Regarding the discussion on thinning, please ask an expert for an answer
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This post was last edited by “I_am_a_pressure_vessel” on March 3, 2012, at 08:37. There are two questions, both related to thinning:1. In Figure 7 on page 325 of GB150.4-2011, it states that for Type B welded joints with unequal wall thicknesses, as well as Type A welded joints connecting cylindrical shells to spherical heads, the standard recommends using a thinning process when the wall thicknesses differ. However, it does not specify that spherical heads themselves cannot be thinned. I’d like to discuss this: what should be done if the thickness of the spherical head exceeds that of the cylindrical shell? Is it permissible to thin the spherical head directly?
2. In high-pressure vessels, forged pipes are frequently used; the wall thickness at their roots is significantly greater than that of the sections welded to flanges. Clearly, this portion constitutes a weak point in the structure, which seems somewhat illogical. I hope experts in stress analysis can help resolve my doubts
Regarding the first question, the original poster is overthinking it. In the same device, the stress on the end caps is generally lower than that on the cylinder; accordingly, their thicknesses are theoretically less than those of the cylinder. It is the cylinder that needs to be thinned
I would like to ask the original poster: 1. Why is the spherical head thicker than the cylinder? Is it a mandatory requirement or something else? The strength should be fine ； 2. Regarding the second question, welded pipes are commonly used in high-pressure vessels. If flanged structures are employed, there is no issue with the strength of the narrowed portion at the flange neck; the main concern is that an excessively small neck may affect the rotational stiffness of the flange. If the flange material is the same as that of the forged pipe, it is possible to thin out the forged pipe, and this factor should be taken into account during design, unless the flange as well is designed to be non-standard ； Of course, with this design, the primary concern is meeting strength requirements. For flanges, strength is secondary; although that factor does matter as well, the most important thing is to ensure that the sealing requirements are met.
I think in the second question raised by the original poster, the root part of the forged pipe is quite thick; this was likely due to the designer taking into account the need for reinforcement through openings……
The second question from the poster refers to thick-walled pipes, right? If so, it’s related to the issue of reinforcement
Thank you all for your answers. I hadn’t been able to identify the problem before; it was the reinforcement of the cylinder itself, not the pipe fittings. Now I understand