What is the nominal pressure for? What’s the use?
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What is the actual use of the nominal pressure of flanges that we usually talk about? For media that pose an extremely high level of hazard, we use 25-kilogram flanges; in reality, the pressure of such media is very low, with the design pressure possibly only 0.3 MPa, which is a significant difference from the nominal pressure. Why is such a high nominal pressure specified? Or rather, what are the differences in flanges depending on the engineering pressure?
Ensures safety by using high pressure.
It is recommended that you read and understand GB/T1048-2005 carefully; the main purpose of this standard is to specify the connection dimensions and the allowable pressure. Of course, this allowable pressure varies depending on the material as well as temperature changes. As for why a pressure of 0.3 MPa is used and why pipes with a nominal pressure of PN25 are selected, the main purpose is to ensure safety. First and foremost, it is necessary to consider the impact of temperature on the material’s capacity to withstand pressure; as temperature rises, the material tends to creep, resulting in a decrease in its pressure-bearing capacity. Additionally, the properties of certain hazardous materials also determine the need for a higher nominal pressure rating. Factors such as the material’s ability to penetrate surfaces, its tendency to cause erosion or delamination, and whether high temperatures can activate materials that are otherwise inert and react slowly must all be taken into account. Each case needs to be handled individually; I’m just talking randomly here.
This post was last edited by xlllv5 on 2019-7-4 at 11:30. The use of nominal pressure is primarily aimed at standardizing connection dimensions. However, in actual use, the nominal pressure of the flange that should be used depends on the design of the process. There are many unexpected factors that can arise during the use of equipment; for example, corrosion of the materials and changes in operating temperature can cause deformation of the flange surfaces, leading to leaks. For safety reasons, it is necessary to choose flanges with a high pressure rating. The selection process primarily relies on past engineering experience, or simulation results, or experimental results; it is not necessarily done without a clear basis or with excessive design.
I think it’s mainly for standardization, to establish parameters for standard components such as connectors and sealing parameters, in order to achieve uniformity