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Material parameter
Common materials: 304, 316, 316L, etc. 304 stainless steel has good corrosion resistance and processing performance, suitable for general corrosive environments; 316 stainless steel due to the addition of molybdenum, has higher corrosion resistance and heat resistance than 304, suitable for more severe corrosive environments, such as marine environments or contact with strong acidic and alkaline mediums, etc.; 316L is a low-carbon version of 316, has better resistance to intergranular corrosion during the welding process and other processing. 316L is a lower carbon version of 316, which has better resistance to intergranular corrosion during welding and other processes.
Pressure Rating Parameters
Common ratings: PN10, PN16, PN25, PN40, PN63, PN100 and so on. Among them, PN10 is suitable for low-pressure pipeline, the working pressure is generally around 1.0MPa; PN16 is suitable for medium-pressure pipeline, the working pressure is about 1.6MPa; PN25 and above are suitable for high-pressure and ultra-high-pressure pipeline, the working pressure of PN25 is 2.5MPa, the working pressure of PN40 is 4.0MPa and so on. In the American Standard system, there are Class150, Class300, Class600, Class900, Class1500 and other pressure levels, Class150 corresponds to PN20 and Class300 corresponds to PN50.
Size specification parameters
Nominal diameter: expressed in DN, such as DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN80, DN100, DN125, DN150, DN200, etc., in millimeters. It represents the size of the inner diameter of the pipe connected by the flange, and the actual size may vary depending on the standard and wall thickness.
Outside diameter: it refers to the size of the overall external diameter of the flange, which is different for flanges with different nominal diameters and pressure ratings.
Thickness: including the thickness of the flange body and the thickness of the sealing surface, etc. Thickness affects the strength and bearing capacity of the flange, generally the higher the pressure level and the larger the nominal diameter, the greater the thickness of the flange.
Bolt hole related size: including the diameter, number and distribution circle diameter of bolt holes. For example, for a PN16 flange of DN100, the diameter of bolt holes may be 18mm, the number is 8, and the diameter of distribution circle is 180mm.
Sealing surface parameters
Forms: Flat face (FF), raised face (RF), concave-convex face (MFM), tongue and groove face (TG), ring-joint face (RJ), etc. Flat sealing surface is suitable for low pressure, non-toxic media occasions; protruding surface sealing surface is more widely used, can be used for low-pressure pipeline; concave-convex and tongue-and-groove sealing surface sealing is better, commonly used in toxic, flammable, explosive and other media pipeline; ring connecting surface for high pressure, high temperature and other harsh working conditions.
Roughness: the surface roughness of the sealing surface will affect the sealing performance, generally require the sealing surface roughness to reach a certain standard, such as Ra3.2 or Ra6.3, etc., in order to ensure a good fit with the gasket, reduce leakage.
Connection parameters
Connection methods: flat welding, butt welding, socket welding, threaded connection, loose sleeve connection and so on. Flat welding flanges are suitable for pipelines with low pressure and small pipe diameter; butt welding flanges are connected with pipelines by butt welding with high quality welds and are suitable for medium and high pressure pipelines; socket welding flanges are used for small diameter pipelines and are easy to install; threaded flanges are connected by threads and are suitable for occasions where welding is not suitable; loose fitting flanges are suitable for occasions where there is a demand for frequent dismantling or need to compensate for the displacement of pipelines.