Understanding the overpressure limit of safety valves!
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In the calculation of safety valves, as specified in GB150 B4.2.1, what does the overpressure limit of \"not more than 10% of the design pressure or the greater of the two values: 20 kPa\" mean? When calculating safety valves, should the formula for the discharge pressure of Pd safety valves be based on the provisions of GB150 or those specified in Appendix 5 of the Pressure Vessels Regulations? How to make a choice? Thank you
The relief pressure according to the pressure vessel standards = 1.1 × starting pressure + 0.1 (atmospheric pressure). The relief pressure per GB150 = design pressure + max{10% of design pressure + 20 kPa}. Since the starting pressure is ≤ the design pressure, the relief pressure calculated using the pressure vessel standards is generally lower than that calculated per GB150; likewise, the discharge area calculated using these formulas is smaller than that calculated per GB150, which makes it safer. However, this results in lower utilization of the thickness, meaning that the margin provided by the thickness is not fully utilized. So my rather forced interpretation is that it should be based on the principle of safety first as per the regulations, or that one should follow those regulations to avoid people who are responsible for troubleshooting finding fault in everything; let the equipment suffer a little loss then. Of course, for making full use of the equipment’s margin, follow GB150.
The relief pressure according to GB150 = design pressure + max{10% of design pressure + 20 kPa}. In this regard, GB150 B4.2.1 stipulates that it should not be greater than max{10% of design pressure + 20 kPa}. Can I use 0 as this value, or can I choose any value within the range of 0 to max{10% of design pressure + 20 kPa}?
The pressure specified in GB150 is gauge pressure, while the pressure in volume specifications is absolute pressure; absolute pressure should be used when calculating safety valves, so the two values are consistent. GB150 adds a requirement of greater than or equal to 20 kPa for the specific volume gauge. It meets the requirements of API and ASME.
In theory, it is possible, but to fully utilize the potential of using round values for the container wall thickness, it is recommended to set the operating pressure equal to the design pressure; the overpressure limit should be determined based on specific circumstances
Please carefully distinguish between operating pressure and design pressure; the operating pressure should be ≤ the design pressure. Also, take a look at how each standard defines the relief pressure – I think these definitions are likely to differ
How did you know about the pot inspection and those who just eat plain rice? Besides, those who just eat plain rice usually don’t pick bones out of eggs; don’t they all keep their mouths closed? Would it be okay to reply like this in 10 years?
May I ask: in the formula \"The relief pressure specified by the regulations = 1.1 times the starting pressure + 0.1 (atmospheric pressure)\", does \"the regulations\" refer to the Safety Technical Inspection Regulations for Fixed Pressure Vessels issued under TSG 21-2016? Thank you