Flange specifications
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Could someone among the experts explain what exactly the nominal diameter DN refers to in terms of flange specifications?
Hehe, different flange standards vary; the most commonly used ones are 20615, 20592A, and 20592B. You should check the relevant specifications yourself.
Diameter of the medium flow pipeline. Flange sizes corresponding to the same pipe diameter but different pressure ratings or different standards (ANSI, JIS) are all different.
DN, or dn, refers to the nominal diameter of a pipe; values such as DN50 and DN100 represent diameters that are close to the inner diameter of the pipe. In simple terms, they denote pipes with standard dimensions whose inner diameter is around 50 or 100. However, the wall thickness of these pipes can vary, but this does not affect the calculations related to the process fluid. Φ denotes the diameter of a circle or pipe (usually referring to the outer diameter): Φ32, Φ76
As clearly stated above, DN refers to the nominal diameter of the pipe; its specific dimensions are related to standards for flanges, pressure ratings, nominal diameter DN, etc. The exact dimensions can be found in the relevant specifications. American standard HG20615 ANSI (ASME) B16.5, European standard HG20592 EN1092, etc
Pathway – check the flange standards!
I’m also looking at the relationship between DN and the inner diameter of the flange
DN, well, it’s not an actual dimension; it roughly corresponds to the grade, with some deviation from the inner diameter of the through-hole