Flange connection involves securing two pipes, fittings, or equipment to separate flange discs first, then inserting a flange gasket between the two flanges and tightening them together with bolts to complete the connection. Some fittings and equipment come with a flange disc already attached, which also falls under flange connection. Flange connection is an essential method for pipeline construction.
According to the type of connection, flange connections can be classified into: flat welding flange, socket welding flange, blind flange, threaded flange, and ring joint flange.
Socket flange, flat welding ring loose flange, ring groove flange and flange cover, large diameter flat flange, large diameter high-neck flange, blind flange with beak, socket weld ring loose flange, etc.


Flat焊接flanges are suitable for steel pipeline connections with nominal pressure not exceeding 2.5 MPa. The sealing surfaces of flat welding flanges can be made in three types: smooth, concave-convex, and tenon-slot. Smooth flat welding flanges are applicable for...
Usage. Typically used under 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 and temperature fluctuations, but easier on-site installation; can omit the weld seam smoothing process, and is well-received.


Flanged loose-fitting flanges are movable flange plates, commonly used with plumbing and drainage accessories (most often with expansion joints). At the factory, each end of the expansion joint is equipped with a flange, which is directly connected to the pipes and equipment in the project with bolts. The general purpose of using flanged loose-fitting flanges is to save materials. The structure is divided into two parts: the pipe section connects to the pipe with one end and is flanged on the other, while the flange plate section fits over the flange. The flange plate is made of low-grade material, and the pipe section is made of the same material as the pipe, achieving the goal of material savings.

Loose-bolt flanges with socket weld rings, socket weld plate flanges, flat weld ring loose-bolt plate flanges, inverted loose-bolt plate flanges. Additionally, for the need of locking after installation, there are bolts with holes in the shank to prevent loosening due to vibration. Some法兰bolts without threads have a slender shank, known as slender shank法兰bolts. These法兰bolts are beneficial for connections subjected to variable forces. Special high-strength bolts are used in steel structures, with larger heads and varying sizes. Hot-dip galvanized round steel is produced by causing the molten metal to react with the iron substrate to form an alloy layer.