I would like to ask whether the length of this cylinder must be at least 300 mm
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For a short cylinder section whose ends are connected to the smaller ends of conical sections, must this middle cylinder section also comply with the 150 rule and have a length of less than 300 mm? Or isn’t this considered an assembled cylinder?
Let’s talk about the image above again. Literally speaking, it means meeting a length of 300. But it still depends on your structure
It’s something like a horizontal container in the attachment, with elliptical end caps on both ends; there is a slightly recessed conical section in the middle. The length of the section marked in red must be no less than 300 mm, right?
It can be less than 300; for example, in some tube boxes, the individual tube sections are less than 300. The requirement of being less than 300 as specified in GB150 applies to the assembled cylinder body, that is, when multiple tube sections are welded together to form a cylinder body. A single tube section cannot be less than 300, and your case likely does not fall into this category
Based solely on the restrictions specified in clause 6.535 of standard GB/T 150.4, your device does not fall under the category of assembled cylinders; therefore, a value of less than 300 is acceptable. However, considering the structural design of your equipment, it is not recommended to use a value lower than 300 mm. The reasons are as follows: 1. To meet the reinforcement length at the smaller end of the conical section (the two conical sections) ； 2. The lengths of the heat-affected zones of the two ring welds in the two conical sections must be satisfied ； Since you haven’t specified any design parameters – such as diameter, pressure, temperature, etc. – it’s up to the original poster to calculate whether 300mm will be sufficient
For non-assembled cylinders with only one section, there are no restrictions...
It’s thought through very thoroughly; I completely agree.
Could I have some water? Everything has been said well; could you please explain why it’s 300mm, rather than 400mm or 250mm? If you know this, there’s no need to worry.
There is no theoretical basis for limiting it to 300mm; it was decided during a meeting :) Just as the technical supervisor of the unit needs to sign off after 2 revisions, this is also a matter of management
I think it’s related to ray detection. The maximum length of a single film for longitudinal seam radiographic inspection is 300 mm. Both 400mm and 250mm will result in waste of sheets. It is necessary to reflect the principles of energy conservation and environmental protection.