How to choose a flange?

How to choose a flange

1. There are currently four flange standards in China, namely:

(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) Petrochemical industry flange standard SH3406-1996

Taking the national standard as an example, explain the selection of flanges. The national standard flange is divided into two major systems: the European system and the American system. The nominal pressure of European system flanges includes PN0.25, PN0.6, PN1.0, PN1.6, PN2.5, PN4.0, PN6.3, PN10.0, and PN16.0MPa; The nominal pressures of flanges in the American system include PN2.0, PN5.0, PN11.0, PN15.0, PN26.0, and PN42.OMPa

2. Basis for selecting flanges

(1) The properties of the conveying medium include general medium, special medium, toxic medium, and flammable and explosive medium;

(2) Based on the parameters of the medium, working pressure, and working temperature, the nominal pressure PN of the flange is determined based on the working temperature and pressure of the medium when the medium is determined.

(3) Determine the connection method and sealing surface form between the flange and the pipe based on the usage location and connection conditions. (4) Determine flange specifications based on the connection object.