It consists of a flat ring or disc with evenly spaced holes for screws and studs that are essential for a strong and tight connection. Flanges vary in size, mounting method and shape of the facing.For a high level sealing between the flanges, while mounting them with bolts, are used gaskets made of various materials. During the production of flanges special attention is paid to the processing of sealing surfaces ("mirror" of the flange), and positioning of connecting holes.
Flanges are made of the same material as the pipe or fitting for which it is produced. They are made of various materials such as carbon and alloy steels, cast irons, non-ferrous alloys. The variety of materials used in the manufacture allows to use these parts in different conditions of external and internal environment.
According to the design, as well as the characteristics of the installation and operation flanges can be divided into several types:
- Flat welded stainless steel flange GOST 12820-80
When mounting the flange is welded by two weld seams around to the end of the tube. They are produced in nominal diameter up to 2400mm for pressure up to 2.5 MPa.
- Butt-weld steel flange to GOST 12821-80
Installation is performed by one weld, which simplifies installation and reduces time costs. Produced in nominal diameter up to 1600 mm for pressure up to 20 MPa.
- Loose ring welded steel flange GOST 12822-80
It consists of a flange and a ring. The flange and ring correspond to one diameter and pressure. When attaching to only one ring is welded, flange remains loose, that allows easy connection of flange to the bolt holes of the fittings attached. Produced in nominal diameter up to 1600 mm for pressure up to 20 MPa.
- Flanges for vessels and devices GOST 28759.2-90
When mounting the flange is welded by one or two weld seams around to the end of the pipe. This type is used for interchangeability and unification of flanges for vessels and devices. Designed for use in the chemical, oil, petrochemical and other industries. Produced in nominal diameter up to 4000mm for pressure up to 1.6 MPa.
- Flanges for fittings, connecting pieces and piping for nominal pressure from PN 1 to PN 200 GOST R 54432-2011.
Produced in nominal size up to 4000 mm for pressure up to 20 MPa.
- Design 1 – raised face flange;
- Design 2 – male flange;
- Design 3 – female flange;
- Design 4 – tongue flange;
- Design 5 – groove flange;
- Design 6 – ring type joint flange;
- Design 7 – oval ring type joint flange;
- Design 8 – tongue flange with compulsory use of PTFE gaskets;
- Design 9 – groove flange with compulsory use of PTFE gaskets.