It’s really not easy to recognize all 12 types of flanges

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It’s really not easy to recognize all these 12 types of flanges, is it? Introduction to flanges: Pipe flanges, together with their gaskets and fasteners, are collectively referred to as flange joints. 1. Applications: Flange joints are a type of component that is extremely common and widely used in engineering design. It is an essential component for piping design, as well as for fittings and valves; it is also a necessary part of equipment and its components (such as manholes, sight glasses, level gauges, etc.). In addition, other specialties such as industrial furnaces, thermal engineering, water supply and drainage, heating and ventilation, and automatic control also frequently use flange joints. 2. Materials: forged steel, WCB carbon steel, stainless steel, 316L, 316, 304L, 304, 321, chromium-molybdenum steel, chromium-molybdenum-vanadium steel, molybdenum-dititanium, rubber-lined, fluorine-lined materials. 3. Classification: face weld flanges, necked flanges, butt weld flanges, ring-connected flanges, socket weld flanges, and blind flanges, etc. 4. Execution standards: There are GB series (**standard), JB series (Ministry of Machinery), HG series (Ministry of Chemical Industry), ASME B16.5 (American standard), BS4504 (British standard), DIN (German standard), and JIS (Japanese standard). 5. International pipe flange standard systems: There are mainly two systems for international pipe flange standards. The European pipe flange system, represented by German DIN (including the former Soviet Union), and the American pipe flange system, represented by American ANSI pipe flanges. 212 types of flanges and their characteristics 1. Plate flat welding flange: Plate flat welding flange (chemical industry standard HG20592, **standard GB/T9119, mechanical industry JB/T81). Advantages: Easy to obtain materials, simple to manufacture, low cost, and widely used. Disadvantages: It has poor rigidity; therefore, it cannot be used in chemical process piping systems where there are requirements regarding supply and demand, flammability, explosiveness, and high vacuum levels, nor in highly hazardous environments. The types of sealing surfaces are flat and convex. 2. Welding flanges with necks: Welding flanges with necks fall under the national standard flange system; they represent one of the types of national standard flanges (also known as GB flanges), and are among the flanges most commonly used on equipment or pipelines. Advantages: It is convenient for on-site installation, and the process of damaging the welds by rubbing can be omitted. Disadvantage: Flanges with a neck for butt welding have a lower neck height, which improves the stiffness and load-bearing capacity of the flange. Compared to butt weld flanges, they require more welding work and consume more welding electrodes; they cannot withstand high temperatures and pressures, as well as repeated bending and temperature fluctuations. 3. Necked weld flanges: The seal surface types for necked weld flanges include raised face (RF), recessed face (FM), male face (M), tongue and groove face (T), grooved face (G), and full flat face (FF). Advantages: It is not prone to deformation during connection, provides good sealing performance, and has a wide range of applications. It is suitable for pipes subject to large fluctuations in temperature or pressure, as well as for pipes operating under high, low temperatures. It is also used in pipes that transport expensive media, flammable and explosive substances, and toxic gases. Disadvantages: Necked butt-weld flanges are large in size, heavy in weight, expensive, and difficult to position during installation; as a result, they are more prone to damage during transportation. 4. Integral flange: The integral flange is a type of flange connection method. It also belongs to the category of welded steel pipe flanges with a neck. Materials include carbon steel, stainless steel, alloy steel, etc. Among various domestic standards, IF is used to denote the overall flange. It is commonly used in pipelines under high pressure, and its manufacturing process is generally casting. In the case of flange types, an “IF” is used to represent the overall type of flange. It is generally a raised face (RF); however, in applications where there is a risk of fire, explosion, or high levels of hazard, sealing surfaces other than RF faces, such as male-female faces (MFM) and tongue-and-groove faces (TG), can be used. 5. Socket weld flange: A socket weld flange is a flange whose one end is welded to the steel pipe while the other end is connected using bolts. Sealing surface types: raised face (RF), male and female face (MFM), tongue and groove face (TG), ring joint face (RJ). Application areas: boiler and pressure vessels, petroleum, chemicals, shipbuilding, pharmaceuticals, metallurgy, machinery, food, and other industries. It is commonly used in pipelines with PN≤10.0MPa and DN≤40. 6. Threaded flange: A threaded flange is one in which the inner hole of the flange is processed into pipe threads, allowing it to be connected to threaded pipes; it is a type of non-welded flange. Advantages: Compared to slip-on flanges or butt-welded flanges, threaded flanges are easier to install and maintain, and can be used on pipelines where welding is not permitted. Alloy steel flanges have sufficient strength, but they are difficult to weld or have poor weldability; threaded flanges can also be an option. Disadvantage: In situations where the pipe temperature changes rapidly, or when the temperature is above 260°C or below -45°C, it is recommended not to use threaded flanges to avoid leaks. 