Flange of different standard classifications

　　2. According to the industry standard of petrochemical (SH), it can be divided into threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose sleeve flange (LJ).

　　3. According to the industry standard of machinery (JB): integral flange, butt welding flange, plate flat welding flange, butt welding ring plate loose sleeve flange, flat welding ring plate loose sleeve flange.

　　4. According to national (GB) standards, there are integral flange, threaded flange, butt-welded flange, flange with neck, flange with neck socket, flange with neck loose sleeve.

　　The neck height of flat welded flange with neck is lower, which improves the stiffness and bearing capacity of flange. Compared with ASTM A182 F304 Carbon Steel Socket Flange, welding workload is large, welding rod consumption is high, and it can not withstand high temperature, high pressure, repeated bending and temperature fluctuation. But field installation is more convenient, and the process of welding seam rubbing can be omitted, which is more popular.