7.5.4 The pneumatic pressure test shall comply with the following provisions: 7.5.4.1 The test pressure for steel pipes and non-ferrous metal pipes subjected to internal pressure shall be 1.5 times the design pressure, while the test pressure for vacuum pipes shall be 0.2 MPa. When the design pressure of the pipeline is greater than 0.6 MPa, a pressure test using gas is only permitted if specified in the design documents or with the approval of the project owner. 7.5.4.2 It is strictly prohibited to bring the test temperature close to the metal’s brittle transition temperature. 7.5.4.3 Before the test, a preliminary test must be conducted using air, with the test pressure preferably set at 0.2 MPa. 7.5.4.4 During the test, the pressure should be increased gradually and slowly. When the pressure reaches 50% of the test pressure, if no abnormalities or leaks are detected, the pressure should be increased further in steps of 10% of the test pressure, with each step being maintained for 3 minutes, until the test pressure is reached. Maintain the pressure for 10 minutes, then reduce it to the design pressure; the duration of pressure maintenance should be determined based on the requirements of the leak detection process. It is considered qualified if no leakage is detected using a foaming agent. 7.5.5 Pipelines transporting highly toxic fluids, toxic fluids, and flammable fluids must undergo leak testing. The leak test shall be conducted in accordance with the following provisions: 7.5.5.1 The leak test shall be carried out after the pressure test is successful, and air is preferably used as the testing medium. 7.5.5.2 The leakage test pressure shall be the design pressure. 7.5.5.3 The leak test can be carried out simultaneously with the commissioning work. 7.5.5.4 The leakage test should focus on inspecting the valve stuffing box, flange or threaded connections, vent valves, drain valves, etc. It is considered qualified if no leakage is detected using a foaming agent. 7.5.5.5 Pipes that have passed the pressure test and have not been disassembled after the test may be exempted from the leak test. 7.5.6 After passing the pressure test, the vacuum system shall also undergo a 24-hour vacuum level test in accordance with the provisions of the design documents, with the pressure increase rate not exceeding 5%. 7.5.7 When the design documents specify that leakage tests be conducted using halogens, helium, ammonia, or other methods, such tests shall be carried out in accordance with the relevant technical specifications. For pressure vessels, the standard \"TSG R7001-2004 Rules for Periodic Inspection of Pressure Vessels\" should be referred to: 1. Check whether the pressure resistance of the pressure vessel meets the design requirements and relevant standard specifications. 2. Under normal circumstances, gases are not permitted as the medium for pressure testing of pressure vessels. However, for those vessels in which it is not possible to safely fill them with liquid due to structural or supporting reasons, or where the operating conditions do not allow the retention of test liquid, pneumatic testing may be used as specified in the design drawings. 3. Article 35: The pneumatic testing of pressure vessels shall comply with the requirements of this article. (1) The basic requirements are as follows: 1. For pressure vessels in which liquids cannot be filled due to structural or supporting reasons, or those for which the operating conditions do not permit the retention of test liquid, a pneumatic test may be carried out in accordance with the specifications provided in the design drawings ； 2. Pressure vessels containing flammable media must be thoroughly cleaned, purged using steam or other effective methods, and have samples analyzed to confirm compliance before undergoing pressure testing; under no circumstances shall air be used as the testing medium ； 3. The gas used in the experiment is dry and clean air, nitrogen, or other inert gases ； 4. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the gas used for testing shall comply with the specifications given in the design drawings ； 5. During the pressure test, the safety department of the testing unit conducts on-site supervision. (II) The procedure for the pressure test is as follows: 1. Slowly increase the pressure to 10% of the specified test pressure, hold it at that level for 5–10 minutes, and conduct an initial inspection of all welds and connection points. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure ； 2. If there are no abnormal phenomena, the pressure is then increased gradually to 10% of the specified test pressure, step by step, until the test pressure is reached; the pressure is held at this level for 30 minutes. After that, it is reduced to 87% of the specified test pressure, and the pressure is held at this level for a sufficient period of time for inspection. The pressure must remain constant during the inspection, and continuous pressure increase cannot be used to maintain the test pressure. It is strictly prohibited to tighten bolts under pressure or apply external force to the stressed components during the pressure test. (III) During the pressure test, it is considered successful if the following conditions are met: 1. The pressure vessel emits no abnormal noises ； 2. No air leakage detected after inspection with soapy water or other leak detection fluids ； 3. No visible deformation. For pressure vessels containing flammable media, if a pneumatic test is carried out using nitrogen or another inert gas, a residual pressure of 0.05–0.1 MPa should be maintained after the test to ensure sealing. It is important to note the difference between a pressure test and a leak test; these two concepts are entirely different. 1. A leak test is primarily used to check whether there are any leaks at the various connection points of a container. 2. Pressure vessels with a medium toxicity level that is extremely or highly hazardous, or those for which minor leaks are not permissible by design, must undergo a leak-tightness test. 3. Pressure vessels shall undergo a gas-tightness test in accordance with the following requirements: (1) The gas-tightness test shall be carried out after the hydraulic test is successful. For pressure vessels for which design requirements call for a pressure test, the airtightness test can be carried out simultaneously with the pressure test, and the test pressure shall be the same as that of the pressure test. 　　(2) For pressure vessels made of carbon steel and low-alloy steel, the temperature of the gas used for testing shall be not lower than 5°C; for pressure vessels made of other materials, it shall be as specified in the design drawings. 　　(3) The gas used for the airtightness test should be dry, clean air, nitrogen, or other inert gases. 　　(4) When conducting a airtightness test, all safety accessories must be installed. 　　(5) During the test, the pressure should be increased gradually; once the specified test pressure is reached, it should be maintained for 10 minutes before being reduced to the design pressure. Soap water should be applied to all welds and joints for inspection, and no leaks are considered acceptable. In the event of a leak, carry out hydraulic and airtightness tests again after repair. 　　A gas-tightness test is different from a pressure test. Firstly, their purposes are different; a gas-tightness test is used to check the tightness of pressure vessels, while a pressure test is used to assess the pressure resistance of such vessels. Secondly, the test pressures are different: the airtightness test pressure is the design pressure of the container, while the pneumatic test pressure is 1.15 times the design pressure. This post was last edited by hw197358 on 2009-2-27 14:03.]

