Flange standard and selection method

- Mar 05, 2018-

Flange standard and selection method

There are two types of flange standards for petroleum and chemical industry, one is flange pressure vessel standard, and one is flange standard.


Both flat-welded and butt-welded flanges are available with and without collar. When the device is made of stainless steel, carbon steel flange 7 plus stainless steel ring, you can save stainless steel.


When using the flange standard to determine the flange size, you must know the nominal flange nominal diameter and nominal pressure. The nominal diameter of the pressure vessel flange and the nominal diameter of the pressure vessel to take the same series of values. For example, DN 1000mm pressure vessels should be equipped with DN 1000mm pressure vessel flanges.


The flange nominal pressure is determined by the flange's maximum operating pressure, operating temperature, and flange material. Because in the development of the flange size series, the calculation of the flange thickness is based on 16MnR mechanical properties at 200 ℃ as a benchmark. Therefore, the provisions of this benchmark to determine the size of the flange at 200 ℃, its maximum allowable operating pressure is considered to have the nominal pressure of the flange size. For example, a so-called flange with nominal pressure of PNO of 6 MPa refers to a flange of a specific size which is made of 16MnR and whose maximum allowable operating pressure at 200 ° C is 0.6 MPa. If this PN0.6MPa flange is used at a temperature higher than 200 ℃, then its maximum operating pressure will be lower than its nominal pressure 0.6MPa. Conversely, if it is used below 200 ℃ conditions, still press 200 ℃ to determine the maximum working pressure. If the flange material is changed to Q235-A, then Q235 A steel mechanical properties worse than 16MnR, the nominal pressure PN0.6MPa flange, even when operating at 200 ℃, its maximum allowable operating pressure will be Below its nominal pressure. On the other hand, if the material of the flange is changed from 16MnR to 15MnVR, then the maximum permissible operating pressure of the flange with PN 0.6 MPa at 200 ° C will be higher than that of 16MnR due to the mechanical properties of 15MnVR It's nominal pressure.

In short, as long as the nominal flange diameter, nominal pressure is determined, the flange size is also determined.

As for the maximum allowable operating pressure for this flange, it depends on the operating temperature of the flange and what material it is made of.