A. Flange types are divided according to national standards: integral flange, threaded flange, butt welding flange, flat welding flange with neck, socket welding flange with neck, butt welding ring with neck loose flange, plate flat welding flange, flat welding ring plate loose flange, flat welding ring plate loose flange, flanging ring plate loose flange and flange cover.
B. Flange types are divided according to chemical work standards: integral flange (if), threaded flange (th), plate flat welding flange (PL), diameter butt welding flange (WN), neck flat welding flange (so), socket welding flange (SW), butt welding ring loose flange (PJ / SE), flat welding ring loose flange (PJ / RJ), fabric flange cover (BL (s)), flange cover (BL).
C. Flange types are divided according to petrochemical work standards: threaded flange (PT), butt welding flange (WN), flat welding flange (so), socket welding flange (SW), loose flange (LJ) and flange cover (not noted).
D. Flange types are divided according to mechanical working standards: integral flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flanging ring plate loose flange and flange cover.
E. Pressure vessel flange, marine flange, high-pressure flange and stamping flange are divided according to grade and race.
F. Flange classification:
a. For flat welding flange, the pipe shall be inserted into the flange welded on the inner ring of the flange.
b. Butt welding flange is a flange with neck, oil sliding transition section and butt welding connection with the pipe.
c. Socket welding flange a flange with a socket and connected with a pipe by socket welding.
d. Threaded flange is a flange with thread and threaded connection with the pipe.
e. Flanging flange is a flange that is looped on the pipe and used in combination with flanging nipple or welding ring.
f. Special flange non-circular flange, such as diamond flange, square flange, etc.
g. The reducing flange is connected with the standard flange, but the flange with nominal diameter less than the standard flange is accepted.
h. The sealing surface of full plane flange is the same plane as the whole flange surface.
i. The sealing surface of the convex flange is slightly higher than the whole flange surface.
j. A pair of flanges with sealing surfaces, one with a tenon and one with a groove matching the tenon.
k. The sealing surface of the flange is a ladder ring groove.
l. The flange cover is connected with the flange at the end of the pipe, which is a circular plate with bolt holes to close the pipe.
