A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength (as the flange of an

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

beam such as an

I-beam An I-beam, also known as H-beam (for universal column, UC), w-beam (for "wide flange"), universal beam (UB), rolled steel joist (RSJ), or double-T (especially in Polish, Bulgarian, Spanish, Italian and German), is a beam with an or -shap ...

or a

T-beam A T-beam (or tee beam), used in construction, is a load-bearing structure of reinforced concrete, wood or metal, with a -shaped cross section. The top of the -shaped cross section serves as a flange or compression member in resisting compress ...

); for easy attachment/transfer of

contact force A contact force is any force that occurs as a result of two objects making contact with each other. Contact forces are ubiquitous and are responsible for most visible interactions between macroscopic collections of matter. Pushing a car or kicking ...

with another object (as the flange on the end of a

pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...

, steam cylinder, etc., or on the

lens mount A lens mount is an interface – mechanical and often also electrical – between a photographic camera body and a lens. It is a feature of camera systems where the body allows interchangeable lenses, most usually the rangefinder camera, sin ...

of a

camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with ...

); or for stabilizing and guiding the movements of a

machine A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecul ...

or its parts (as the inside flange of a

rail car A rail car can be: * Railcar A railcar (not to be confused with a railway car) is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is usually used in reference to a train consisting of a single coach ...

tram A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport ...

wheel A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the key components of the wheel and axle which is one of the six simple machines. Wheels, in conjunction with axles, allow heavy objects to be ...

, which keep the wheels from running off the

rails Rail or rails may refer to: Rail transport *Rail transport and related matters *Rail (rail transport) or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' ( ...

). Flanges are often attached using bolts in the pattern of a bolt circle. The term "flange" is also used for a kind of tool used to form flanges.

Plumbing or piping

A flange can also be a plate or ring to form a rim at the end of a pipe when fastened to the pipe (for example, a closet flange). A blind flange is a plate for covering or closing the end of a pipe. A flange joint is a connection of pipes, where the connecting pieces have flanges by which the parts are bolted together. Although the word 'flange' generally refers to the actual raised rim or lip of a fitting, many flanged plumbing fittings are themselves known as flanges. Common flanges used in plumbing are the Surrey flange or Danzey flange, York flange, Sussex flange and Essex flange. Surrey and York flanges fit to the top of the hot water tank allowing all the water to be taken without disturbance to the tank. They are often used to ensure an even flow of water to showers. An Essex flange requires a hole to be drilled in the side of the tank. There is also a Warix flange which is the same as a York flange but the shower output is on the top of the flange and the vent on the side. The York and Warix flange have female adapters so that they fit onto a male tank, whereas the Surrey flange connects to a female tank. A closet flange provides the mount for a

toilet A toilet is a piece of sanitary hardware that collects human urine and feces, and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry or non-flush toilets do not. They can be designed for a sitting position popu ...

Pipe flanges

Piping components can be bolted together between flanges. Flanges are used to connect pipes with each other, to valves, to fittings, and to specialty items such as strainers and pressure vessels. A cover plate can be connected to create a "blind flange". Flanges are joined by bolting, and sealing is often completed with the use of gaskets or other methods. Mechanical means to mitigate effects of leaks, like spray guards or specific spray flanges, may be included. Industries where flammable, volatile, toxic or corrosive substances are being processed have greater need of special protection at flanged connections. Flange guards can provide that added level of protection to ensure safety. There are many different flange standards to be found worldwide. To allow easy functionality and interchangeability, these are designed to have standardised dimensions. Common world standards include ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean). In the USA, the standard is ASME B16.5 (ANSI stopped publishing B16.5 in 1996). ASME B16.5 covers flanges up to 24 inches size and up to pressure rating of Class 2500. Flanges larger than 24 inches are covered in ASME B16.47. In most cases, standards are interchangeable, as most local standards have been aligned to ISO standards; however, some local standards still differ. For example, an ASME flange will not mate against an ISO flange. Further, many of the flanges in each standard are divided into "pressure classes", allowing flanges to be capable of taking different pressure ratings. Again these are not generally interchangeable (e.g. an ASME 150 will not mate with an ASME 300).ASME B16.5 These pressure classes also have differing

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...

and

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

ratings for different materials. Unique pressure classes for piping can also be developed for a process plant or power generating station; these may be specific to the corporation, engineering procurement and construction (EPC) contractor, or the process plant owner. The ASME pressure classes for flat-face flanges are Class 125 and Class 250. The classes for ring-joint, tongue and groove, and raised-face flanges are Class 150, Class 300, Class 400 (unusual), Class 600, Class 900, Class 1500, and Class 2500. The flange faces are also made to standardized dimensions and are typically "flat face", "raised face", "

tongue and groove Tongue and groove is a method of fitting similar objects together, edge to edge, used mainly with wood, in flooring, parquetry, panelling, and similar constructions. Tongue and groove joints allow two flat pieces to be joined strongly together ...

", or " ring joint" styles, although other obscure styles are possible. Flange designs are available as " weld neck", "slip-on", "lap joint", "socket weld", " threaded", and also "blind".

ASME standards (U.S.)

Pipe flanges that are made to standards called out by

ASME The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing ...

B16.5 or ASME B16.47, and MSS SP-44. They are typically made from forged materials and have machined surfaces. ASME B16.5 refers to

nominal pipe size Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. "Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number (for ...

s (NPS) from " to 24". B16.47 covers NPSs from 26" to 60". Each specification further delineates flanges into

classes: 150, 300, 400, 600, 900, 1500 and 2500 for B16.5, and B16.47 delineates its flanges into pressure classes 75, 150, 300, 400, 600, 900. However these classes do not correspond to maximum pressures in psi. Instead, the maximum pressure depends on the material of the flange and the temperature. For example, the maximum pressure for a Class 150 flange is 285 psi, and for a Class 300 flange it is 740 psi (both are for ASTM a105 carbon steel and temperatures below 100°F). The

gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to ...

type and bolt type are generally specified by the standard(s); however, sometimes the standards refer to the ASME

Boiler and Pressure Vessel Code A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central h ...

