Flange Assembly
Flanges offer a mechanical means of joining pipes, fittings (elbows, tees etc.), and valves. Compared to welds, flanges are a non-permanent type of joint that can be easily assembled and disassembled (ideal for systems that require maintenance). Flanges are installed via welding, screwing, or lapping, and they are the second most popular joining method after welding.
Flange (blade, hub).
Gasket (metallic, composite, or non-metallic).
Fasteners (nuts, bolts, or studs).
Flanges Construction
Flanges are split into two main areas, the ‘blade’, and the ‘hub’.
The flange blade encompasses the area where the bolts penetrate through the flange and the flange face.
The flange hub is the area that accommodates the pipe which attaches to the flange.
To ensure no leaking between the mating2 flanges occurs, gaskets are used. It is possible to mate two metal flanges together without the use of gaskets, but sealing is difficult and can only be achieved with specially designed flanges.
The end connection specifies how the flange is connected to its accompanying pipe (threaded connection or welded).
How Flange Work
A flange is created when two opposing surfaces are intentionally pressed together in order to create a leak tight seal. To obtain a seal, force must be applied and maintained to each of the opposing flange faces. As many flange faces have manufacturing imperfections (scratches, dents, pits etc.), it is necessary to put a softer material between the two mating sealing surfaces to obtain the seal; this softer material is the gasket.