How to choose flange?

How to choose flange?

1. At present, there are 4 flange standards in my country, which are:

(1) National flange standard GB/T9112~9124-2000;
(2) Chemical industry flange standard HG20592~20635-1997
(3) Mechanical Industry Flange Standard JB/T74~86.2——1994;
(4) The petrochemical industry flange standard SH3406-1996.

Now take the national standard as an example to illustrate the choice of flange. The national standard flange is divided into two systems: the European system and the American system. The nominal pressures of European system flanges are: PN0.25, PN0.6, PN1.0, PN1.6, PN2.5, PN4.0, PN6.3, PN10.0 and PN16.0MPa; American system flanges Nominal pressures are: PN2.0, PN5.0, PN11.0, PN15.0, PN26.0 and PN42.0MPa

2. The basis for selecting flanges

(1) The nature of the conveying medium, general medium, special medium, toxic medium, flammable and explosive medium;
(2) According to the parameters of the medium, the working pressure and the working temperature, in the case that the medium is determined, the nominal pressure PN of the flange is determined according to the working temperature and working pressure of the medium.
(3) Determine the connection method and sealing surface form of flange and pipe according to the place of use and connection conditions. (4) Determine the flange specification according to the connection object.