Regarding the selection of heat exchange tube wall thickness
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When designing heat exchangers, the process engineering team usually determines the specifications of the heat exchange tubes in advance, including the outer diameter, wall thickness, and length. Design manuals and standards specify common specifications such as 19x2; moreover, the wall thickness is typically fixed. However, there is no indication of the maximum design pressure to which these heat exchange tubes can be subjected. If the pressure is high, how should the heat exchange tubes be selected? Are there any standards or manuals that provide guidance on this?
These need to be calculated: at different temperatures and pressures, the diameter of the material, the allowable pressure, the corrosion allowance, the amount of thinning due to processing, etc. The higher the pressure, the greater the margin allowed for wall thickness. We use 25-mm diameter pipes quite often; for pressures below 40 kilograms, the wall thickness is 2.5 mm, for 160 kilograms it’s 4 mm, and for 320 kilograms it’s 6 mm
This generally requires experience; those who haven’t done it can just count it as such.
There is a default value for the wall thickness of the heat exchange tubes, but it should be determined in conjunction with the mechanical engineering team after the outer diameter has been initially fixed in the process design. The reason why the process determines this value is that, under most operating conditions, the default wall thickness of 2 mm is sufficient to meet the requirements; in other words, verifying whether the wall thickness of the heat exchange tubes meets the specified standards is one of the tasks carried out by the mechanical engineering team.