Zhengde Classification of flanges
1. Divide carbon steel, cast steel, alloy steel, stainless steel, copper, aluminum alloy by material
2. According to the production method, it can be divided into forged flanges, cast flanges, welded flanges, etc.
3. According to manufacturing standards, it can be divided into national standards (Ministry of Chemical Industry standards, petroleum standards, electric power standards), American standards (ASTM), German standards (DIN), Japanese standards (JB), etc.
my country's National Standard System for Steel Pipe Flanges GB
1Flange nominal pressure: 0.25Mpa-42.0Mpa
Series 1: PN1.0, PN1.6, PN2.0, PN5.0, PN10.0, PN15.0, PN25.0, PN42
Series 2: PN0.25, PN0.6, PN2.5, PN4.0
2. Structural form of flange:
a. Flat welding flange PL;b. Flat welding neck SO;c. Butt welding flange WN;d. Socket welding flange SW;e. Loose flange PJ/SEf. Overall tube IF;g. Threaded flange Th;h. Flange cover BL, lining flange cover BL(S).
3. Flange sealing surface types: flat FF, raised surface RF, concave surface FM, convex surface MF, tongue and groove surface TG, ring connection surface RJ
Flange application
Butt welding steel flange: used for butt welding of flanges and pipes. It has a reasonable structure, high strength and steel, can withstand high temperature and pressure, repeated bending and temperature fluctuations, and has reliable sealing performance. The butt welding flange with a nominal pressure of 0.25-2.5Mpa adopts a concave and convex sealing surface.
Flat welded steel flange: suitable for carbon steel pipe connections with nominal pressure not exceeding 2.5Mpa. The sealing surface of flat welding flange can be made into three types: smooth type, concave and convex type and tongue and groove type. The smooth flat welding flange has the largest application volume and is mostly used when the medium conditions are relatively mild, such as low-pressure non-purified compressed air and low-pressure circulating water. Its advantage is that it is relatively cheap.
Socket welding flange: commonly used in pipelines with PN≤10.0Mpa, DN≤40;
Loose flange: Loose flange is commonly known as loop flange, divided into welding ring loop flange, flanged loop flange and butt welding loop flange. It is often used in situations where the medium temperature and pressure are not high but the medium is highly corrosive. When the medium is highly corrosive, the part of the flange that contacts the medium (the flanged nipple) is made of corrosion-resistant high-grade materials such as stainless steel, while the outside is clamped by a flange ring of low-grade material such as carbon steel. to achieve sealing;
Integral flange: The flange is often integrated with equipment, pipes, valves, etc. This type is commonly used on equipment and valves.

Shandong Zhengde Metal Manufacturing Co., Ltd. is a production and sales company integrating hot-rolled steel coils, cold-rolled steel coils, galvanized steel coils, color-coated steel coils, section steel, steel pipes, steel wires, metal mesh, stainless steel, aluminum, copper and other metal products integrated large enterprises. Five production and sales bases have been formed in Binzhou, Liaocheng, Wuxi, Tianjin, Jinan and Tai'an, with more than 100 production lines, 4 nationally recognized laboratories, 2 technical engineering centers, and 5 enterprise technology centers. Products are exported to more than 50 countries and regions such as North America, South America, Europe, Africa, Oceania, Middle East, and Southeast Asia.