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The Differences Between Butt Welding Flanges and Flat Welding Flanges


Butt welding flanges and flat welding flanges are very common pipeline components in the construction process, but many people do not know the difference between these two types of flanges, which brings trouble to many construction workers. After all, the application range of flat welding flanges and butt welding flanges is different. If the wrong operation is used, it may cause some problems for the project. So what is the specific difference between butt welding flange and flat welding flange? Let's give you a specific introduction.

1. Different types of welds: the welds of flat welded flanges cannot be radiographed, while butt-welded flanges can. The weld between the pipe and the flange of the flat welded flange is a fillet weld. The weld between the pipe with the neck flange and the pipe is a girth weld. Flat welds are two circular fillet welds. Butt welds are circular welds. The difference between necked flat welding flange and flat welding flange has an additional point in necked flat welding and pipe welding. The weld between the necked butt-welded flange and the connecting pipe belongs to category B weld, while the weld of necked flat-welded flange belongs to category C weld. Non-destructive testing after welding is different.

2. Different materials: The flat welding flange with the neck is made of the ordinary steel plate and has the required thickness. The neck butt welding flange is mainly made of forged steel.

3. The nominal pressure is different: the nominal pressure of the flat welding flange is 0.6-4.0MPa. The nominal pressure of the butt welding flange is 1-25MPa. Obviously, the adaptable pressure level of flat welded flanges is low.

Long Weldneck Flange

Long Weldneck Flange

4. Different connection methods: The biggest structural difference between flat welding flanges and butt welding flanges lies in the different connection methods of pipes and flanges. Long Weldneck Flange is generally connected by a connecting pipe, and the neck flange is connected with the connecting pipe.

Generally, flat welding flanges can only be connected by pipes. It cannot be directly connected with the butt welded pipe. Butt welding flanges can be directly connected to all butt welding pipe fittings (including elbows, tees, reducers, etc.), of course, can also be connected to pipelines.

The rigidity of the butt welding flange is higher than that of the flat welding flange, and the butt welding strength is higher than that of the flat welding, and it is not easy to leak.

Flat welding flanges cannot replace butt welding flanges. From a manufacturing point of view, the inner diameter of a flat welded flange is larger. This means lightweight and low cost. In addition, butt-welded flanges with a nominal diameter greater than 250mm need to be tested, while flat-welded flanges do not need to be tested, so the cost is relatively low.

The above has introduced in detail some of the main differences between flat welding flanges and butt welding flanges. Although the small part of the flange is not obvious in the whole product, pipeline or machinery, the role played by the flange is very important. With the development of flange material and technology in the future, the entire joint connection process can be guaranteed The medium is more precise and firm, ensuring safe and reliable use by people. I hope this knowledge can help you to better understand the products of butt welding and flat welding flanges so that you can choose the right butt welding and flat welding flanges during the construction process, so as to improve the quality of the project. We are the Stainless Steel Elbow 90° supplier. If you are interested in our products, please feel free to contact us.