In this article, you will learn the different types of flanges and how they work. Their advantages and application all explained with pictures.
Also, you can download the PDF file at the end of this article.
What is a Flange?
Flanges are devices used to connect pipes to each other, to valves, to pumps, to fittings, and to other equipment such as filters and pressure vessels. It is usually welded or threaded, and the two flanges are joined together by bolting them with gaskets to provide a seal, providing easy access to the piping system.
Many different flange standards are found worldwide to allow easy functionality and interchangeability. Common standards include ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean).
The flange can withstand high pressure and temperature, so they have different pressure and temperature ratings for different materials. In a piping application, the type of flange to be used depends largely on the strength requirements.
Flanges come in many different shapes and sizes and are used in a wide range of industries around the world. With so many varieties and specifications, it may not be easy to identify which one is right for your need. Here is a simple guide to the most common and popular types of flanges and their uses.
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Types of Flanges
Following are the different types of flanges:
- Weld neck flange
- Long welding neck flange
- Slip on flange
- Threaded flange
- Socket weld flange
- Lap joint flange
- Blind flange
- Orifice flange
- Swivel flange
- Expanding flange
- Reducing flange
- Elbow flange
- Puddle flange
- Split flange
- Cast flange
- Square flange
- Anchor flange
#1 Weld Neck Flange
This type of flange consists of a long tapered hub. Usually machined from a forging, these flanges are welded to a pipe. Flanges with weld necks are great for applications when there is a requirement for a continuous flow of fluid through the piping system.
These flanges are commonly used in high-pressure and high/low-temperature applications. There are two types of welding neck flanges: a regular type for use with pipes and an elongated type for use in process plants. By preventing pressure drops, turbulence and erosion/corrosion of metals near flanged joints are prevented.
#2 Long Welding Neck Flange
These flanges are similar to weld neck flanges, except that the neck is extended and acts like a boring extension. Long Weld Neck Flanges are designed to be used in place of weld neck flanges and pipe pieces for bolt-up connections to ships, columns, or barrels.
This design reduces stress on the neck and transfers it to the base, which attaches to the vessel. These are generally used to connect large networks of pipes as they can withstand high pressures. Heavy barrel (HB) and equal barrel (E) are two common types of these flanges.
#3 Slip-on Flange
These types of flanges are connected to the pipe and welded inside and outside. Slip-on flanges have a larger bore size than the outside diameter of the pipe to be connected, as the pipe must slide inside the flange to be welded.
These flanges are also referred to as “hubbed flanges” because their slim and compact shape makes them easy to identify. It is mainly used for liquids with low pressure or low risk of leakage. Apart from their application, the slip-on flange is much cheaper and quite popular among other types.
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#4 Threaded Flange
Threaded flanges are similar in design to slip-on flanges, the only difference being that they have a tapered thread. This design allows it to be attached to the pipe without welding. It has threads inside the flange bore that are fitted with matching male threads on the pipe or fitting.
The best application for them is in low-pressure, low-temperature environments, like slip-on flanges. These are available in sizes up to 4 inches and in several pressure ratings; however, they are used in smaller pipes such as water and air utility services.
Also, these flange requirements apply to explosive environments like gas stations and plants, where welding connections would be harmful.
#5 Socket Weld Flange
Socket weld flanges are joined to the pipe using a single fillet weld held outside the flange. These flanges are typically used on small-size high-pressure pipes that do not transfer highly corrosive fluids.
It is because these flange types tend to corrode in the gap between the pipe end and the socket shoulder. It is not often used for critical services. In this flange, the static strength is comparable to that of slip-on flanges, but the fatigue strength is 50% higher than that of double-welded slip-on flanges.
#6 Lap Joint Flange
Lap joint flanges have a flat face and are always used with a stub end. These flanges resemble slip-on flanges in shape, except for the radius at the crossing of the flange face and the bore to adjust the flanged portion of the stub end.
A lap joint flange slips over the pipe and seats behind the stub end, and the two are held together by bolt pressure. These flanges have freedom of movement around the pipe, facilitating opposing flange bolt holes. For stainless steel or nickel alloy pipelines, lap joint flanges are a cost-effective solution since the lap joint flange material can be of a lower grade.