I agree with the view from the ninth floor! ! ! :handshake

According to the **Regulations on Safety Inspection of Pressure Vessels issued by the Quality and Technical Supervision Bureau**, the purpose of pressure testing is to evaluate the pressure-bearing capacity and stress resistance of pressure vessels, including those under positive or negative pressure. Condition: Pneumatic testing can be used for pressure vessels that cannot be filled with liquid due to structural or support reasons, as well as those for which the retention of test liquid is not permitted under operating conditions. Requirements: 1. The gas used in the experiment should be dry and clean air, nitrogen, or another inert gas. 2. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 3. During the pressure test, the safety department of the testing unit shall conduct on-site supervision. 4. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased step by step to 10% of the specified test pressure, until reaching the test pressure, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. 5. During the pressure test, if the pressure vessel produces no abnormal noises, shows no leaks when inspected with soapy water or other leak-detection fluids, and has no visible deformation, it is considered qualified.

1. Purpose of pneumatic testing — Pneumatic testing is a type of pressure test. Whether it is a pressure pipeline or a pressure vessel, the purpose of conducting such tests is to evaluate the strength of the pipeline or vessel； The pressure test conducted after the manufacture of a container or the installation of a pipeline is intended to verify the quality of the design, manufacturing, or installation, whereas the pressure test carried out between two full inspection cycles for an in-service pressure container is aimed at assessing its practical reliability. 2. Conditions and requirements for the pneumatic testing of pressure vessels: (1) Refer to Article 100 of the 99th edition of the \"Regulations on Pressure Vessels\" for detailed provisions (LS has already written it down!) ） ； ⑵Article 35 of TSG R7001-2004 \"Rules for Periodic Inspection of Pressure Vessels\": Requirements for pressure testing of pressure vessels: ① As specified in the \"Vessel Regulations\" ； ②For pressure vessels containing flammable media, before conducting a pneumatic test, they must be thoroughly cleaned and purged using steam or other effective methods, and sample analysis must show satisfactory results; otherwise, it is strictly prohibited to use air as the testing medium ； ③The gas used in the experiment is dry and clean air, nitrogen, or other inert gases ； ④The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the gas used for testing shall comply with the specifications given in the design drawings ； ⑤During the pressure test, the safety department of the testing unit conducts on-site supervision. 3. It should be noted that, in accordance with Article 94 of the Pressure Vessels Regulations, when conducting a pressure test on vessels: the test pressure for new vessels is 1.15 times the design pressure, while for existing vessels it is either their maximum operating pressure or 1.15 times the maximum allowable operating pressure specified on their nameplate ； 4. However, in accordance with Article 29 of TSG R7001-2004 \"Rules for Periodic Inspection of Pressure Vessels\", the hydrostatic test pressure shall be 1.15 times the \"maximum operating pressure determined during this inspection\". This post was last edited by clguan on 2009-2-27 15:43]

