What is a Flange: Purpose, Characteristics, Types and Uses

Flanges are important parts used widely in various mechanical systems. They help assemble fittings, valves, and pipes. There are different kinds of flanges, and each caters to different applications.

If you want to learn more about the uses and types of flanges, this guide below can greatly help.

What is the Purpose of A Flange?

Flanges are used to join valves and other equipment, and some of the functions of flanges are the following:

• Flanges allow the assembling of the components. One flange is mounted on the pipe’s outer area, whereas the other is on the opposite side so that they can be connected with nuts and bolts.
• Flanges offer resistance against temperature and pressure. Hence, in case of temperature and pressure changes in the pipelines or the equipment, the connection doesn't break and stays intact in the long run.
• The joints can be sealed with the help of flanges. Other sealing materials and gaskets at the joint are meant to manage the leaks and ensure that environmental protection is achieved.
• Flanges can be assembled and disassembled in no time. Hence, when maintenance is required, they can be removed, and pipes can be separated.
• Flanges also offer a transition between the different pressures, materials, and diameters the pipes may have, and they ensure compatibility.

Characteristics of Flanges

Flanges are used because of their characteristics and how they cater to various applications. Some of these characteristics of flanges are as follows:

• Flanges consist of holes that are drilled perfectly for quick assembly.
• The grain flow of the flanges is controlled and hence offers stiffness and strength.
• Flanges consist of accurate bore and ensure unrestricted flow through the entire piping system.
• The faces of the flanges are machined with tight tolerance to ensure they align properly.
• It offers machined land and bevel to ensure excellent welding.

7 Main Types of Flange and Their Uses

There are 7 main flange types, and these are discussed below:

Welding Neck Flange

Welding neck flange consists of a long tapered hub and hence offers excellent resistance against deformation followed by high strength. In applications where high pressure and high temperature are common, the welding neck flange proves to be a suitable choice.

Slip-On Flange

Slip-on flanges consist of a larger diameter compared to the pipe, and it slips over it. It is very easy to align and is suitable for low-pressure applications. The pipes where too much bending and temperature fluctuations take place may not find slip-on flanges suitable.

Socket Weld Flange

Socket weld flanges connect, and you pass the pipe into the flange. There is a multi-pass filet weld that helps secure the joint. It is suitable for pipes with small diameters and low pressure and temperature conditions.

Threaded Flange

Threaded flanges have threads that help to screw the flange with the pipe. They are used in applications where frequency assembling and disassembling is needed.

Blind Flange

Blind flanges are equipped with solid discs which are used to act as a barrier at the end of the pipes. They are used for future maintenance or expansion and can also be used as covers for inspection.

Lap Joint Flanges

These flanges have a flat face and consist of a separate backing flange. The backing flange is made using a different material and offers support. These are usually opted-for piping systems where dismantling is frequent.

Long Neck Welding Flanges

Long neck welding flanges consist of a lengthy neck of the flange. It has a bevel end and a conical neck, which are fixed together with the help of a pipe.

What is a Flange’s Standard?

The dimensions of the flange are based on some design parameters and standards. Some of these conditions are the following:

• The dimensions of flanges are determined by international standards like ANSI or ASME, JIS, and DIN. They specify the classes, dimensions, and tolerance of the flange. The selection of flange for the application is carried out based on the product's suitability.
• The pressure, size, and class of the pipelines also need attention when choosing the flange dimensions. The inner and outer diameter of the pipe must be considered when choosing the flange.
• Different types of flanges have different dimensions. Projects are selected based on the specific dimension of each flange.
• The pipeline material is also a consideration. It could be carbon steel, steel, or stainless steel, and each has a different dimension. So, flange dimensions are also determined based on pipeline material.
• When it comes to flange dimensions, tolerance is also considered. It is important to ensure that the flange is assembled with the right pipeline aligning with the tolerance to achieve the perfect connection.

Machining Process of Custom Flange Parts

The machining process of custom flange parts consists of the following steps:

Selection of Materials

When machining flanges, the most important stage is the selection of materials. The flanges can be made using different materials like stainless, carbon, and alloy steel. The right material selection is made based on the pressure, temperature, and corrosion resistance required.

Shaping and Cutting of Material

Once the material is chosen, the slices of material are formed. Big metal plates are transformed into smaller ones to achieve the right flange size. The parts which are produced are then heated for further processing.

Trattamento termico

Based on the purpose and material of the flange, it goes through heat treatment. Methods like tempering, annealing, and quenching are used so that the mechanical properties of the flange can be boosted.

Forging and Forming

The process of heating adds malleability to the flange and allows for shaping them. Methods of forging are then selected, which include cold or hot forging. In the case of cold forging, the metal is formed at room temperature. Meanwhile, in hot forging, heat is provided, followed by high pressure.

Machining

Once the process of forging is done, the flange is subjected to machining so that precise tolerance can be achieved. The process of machining consists of drilling holes, chamfering edges, and facing sealing surfaces. The process of machining is usually carried out through CNC machining.

Finitura delle superfici

The flanges also undergo processes for surface finishing, like polishing and grinding, so that the required smoothness on the surfaces can be achieved.

Inspection and Testing

Quality control is one of the most important stages in flange production. It makes the flanges pass through an examination process ensuring that the specifications required are present in them. The finishing inspections or the surface measurement of dimensions and testing methods that are not destructive are done.

Conclusion: What is a Flange: Purpose, Characteristics, Types and Uses

Almost every piping system uses flanges. As you have read about the different types and characteristics of flanges, understanding their purpose must have been very clear.

DEK can provide you with the high-quality, finely machined custom flanges you need, with the required dimensions and specifications suitable for your projects.

Domande frequenti

What materials are ideal for making flanges?

Carbon steel is one of the most common materials opted for manufacturing flanges. In addition, stainless steel and cast iron can also be used.

What are the types of flange faces?

The most common types of flange faces include raised, plain/flat, or ringed faces.

What is a flanged connection? How are flanges connected to pipes?

A flanged connection is a joint that is used in piping systems and other equipment that helps join two different sections. The joint of the flange is formed by having the pair of flanges bolted together with a gasket in between so that a leakproof and tight connection is created.