4 replies to this topic

[vjmenon]

Hello,

 

We are trying to determine the maximum design pressure and vacumn for conical fixed roof tanks based on API 650. the client would like to know these values to determine the set points of the PVRV. on further research of the standard, we found the following:

 

design external pressure shall not be less than 0.25 kpa

internal design pressure shall not exceed 18kpa based on 5.2 Design conditions
 

Does this mean that the PVRV's cannot exceed 18kpa in operation? If not, please guide on what we are missing here. Along with the calculations, the client would also like an FEA to show that the tanks can sustain the pressures we are indicating.

 

Any help would be highly appreciated.

[latexman]

API-650 does not allow any pressure accumulation above internal design pressure, so, yes, "the PVRV's cannot exceed 18kpa in operation" and during an emergency.

[vjmenon]

thank you very much for the information. it is highly appreciated.

[vjmenon]

Is there any information regarding the limit for the vacuum?

[Pilesar]

The tank designer sets the design pressures. For the tank to conform to API-650, the rated pressures must be within the range listed in that standard. Not all tanks designed to API-650 standard have the same pressure ratings, but their pressure ratings are in the range allowed by the standard. Use the external pressure spec for the vacuum limit. The difference between internal and external pressures is read on a tank pressure gauge as an internal vacuum.