Flange connection involves fixing two pipes, fittings, or equipment individually to flange discs, inserting a flange gasket between them, and securing them together with bolts, thus completing the connection. Some fittings and equipment come with a built-in flange disc, which also falls under flange connection. Flange connection is an important method in pipeline construction.
According to the connection method, flange types can be classified as: flat welding flange, socket welding flange, blind flange, threaded flange, and flange cover with socket welding ring.
Socket flange, flat welding ring loose flange, ring groove face flange and flange cover, large diameter flat flange, large diameter high neck flange, L-shaped blind flange, welding ring loose flange, etc.


Flat welding flanges are suitable for steel pipe connections with nominal pressure not exceeding 2.5MPa. The sealing surfaces of flat welding flanges can be made in three types: smooth, concave-convex, and tenon-slot. Smooth flat welding flanges are used for...
Usage. Commonly used in milder medium conditions, such as low-pressure non-purified compressed air, low-pressure circulating water.
The neck height of the socket welding flange is lower, which improves the rigidity and load-bearing capacity of the flange. Compared to the blind flange, it requires more welding work and consumes more welding rods.High-pressure andBend recovery and temperature fluctuations, but easy on-site installation, and can omit the process of welding seam knocking, which is quite popular.


A flat welding ring loose flange is a movable flange plate, commonly used with plumbing and drainage accessories (most often with expansion joints). When the manufacturer ships the product, each end of the expansion joint comes with a flange, which is directly connected to the pipeline and equipment in the project using bolts. The general purpose of using a flat welding ring loose flange is to save materials. Its structure is divided into two parts: one part connects to the pipe, and the other is formed into a flange edge. The flange is then fitted over the flange edge. The flange is made of low-grade material, while the pipe section uses the same material as the pipeline, achieving the goal of material savings.

Loose-bolt flange with socket weld ring, socket weld loose flange, flat weld ring loose flange, loose flange with flipped plate, and additional flanges with bored shafts for post-installation locking, which prevent bolts from loosening due to vibration. Some flange bolts have smooth rods without threads and need to be made finer, known as slender rod flange bolts. These bolts are beneficial for connections subjected to variable forces. High-strength bolts with larger heads are used in steel structures, and their sizes may vary. Hot-dip galvanized round steel is produced by causing the molten metal to react with the iron substrate to form an alloy layer.