For standard elliptical end caps with a diameter of over 6 meters, the length of the straight edges should be 40 mm or 50 mm; are there any other considerations?
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I noticed that the approaches taken by several manufacturers are a bit inconsistent. I would appreciate it if someone could advise me on whether there are any particular rules or principles involved in this. O(∩_∩)O Thank you
According to the provisions in GB25198, for values exceeding 2000, the straight edge length is taken as 40. If the design drawings specify different requirements, fabricate it according to the dimensions shown in the drawings.
GB/T 25198 allows a maximum diameter of 6 meters; it is not suitable for diameters larger than that. Moreover, how would such large sizes be transported?
The length of the straight edges can be adjusted; 40 or 50 mm are both acceptable. However, when performing edge trimming, it is necessary to ensure that the length of the bevel does not exceed that of the straight edges. Long straight edges are prone to wrinkling.
For catalytic reaction-regenerator units, the diameter is generally over 10 meters; the straight edge length of the end caps is usually set at 50 mm. Considering transportation issues, these components are typically manufactured in segments and welded on-site.
What I want to say is that the height of the straight edges mainly depends on the wall thickness; of course, the diameter is also taken into consideration, but its impact isn’t very significant – it should be left up to the designer to decide. The standard GB/T25198 uses “preferably” rather than “shall”; therefore, designers need to conduct a specific analysis based on the actual circumstances. If the pressure is particularly low and the wall thickness is below 20 mm, a double V-groove or single U-groove can be used along with a straight edge of 40 mm. In the case of a single V-groove or a thicker wall thickness, values of 50, 60, or even higher may be required. Our experience dictates that European standards should be followed, with the height of the straight edges being at least 3 times the wall thickness.
In principle, the longer, the better. For example, LPG cylinders are welded using double-sided welding, but due to limitations in manufacturing processes, as long as the length meets the requirements of GB25198, a longer length is acceptable
40 or 50 should work; for devices with a larger diameter, a relatively longer straight edge length should make processing easier.
According to the provisions in GB25198, for values exceeding 2000, the straight edge length is taken as 40.