What are the differences between [flat welding flange] and [Welding Neck Flange]?

Flat Welding Flange and Welding Neck Flange are the two main forms of flange connection. We have already introduced the classification of flanges. As for the differences between the two, we will sort them out for you here.

1. Different materials

● Flat welding flange:

Mostly ordinary steel plates (such as carbon steel plates, etc.) are used, and the cost is relatively low;

● Welding Neck Flange :

Mostly made of forged steel, with higher density, stronger mechanical properties, and higher cost;

 2. Structural design:

● Flat welding flange:

The flange plate is thinner and has no protruding neck design. The flange is directly welded to the pipe and cannot be directly connected to the butt welding pipe fittings.

● Welding Neck Flange:

Usually there is a protruding long neck design to enhance the rigidity and strength of the flange. The neck matches the outer diameter of the pipe. It can not only be connected to the pipe, but also directly connected to various butt welding pipe fittings, such as tees and elbows.

3. Welding method:

● Flat welding flange:

The flat welding flange adopts corner weld, that is, the weld between the pipe and the flange is a two-corner ring weld, which cannot be detected by X-ray.

● Welding Neck Flange:

Butt welding flange adopts ring weld, and the pipe needs to be welded on both sides inside and outside. It can be detected by X-ray or other methods to ensure the quality of the weld.

4. Sealing performance:

● Flat welding flange:

Because the weld is located on the outside of the flange, the sealing performance is relatively weak, and leakage may occur under high pressure or frequent temperature changes.

● Welding Neck Flange:

Because the weld is located on both sides of the flange, the sealing performance is strong and can withstand higher pressure and temperature changes.

5. Pressure bearing capacity:

● Flat welding flange:

Since only one side is welded, the bearing capacity is low, which is suitable for medium and low pressure pipeline systems.

● Welding Neck Flange:

Because double-sided welding is adopted, the bearing capacity is high, which is suitable for high-pressure pipeline systems.

6. Scope of application:

● Flat welding flange:

Applicable to low-pressure and small-diameter pipelines, widely used in construction, water supply and drainage, HVAC and other industries;

●Welding Neck Flange:

Applicable to high-pressure and large-diameter pipelines, widely used in high-demand industries such as petrochemical, electric power, nuclear energy, etc.;

7. Installation and maintenance:

● Flat welding flange:

The installation is relatively simple, but due to single-sided welding, more attention may be needed to the quality of the weld during maintenance.

● Welding Neck Flange:

The installation is more complicated, but due to double-sided welding, the weld quality is more guaranteed and maintenance is relatively less.

In summary, there are significant differences between flat welding flanges and Welding Neck Flange in terms of material, structure, welding, pressure, application, etc., but in the final analysis, the connection strength of flat welding flanges is relatively low and is suitable for medium and low pressure pipeline systems; while the connection strength of Welding Neck Flange is high and is suitable for high pressure and high temperature pipeline systems.