I would like to ask what the difference is between a leakage test and a airtightness test

A leakage test is a test that uses gas as the medium, and at the design pressure, it employs foaming agents, colorants, gas molecule sensors, or other specialized methods to detect leak points in the piping system.

Pipelines transporting extremely and highly hazardous media as well as flammable media must undergo leak testing. The leak test should be conducted after the pressure test is successful, and air is preferably used as the testing medium. The leakage test pressure is the design pressure. The leak test can be carried out simultaneously with the commissioning test. The leakage test should be conducted by gradually increasing the pressure step by step. Once the test pressure is reached, and after holding that pressure for 10 minutes, inspections should be carried out using a neutral foaming agent. The focus of the leakage test is to check for any leaks at all sealing points, including the valve stuffing boxes, flange or threaded connections, as well as the vent valves, exhaust valves, and drain valves.

A gas-tightness test is a type of integrity test that uses gas as the pressurizing medium in order to prevent pressure vessels from leaking. This is because pressure vessels containing media with an extremely high degree of toxicity, high hazard levels, or for which minor leaks are not permissible by design must undergo a leak-tightness test. The airtightness test must be carried out only after the hydraulic test is successful. Containers that have passed the pressure test can generally be exempted from the airtightness test, or in accordance with the provisions of the design drawings. The gas used for the airtightness test meets the requirements of the pressure test.

A gas-tightness test is different from a pressure test. Firstly, their purposes are different; the airtightness test is used to check the tightness of pressure vessels, while the 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. Many products in our daily lives require airtightness testing, and in Beijing the main facility for this purpose is the Aerospace Environmental Reliability and Testing Center ； Zikai Environmental Reliability and Electromagnetic Compatibility Testing Center ； Department 3 of the 3rd Aerospace Institute, wireless power plants, and inspection institutes for various types of special equipment can handle it. CJJ33-2005: Air is recommended as the medium for integrity tests, and the test pressure shall meet the following requirements: 1. When the design pressure is less than 5 kPa, the test pressure shall be 20 kPa. 2. When the design pressure is greater than or equal to 5 kPa, the test pressure shall be 1.15 times the design pressure, and shall not be less than 0.1 MPa. 3. The voltage rise rate during testing should not be too fast. For pipelines with a design pressure greater than 0.8 Mpa, during pressure testing, the pressure should be increased slowly; when it reaches 30% and 60% of the test pressure, the increase in pressure should be halted temporarily for 30 minutes to check for any abnormalities in the system. If no abnormalities are detected, the pressure can be increased further. After the pressure inside the pipe rises to the tightness test pressure, recording begins once the temperature and pressure stabilize. 4. The duration of the pressure stabilization during the tightness test should be 24 hours, with records to be taken at least once per hour; the test is considered successful if the corrected pressure drop is less than 133 Pa. The corrected pressure drop shall be determined using the following formula: ⊿P’=(H1+B1)-(H2+B2)(273+ t1)/(273+ t2) (12.4.5) Where: —— Corrected pressure drop (Pa) ； H1, H2 —— Gauge readings at the start and end of the test (Pa) ； B1, B2 —— Barometer readings at the start and end of the test (Pa) ； t1, t2 —— Temperature of the medium inside the pipe at the start and end of the test (°C). 5. All equipment, instruments, and pipe fittings that did not participate in the leak test should be reset after the leak test is successful. The system should then be pressurized to the design pressure. A blowing agent should be used to check the equipment, instruments, pipe fittings, as well as their connections to the pipes; no leaks being present indicates success.

One is to test the sealing performance, and the other is to test the strength performance

I still can’t tell the difference between leak testing and airtightness testing

I’d like to ask again: airtightness refers to strength, while leakiness relates to sealing, is that correct? Are these two tests related? Do pressure vessels containing highly hazardous media at high pressures need to undergo both tests?

Thank you to the teachers upstairs; I have found an answer to this question. To put it simply, for more details see clause 6.6.1 of HG 20231-2014. The leakage test is a method used to assess the construction quality of piping systems, with the aim of checking whether there are any leaks in the pipes after installation. The airtightness test, on the other hand, is conducted before hot commissioning on the entire process system (including all equipment, pipes, and instrumentation), to verify its tightness. The two tests cannot be considered equivalent or interchangeable; the former falls within the responsibilities of the constructors, while the latter lies within the responsibilities of the operators

The term \"leakage test\" is a general designation; for steel chemical storage vessels, leakage tests include airtightness tests, ammonia leak detection, halogen leak detection, and helium leak detection. For detailed requirements, refer to Section 11.3 on leakage tests in HG/T 20584-2011 \"Technical Specifications for the Manufacturing of Steel Chemical Storage Vessels\", which stipulates that leakage tests are necessary when storing extremely hazardous or highly hazardous substances.

Thank you. 20231 has a different interpretation of this term, but I think what you said is more correct