Why is the maximum allowable operating pressure of a container lower than the design pressure?
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Why is the maximum allowable operating pressure indicated on the nameplate of this container lower than the design pressure? How should the setting pressure of a safety valve be determined? The safety supervision department stated that the pressure must not exceed 0.099 MPa and that corrective actions are required; for pipeline purging, a nitrogen pressure of 0.15 MPa is needed. If the set pressure is reduced, won’t the tank’s safety valve activate then?
Is there a problem with the nameplate? Is there still a problem with the equipment?
As a supplementary note, the purpose of this device is to serve as a tank for storing waste liquid within the factory; it doesn’t pose any significant challenges in daily use. The waste liquid is collected in this tank, then transferred to a larger tank using a diaphragm pump. After the transfer is complete, the supply and return pipelines are purged with 1.5 bar of nitrogen pressure, and at that moment the pressure inside the tank is slightly over 1 bar. The tank is equipped with a safety valve set at a pressure of 0.2 bar, and this works fine. One day, the safety inspection team saw that the maximum allowable operating pressure indicated on the nameplate was 0.099 MPa, and they demanded that the setting of the safety valve be reduced; otherwise, the safety valve might activate during pipeline purging Generally, for containers, the maximum allowable operating pressure is higher than the design pressure, which is in turn higher than the set pressure, and that value is again higher than the actual operating pressure. I don’t understand why the nameplate shows these values in this order; someone please explain! Are there any issues with the safety inspection requirements?
Check what it says on the design drawings and contact the equipment manufacturer.
I couldn’t see clearly. Is there another explosion-proof membrane below the safety valve? Connected in series?
Take a look at this container manufacturing diagram to see if the design specifies a \"maximum allowable working pressure of 0.099 MPa\"”； If so, there’s no problem with the chromium plate; what the safety officers said is also correct. It is necessary to ask the container design unit for the reason behind determining the maximum allowable working pressure as 0.099 MPa.
Yes, there is a burst disc; the two are connected in series
To correct this: the set pressure of the safety valve is 2 bar. There is also a burst disc below the safety valve. It worked fine in previous use. Now, the safety inspection team, after checking the nameplate which indicates a maximum allowable working pressure of 0.099 MPa, has required that both the safety valve and the burst disc be adjusted to this maximum allowable pressure. As a result, when nitrogen at 1.5 bbar is used for purging the pipeline, the safety valve might activate, and the burst disc might break Next week, I’ll check the drawings and ask the container design team why the maximum allowable working pressure has been set at 0.099 MPa; I don’t understand why this pressure has to be specified as being lower than the design pressure
The pressure at the inlet during purging cannot be considered as the operating pressure of the pressure vessel, as there is an outlet. The operating pressure of a pressure vessel can be determined only in the absence of an exhaust port. It’s like a pipe, with material entering at one end and exiting at the other – is it a pressure vessel?
According to current design principles, the maximum allowable operating pressure for this device should be greater than 0.32 MPa.