Questions regarding the calculation of container flanges – long-neck butt weld flanges
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As shown in the figure, δ0 represents the effective thickness of the smaller end of the flange neck; it is given as 28 in the calculation sheet, but based on Figure 7-1 f) for 150.3 P187, it seems to should be 18. What are everyone’s opinions? (The pictures show the company’s previous drawings and calculation documents; I was browsing through them in my free time to learn a bit*: lol) The company requires that, in order to save costs, flanges for containers with large diameters and high pressures (PN40 and above) be designed as custom-made ones. (The flanges shown in the attached drawings follow standard specifications regarding outer diameter, bolts, and sealing surfaces, but their thickness and total height are smaller than those of standard flanges.) ； I have designed flanges for several custom equipment units. Perhaps due to the larger diameters, when following the standards, the thickness of the straight sections of the flanges is much greater than that of the cylinder wall. Making adjustments according to the standards or recalculating δ0 only results in an **increase in the flange thickness, which in turn raises the costs. How do people design custom long-neck butt weld flanges?
The thickness of the smaller end of the conical neck should be entered as 18, and there is also an issue with the height of the conical neck as per figure f) on page P187 of GB/T150.3.
There are so many mistakes. I thought I had discovered a new approach to flange design
There’s nothing wrong with the calculations and diagrams. The value of 18 you’re looking at exceeds the range allowed for the flange; it belongs to the cylinder section. As long as the calculations for cylinder 18 are valid, then there’s no issue with this design
Compared to 150.3 P187 Fig. 7-1 f), it doesn’t seem right: Q
h=48 and 150 do not conflict. . .
This post was last edited by fzujunru on 2019-3-26 at 20:07. I agree with the view in post 2: when performing calculations, the thickness at the smaller end of this structure should be entered as 18. If 28 is entered for that thickness, it is necessary to ensure that the length between 28 and 18 is long enough (to allow for stress attenuation), such that the stress level at 18 is not higher than that at 28. Pay attention to studying and understanding Figure 7-7 in 150.3, as well as the reason why it is necessary to increase H when the thickness of the flange connecting to the tank body is relatively thin
Remove the part I marked with crosshatching; in the calculations, this portion’s strength is not taken into account, and only the transition reduction is considered. Take another look and it will become clear
Thank you! The non-standard long-neck flange design has less contact: lol
Looking at the calculation sheet, is there any relationship between h=48 and 18? If H loses by 110, then input 18
Is corrosion allowance not considered in flange calculations?