Why does SW6 not need to consider corrosion allowance when calculating the wall thickness of heat exchange tubes?
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For a heat exchanger, the corrosion allowance on the tube side is 4mm, and the heat exchange tube material is 15CrMo. When performing SW6 calibration calculations, why do we not need to consider the impact of the corrosion allowance on the wall thickness of the heat exchange tube? The heat exchange tube calculation part of the calculation book output by SW6: Corrosion allowance does not work
When performing SW6 (tube sheet strength calculation for shell side heat exchangers), the main consideration is the bearing capacity of the tube sheet under internal pressure. The corrosion allowance is set based on the internal corrosion of pipelines and equipment. The purpose is to prevent the pipe wall from failing after it is completely corroded, thereby ensuring safe operation. In the SW6 calculation, the main concern is the pressure condition inside the tube sheet, which does not directly involve the corrosion problem of the tube wall. Therefore, the effect of corrosion allowance on pipe wall thickness usually does not need to be considered in SW6 calculations. .
Thank you for your reply. What I am very confused about is, putting aside the calculation aspect, from the perspective of actual use, does the tube side medium not corrode the inner wall of the heat exchange tube? Can the heat exchanger wall thickness calculated without considering corrosion margin meet actual needs?
GB/T151-2014 No. 4.4.5.4 Article e provisions: Heat exchange tubes, hook rings, floating head bolts and longitudinal partitions generally do not consider the corrosion allowance. If the heat exchange tube takes the corrosion allowance into consideration, the calculation result will be relatively too thick, which will have a great impact on heat transfer.
GB/T151-2014 No. 4.4.5.4 Article e provisions: The corrosion allowance is generally not considered for heat exchange tubes, hook rings, floating head bolts and longitudinal partitions. ； In actual use, if it leaks, just plug the pipe.
The design life of the heat exchanger does not include the heat exchange tubes. Of course, there is no need to calculate the corrosion allowance.
1. Too thick affects heat transfer. 2. Heat exchangers generally have design margins. Even if some corrosion occurs, the tubes can be blocked. 3. The design service life of the heat exchanger does not include the heat exchange tubes.
There is no way to consider it. If the carbon steel uses a corrosion allowance of 1.6, the pipe will be too thick, which will seriously affect the heat transfer effect.
The corrosion allowance is determined based on the design life of the equipment and the corrosion rate. The design life of heat exchanger equipment generally does not include heat exchange tube bundles and does not follow this corrosion margin.
According to the requirements of GB/T151-2014 4.4.5.4 Article e provisions: The corrosion allowance is generally not considered for heat exchange tubes, hook rings, floating head bolts and longitudinal partitions.