Use Of Weld Neck Flange

The use of weld neck flange is very important for production. Elite Piping Manufacture attaches great importance to correctly using weld neck flange.

Weld neck flanges are pipe fittings connected to pipes with necks and round pipes and butt-welded. Unlike flat-weld flanges, butt-weld flanges are not easy to deform and have good sealing properties. In addition, they are relatively cheap, so they are widely used.

Pipes with large pressure or temperature fluctuations or high-temperature, high-pressure, and low-temperature pipelines are suitable for butt-weld flanges. Pipes used to transport precious, flammable and explosive media.

Weld neck flange is a flange that is directly welded to equipment or pipelines through fillet welds. It has a simple structure and is easy to process. Its force characteristics are between the integral flange and the slip-on flange.

Weld neck flanges are divided into plate flat welding flanges and neck flat welding flanges. Flat welding flanges have low cost and short production cycle. They are the most commonly used flange type and are widely used in various fluid pipelines.

Installation Precautions For Weld Neck Flange

Before installing the weld neck flange, pay attention to check whether the nominal pressure of the flange meets the design requirements; check whether the sealing surface of the flange is smooth, clean, whether there are burrs and radial grooves, and whether the threaded part of the flange is complete and intact.

 Whether the concave and convex flanges can be naturally embedded, especially the non-destructive testing of the butt-weld flange must be done well to avoid damaging the inside of the butt-weld flange and affecting the performance and service life of the flange.

Before installing the butt-weld flange, pay attention to cleaning. After all, the sealing surface of the flange is tightly connected with gaskets and bolts. The flange sealing surface should be cleaned with special cleaning tools and methods, the purpose of which is to prevent damage to the butt-weld flange.

The installation and use of butt-weld flanges must pay attention to the method and sequence. After all, if the installation method and installation sequence are wrong, it will affect the installation of the flange and make the flange unable to be installed. During use, due to the influence of the transportation medium and operating conditions, loosening and slipping may also occur, which will cause pipeline leakage.

Therefore, in order to use the butt-weld flange better and longer in the future, we need to master the correct installation method and installation sequence of the welding flange.

Use Of Weld Neck Flange

Before connecting the butt-weld flange, arrange the inside and outside of the stainless steel pipe fittings, and then install the flange with a grooved ring on the pipe to be connected.

Above, the pipe port needs to be flanging at 90 degrees. After processing, the port surface of the pipe needs to be polished. After polishing, it should be free of burrs, bumps, and deformations, vertical and flat, and special tools need to be used to round it.

Use the finished product to flange the short pipe and then weld it on the pipe for use. Insert the O-ring rubber seal and stainless steel seal installed on both sides into the flange with a groove ring for sealing.

The inner diameter of the inner hole of the sealing ring is the same as the inner diameter of the pipe, and then the flange holes are connected with bolts. The bolt assembly needs to be tightened symmetrically. When tightening the butt welding flange, pay attention to the sealing of each joint and meet the required specifications.

The flat welding flange is a concave platform slightly larger than the outer diameter of the pipe processed at the interface, and the pipe is inserted and welded inside. The welding performance of the butt welding is relatively good and the corrosion is relatively small. Flat welding flanges are commonly employed for low to medium pressure pipelines, while butt welding flanges are utilized for connecting medium to high pressure pipelines. The use of butt welding flanges is recommended for pressures of at least PN2.5MPa due to their ability to reduce stress concentration effectively.

Comparison Between Neck Slip-On Flange And Neck Butt Weld Flange

Flat welding flange is a flange connected to a container or pipeline by a fillet weld, which belongs to an arbitrary flange. In the design phase, we meticulously assess the connection between the flange ring and the straight section to ensure optimal integrity. This crucial check allows us to determine whether the connection is integral or loose.

While the butt welding flange with a neck is effective, the flat welding flange offers a simpler and more efficient structure，so less material is used in the manufacturing process, but its rigidity and sealing are not as good as the butt welding flange with neck. However, since the flat welding flange is easy to center during welding and assembly, and the price is relatively cheap, it has been widely used in many applications. Flat welding flanges are mainly suitable for pipeline systems with relatively low pressure levels and no serious pressure fluctuations, vibrations and shocks. Its product specifications range from DN10 to DN2000.

It is worth noting that flat welding flanges are not allowed to be directly welded with pipe fittings such as tees and elbows, but a straight pipe section needs to be added between these pipe fittings and the flange. In addition, flat welding steel flanges are the most commonly used pipe fittings in medium and low pressure pipelines, and the operating pressure range is generally PN0.25MPa to PN4.0MPa.

Necked flat welding flanges are also flat welding flanges. Because of the short neck, the strength of the flange is improved and the bearing capacity of the necked flat welding flange is improved. Therefore, it can be used on pipelines with higher pressure. However, it is more expensive than plate-type flat welding flanges, and it is more likely to bump during transportation due to its shape.

Due to the unique transition structure of the cone neck and the efficient shortcut butt welding connection,the strength and rigidity of the necked butt welding flange are enhanced, and the sealing is better than that of the flat welding flange. It is suitable for occasions with high pressure, high neck or high sealing requirements.