Flat welding flange refers to a flange that is connected with a container or pipeline by fillet welds. It is an arbitrary flange. When designing, according to the integrity of the connection between the flange ring and the straight cylinder section, check the integral or loose flange respectively. Flange rings are available with or without a neck. Compared with the butt welding flange with neck, the flat welding flange has a simple structure and saves materials, but the rigidity and sealing performance are not as good as that of the butt welding flange with neck. Flat welding flanges are widely used in the connection of medium and low pressure vessels and pipelines.

This issue about flat welding flanges has always been a topic of concern to people. It is related to the production cost or economic benefits of companies and enterprises. Therefore, the sealing principle of flat welding flanges is constantly being improved and perfected.

However, the main design disadvantage of the flat weld flange is that it is not guaranteed to be leak-free. This is its design flaw: the connection is dynamic, and cyclic loads such as thermal expansion and fluctuations can cause movement between the flange faces, affecting the function of the flange, thereby compromising the integrity of the flange, ultimately resulting in leakage. It is impossible for any product to be free of defects, but to minimize the defects of the product as much as possible, so the company tries to improve the performance of the product when producing flat welding flanges, so that it can play the greatest role.

Features of flat welding flanges: Flat welding flanges not only save space and weight, but more importantly, ensure that the joints will not leak and have good sealing performance. The reduction in size of the compact flange is due to the reduced diameter of the seal, which reduces the cross-section of the sealing face. Second, the flange gasket has been replaced by a sealing ring to ensure the matching of the sealing face to the sealing face. In this way, only a small amount of pressure is required to compress the cover. As the required pressure decreases, the size and required number of bolts can be reduced accordingly, so a new small and light weight (70% to 80% lighter than the traditional flange) is finally designed. product. Therefore, the flat welding flange type is a relatively high-quality flange product, which reduces the quality and space and plays an important role in industrial use.

The sealing principle of the flat welding flange: the two sealing surfaces of the bolt press the flange gasket against each other and form a seal, but this also leads to the destruction of the seal. In order to maintain the seal, it is necessary to maintain a huge bolt force, and for this reason, the bolt must be made larger. And larger bolts match larger nuts, which means that larger diameter bolts are needed to create conditions for tightening the nuts. However, the larger the diameter of the bolt, the more curved the applicable flange becomes, and the only way is to increase the wall thickness of the flange part. The entire device will require enormous size and weight, which is a particular problem in the offshore environment, where weight is always the main concern one has to take. And, fundamentally, a flat weld flange is an ineffective seal, requiring 50% of the bolt load to squeeze the gasket, leaving only 50% of the load to hold the pressure.