1. Purpose of the pressure test: The pressure test is used to determine the pressure resistance of pressure vessels; the pressure applied during this test is 1.15 times the design pressure. There is a difference between a pressure test and a leak test. 2. Conditions: Under normal circumstances, gas is not allowed to be used as the medium for pressure testing of pressure vessels. However, for those vessels in which it is not possible to safely fill them with liquid due to structural or support reasons, or where the operating conditions do not permit the retention of test liquid, pressure testing with gas may be employed in accordance with the specifications provided in the design drawings. If the container’s volume is too large, it cannot withstand the weight of water ； Or the casing is not suitable for media containing chloride ions, and the water used for the hydrostatic test contains a high amount of chloride ions ； Furthermore, in extreme cold, the liquid inside the container may freeze and cause the container to burst. A pneumatic test can be used. 3. Requirements: 1. For pressure vessels that, due to their structure or support conditions, cannot have liquids filled into them, or those for which the operating conditions do not permit the retention of test liquids, pneumatic testing may be employed in accordance with the specifications provided in the design drawings. 2. The gas used for pressure vessel testing should be dry and clean air, nitrogen, or other inert gases. 3. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 4. During the pressure test, the safety department of the testing unit shall conduct on-site supervision. 5. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased in stages by 10% of the specified test pressure until the test pressure is reached, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. 6. During the pressure test, if the pressure vessel produces no abnormal noises, shows no leaks when inspected with soapy water or other leak-detection fluids, and has no visible deformation, it is considered qualified.

Refer to the relevant provisions of the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" TSG_R0004-2008

A hydraulic test must be passed first before a gas-tightness test can be conducted. The specific requirements and purposes are as follows: 1. For pressure vessels that, due to their structure or support conditions, cannot have liquids filled into them, or those for which the operating conditions do not permit the retention of test liquids, a gas-tightness test may be carried out in accordance with the specifications provided in the design drawings. 2. The gas used for pressure vessel testing should be dry and clean air, nitrogen, or other inert gases. 3. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 4. During the pressure test, the safety department of the testing unit shall conduct on-site supervision. 5. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased in stages by 10% of the specified test pressure until the test pressure is reached, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. 6. During the pressure test, if the pressure vessel produces no abnormal noises, shows no leaks when inspected with soapy water or other leak-detection fluids, and has no visible deformation, it is considered qualified. The purpose of a pressure test is to evaluate the pressure resistance of pressure vessels; the pressure used for such tests is 1.15 times the design pressure. There is a difference between a pressure test and a leak test.

I. Purpose: To test the pressure resistance and sealing performance of pressure vessels. II. Pressure: 1.15 p/t. III. Conditions: Under normal circumstances, gases are not allowed to be used as the medium for pressure testing of pressure vessels. However, for those vessels for which it is not possible to safely fill them with liquid due to structural or supporting reasons, or where the operating conditions do not permit the retention of test liquid, pressure testing with gas may be carried out in accordance with the specifications provided in the design drawings. IV. Requirements: 1. The gas used for pressure vessel testing should be dry and clean air, nitrogen, or other inert gases. 2. The temperature of the test gas for pressure vessels made of carbon steel and low-alloy steel shall not be lower than 15°C. For pressure vessels made of other materials, the temperature of the test gas shall comply with the specifications in the design drawings. 3. During the pressure test, the safety department of the testing unit shall carry out on-site supervision. 4. The pressure should first be increased slowly to 10% of the specified value, held at that level for 5–10 minutes, after which a preliminary inspection of all welds and joints should be carried out. If there is no leakage, the pressure can be increased further to 50% of the specified test pressure. If there are no abnormal phenomena, the pressure is then increased in stages by 10% of the specified test pressure until the test pressure is reached, after which it is held at that level for 30 minutes. Then reduce it to 87% of the specified test pressure, and maintain that pressure for a sufficient period of time for inspection; the pressure must remain constant during this inspection. Continuous pressurization shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pneumatic test. V. Qualification criteria: During the testing process, the pressure vessel shall show no abnormal noises; no air leakage shall be detected when inspected with soapy water or other leak detection fluids; and there shall be no visible deformation, in which case it is considered qualified.

