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Custom flange: all the information worth knowing

1. What is a custom flange?

Flange manufacturers on the market in the production of flanges, is to be in accordance with the standard to produce, and also more in accordance with the national standard to produce flanges, that is: in accordance with the national standard requirements of the size, tolerance range, etc. production flange, such a standard flange in use, although also can be used, but more often than not, industrial production requirements of the flange is not the same, so that the flange specifications will also change, such as the Industrial production will not be able to use the standard flange, can only use large flanges; some industrial production can only use smaller flanges to use, so, in the face of such a situation, the standard flange on the market is no longer applicable, can only be customized to get the desired flange.
Custom flanges, belonging to the pipeline engineering in the custom products. OEM is due to the needs of the pipeline engineering design and site construction needs. Custom pipeline fittings to facilitate the use of non-standard pipeline projects, standard pipeline projects in the disassembly and later construction continuity, are to use to custom pipeline fittings, custom flanges.
For example, custom slip on flange, because the pipeline into the monoflanges before welding. Need to provide sufficient strength internally and externally to prevent leakage. Slip on flanges, are slightly larger outside diameter in the pipeline match. They are superior to neck flanges for welding.
Custom lap joint flanges, the welded flange is a similar sliding flange unless it has a hole and counter bore dimension. Custom flanges are matched to the pipe so that the pipe is inserted inside the flange. The diameter of the smaller bore is the same as a shoulder sleeve that rests on the bottom specifically for the pipe. This eliminates any flow restrictions and improves ease of operation while using custom welded flanges.
Shaped flanges are used as sealing and fastening connections, also known as shaped flanges. They have a wide range of applications in large vessels in aerospace and petroleum and chemical industries. Although processing capacity is not considered, for profiled flanges, their size is too large, which makes the overall processing of profiled flanges to be divided into flaps due to transportation reasons alone. As a rule, the profiled flange is always processed in several arc segments.
First, the blank is forged into a square billet, then cold bent into arc segments, annealed to stress heat treatment, put together into a whole circle in the vertical car processing to the design of the shape and size, and finally transported to the construction site, and then a number of arc segments group welding into a complete shaped flange and pressure vessel group welding. As the nominal diameter of the container barrel of the shaped flange and the nominal diameter of the pipe represents a different specific size, so the same nominal diameter of the container flange and pipe flange, their dimensions are not the same, the two can not be used in place of each other. Shaped flange pressure level, material, standards, etc. have different characteristics and features, in use in accordance with certain principles and ways and means of use, can be produced and processed in accordance with the corresponding standards to ensure that in use with good use value and role. Materials are mostly carbon steel, alloy steel and stainless steel.

2. How to make custom flanges?

To design a custom flange, we need to understand some key information. Flanges start with understanding the type of flange, size, pressure rating and type of flange face.
Once we understand your needs, our team can design a flange that meets or exceeds your requirements. We have an in-house engineering department with over 10 years of combined experience, so you can be sure that we will create a perfect flange for your application. The following considerations need to be understood before any major custom flanges are fabricated.

Types of pipe flanges

Flanges are available in a variety of types and can be selected based on site requirements. In order to match the design of the ideal flange, reliable operation as well as long service life must be ensured and the most suitable price should be considered.

Threaded flanges

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A threaded flange, with a thread in the flange bore, mates with an external thread on the fitting. The threaded connection here means avoiding welding in all cases. It is mainly connected by a thread that matches the pipe to be installed.

Socket weld flange

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This type of flange is usually used for smaller pipes where the diameter of the low temperature and low pressure area is characterized by a connection where the pipe is placed inside the flange to ensure a connection with a single or multi-pass fillet weld. Compared to other welded flange types, this approach avoids the restrictions associated with threaded ends, thus making installation simple.

Lap joint flanges

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A lap joint flange is a flange that requires the stub end to be butt welded to the fitting in order to be used with a support flange to form a flange connection. This design makes this approach popular in a variety of systems where physical space is limited, or systems that require frequent disassembly, or a high level of maintenance.

Slip on Flanges

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Slip on flanges are very commonly used and are also available in a variety of sizes to accommodate systems with high flow rates and high throughput. They are easy to install by simply matching the flange to the outside diameter of the pipe for connection. Installation of these flanges is somewhat technical, as fillet welds are required on both sides to secure the flange to the pipe.

