The core definition and functions of flange

A flange is a disc-shaped part with bolt holes, which forms a detachable rigid connection between pipes and pipes or between pipes and equipment through bolt connections. Its core functions include:

Connection and sealing: Fill the gap of the flange sealing surface with gaskets (such as rubber or metal wound gaskets) to prevent medium leakage.

Support the pipeline: Disperse the stress of the pipeline to prevent damage at the connection points due to concentrated force.

Easy to maintain: The detachable structure facilitates pipeline inspection, replacement or expansion.

Classified by structural form

Flat welding flange (SO) : The flange is directly fillet welded to the pipeline. It is easy to install but has relatively low rigidity. It is suitable for low-pressure (≤2.5MPa) and normal temperature scenarios.

It is applied to building water supply and drainage and ordinary industrial pipelines

Butt-weld flange (WN) : The flange and the pipeline are welded by butt welding, with high weld strength, capable of withstanding high pressure (≥4.0MPa), high temperature or corrosive media.

It is applied to high-pressure pipelines in chemical engineering, petroleum and power stations

Socket welding flange (SW) : The pipe is inserted into the inner hole of the flange for welding to prevent medium retention. It is suitable for small-diameter (DN≤50) and high-pressure pipes.

It is applied to the connection of instrument pipelines and autoclaves

Loose flange (LF/SE) : The flange is placed on the pipe and can rotate freely, facilitating alignment with bolt holes. It is suitable for corrosive pipes (such as stainless steel).

Scenarios that require frequent disassembly or have high anti-corrosion requirements

Threaded flange (Th) : It is connected to the pipe through threads without welding and is suitable for galvanized steel pipes or plastic pipes.

It is applied to low-pressure water pipelines and temporary pipeline systems