A pneumatic test is a type of pressure test. The purpose of a pressure test is to examine the strength and tightness of the pressure-bearing components of a pressure vessel. During the testing process, it is determined whether the pressure vessel possesses the load-bearing capacity necessary for safe operation at the designed pressure by observing whether there is any significant deformation or cracking in the pressure-bearing components. At the same time, the tightness of pressure vessels is checked by observing for any leaks at joints such as welds and flanges. 　　Since the test pressure for pressure testing is higher than the maximum operating pressure, the possibility of the pressure vessel rupturing during the test must be taken into account. Since gases of the same volume and pressure release much more energy upon explosion than liquids, liquids are generally used as the testing medium in order to reduce the risks associated with the rupture of boilers and pressure vessels during pressure tests. Since water is readily available for use and possesses all the properties required for pressure testing, it is commonly used as the medium for such tests; hence, pressure testing is often referred to as hydrostatic testing. II. Under what circumstances can pressure vessels be subjected to a pneumatic test? Under normal circumstances, gas is not permitted as a medium for pressure testing of pressure vessels. However, for those vessels that cannot be safely filled with liquid due to structural or support reasons, or where the operating conditions do not allow the retention of test liquid, pressure testing with gas may be employed in accordance with the specifications provided in the design drawings. If the container’s volume is too large, it cannot withstand the weight of water ； The casing is not suitable for media containing chloride ions, and the water used for pressure testing contains a high amount of chloride ions ； In extreme cold, the liquid inside the container may freeze and cause the container to burst. III. What are the requirements for barometric tests? As can be seen from the above, pneumatic testing is conditional, and the main reason is that it is more dangerous than hydraulic testing. Therefore, the following technical requirements should be considered when conducting a pressure test: (1) Safety measures must be in place for the pressure test, and these measures need to be approved by the technical supervisor of the testing unit. During the test, the safety department of the testing unit shall conduct on-site supervision. (2) The gas used for the pressure test should be dry, clean air, nitrogen, or another inert gas. (3) For containers made of carbon steel and low-alloy steel, the temperature of the medium during pressure testing must not be lower than 15℃ ； The pressure testing temperature for containers made of other steel grades is specified in the design drawings. (4) During the test, the pressure should be increased gradually until it reaches 10% of the specified test pressure; then the pressure should be maintained for 5–10 minutes, during which a preliminary inspection of all welds and joints is carried out ； If there is no leakage, the pressure can be increased further to 50% of the specified pressure ； If no abnormal phenomena occur, the pressure is then increased step by step to the test pressure, with each increase representing 10% of the test pressure; the pressure is maintained at this level for 10 to 30 minutes, depending on the volume ； Then it is reduced to the design pressure, and a pressure hold test is conducted; the pressure hold time should be no less than 30 minutes. The passing criterion for the pressure test is that, after conducting the test in accordance with the specified procedures, there are no leaks and no visible abnormal deformations as detected by soap solution and other leak detection fluids, in which case it is considered successful. In the event of a leak, repair it and then retest in accordance with the above requirements. Reference standards: \"Rules for Periodic Inspection of Pressure Vessels\" TSG R7001-2004, \"Safety Technical Supervision Regulations for Fixed Pressure Vessels\" TSG R0004-2008, \"Recommended Practices for Inspection of Pressure Vessels in Use in the Petroleum Industry\" SY/T6552-2003. Once again, thank you all for your participation; those from the 10th and 13th floors gave excellent answers.