Seeking help with flange verification
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I need help determining whether the flange of this equipment can meet the design requirements under the following conditions: Design pressure: 1.0 Mpa; Design temperature: 60°C; Nominal diameter of the equipment: 500; Length of the cylinder: 2000; Nominal thickness: 6; Material: S30408 welded pipe; Gaskets are made of PTFE with a thickness of 3 mm; The flange is made of S30408Ⅱ. Some data regarding the flange come from NB/T47023, with slight differences mainly in the neck portion
It is a vertical container with no pressure in the tube side
In the past, when designing stainless steel long-neck butt weld flanges, the solution was simply to increase their thickness. However, given that stainless steel forgings are expensive, it was discovered that the height of the conical neck has a significant impact on the effective thickness of the flange surface. That’s why this type of flange was conceived; it allows for a reduction in weight of nearly half. I would appreciate it if experts could help assess its feasibility.
The thickness of the neck flange’s neck portion must be the same as the thickness of the pipe wall.
Is the thickness of the wall at the small end of the conical neck the same as that of the cylinder wall, or is it necessary to leave a certain length of straight section at the bottom? Is there any fixed requirement for the length of this section?
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This post was last edited by wanlirn on 2023-1-12 at 08:48. For those with long necks like you, a lower weight doesn’t necessarily mean lower costs; the longer the neck, the higher the unit cost. It’s more common to increase the thickness of the flange rings according to the standards for steel materials. My experience is that adding 4mm generally works fine. Additionally, I checked the standard RF 500-1.0 model; the one made of stainless steel is even smaller than the standard flange size, so it’s not possible to calculate a pass for it
Initially, I designed it by increasing the effective thickness in the conventional way – a increase of 6 mm was required. However, after conducting the verification, I wasn’t sure whether this effective thickness included the height of the sealing surface; as a result, the final version actually needed to be 9 mm higher than the standard specification, which led to a significant increase in costs
As for the calculations, strangely enough, I only came back to ask after completing them; rationally speaking, I knew there was likely some issue, as the thickness should ideally not be less than the standard value of 47023 – though I can’t really explain why
I hope the experts will not hesitate to offer their guidance; let’s have more discussions!