Questions regarding pressure testing, flaw detection, and purging

1. After the installation of pressure pipelines is completed, and once heat treatment and non-destructive testing have been successful, a pressure test of the pipeline system must be carried out. The specific procedures shall be determined in accordance with the design requirements, as well as relevant regulations such as SH3501 \"Code for Construction and Acceptance of Petrochemical Pipelines Transporting Toxic and Flammable Media\" and GB50235 \"Code for Construction and Acceptance of Industrial Metal Pipelines\". 2. The specific inspection requirements for pressure pipelines should also be in accordance with the design specifications, as well as standards such as SH3501 and GB50235. 3. Pressure vessels generally undergo their pressure resistance tests (hydraulic or pneumatic tests) before leaving the factory; however, some special equipment requires pressure testing on-site, depending on the actual conditions and/or the specific terms of the equipment manufacturing contract. 4. Instrument valves (control valves, on-off valves, etc.) usually undergo their pressure resistance tests before leaving the factory, but control valves generally require further tuning prior to installation on site. 5. The pressure testing values for instrument air pipelines and similar components are usually determined in accordance with the requirements of the construction drawings ； And it shall be carried out in accordance with standards such as SH3501 and GB50235. 6. The requirements regarding the purging of pipeline systems are specifically specified in SH3501 and GB50235. It is recommended that LZ carefully read the above two standards that are closely related to the construction and acceptance of pipeline installation projects!

1. Do all pipes need to be pressure-tested? All pressure pipelines must undergo pressure testing; those that are not pressure pipelines generally do not require it. 2. Which pipes require flaw detection? Are water pipes generally not inspected for defects? Pressure pipelines generally require flaw detection, while ordinary water pipes do not. 3. Is on-site pressure testing required for the equipment? Was it pressure-tested before leaving the factory? Pressure vessels require on-site pressure testing, regardless of whether they have been tested before leaving the factory. 4. Is on-site pressure testing required for control valves (regulating valves, on/off valves)? During pipeline pressure testing, the valves are also tested; generally, there is no need to conduct separate pressure testing for the valves using their own specific methods. 5. What is the pressure used for testing the instrument air pipelines (those connected to the instrument valves) and the pressure transduction pipes? The testing pressure for the pressure lead pipe is determined in accordance with SH3501 and similar standards. 6. Are there any requirements regarding pressure for purging? Is it mainly about flow rate (velocity)? There are certainly specific requirements for purging; please refer to the standards provided on the 2nd floor. Suggestion: Many issues are clearly specified in the relevant standards; it is recommended that the original poster study those standards carefully.

It is recommended that the original poster participate more in construction practice activities. After gaining experience through one or two large-scale projects, especially those in the petrochemical and chemical industries, and by studying relevant standards and regulations, such problems should be able to be resolved effectively and applied flexibly.

All pipes that have welds must undergo pressure testing, and some pipes are subject to flaw detection; there is a specified proportion for such inspections. Generally, water pipes do not require flaw detection – for example, fire protection pipelines do not need it, as they are made of welded pipes.

1. Do all pipes need to be pressure-tested? Of course not. For example, vent pipes. 2. Which pipes require flaw detection? Are water pipes generally not inspected for defects? Pressure pipelines must definitely be inspected for defects ； No, there’s no need to memorize which pipes need to be inspected; you need to understand why certain pipes require such inspection. 3. Is on-site pressure testing required for the equipment? Was it pressure-tested before leaving the factory? It’s best to do it ； It is usually done; it is stated in the product manual. 4. Is it necessary to conduct on-site pressure testing for the control valves (regulating valves, on/off valves)? Valves – they can be installed on site quickly. Valves are necessary for important pipelines, but they aren’t essential for ordinary water pipes; usually, they are installed before the equipment leaves the factory. 5. What is the pressure used for testing the instrument air pipelines (those connected to the control valves) and the pressure transduction pipes? Look at the comment above, 6. Are there any requirements regarding pressure for cleaning? Is it mainly about flow rate (velocity)? The purging pressure must not exceed the design pressure of the containers and pipelines, and the flow rate should be no less than 20 m/s