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#7 Blind Flange
A blind flange is a type of flange that has no bore center and is used to terminate or close the end of a piping system. These flanges are subjected to significant mechanical stress due to system pressure and the required bolting forces.
Because of this, they are suitable for high-pressure applications and testing the flow of a gas or liquid through pipes. A blind flange allows easy access to the pipeline since it can be easily unbolted by the operator to perform activities inside the terminal end. They can also seal a nozzle opening on a pressure vessel.
#8 Orifice Flange
Orifice flanges are used with orifice plates to measure or restrict the pressure or flow of gases and liquids in pipelines. They are found with an additional set of bolts called jack screws. They are often available with a plate and jack screw, allowing complete product.
An orifice flange’s primary function is to measure fluid or gas flow rate through a piping system. In these flanges, a hole is drilled through the face perpendicular to the pipe, making them easy to identify.
#9 Nipo Flange
Also known as a weldoflange, this flange is a combination of a welding neck flange and a weldolet or nipolet. However, it is a solid piece of forged steel flange, not two separate products welded together.
Nickel flanges are available in several different materials, including carbon steel ASTM A105 (high-temperature), stainless steel ASTM A182 and nickel alloys. These are used to branch pipelines at 90 degrees. They are also fabricated in a reinforced version, which holds additional mechanical strength compared to the standard flange.
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#10 Swivel Flange
A swivel ring flange enables bolt holes to be aligned between two mating flanges, a feature that is important for various applications, including the installation of large-diameter pipelines, subsea and offshore pipelines, and pipeworks in shallow water.
These types of flanges are suitable for oil, gas, hydrocarbon, water, chemical, and other fluids in petrochemical and water-handling applications. This flange is ideal for offshore or subsea pipeline operations, allowing divers to more quickly and easily adjust bolt holes.
A swivel flange is available in all standard shapes, e.g. weld-neck, slip-on, lap-joint, socket weld, etc., and in all material grades.
#11 Expanding Flange
The purpose of expanding flanges is to increase the bore of a pipeline from one point to another or to connect pipes with other mechanical devices such as pumps and compressors. It is type of welding neck flange has a larger bore on the non-flange end.
It is not possible to increase pipe bores by more than two sizes with expanding flanges. The extended flange is compact and saves space compared to the reducer-welding neck flange.It only requires a butt-weld to install, which is very cost-effective and competitively priced.
#12 Reducing Flange
As the name suggests, the reducing flange is used to reduce the diameter of the pipe. These flanges are used where pipe installation space is limited. These are available in various sizes and material grades and are usually unavailable from stock.
An advantage of using a reducing flange is that the piping can be assembled without welding. Reducing flanges are easy to bolt on, provide a simple solution and are most cost-effective. This allows for the same considerations in terms of specifications, sizes, and material grades as the expansion flange.
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#13 Elbow Flange
An Elbow flange is widely used for piping connections that require compact pipe routing. The flanged elbow is used as a fitting. In contrast, flanged bends are made by welding a flange directly to a piping elbow (weld neck or any other type).
Compared to carbon steel elbow flange, stainless steel elbow flange will not erode, pitting or rust. A stainless steel elbow fitting has a smooth inner wall that prevents impurities from condensing.
#14 Puddle Flange
These flanges are used to seal pipes and cables made of plastic, steel, fiber cement, and vitrified clay against high-water columns. They prevent groundwater and pressurized water from entering concrete foundations and walls. ANSI B16. 5, ASTM A 182, ASTM A 105, and ASTM A 351 are the material standards for this type of flanges.
#15 Split Flange
A split flange comprises two interlocking pieces that securely fit together using nuts and bolts or welding in place. As split flanges are made of two parts, they can be used to strengthen piping, or to add attachments in areas where conventional flanges cannot.
Due to their suitability for high pressure, shock and vibration, these flanged fittings are used in challenging applications. In addition, they also allow easy connection between the hose and pipe, as well as between rigid lines. The advantage of using this flange is that it is easy to install over existing piping and hydraulic tubing.
