The common sense of flange classification

Pipeline flanges can be divided into five basic types according to their connection with pipes: flat welding flanges, butt welding flanges, threaded flanges, socket welding flanges, and loose flanges. There are many types of flange sealing surface, generally convex surface (RF), concave surface (FM), concave and convex surface (MFM), tongue and groove surface (TG), full plane (FF), ring connection surface (RJ).


Flat welded steel flange:

It is suitable for the connection to carbon steel pipes with a nominal pressure not exceeding 2.5MPa. The sealing surface of the flat welding flange can be made into three types: smooth, concave and convex and tongue and groove. The smooth flat welding flange is the most widely used. It 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 cheaper.


Butt welding steel flange:

Used for butt welding of flanges and pipes. It has a reasonable structure, high strength, and rigidity, can withstand high temperature and pressure repeated bending and temperature fluctuations, and has reliable sealing. The butt welding flange with a nominal pressure in 0.25 to 2.5 MPa adopts a concave and convex Type sealing surface.


Socket welding flange:

Commonly used in pipelines with PN10.0MPa and DN40


Loose flange:

Loose flanges are commonly known as loose flanges, sub-welded ring loose flanges, flange loose flanges, and butt-welded loose flanges. They are often used when the medium temperature and pressure are not high and the medium is highly corrosive. When the medium is highly corrosive, the part of the flange contacting the medium (flanging nipple) is made of corrosion-resistant high-grade materials such as stainless steel, and the outside is clamped to low-grade materials such as carbon steel flange rings To achieve sealing.


Integral flange:

Flanges are often integrated with equipment, pipes, fittings, valves, etc. This type is commonly used on equipment and valves.