I would like to ask everyone some questions regarding pressure vessels
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1. When conducting a hydrostatic test on pressure vessels, the pressure gauges used must meet the requirements specified in Chapter 4, Manufacturing, 11.2 of GB150.4, which stipulate that two pressure gauges with identical ranges and that have passed calibration are required, as shown in the figure. However, according to Article 4.1.9.1 of the TSG21-2016 Regulations on the Safety Technical Inspection of Fixed Pressure Vessels, it is required to use two pressure gauges that have been inspected; the requirements for these two pressure gauges are different – one requires mandatory calibration, while the other only needs to be inspected. Is mandatory inspection required, or is regular inspection sufficient? ? As I understand it, as long as it’s not a pressure gauge related to safety, a regular inspection is sufficient, is that correct? ? 2. According to the steel pipe standards GB150.2 and GB8163, no requirement for impact testing is specified. However, some inspection experts have suggested that if the pipes are to be used as shell components, especially when their thickness reaches the maximum limit of 10, then a warranty certificate should indicate that impact testing has been conducted. If this is not stated, our company needs to carry out re-inspection. Is there any basis for this suggestion? I couldn’t find any such requirement in GB150 or TSG21; it is only mentioned in 5.3.9 of HG21581-2020, the Specification for the Selection of Materials for Steel Chemical Vessels, where it states that for steel pipes used as pressure vessel shells, impact and tensile tests are required when the design pressure is 1.6 MPa or higher. Is this suggestion based on that requirement? ? Dear expert, I hope you can take a look and give me a reply. Thank you! ! !
Yes, the two pressure gauges used during hydrotesting need to have the same range and must be calibrated properly to ensure the accuracy of the test results. Regarding the retesting of steel pipes, pressure vessels with a design pressure of 1.6 MPa or higher do indeed require impact and tensile tests, in order to ensure the safety and reliability of the material under high pressures. These requirements are all implemented in accordance with the provisions of GB150.4. .
1. Verification and calibration are the same thing, and a metrological compliance report is required. 2. If the standard to be followed is specified as HG/T20581 on the drawing, it must be complied with; if it is not specified, compliance is not required. But since the experts said it needs to be done, then it should be done; it’s not a bad idea from a safety perspective either. Improving safety generally reduces economic efficiency; the two are relative to each other.
1. Inspection and verification seem to be different; verification refers to those that must be carried out by authorized metrology institutions, while inspection is similar to calibration – ordinary metrology testing companies can provide calibration reports directly. 2. The drawing does not specify the execution standard as HGT20581; so it’s optional to follow this standard, right?
For question one, since the two specifications are inconsistent, it is sufficient to follow the one with stricter requirements. It’s probably because the requirements for mandatory inspections are higher.
For mandatory calibration, one must go to a metrology institute to have it done; these institutes do not provide on-site services. The pressure gauge has to be sent there for calibration, and the inspection cannot be carried out immediately – it takes some time before calibration is possible； If you look for a metrology and testing company, they will provide on-site inspection services, and the process can be completed in 1 day or even half a day~~ Moreover, according to the regulations set by the Market Supervision Bureau, as shown in the diagram, only pressure gauges with safety protection features are required to undergo mandatory periodic inspections; nothing is specified regarding the others~~