Flat welding flanges are mainly used for gas valves and natural gas pipelines. Because the short neck can improve the stiffness and load-carrying capacity of the flange. Flat welded flanges are used for general media. Flat welding flange with neck is suitable for flammable, explosive, corrosive and toxic places. The sealing surface of the flat welding flange can be convex surface, concave-convex surface and tongue and groove surface. They differ in structure, sealing effect and strength.

Flat welding flanges are generally referred to as flat plates, also known as lap welding flanges. The connection between the flat welding flange and the pipeline is to insert the pipeline into the inner hole of the flange to a suitable position before lap welding. Features of flat welding flange: Flat welding flange not only saves space and weight, but also ensures no leakage at the joint and good sealing performance. The reason for the reduced size of the compact flange is the reduced diameter of the seal, which will reduce the cross-section of the sealing surface. The advantages of flat welding flanges are as follows:

1. In order to compact the sealing surface of the flat welding flange, only a small amount of pressure is required. As the required pressure decreases, so does the size of the bolts and the number of bolts required.

2. The production of flat welding flanges can save data and reduce costs. When the raw material of the pipeline is special and the price is high, the welding cost of the flange of the same raw material will be high, and the use of this flange can effectively save the material cost. Conducive to construction, the flange bolt holes are inconvenient to be centered during connection or to avoid the replacement of equipment flange bolt holes, etc. This kind of flat welding flange is very suitable.

3. Flat welding flange can save space and reduce weight during application. It is important to ensure that the head does not leak air. It has a very good sealing function. The reason for the reduced size of the compact flange is because the diameter of the seal is reduced, which reduces the cross-section of the sealing face. In addition, the flange gasket has now been replaced by a seal ring to ensure an excellent match of the flat weld flange seal facing the sealing face.

But it also has some disadvantages, the disadvantages of flat welding flange:

The main disadvantage of flat welding flanges is that there is no guarantee that they will not leak. This is a lack of planning: connections are dynamic, for example thermal expansion and fluctuating cyclic loads can cause motion between flange faces that can affect the function of the flange, thereby destroying the integrity of the flange and leading to leaks.