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#16 Cast Flange
Cast pipe flanges are also types of flanges that are used in pipe systems to join pipes. Cast flanges typically have two types of bolts: one for sealing and one for tensioning. The main reason why cast iron is used for flanges is because it is cheap to produce, allows for more complex parts to be made at a lower cost, and has no real size limit.
#17 Square Flange
These types of flanges are square in shape and are used between pipe-to-pipe or pipe-to-component connections, such as valves, tees, and elbows. The square flange is made according to JIS B2291 / JIS F7806 standard.
These flanges are helpful in joining pipes of JIS standard nominal bore size together in hydraulic systems. The square flange is usually available in various pressure ratings to serve its purpose. Square flanges are widely used in a variety of high-pressure applications, such as pipe connections.
#18 Anchor Flange
An anchor flange is installed on a pipeline to counteract axial movement and prevent the pipeline from moving. Typically, after the flange has been welded to the pipe, it is anchored to a concrete foundation.
The purpose of these types of flanges is to restrain or limit main line thermal expansion and contraction, as well as to transfer built-up stress to external structures or a larger foundation. Using these flanges, equipment and valves protect against excessive stresses that can arise due to line temperature and pressure.
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Material Used to Manufacture Flange
Depending on the piping material and the application’s requirements, flanges are manufactured from many different materials. Factors such as economy, flow pressure, operating temperature, and environmental corrosion are considered when selecting a flange for a particular application.
The following are common materials used to make flanges:
#1 Carbon Steel
It is a type of steel alloy that contains carbon. It offers high strength and hardness, increased carbon content, low melting point, and ductility.
#2 Alloy Steel
Metallurgy refers to alloying steel with elements that alter or enhance its properties. Common alloy steels are chromium, molybdenum, nickel, and manganese.
#3 Stainless Steel
Stainless steel contains chromium in excess of 10%. This chromium property enables stainless steel to have a higher corrosion resistance than carbon steel which rusts easily from exposure to air and moisture.
Aluminum provides a low-density, ductile and malleable metal with moderate strength. It has better corrosion resistance properties than any other special alloy steel. This is important during flange manufacturing which requires low weight and strength.
#5 Cast Iron
Cast iron is made when the iron is alloyed with silicon, carbon, and many other alloys. Cast iron has many properties, such as machinability, castability, and fluidity.
It is an alloy of zinc and copper, often containing tin or lead as well. It has good conductivity, cold ductility, high-temperature ductility, and good strength.
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Common Performance Features of Flange
There are many factors that affect the performance of a flange, but they need to be taken into consideration in order to achieve the best performance. The following are the common performance properties of flange:
Durability defines the toughness or strength of the pipe flange under pressure or tension. It depends on flange design and compatibility with pipe and material strength.
#2 Ease of Assembly
In other words, it describes how effectively the disassembly and assembly processes work. Ease of setup and takedown is critical in applications where flanges are used as temporary attachments or fixes.
The weight property defines the heaviness or mass of the flange. Weight depends on material density and size. In the case of high or large-density flanges, industrial buyers must pay attention to the strength of the pipe or pipe support.
Closing It Up
I hope I have covered everything about the “Types of Flanges.” If I missed something, or if you have any doubts, let me know in the comments. If you liked this article, please share it with your friends.
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2 thoughts on “18 Different Types of Flanges and Their Applications [PDF]”
Fascinating rundown on flanges. Definitely learned more than I was expecting. Considering I was just looking into the purpose for what you call “cast flanges” because I’ve only ever seen them used to make railings out of schedule 40 iron pipe. Hahaha. Right now I’m using one as a hilt on a apocalypse style short sword, just for funsies, that I made with a 7 inch 3/4 bolt and some 3/16 flat stock sheet metal. Aside from an anchor for railings, or the occasional ceiling mount for a similar purpose for steam pipe, I have never seen the practical purpose for them. I appreciate your article. Beyond basic enough to be useful, but brief enough to be an interesting quick read.
Thanks for the positive feedback! We’re glad our article was informative and provided more insight on flanges than you were expecting.