System pressure test after shutdown and major maintenance
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I would like to ask everyone: after a shutdown for major maintenance, what is the standard pressure test value for the system before it resumes operation – 1.25 times the design pressure or 1.25 times the operating pressure? I believe that 1.25 times the design pressure is the standard for strength testing. If no equipment replacements have been made prior to resuming production, it’s sufficient to test up to 1.25 times the operating pressure; in other words, only a leak test needs to be conducted, and no strength test is required. How do others handle this situation?
System pressure test after the system is taken out of service for major repairs? ? ? Is that too general? ? ? If the surface area of the system is too large and its components vary, the required pressure testing standards will also differ. However, one thing is certain: when conducting a pressure test, it’s essential to establish standard pressure levels; for cases with special requirements, those levels must be increased accordingly. The specific pressure testing multiples vary; the standards for gas and liquid pressure testing are different. For reference.
During the regular inspection of pressure vessels, the test pressure is 1.1 times the design pressure. If the pre-production inspection does not meet the requirements for regular container inspections, an operating pressure of 1.25 times is sufficient. There’s no need to apply excessive pressure, as it can damage containers and pipelines
Major equipment repairs mainly involve disassembling the equipment for inspection, replacing internal components, packing materials, catalysts, etc. For these parts, strength tests are generally not required; it is sufficient to conduct airtightness tests in accordance with the procedures； If there are new technical improvement projects such as the addition of pipes, a hydrostatic strength test must be carried out first, followed by an airtightness test based on factors such as the medium used
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After the pipeline renovation, 100% non-destructive testing was carried out; is it also necessary to conduct strength tests? I believe that conducting a proper leak tightness test is sufficient
During the major repair, inspections and cleaning inside the container were carried out, and several valves that were leaking internally were replaced. I believe that a strength test is not necessary; it is sufficient to conduct a airtightness check on the system and pipelines together. However, no specific guidelines could be found when preparing the plan, as GB50235 and the standards for pressure vessels relate to strength testing under pressure. Are there any clear standards for conducting airtightness tests before the system is put into operation?
Flaw detection can only identify whether there are defects in the weld; how can we ensure that its strength is sufficient?