Blind flanges

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These types of flanges are very suitable for the termination of piping systems. The blind flanges are shaped like a blank disc that can be bolted. Once these are properly installed and combined with the correct gasket, it allows for an excellent seal and is easy to remove when needed.

Weld Neck Flanges

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Weld neck flanges are very similar to lap flanges, but require butt welding to install. And the integrity of this system performance and the ability to bend repeatedly and use in high pressure and high temperature systems makes it the primary choice for process piping.

Special flanges

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This type of flange is the most well known. However, there are a variety of additional specialty flange types available to suit a variety of applications and environments. There are various other options such as nipoflanges, weldoflanges, expansion flanges, orifices, long weld necks and reducer flanges.

1. Weldoflange

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Weldoflange is very similar to Nipoflange because it is a combination of a butt weld flange and a branch fitting connection. Weldoflange is made from a single piece of solid forged steel, rather than individual parts being welded together.

2. Nipoflange

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Nipoflange is a branch pipe inclined at an angle of 90 degrees, and it is a product manufactured by combining a butt-weld flange and a forged Nipolet. While the Nipoflange is found to be a solid single piece of forged steel, it is not understood to be two different products welded together. the installation of the Nipoflange consists of welding to the Nipolet section of the equipment to run the pipe and bolting the flange section to the branch pipe flange by the pipe crew.

It is important to know that Nipoflanges are available in various types of materials such as carbon, high and low temperature carbon steel, stainless steel grades and nickel alloys. Nipoflanges are mostly manufactured in reinforced versions, which help give them extra mechanical strength compared to standard Nipoflange.
3. Elbolet and Latrolet

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Elboflange is known as a combination of flange and Elbolet, while Latroflange is known as a combination of flange and Latrolet. Elboflange is used to branch pipes at an angle of 45 degrees.

4. Swivel ring flange

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Swivel ring flanges are used to facilitate the alignment of bolt holes between two mating flanges, which is more helpful in many situations, such as the installation of large diameter pipelines, subsea or offshore pipelines and similar environments. These types of flanges are suitable for demanding fluids in oil, gas, hydrocarbons, water, chemicals and other petrochemical and water management applications.

In the case of large diameter pipelines, the pipe is installed at one end, maintaining a standard butt weld flange, and the other end is a swivel flange. This works by simply rotating the swivel flange on the pipe so that the operator can achieve proper alignment of the bolt holes in a very easy and faster manner.
Some of the major standards for swivel ring flanges are ASME or ANSI, DIN, BS, EN, ISO, etc. One of the most popular standards for petrochemical applications is ANSI or ASME B16.5 or ASME B16.47. Swivel flanges are flanges that can be used in all common flange standard shapes. For example, weld neck, slip on, lap, socket weld, etc. in all material grades in a wide range of sizes from 3/8″ to 60″ and pressures from 150 to 2500. these flanges can be easily manufactured from carbon steel, alloy steel and stainless steel.
5. Expansion flange

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Expansion flanges are used to increase the aperture of a pipe from any particular point to another in order to connect the pipe to any other mechanical equipment, such as pumps, compressors and valves, which are found to have different inlet sizes.

An expansion flange is usually a butt weld flange with a very large bore at the non-flanged end. It can be used to add just one or two sizes or a maximum of 4 inches to the running pipe bore. These types of flanges are preferred over a combination of butt-weld reducers and standard flanges because they are cheaper and lighter. One of the most common materials used for expansion flanges is A105 and stainless steel ASTM A182.

Expansion flanges are available in pressure ratings and sizes in accordance with ANSI or ASMEB16.5 codes, which are primarily available in convex or flat (RF or FF). Reducing flanges, also known as reducer flanges, have the exact opposite function compared to expansion flanges, which means they are used to reduce the bore diameter of the pipe. The bore diameter of a running pipe can be easily reduced, but not by more than 1 or 2 sizes. If an attempt is made to reduce beyond this, a solution based on a combination of butt-weld reducers and standard flanges should be used.

