Thread Content
In GB150.1, how are the discharge pressure of the Pf relief device specified in clause B8.2 and the operating pressure of the relief device specified in clause B3.2.2 determined? What is the relationship between the two? Let’s see what the answers to the questions in GB 150-2011 \"Pressure Vessels\" say. Discharge pressure refers to the pressure on the inlet side of a safety valve or rupture disc device under discharge conditions; the theoretical maximum value of this pressure is the maximum discharge pressure, which equals the sum of the design pressure of the container and the overpressure limit (absolute pressure). It is only used in the theoretical calculation of the discharge area. Operating pressure is the set pressure of the safety valve or the designed burst pressure of the rupture disc; it is a theoretical value based on design considerations. Its upper limit is determined in accordance with the following provisions: As specified in B3.2.1, for systems equipped with only a single overpressure relief device, the operating pressure shall not be greater than the design pressure ； In accordance with B3.2.2, when multiple overpressure relief devices are installed, the operating pressure of one of them shall not be greater than the design pressure, while the operating pressure of the other relief devices may be increased to 1.05 times the design pressure ； In accordance with B3.2.3, when an auxiliary relief device is installed, its operating pressure shall not exceed 1.1 times the design pressure. To ensure the performance of the relief device, its minimum operating pressure is determined based on the expected operating pressure of the pressure vessel. For a safety valve, the lower limit of its operating pressure is equal to the maximum expected operating pressure plus the minimum operating pressure difference of the safety valve. For rupture discs, the selection of the minimum rated burst pressure should ensure that there is an appropriate margin between this pressure and the expected operating pressure of the container; (the ratio of the minimum rated burst pressure to the expected operating pressure of the container must meet the requirements specified in Table B.1 of Appendix B) in order to prevent the rupture disc from failing prematurely during normal use. The lower limit of the rupture disc operating pressure shall not be lower than the sum of the minimum calibrated rupture pressure and the absolute value of the lower deviation within the manufacturing range. The operating pressure of the relief device must be within the aforementioned upper and lower limits.