China's steel stainless steel flange national standard system GB.
1, nominal pressure: 0.25Mpa~42.0Mpa
Series 1: PN1.0, PN1.6, PN2.0, PN5.0, PN10.0, PN15.0, PN25.0, PN42 (main series)
Series 2: PN0.25, PN0.6, PN2.5, PN4.0
Among them, PN0.25, PN0.6, PN1.0, PN1.6, PN2.5, PN4.0, a total of 6 grades of flange size belong to the European flange system represented by the German flange, and the rest are the American flange system represented by the American flange stainless steel flange.
In the GB standard, the maximum nominal pressure level belonging to the European flange system is 4Mpa, and the maximum nominal pressure level belonging to the American flange system is 42Mpa.
2, nominal diameter: 10mm~4000mm
3, flange structure form:
① Integral flange ② unit flange
Threaded flange;
Welded flange, butt welded flange;
Flat welded flange with neck, flat welded flange with neck socket, flat welded flange: loose sleeve flange, butt welded ring with neck flange, butt welded ring with loose sleeve flange, flat welded ring with loose sleeve flange, plate over loose sleeve flange
Flange cover (blind hole flange).
4, flange sealing surface: plane, concave, concave and convex surface, mortise and groove surface, ring connection surface
Flange assembly
1. Before assembling the flange, the surface of the flange must be cleaned, especially the sealing surface.
2. When assembling the plate welded flange, the pipe end should be inserted into the inner diameter thickness of the flange 2≤3, and then the flange and the pipe should be spot-welded. If it is a horizontal pipe, the flange should be spot-welded from above, and then the flange position is checked and corrected with a 90° Angle ruler from different directions, so that the sealing surface is perpendicular to the center line of the pipe, and then the second point under the spot welding is correct.
3. Check and correct the flange position from the left and right directions with the 90° Angle ruler, and finish the spot welding and fixing of the flange through the third and fourth points.
4. As far as the assembly of flanges is concerned, the bolt holes of the mounting flanges should be aligned with the corresponding bolt holes of the fixed flanges, and parallel to the fixed flanges, the deviation shall not be less than 1.5% of the outer diameter of each thousand flanges, and shall not be greater than 2mm.
5. When selecting the matching flange of the equipment or valve parts, pay attention to whether the flange of the original equipment or valve parts is the same as the connection size of the flange used in the pipeline.