The issue of the minimum thickness of end caps
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When calculating containers using SW6-5.05, the minimum thickness δmin of the head in the generated calculation sheet should be 0.15%Di; however, for containers with small diameters, the minimum thickness is always 3 mm. I don’t know why? I’ve seen other people’s calculations; δmin is 0.15%Di. The data was entered correctly; there are no errors. I’m not sure what caused this issue. Let’s all discuss it.
The minimum thickness is determined based on the design of the head structure. Due to the tendency of elliptical heads to become circular under internal pressure, coupled with the complex stress conditions in the transition zone of the head, it is necessary to prevent the head from becoming unstable. However, calculating this value is difficult in practical applications; hence, minimum thickness requirements are established. These requirements are also specified in GB150, where the minimum thickness δmin for standard elliptical heads should be 0.15% of Di, while for non-standard elliptical heads, it should be 0.3% of Di.
I’ve learned it; the person upstairs explained it very clearly. Thank you, I’ll support them
The thickness must not be less than the specified minimum thickness
According to GB150, for a standard elliptical head with DN800, δmin=0.15%x800=1.2; however, the calculation sheet from SW6 shows δmin=3mm – I’m not sure why. But on some computers, the calculation shows δmin=1.2mm; is it a problem with the computer system or with SW6?
Is it in accordance with Article 3.5.6 of GB150?
Replying to floor 5: This is a problem with SW6. Sometimes, the calculation results produced by SW6 show δmin=3mm, which takes into account the minimum thickness of the cylinder; it seems that this issue has also been taken into consideration after the upgrade.
It’s the minimum thickness of the steel plate that is taken into consideration, I guess. This minimum thickness should also be calculated based on the amount of thinning of the steel plate, but there should be a lower limit, namely 3 mm, to regulate it.
GB150 also stipulates that for standard elliptical heads, the minimum thickness δmin should be 0.15% of Di, with this value not being less than 3 mm. According to GB150, for a standard elliptical head with DN800, δmin = 0.15% x 800 = 1.2, which is already less than 3 mm; therefore, SW6 specifies δmin as 3 mm. The thickness must not be less than this specified minimum of 3 mm. There are no issues with either the computer system or SW6
According to Amendment 1 to GB150, for elliptical heads with K1, the effective thickness shall be not less than 0.30% of the inner diameter of the head; in accordance with Article 3.5.6 of GB150, the larger of these two values shall be adopted
GB150-2011 P117
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Why is the minimum wall thickness requirement for the cylinder not specified in the SW6 strength calculation?
The minimum thickness δmin of the head should be 0.15% Di, but for containers with small diameters, the minimum thickness is always 3 mm. This is because GB/T 150 specifies minimum thickness requirements: for carbon steel and low-alloy steel, it should be no less than 3 mm, and for stainless steel, it should be no less than 2 mm.