How to divide the pressure class of flange

　　The flange is used in different places, so the pressure level is different to a certain extent. For example, large stainless steel flange is mainly used in high temperature resistant pipeline of chemical engineering, so it has high requirements for its material pressure bearing function.

　　As a result, customers often require forged flange, because the data through forging to improve the arrangement density, but also enhance its ability to bear pressure.

　　In the domestic and international standards, there are clear requirements for the compression grade of large stainless steel flange. Large stainless steel flange is generally divided into PN25, pn6, PN10, PN16, PN25, PN40 and so on. Among them, the most commonly used are PN10 and PN16.

　　Common flange pressure rating

　　The following example: the determination of the flange design pressure of internal pressure vessel with safety valve should be determined according to the open pressure of safety valve. The design pressure is equal to or slightly greater than the open pressure of the safety valve, and the open pressure of the safety valve is 1.05 ~ 1.1 times of the working pressure.

　　Given that the working pressure is 0.8MPa, the opening pressure of the safety valve can be taken as 0.88mpa, so the design pressure can be taken as 0.9mpa. In this way, it is reasonable to choose the maximum allowable working pressure of 0.9mpa for 1C4 data of vessel pipe flange at 50 ℃.