Questions regarding design pressure
Thread Content
I have a question that puzzles me: the design pressure for the tubular side of the ethylene oxide reactor in the ethylene glycol plant is 2.34 MPa, while the design pressure for the shell side is 6.44 MPa. The operating pressure on the shell side is also around 5.5 MPa. Although the operating pressure on the tubular side is around 2.1 MPa, does the design pressure of the tubular side meet the requirements of the operating conditions on the shell side? I wonder if anyone can answer this
The design pressure shall be at least 1.5 times the operating pressure; when selecting the nominal pressures for the pipes and flanges, the pressure for the tube side is set at PN4.0 MPa, while that for the shell side is PN10.0 MPa
What I mean is that the design pressure of the pipe train is 2.34 MPa, while the external pressure it has to withstand is around 5.5 MPa – is there a problem with this?
The design pressure can be determined in this way, but when selecting the piping material, the value must be calculated based on the external pressure!
The design pressure can be determined in this way. When calculating the strength of equipment or pipes, three scenarios should be taken into consideration: 1) external pressure alone; 2) internal pressure alone; 3) combined effect of internal and external pressures. The strength under these three scenarios should be considered comprehensively.
I think there is a problem with this design: the operating pressure in the tube side is 2.1 MP, while the operating pressure in the shell side is 5.5 MP. Therefore, the operating pressure in the tube side should be the pressure difference between the two, which is 3.4 MP, and the design pressure should be determined as a multiple of this operating pressure. The originally designed pressure of 2.34 MPa cannot even be maintained under normal operation, posing a great risk.
There is indeed a problem with the design pressure of the tube side; there’s no issue with the shell side!
If I were to consider only the design values, I wouldn’t dare use this device.
It does seem very dangerous; it’s necessary to calculate carefully
The tube side and shell side of a heat exchanger should be selected separately, as this is more economical and reasonable.
The design pressure does not necessarily have to be 1.5 times the operating pressure, but excessive external pressure does indeed pose a problem