Scope of application of different types of pipe flanges

Flat welding flange
They are suitable for connecting carbon steel pipes with nominal pressure not exceeding 2.5MPa. The sealing surface of flat welding flanges can be made into smooth, concave and tongue and groove type. Smooth type flat welding flange has the largest application. Most of the media conditions are more moderate, such as low-pressure non-nitrification compressed air, low-pressure circulating water, it has the advantage of relatively cheap.
Butt-welding flange
Used for flange and pipe butt welding, its structure is reasonable, strength and rigidity, withstand high temperature and high pressure and repeated bending and temperature fluctuations, reliable sealing. Nominal pressure of 0.25 ~ 2.5MPa butt welding flange using concave and convex sealing surface
Socket welding flange
Commonly used in the pipeline of PN10.0MPa, DN40.
Loose flange
Commonly used in the medium temperature and pressure are not high and the medium is more corrosive. When the medium is more corrosive, the part of the flange in contact with the medium (flanged short section) is corrosion-resistant high-grade materials such as not steel, while the external use of low-grade materials such as carbon steel material flange ring clamping it to achieve sealing.
Integral flange
Often the flange and equipment, pipe, pipe fittings, valves, etc. into one, this type is commonly used in equipment and valves.

Flange dimensions and common precautions

In addition to the functional design of the flange, its size is the most likely factor to affect the flange selection when designing, maintaining and updating the piping system. The interface between flange and pipe and the gasket used must be considered to ensure the correct size. In addition, some common considerations are as follows:

  • Outer diameter: the outer diameter refers to the distance between two opposite edges of the flange surface.
  • Thickness: the thickness is measured from the outside of the rim.
  • Bolt circle diameter: This refers to the distance between relative bolt holes measured from center to center.
  • Pipe size: pipe size refers to the size corresponding to the flange.
  • Nominal bore diameter: nominal bore diameter is the inner diameter of flange connector.

Pressure class of flanges

Flanges are classified primarily by their ability to withstand different temperatures and pressures. It is designated by the use of letters or the suffixes “#”, “lb” or “class”. These are interchangeable suffixes and also vary by region or supplier. The pressure rating standards for flanges are divided into two systems, PN series (European system) and Class series (American system).

  1. PN series nominal pressure grade is expressed by PN and includes the following nine grades: PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160.
  2. Class series nominal pressure grade is expressed by Class, including the following six grades: Class150, Class300, Class600, Class900, Class1500, Class2500.

Because the pressure class itself should be no secondary, just different class standards, interchangeable except to consider the conversion relationship between LB and MPa, roughly MPa = 0.007 × LB. LB and PN are pressure classes, not simply pressure units, that is, LB can be interchanged with MPa, but LB and PN are not simply interchangeable.
The same pressure and temperature tolerances vary depending on the materials used, flange design and flange size. However, the only constant is the pressure rating, which decreases as the temperature rises.

Flange Face Type

Face type is also a very important characteristic that has a significant impact on the final performance and service life of the flange. Therefore, some of the most important flange face types are analyzed below.
1. Flat Flange (FF)

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The gasket surface of a flat flange is in the same plane as the surface of the bolt frame. Goods using flat flanges are usually goods with molds to make matching flanges or flange covers. Flat flanges should not be placed on inverted side flanges.ASME B31.1 states that when connecting a flat cast iron flange to a carbon steel flange, the raised face on the carbon steel flange must be removed and a full face gasket is required. This is to prevent the small, brittle cast iron flange from splashing into the void formed by the raised nose of the carbon steel flange.

This type of flange face is used in the manufacture of equipment and valves for all applications where cast iron is fabricated. Cast iron is more brittle and is typically used only for low temperature, low pressure applications. The flat surface allows both flanges to be in complete contact over the entire surface. The contact surface of a flat flange (FF) is the same height as the bolt threads of the flange. Full face gaskets are used between two flat flanges and are usually soft. According to ASME B31.3, flat flanges should not be mated with elevated flanges due to the potential for leakage of the resulting flange joints.
2. Raised Face Flange (RF)

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The raised face flange is the most common type used in process plant applications and is easily identified. It is called convex because the face of the gasket is located above the face of the bolt ring. Each type of faceplate requires the use of several types of gaskets, including various flat ring pieces and metal composites such as spiral wound and double sheathed forms.

RF flanges are designed to concentrate further pressure on a smaller area of the gasket, thereby improving the pressure control of the joint. diameters and heights by pressure level and diameter are described in ASME B 16.5. The flange pressure level specifies the height of the face being lifted. RF flanges are intended to concentrate further pressure on smaller areas of the gasket, thereby increasing the pressure holding capacity of the joint. Diameters and heights by pressure class and diameter are described in ASME B 16.5. Pressure flange class.
3. Ring joint flange (RTJ)

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Ring joint flanges (RTJ) are used when a metal-to-metal seal between mating flanges is required (this is a condition for high pressure and high temperature applications, i.e. above 700/800°C).

