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Forging Process and Characteristics of Weld Neck Flange

Aug. 01, 2020

Welded neck flanges can also be called forged flanges, steam pipe flanges, they are used to connect carbon steel pipes. The nominal pressure does not exceed 2.5MPa. The connection form of welding neck flange includes single-sided welding. It is connected by a double-sided nut, only one-sided welding is required when welding, and the inner hole and flange connection of the welded pipe is not required. Usually used in low and medium pressure pipelines.

The forging of weld neck flanges can be divided into rotary forging, ring rolling, and cross rolling according to the movement mode of the forging die. Precision forging can also use rotary forging, rotary forging, and ring rolling. In order to improve the utilization rate of heat treatment, some complex forging processes are completed through one or more processes.

Forging method

The forging of Long Weldneck Flange can be divided into free forging and extrusion. Generally, the crystallization temperature region is called hot forging, and the unheated region at room temperature is called cold forging. When forging weld neck flanges at low temperatures, the forging size changes have little effect. Forging below 700°C will not decarburize the surface. The advantage is that it can be formed even when the forging force is small compared to the forging size.

During the machining process, the weld neck flange will extend from the vicinity of the mold surface to the free surface, which is difficult to ensure accuracy. Products with complex shapes and high precision can be obtained under low forging force. Therefore, in order to better process products, such as the forging of large and various large steam turbine blades produced and operated by enterprises, the moving direction of the forging die and the rotary forging process is controlled by a computer.

Long Weldneck Flange

Weldneck Flange

Features of the weld neck flange

The weld neck flange is a movable flange piece. In fact, the flange is sleeved on the pipe end with a steel ring, flange, etc., so that the flange can move on the pipe end, flange or flange steel ring. This kind of flange is usually used in conjunction with the fittings of the water supply and drainage pipe. When the manufacturer leaves the factory, the two ends of the expansion joint are designed with flanges, and the bolts are used directly between the pipes and equipment in the project. establish a connection.

The weld neck flange not only saves space and weight but also ensures that the joint does not leak and has a good sealing performance. Then, replace the flange gasket sealing ring to ensure that the sealing surface matches the sealing surface. As the stress area of the forging is reduced, the reason why the size of the compact flange can be reduced is that the diameter of the sealing ring is reduced, so that the cross-section of the sealing working surface is continuously reduced. In this way, only a small amount of pressure is required to compress the sealing surface. As the pressure decreases, the size of the bolts and the number of bolts required are correspondingly reduced, thereby designing lightweight products.

BSP Fittings supplier believes that the main materials of flanges are carbon steel, alloy steel, and stainless steel. The main standards are national standard, electric standard, American standard, German standard, Japanese standard, etc. The main anti-corrosion treatment is oiling and galvanizing. Flanges have good pressure and temperature resistance and are usually suitable for high pressure and high temperature working environments.