(B&PVC) for details (see ASME Code Section VIII Division 1 – Appendix 2). These flanges are recognized by ASME Pipe Codes such as ASME B31.1 Power Piping, and ASME B31.3 Process Piping. Materials for flanges are usually under ASME designation: SA-105 (Specification for Carbon Steel Forgings for Piping Applications), SA-266 (Specification for Carbon Steel Forgings for Pressure Vessel Components), or SA-182 (Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service). In addition, there are many "industry standard" flanges that in some circumstance may be used on ASME work. The product range includes SORF, SOFF, BLRF, BLFF, WNRF (XS, XXS, STD and Schedule 20, 40, 80), WNFF (XS, XXS, STD and Schedule 20, 40, 80), SWRF (XS and STD), SWFF (XS and STD), Threaded RF, Threaded FF and LJ, with sizes from 1/2" to 16". The bolting material used for flange connection is stud bolts mated with two nut (washer when required). In petrochemical industries, ASTM A193 B7 STUD and ASTM A193 B16 stud bolts are used as these have high tensile strength.

European dimensions (EN / DIN)

Most countries in Europe mainly install flanges according to standard DIN EN 1092-1 (forged stainless or steel flanges). Similar to the ASME flange standard, the EN 1092-1 standard has the basic flange forms, such as weld neck flange, blind flange, lapped flange, threaded flange (thread ISO7-1 instead of NPT), weld on collar, pressed collars, and adapter flange such as flange coupling GD press fittings. The different forms of flanges within the EN 1092-1 (European Norm/Euronorm) is indicated within the flange name through the type. Similar to ASME flanges, EN1092-1 steel and stainless flanges, have several different versions of raised or none raised faces. According to the European form the seals are indicated by different form:

Other countries

Flanges in the rest of the world are manufactured according to the ISO standards for materials, pressure ratings, etc. to which local standards including

DIN DIN or Din or din may refer to: People and language * Din (name), people with the name * Dīn, an Arabic word with three general senses: judgment, custom, and religion from which the name originates * Dinka language (ISO 639 code: din), spoken by ...

, BS, and others, have been aligned.

Compact flanges

As the size of a compact flange increases it becomes relatively increasingly heavy and complex resulting in high procurement, installation and maintenance costs. Large flange diameters in particular are difficult to work with, and inevitably require more space and have a more challenging handling and installation procedure, particularly on remote installations such as oil rigs. The design of the flange face includes two independent seals. The first seal is created by application of seal seating stress at the flange heel, but it is not straight forward to ensure the function of this seal. Theoretically, the heel contact will be maintained for pressure values up to 1.8 times the flange rating at room temperature. Theoretically, the flange also remains in contact along its outer circumference at the flange faces for all allowable load levels that it is designed for. The main seal is the IX seal ring. The seal ring force is provided by the elastic stored energy in the stressed seal ring. Any heel leakage will give internal pressure acting on the seal ring inside intensifying the sealing action. This however requires the IX ring to be retained in the theoretical location in the ring groove which is difficult to ensure and verify during installation. The design aims at preventing exposure to oxygen and other corrosive agents. Thus, this prevents corrosion of the flange faces, the stressed length of the bolts and the seal ring. This however depends on the outer dust rim to remain in satisfactory contact and that the inside fluid is not corrosive in case of leaking into the bolt circle void.

Applications of compact flanges

The initial cost of the theoretical higher performance compact flange is inevitably higher than a regular flange due to the closer tolerances and significantly more sophisticated design and installation requirements. By way of example, compact flanges are often used across the following applications: subsea oil and gas or riser, cold work and

cryogenics In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “c ...

, gas injection, high temperature, and nuclear applications.

Train wheels

Trains and trams stay on their tracks primarily due to the conical geometry of their wheels. They also have a flange on one side to keep the wheels, and hence the train, running on the rails, when the limits of the geometry based alignment are reached, e.g. due to some emergency or defect.

Vacuum flanges

A vacuum flange is a flange at the end of a tube used to connect vacuum chambers, tubing and vacuum pumps to each other.

Microwave

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...

telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that ...

s, a flange is a type of cable joint which allows different types of

waveguide A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ...

to connect. Several different microwave RF flange types exist, such as CAR, CBR, OPC, PAR, PBJ, PBR, PDR, UAR, UBR, UDR, icp and UPX.

Ski boots

Ski boot Ski boots are footwear used in skiing to provide a way to attach the skier to skis using ski bindings. The ski/boot/binding combination is used to effectively transmit control inputs from the skier's legs to the snow. History Ski boots were lea ...

s use flanges at the toe or heel to connect to the binding of the ski. The size and shape for flanges on

alpine skiing Alpine skiing, or downhill skiing, is the pastime of sliding down snow-covered slopes on skis with fixed-heel bindings, unlike other types of skiing ( cross-country, Telemark, or ski jumping), which use skis with free-heel bindings. Whether ...

boots is standardized in ISO 5355. Traditional

telemark Telemark is a traditional region, a former county, and a current electoral district in southern Norway. In 2020, Telemark merged with the former county of Vestfold to form the county of Vestfold og Telemark. Telemark borders the traditional ...

and cross country boots use the 75 mm Nordic Norm, but the toe flange is informally known as the "duckbill". New cross country bindings eliminate the flange entirely and use a steel bar embedded within the sole instead.