Ring joint flanges have circular recesses to accommodate ring joint gaskets (oval or rectangular).
When two ring joint flanges are bolted together and then tightened, the applied bolt force deforms the gasket in the flange groove, creating a very tight metal-to-metal seal. In order to achieve this, the material of the ring joint gasket must be softer (more ductile) than the material of the flange.
RTJ flanges can be sealed by RTJ gaskets of different types (R, RX, BX) and profiles (e.g. octagonal/elliptical for R type).

The most common RTJ gasket is the R type with octagonal cross-section, as it ensures a very strong seal (oval cross-section is the older type). However, the “flat groove” design accepts two types of RTJ gaskets with octagonal or oval cross-section.

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4. Tongue and groove flanges (T and G)

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Two tongue and groove flanges (T & G face) fit perfectly: one flange has a raised ring, the other has a groove, they can easily fit (tongue into the groove and seal the joint).

Tongue and groove flanges are available in large and small sizes.
5. Male and female flanges (M and F)

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Similar to tongue and groove flanges, male and female flanges (M & F face type) are matched to each other.

One flange has an area that extends beyond its surface area, the male flange, and the other flange has a matching depression machined into the facing surface, the female flange.

Flange Face Finishing

To ensure a perfect fit of the flange with the gasket and mating flange, the flange surface area needs a certain degree of roughness (RF and FF flange surface treatment only). The type of roughness of the flange face surface defines the type of “flange face finish”.
Common types are stock, concentric serrations, spiral serrations and smooth flange faces.

There are four basic surface finishes for steel flanges, but the common goal of any type of flange surface finish is to produce the required roughness on the flange surface to ensure a solid fit between the flange, gasket and mating flange to provide a quality seal.

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3. What are the advantages and disadvantages of using custom flanges?

Custom flanges can be designed and manufactured quickly for a variety of applications. This allows you to obtain flanges that meet specific requirements rather than using standard flanges that do not work. Below, you will find some of the advantages of using custom flanges.
Better Performance
Custom flanges can be designed to provide the customer with the size or construction required for the application, with low machining errors.
Longer Durability
Custom flanges are typically made with quality materials and construction techniques. This results in flanges that last longer than standard flanges and can withstand harsher environments.
Flange Finish
Sometimes, the finish of a flange is as important as its performance. The surface roughness of the flange sealing surface is one of the most important factors affecting the sealing performance. Some people have tested, when the flange sealing surface roughness of about Ra3.2μm, with metal wrapped asbestos gasket sealing pressure of 0.49MPa air, found a micro-leakage phenomenon; when the value of the surface roughness is reduced to 1.6μm, it can be sealed.
In various flange standards, the surface roughness of the sealing surface is required, but because of the wide variety of gaskets and different roughness requirements, the standards cannot be specified one by one. When using metal flat gasket, metal toothed gasket, metal waveform gasket and metal pack gasket, the surface roughness of flange sealing surface needs Ra3.2-1.6μm, which is difficult for the processing of large diameter flange surface.
Because custom flanges are not limited to standard designs, they can be used for a wider range of applications. This provides you with greater flexibility in selecting flanges as needed.
Now that we understand the basics of creating custom flanges, let’s look at some of the disadvantages.
Higher Costs
Custom flanges typically cost more than standard flanges due to the design and manufacturing time required. However, the additional benefits often make them worth the investment.
Limited Availability
Custom flanges are not always available from stock, so they may take longer to deliver.
Fewer Options
Since custom flanges are usually not available off the shelf, the choice of materials and styles may be limited.
Yaang offers a wide variety of products to help meet the needs of our customers for flanges. You can choose from a variety of different flange types and materials that we offer. We offer custom vessel flanges, pipe flanges, marine flanges and pressed flanges to provide the perfect product for your application.

4. Where to order custom flanges?

If you are looking for a custom flange supplier, the market can be a bit overwhelming. Many companies offer custom flanges, but not all of them offer high quality custom flanges.
Yaang is one of the few companies that offers a full range of custom flange services from design to fabrication and delivery. We have the experience and expertise to manufacture high quality flanges for any industry. If you have performance, durability or aesthetic concerns, our team of professionals can help you find the perfect custom flange solution.
If you are ready to order a custom flange, contact us today. We will be happy to work with you to create the perfect flange for your needs. You can also visit our website to learn more about our products and services.

Source: China Custom Flanges Manufacturer – Yaang Pipe Industry (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at [email protected]

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