7. Welded ring loose-flange: A welded ring loose-flange is a type of flange that can move; it is typically used in water supply and drainage fittings. The manufacturer installs a flange at each end of the expansion joint, which are then connected directly to the pipes and equipment in the system using bolts. Function: The purpose of using butt-welded ring loose-flange connections is generally to save material. Its structure consists of two parts: one end of the pipe section is connected to the pipeline, while the other end is designed as a butt-welding ring. The flanges are made of lower-grade materials, while the pipe sections use the same material as the pipelines, in order to save materials. Advantages: Cost savings; when the pipe material is special and expensive, welding flanges of the same material is costly as well. Materials that are difficult to weld or process, or require high strength, such as plastic pipes and fiberglass pipes. It facilitates construction, such as when alignment is difficult due to the mismatched flange bolt holes during connection, or to prevent changes in the flange bolt holes if the equipment needs to be replaced in the future. Disadvantages: Low stress resistance, low strength at the weld ring (especially when the thickness is below 3 mm). 8. Weld-on ring loose-flange: A weld-on ring loose-flange is a movable flange plate that is connected directly to pipes and equipment in a project using bolts. The purpose of using socket flanges with flat welding rings is generally to save material. Its structure consists of two parts: one end of the pipe is connected to the pipeline, and that end is formed into a flange; the flange part is then fitted over this flange. Advantages: easy to weld or process, or requires high strength, such as plastic pipes, fiberglass pipes, etc. It facilitates construction, such as by ensuring that the flange bolt holes align properly during connection, or preventing any changes in those bolt holes when the equipment is replaced in the future. When prices are high, save on costs. When the pipe material is special, welding flanges of the same material is costly. Disadvantage: Low tolerance for stress. The strength at the weld ring is low (especially when the thickness is below 3 mm). 9. The flange cover, also known as a blind flange or blind plate, is a flange without holes in the middle, used to seal pipe plugs. Its function is the same as that of welded end caps and threaded pipe caps, except that blind flanges and threaded pipe caps can be removed at any time, whereas welded end caps cannot. Flange cover sealing surfaces: flat (FF), raised face (RF), male and female face (MFM), tongue and groove face (TG), ring joint face (RJ). 10. Lined flange cover: A type of blind flange in which stainless steel is weld-ond on the side in contact with the medium, forming a single unit. The lined flange cover is used as a blind plate on pipes containing corrosive media. Its difference from ordinary flange covers lies in the addition of an anti-corrosion lining to the surface in contact with the media. 11. American standard wafer flanges with necks: Wafer flanges with necks are connected to the ends of pipes; they serve as components that enable pipes to be connected to one another. The butt-weld flange with a neck features holes through which bolts can be passed to tightly connect the two flanges, with gaskets used for sealing between them. The gasket is placed between the sealing surfaces of the two flanges; once the nuts are tightened, the compressive stress on the surface of the gasket reaches a certain level, causing it to deform and fill in any unevenities on the sealing surfaces, thereby ensuring a tight seal with no leaks. Flange connection is a detachable type of connection, and it can be divided into vessel flanges and pipe flanges depending on the components being connected. Flat welding flanges with necks are suitable for connecting steel pipes with a nominal pressure not exceeding 2.5 MPa. The necked butt-weld flange is used for the butt welding of flanges and pipes. It features a rational design, high strength and stiffness, enabling it to withstand high temperatures and pressures as well as repeated bending and temperature fluctuations, while providing reliable sealing. Flat-welded flanges with necks having a nominal pressure of 0.25–2.5 MPa feature male and female sealing surfaces. 12. American standard butt-weld flanges. American standard flanges are components used to connect pipes to each other, and they are attached to the ends of pipes. American standard butt weld flanges are manufactured by two methods: forging and casting. According to the presence of a neck, ANSI welded flanges can be divided into ANSI welded flanges with a neck and ANSI welded flanges without a neck. A US standard butt weld flange is formed by two flange discs along with a flange gasket, which are fastened together with bolts to complete the connection. Standard American flanges have holes, and bolts are used to fasten the two flanges together; gaskets are used for sealing between them. 3 Flange types and seal surface configurations