Flanges

Flanges are connecting elements that consist of flat rings with holes for bolts or studs. They are used for leak-proof and durable connections of pipelines, pipeline fittings, equipment, and other components. The main function of flanges is to provide reliable connections that can be easily disassembled for maintenance, repair, or replacement of parts.

Working principle of flanges

A flanged connection consists of two flanges with a sealing gasket placed between them. These elements are tightened with bolts or studs to ensure leak-proofness. 

Types of flanges

There are several main types of flanges depending on their design:

1. Flat welded flanges: Used for low pressure (up to 2.5 MPa).
2. Collar flanges: Provide increased strength due to their conical projection ("collar"). 
3. Loose flanges: Used in hard-to-reach places or when frequent disassembly/repair is needed.
4. Threaded flanges: Applied without welding on small diameter pipes at low pressure.
5. Blind flanges: Used to seal the end of pipes or equipment.

Main standards for different types of flanges

GOST 12820-80 describes flat welded steel flanges designed for operating pressures from 0.1 to 2.5 MPa. These flanges have a simple design and are used in various industries. They consist of metal discs with fastener holes that are welded to pipes. Flanges according to this standard are widely used in water supply and heating systems.

GOST 12821-80 describes collar welded flanges that are also used for pipeline connections. These flanges have a conical projection (collar) that provides additional connection strength. Collar flanges ensure high leak-proofness and reliability of connections under high pressure.

GOST 12822-80 describes loose flanges with welded rings. These flanges consist of two parts: the flange itself and a ring that is welded to the pipe. They are convenient for installation in hard-to-reach places and are used in systems requiring frequent repairs. This type of flange allows easy equipment installation and disassembly without pipe cutting.

GOST 12836-67 describes flange blinds (blind flanges) for pipelines. Blinds are special elements for sealing pipe ends or nozzles. They are used for temporary or permanent sealing of pipeline systems.