Classification of pressure vessels
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The Code specifies that for multi-chamber pressure vessels (such as the tube side and shell side of heat exchangers, the drum and heat exchange chamber of waste heat boilers, jacketed vessels, etc.), the pressure chamber with the higher classification shall be used as the classification for that vessel, and it shall be managed accordingly. I have some questions about this sentence; please give me some guidance. Firstly, the nominal diameter of the tube side of heat exchangers is generally less than 0.15 m; since it seems not to be subject to dimensional tolerance regulations, how can it be classified? Secondly, do pressure vessels with internal coils also fall into this category of multi-chamber pressure vessels? If there is a substance with a lower pressure than steam inside the coil, should it also be classified in this way?
Is the nominal diameter of the tube side in heat exchangers generally less than 0.15 m? There is a problem here. The tube bank size of the tube train is often larger than this 0.15M
The original poster has a slight misunderstanding; the diameter of the tube side in a heat exchanger does not refer to the diameter of the heat exchange tubes, but rather to the diameter of the tube box. For internal coil containers, if only the medium inside the coil meets the conditions of the above category, such containers generally do not fall into that category, as the inner diameter of the coil is usually not greater than 150 mm.
First of all, what is stipulated in the Code of Practice is correct. In my opinion, the nominal diameter of the tube side in a heat exchanger should not be the diameter of the tubes themselves, but rather the diameter of the tube sheet. Additionally, pressure vessels with coils inside also fall under this category of multi-chamber pressure vessels; in such cases, the tube side cannot be classified in a specific way, while the shell side should be considered for classification.
All the friends above have provided fairly comprehensive answers. Multi-chamber containers include jacketed containers, heat exchangers, and other types of containers. It is important to note that for jacketed containers, the internal components are not deducted from the nominal diameter; whereas in the case of heat exchangers, the tube side refers to the tube sheet, not the heat exchange tubes themselves
What the five poster mentioned above have said makes sense. What I am saying is that for containers with coils (containing low-pressure steam, usually at a pressure of 0.6 MPa), as long as their volume is >= 4.2 liters, according to Article 88 of the Regulations on the Supervision of Special Equipment, since P*V >= 2.5 MPa·L, such containers should be classified as category I pressure vessels.