Determination of airtight pressure
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1. Purpose of airtightness: During major overhauls of equipment, many sealing surfaces (points) of various devices and pipelines are altered, such as the manholes on containers, the heads of heat exchange equipment, the flanges on pipelines, and the new welds on modified pipelines. After these moved sealing surfaces are reset, it is unknown whether their sealing performance meets the requirements; therefore, a gas-tightness test must be conducted on them. Therefore, the purpose of a gas tightness test is to check whether the sealing performance of the system meets the technical requirements, and to eliminate any detected leaks. 2. Technical requirements for airtightness: ① The airtight system must be reliably isolated from external systems. ②The airtight pressure retention time shall be no less than 4 hours. ③The temperature and pressure of the system are recorded once per hour. ④The leakage rate is calculated using the following formula: Leaksage rate = P1, T1: Absolute pressure and temperature at the start of the pressure test; P2, T2: Absolute pressure and temperature at the end of the pressure test; H: Pressure holding time (hours). The standard for a leak-free system is that the average leakage rate should not exceed 0.2% per hour. ⑤Ensure airtightness strictly in accordance with the airtight pressure rating to prevent overpressure in the equipment. ⑥The airtight pressure should be 1.05 to 1.1 times the system operating pressure, and it must not be altered without permission. ⑦When each system is airtight, cross-pressure is prevented to avoid the activation of safety valves. ⑧Seal surfaces such as flanges, manholes, and welds that have been modified during maintenance should be tested for leaks using a leak detection bottle. ⑨The etherification reaction system can be made airtight only after the catalyst has been loaded. 3. Division of airtight systems: The equipment should have its airtight systems divided according to the operating pressure; different airtight systems have different airtightness pressures.
Thank you for sharing, but the file seems incomplete
The airtight pressure should be 1.05 to 1.1 times the system operating pressure, and it must not be altered without permission. I don’t know where it came from? If the operating pressure of the system is very high and you don’t know what to do, with the pipes getting hot during pressurization, I wonder who set this value?
Are these all experiences? There are still standards; which devices are applicable? Can high-pressure vessels be treated in this way?
The standard for acceptable system airtightness is an average leakage rate of no more than 0.2% per hour. Which standard specifies this requirement?
The airtightness pressure must be higher than the operating pressure; otherwise, it is not possible to ensure no leakage at the operating pressure. In actual operation, the pressure fluctuates and sometimes becomes slightly higher, which is why it makes sense to set the airtightness pressure at 1.1 times the operating pressure.