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The characteristics and sealing principle of flat welding flanges

Flat welding flange refers to a flange that is connected to a container or pipeline through fillet welding. It can be any flange. Check the overall flange or loose flange separately based on the integrity of the flange ring and straight tube section during design. There are two types of rings for flat welding flanges: neck and non neck. Compared with neck welding flanges, flat welding flanges have a simpler structure and fewer materials, but their rigidity and sealing performance are not as good as neck welding flanges. Flat welded flanges are widely used for connecting medium and low pressure vessels and pipelines.

Flat welding flanges not only save space and weight, but more importantly, they ensure that joints do not leak and have good sealing performance. Due to the reduction in the diameter of the sealing element, the size of the compact flange is reduced, which will reduce the cross-sectional area of the sealing surface. Secondly, the flange gasket has been replaced by a sealing ring to ensure that the sealing surface matches the sealing surface. In this way, only a small amount of pressure is needed to tightly compress the cover. As the required pressure decreases, the size and quantity of bolts can be correspondingly reduced. Therefore, a new type of flat welded flange with small size and light weight (70% to 80% lighter than traditional flanges) has been designed. Therefore, flat welding flange is a relatively high-quality flange product that reduces quality and space, and plays an important role in industrial applications.

The sealing principle of flat welding flange: The two sealing surfaces of the bolt squeeze the flange gasket and form a seal, but this can also cause seal damage. To maintain sealing, it is necessary to maintain a significant bolt force. Therefore, it is necessary to make the bolts larger. Larger bolts must match larger nuts, which means larger diameter bolts are needed to create conditions for tightening the nuts. However, the larger the bolt diameter, the bending of the applicable flange will occur.

This method is to increase the wall thickness of the flange section. The entire equipment will require enormous size and weight, which becomes a special issue in offshore environments, as the weight of flat welded flanges is always a major concern that people must pay attention to.