What is a flange? Are there any common flanges?

What is a flange? >>> In the water industry, you want to connect large size water pipes together using soft joints, joints. In the middle of the smaller pipes, there is numbness, contraction and elbow. However, when installing water supplies such as water meters, industrial valves, water pumps, ... size from DN50 and above into the pipe, the flange is the most suitable accessory.

What is the concept of flange?

Flange is a round (square) steel, stainless steel block, flat section is machined from steel or solid stainless steel ingot, so it is quite heavy when holding. There are also many types of flanges made from plastic, cast iron and other materials.

Flanges are very familiar pipe fittings in material installations and projects. Is a device connecting materials - supplies, materials - pipes through bolts to catch bolts around the flange body edge to form a complete pipeline system in factories, factories, buildings, people use.

How is the flange structured?

Application of flanges in industry

Because the flanges are easy to install, operate, adjust and maintain, flanges are widely used in industrial fields: water supply and drainage pipes, factories, factories, building constructions. high-rise, petroleum, chemical, pneumatic, ...

Types of flanges are most commonly used today

Flanges are not only one type but there are many different types like other water supplies. People classify flanges according to criteria such as: materials, installation standards, pipeline pressure, purpose of use, ... Specifically, each classification is as follows:

Classify flanges according to materials:

- Steel flange: the most common type of flange available today, is used most in every industrial field.

- Stainless steel flange: the type of flange used is not as common. Installed in high temperature environments and resistant to chemical corrosion such as acids, chemicals, ...

- Plastic flange: less popular than the above 2 types. Use with pipes for clean water supply or chemical corrosion is not high, saline environment, alum.

- Copper flanges, cast iron and some machining flanges from other less used materials, only in separate cases.

Classification of flanges according to installation standards:

Flange standards are very important in the process of purchasing, installing pipes because each standard will have different criteria, size, operation, working environment. If you choose to buy flanges that meet European standards, it is not possible to fit standard German pipelines.

Flanges are like pipes, classified according to the following criteria:

- British BS standard flange:

Flange BS 4504, BS 6735, BS PN10, BS PN16, BS PN40 ...
- Japanese JIS standard flange:

JIS 5k flange, jis 10k, jis 16k, jis 20k

- German DIN standard flange:

DIN 2502 / DIN 2503 / DIN 2527

DIN 2565 / DIN 2566

DIN 2573 / DIN 2576

DIN 2627 / DIN 2628 / DIN 2629

DIN 2630 / DIN 2631 / DIN 2632

DIN 2633 / DIN 2634 / DIN 2635

DIN 2636 / DIN 2637 / DIN 2638

- American ANSI standard flange:

Ansi class 150, ansi class 300, ansi 600, ansi 900, ansi 1500, ansi 2500 flanges ...
Flange classification according to purpose of use:

In different industrial sectors, the use of pipes is suitable and the operation is also very different. Therefore, for each purpose of use, it is necessary to have suitable flange type.

- Hollow flange:

As the name of the middle round hole flange, it is duty to connect the pipes with water supplies.

- Blind flange - BLIND FLANGE (BF):

As the name of the middle hole without flanges, used to temporarily block the ends of pipes, can be easily removed.

- Thread flange - THREADED FLANGE (TF):

The name of a flange with a threaded hole in the middle, connecting small pipes by swirling the thread.

Threaded flanges are used in cases where flange welding is not feasible, flammable, broken joints. Therefore threaded machining is easier and more efficient.

- Neck welding flange - WELDING NECK FLANGE (WN):

As the name of the hollow flange, it is processed to make the neck by forging, so it is not as thick as the flange with the same size but quite solid (figure below). This neck will be chamfered to the end of the tube, so it can only be used in special cases that use ultrasound technology, support quality screening scans.

Therefore, for piping systems with high pressure, high pressure, the choice of neck welding flange is most reliable and effective.

- Molded welding flange - SOCKET WELD FLANGE (SW):

As the name of a flange with welded joints protruding on one side, the other side is covered with castings to block the pipe. This position is attached to pipes with small size but high pressure. Therefore, the pipe is inserted deep inside the flange and then drawn slowly from the cast section about 1/16 ”. Welds fill the external contact between the flange and the pipe body.

Note: Cast-welded welding flanges are only welded directly to the pipe, not for fitting fittings.

- Slip welding flange - SLIP-ON FLANGE (SO):

The name of the cast welding flange but not cast and the diameter in the flange is slightly larger than the pipe diameter in order to easily slip on the pipe.

In addition, the welded welding flange mounted to the pipe is also different from the cast welding flange that is welded both on the outside and in the flange:

+ For welds filled with the outer surface, it is done in the same way as welds of cast-welded welding flanges.

+ With inner filler, it is done between the contact inside the flange and the pipe end. In the process of inserting the pipe, it is important to avoid welding the pipe surface too close to the inside diameter of the flange because it is easy to cause the flange to fail. You need to create a sufficient distance between them according to the formula of the wall thickness plus about 3mm.

Note that the welding flange is also not used to directly align with fitting fittings.

- Liquid flange - LAP JOINT FLANGE (LJ):

The name of the flange used with a short section of Stub End support. This pipe is welded directly to the end of the pipe and is held in place by the flange. Due to such a structure, the liquid flange is only attached to short pipelines with low pressure which is not important to save the operation and assembly costs.

In return, the liquid flange has several advantages:

+ Flanged weld flange at the point where it can slide on the pipe, around the short Stub End tube.

+ Stub End is processed to make anti-corrosion materials. And the flange is made from low-cost carbon steel because it does not come in direct contact with the fluid so it is quite light and easy to operate.

+ Loose flange full of sizes than the flanges listed above and reused many times.

Thus it can be affirmed that flange is one of the pipe fittings that plays a very important role in the assembly and operation of piping systems in all areas of life.