Calculation of flange neck thickness for non-standard containers
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I have a question for everyone: when calculating the flanges of non-standard containers using SW6 software, do the values entered for δ0 and δ1 already include a corrosion allowance? In the SW6 software, there is no field for entering a corrosion margin in the calculations for container flanges; can it be assumed that the default values entered by the system already take the corrosion margin into account? However, in GB150, δ0 and δ1 represent the effective thicknesses of the larger and smaller ends of the flange neck, that is, without including the corrosion allowance. Could some expert please help clarify this? Thank you. :)
This post was last edited by Slay demons and evil forces on 2016-2-28 09:57. Standardly, the corrosion allowance is set at 2 mm or less. Some people adopt the approach of ignoring the effect of corrosion allowance when it is 2 mm or less. I simply selected it according to the standards. Some approaches consider that, regardless of the amount of corrosion allowance, the calculation is simply done by subtracting the corrosion allowance from the standard thickness value.
Standard flanges are not taken into account (in fact, if corrosion allowance is considered, doing the calculations oneself will show that many of them fail the verification). However, in the design of non-standard flanges, it is still necessary to consider a corrosion allowance as a precaution. The reason is that, in the case of uniform corrosion at both the larger and smaller ends, the ratio of the thicknesses at these ends increases as corrosion progresses; consequently, the f value also increases, leading to uneven stress distribution between the larger and smaller ends and thus affecting the strength of the flange.
Please refer to GB150-2011, P183, clause 7.1.2, paragraph 2
The SW6 software calculates the major and minor dimensions of custom flanges, with both values being entered based on the effective thickness, right?
The specifications certainly take corrosion and low temperatures into account. The calculation failed because, in the initial standards, an error was made in entering a parameter during the calculation process; however, no problems arose despite using this incorrect value all these years, so the error was left uncorrected. As a result, the actual calculations for standard flanges do not meet the requirements