Welding Flange Fabrication

Welding flanges are a type of disc-shaped component commonly used in pipeline engineering, and they are always used in pairs. In pipeline construction, flat welding flanges are primarily used for pipe connections. For pipes that need to be connected, a flange disc is installed. Low-pressure pipelines can use threaded flanges, while flanges for pressures above 4 kg are焊接 flanges. A sealing point is added between the two flange discs, and then they are securely fastened with bolts. Flanges of different pressures have different thicknesses and require different bolts.

The forging of flat welding flanges can be divided into free forging, upsetting, extrusion, die forging, closed die forging, and closed upsetting forging. Closed die forging and closed upsetting forging have higher material utilization rates due to the absence of flash. The finishing of complex forgings can be achieved in one or several processes. The reduction in the area of the forging subjected to force also reduces the required load. However, it is important to ensure that the billet is not completely restricted, so strict control of the billet volume, the relative position of the die, and measurement of the forging are necessary to minimize die wear. During low-temperature forging, the size change of the forgings for flat welding flanges is minimal. Below 700°C, oxidation scale is minimal, and there is no decarburization on the surface. Therefore, cold forging is easy to achieve good dimensional accuracy and surface finish as long as the deformation is within the forming range. Good precision can also be obtained below 700°C with proper temperature and lubrication cooling. Hot forging, with low deformation energy and resistance, allows for the forging of complex large forgings. To achieve high dimensional accuracy, hot forging should be performed within the temperature range of 900-1000°C. Additionally, attention should be given to improving the working environment for hot forging. The die life (hot forging: 2-5 thousand, warm forging: 1-2 thousand, cold forging: 2-5 thousand) is shorter compared to forging in other temperature ranges, but it offers greater freedom and lower costs. Flat welding flanges have certain technical requirements and parameters for production and use, which are produced and processed in a specific manner: 1. Flat welding flanges should be cut into strips along the rolling direction of the steel, bent and welded into a circular shape, forming a cylindrical surface on the steel surface. Direct machining of steel plates into flanged necks is not allowed during the production of flat welding flanges, and specific processes should be used for manufacturing and processing. 2. The steel plates used to produce flat welding flanges should undergo ultrasonic testing to ensure there are no delamination defects, guaranteeing good quality and performance. Production and inspection should meet certain quality requirements to ensure that there are no quality issues with the steel plates used in production and use.