When sizing relief devices, I frequently come across old tanks and vessels that do not state a design pressure/MAWP. One of our plants has this issue now.
They contracted with a local Engineering firm (Italy) to guide us on what the design pressure/MAWP is.
Their report says, “Analysis was conducted by stress analysis and not by formula. Doing it in this way the design pressure is obtained considering the weakest point.
The design pressure applicable is equal to pressure yield stress with a safety coefficient equal to 1.5."
So, the yield stress of 1.5 barg came from the flat, I- or C- beam reinforced top, which is the weakest point. Therefore design pressure/MAWP is 1 barg.
Does this meet Code? Why or why not?
Hi, I perform such kind of analysis, feel free to send me the FEA report by private message in order to see if I can help you.
Thanks and welcome to SimpliEngineering! I sent you one of the six FEA reports we received from an Engineering firm for six similar blenders.
I asked my plant contact how the stress analysis related to design pressure, and the Engineering firm e-mailed back:
“Analysis was conducted by stress analysis and not by formula. Doing it in this way the design pressure is obtained considering the weakest point (our case the flat head that has a bending behavior; in the characterization of the stress the reference value is 1.5 allowable stress material value).
The design pressure applicable is equal to pressure yield stress with a safety coefficient equal to 1.5.
Per il 220-SA-01 è pari a 1.0 barg."