Strength issues of heat exchange tubes
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In my opinion, the heat exchange tubes should also be subjected to strength checks based on the pressures in the tube side and the shell side respectively. However, the standards state that there is no need to perform strength verification on the heat exchange tubes, nor is it necessary to consider a corrosion margin. I don’t understand why the standard is set this way Confused! !
I think the ratio of the diameter to the wall thickness of the heat exchange tubes is quite small; it might be close to the parameters for high-pressure containers (I’ve forgotten the exact values). That’s probably the reason. There’s no possibility of instability in the heat exchange tubes, right? No verification is needed. This post was last edited by fdsunset on 2009-4-2 at 17:55.]
For heat exchange tubes, there is no need to consider a corrosion allowance, as the fluid continuously flows inside the tubes. Corrosion generally occurs due to flow dead zones or electrode reactions; therefore, it is not necessary to take corrosion allowances into account for these tubes. Although the strength of the heat exchange tubes does not need to be verified, GB151 specifies the pressure-bearing capacity corresponding to various tube diameters and wall thicknesses, as these values have already been calculated, so no further verification is required
Heat exchange tubes sometimes require stability verification, that is, to assess their ability to withstand external pressure when the pressure in the shell side is high; there have been instances in the past of heat exchange tubes losing stability
The heat exchange tubes in question do not take corrosion allowance into account, but corrosion must be considered; otherwise, it would be sufficient to use the same material for all heat exchange tubes. As for the issues of strength and stability, the calculation software has already done the calculations, so there is no need to worry about them.
To correct the mistake in my answer: the pressure-bearing values corresponding to various pipe diameters and wall thicknesses are provided in a data sheet that was given to us during training by foreigners; it was compiled by them based on analytical calculations. Such information is indeed not available in GB151. Additionally, when calculating SW6, the strength of the heat exchange tubes is taken into account
Generally, the strength is checked based on the tube side pressure, and the TEMA standard can be followed； Even if the shell side pressure is high, stability must still be checked based on external pressure. This post was last edited by email_cao on 2009-4-4 13:49]
There is no need to perform strength checks on the heat exchange tubes; as has been explained by colleagues earlier, there is also no need to take corrosion allowance into account. In my opinion, considering corrosion allowance might lead to an increase in the tube wall thickness, which in turn increases thermal resistance and affects heat transfer performance
What was described above is very detailed; those who participate in the study*
I’m learning*; with respect to the site, I would like to ask the experts: under what circumstances is it necessary to take corrosion allowance into account for heat exchange tubes?