Calculation methods for non-standard pipe flanges
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I need to design a device with a design pressure of 10.5 MPa and a temperature of 80 degrees. HG20615 flanges are to be used; according to the pressure-temperature classification table, flanges with a pressure rating of 15 MPa should be selected, but the client refuses to allow this and insists that we carry out the design calculations using flanges with a pressure rating of 11 MPa, resulting in custom-made flanges. However, sometimes even with flanges of the 15MPa grade, calculations using SW6 fail to meet the requirements, though some cases do succeed. Dear colleagues, what method should be used to calculate flanges? Can it be calculated using SW6 components? There is another question: based on what are the flanges specified in the HG flange standards calculated, so that the parameters for various pressure grades of flanges can be determined?
The issue of flange calculations has always been a problem. I conducted calculations before; for a non-standard flange, the calculations did not yield successful results, and even when using standard flanges and applying SW6 for calculations, success was not achieved. This issue troubled me for a long time, until I consulted experts during a training session. They told me that even with standard flanges, calculations using GB150 standards may not necessarily yield successful results; therefore, they suggested using standard flanges, as this eliminates the need for any calculations. So according to this reasoning, the poster can only choose based on flanges of 15MPa
I wonder why the owner would make such a request. It would be better to use standard flanges to simplify things; if that’s not possible, then there’s no choice but to calculate the dimensions of custom flanges using the calculation methods specified in GB150
It is recommended to use 150 as the figure; this is the most basic method
It can be calculated using SW6 components, with the structural dimensions determined in accordance with GB150 regulations. I believe that the flanges specified in the HG flange standards are also calculated based on the shape of the flange, the stress conditions, and mechanical formulas (in fact, similar to GB150), taking into account factors such as the properties of different materials and economic viability. The American system basically follows the ANSI B16.5/ASME B16.5 standards.
We design it based on the equipment flanges, calculate the thickness required for the design pressure, and then add some extra margin.
The calculation method specified in GB150 is the Waters method, whereas the flange standards for equipment that are commonly used rely on finite element analysis. The calculation methods for pipe flanges in the American system are similar to those in GB150, and they are based on the Taylor Forge method; both represent accurate elastic analysis techniques!
At present, it is only possible to calculate according to GB150, as that is what the standards require.