Introduction to Titanium Flanges
Flange, introduced by a British individual named Erlcharlt in 1809, also proposed the casting method for flanges. However, for quite some time afterward, flanges were not widely used until the early 20th century when they became extensively utilized in various mechanical equipment and piping connections.
Flange, also known as a flange disk or flange protrusion, typically refers to a metal body with a disc-like shape with several fixed holes around its perimeter for connecting to other components. Flanges are widely used in various mechanical equipment and piping connections. They serve as parts for connecting shafts and pipes, used for connecting the ends of pipes, and are also used in equipment inlets and outlets to facilitate connections between two devices, such as gearbox flanges.
Classification of Flanges:
1. According to the Chemical (HG) Industry Standard:
ntegral Flange (IF)
Threaded Flange (Th)
Plate Flat Welding Flange (PL)
Weld Neck Flange (WN)
Slip-on Flange (SO)
Socket Welding Flange (SW)
Loose Flange with Welding Ring Joint (PJ/SE)
Loose Plate Flat Welding Flange (PJ/RJ)
Lined Flange Cover (BL(S))
Flange Cover (BL)
2. According to the Petrochemical (SH) Industry Standard:
Threaded Flange (PT)
Weld Neck Flange (WN)
Slip-on Flange (SO)
Socket Welding Flange (SW)
Loose Flange (LJ)
Flange Cover (Unspecified)
Flange Standards:
Flanges, as connectors, are widely used internationally, necessitating unified standards. For example, there are currently two main standard systems for pipe flanges: the European pipe flange system represented by Germany's DIN and the American pipe flange system represented by the American National Standards Institute (ANSI). The following is a brief introduction to pipe flanges from various countries:
1. European Flange System:
European Flange System: German DIN
Nominal Pressure: 0.1, 0.25, 0.6, 1.0, 1.6, 2.5, 4.0, 6.4, 10.0, 16.0, 25.0, 32.0, 40.0 MPa;
Nominal Diameter: 15 to 600 mm;
Flange Structure Forms: Plate Flat Welding, Loose Plate Flat Welding, Rolled Loose Plate, Weld Neck Rolled Loose Plate, Weld Neck Loose Plate, Welding, Neck Threaded Connection, Integral, and Flange Cover;
Flange Sealing Surfaces: Flat, Concave, Convex, Tongue and Groove, Rubber Ring Connection, Lens, and Diaphragm Welding.
2. American Flange System:
American Flange System: American ANSI B16.5 "Steel Pipe Flanges and Flanged Fittings"
Nominal Pressure: 150 psi (2.0 MPa), 300 psi (5.0 MPa), 400 psi (6.8 MPa), 600 psi (10.0 MPa), 900 psi (15.0 MPa), 1500 psi (25.0 MPa), 2500 psi (42.0 MPa);
Nominal Diameter: 6 to 4000 mm;
Flange Structure Forms: Butt Welding, Socket Welding, Threaded Connection, Loose, Welding, and Flange Cover;
Flange Sealing Surfaces: Concave, Convex, Tongue and Groove, Metal Ring Connection.
Flange Assembly
1. Before assembling the flange, it is essential to clean the flange surface, especially the sealing surface.
2. When assembling flat welding flanges, the pipe end should be inserted into the flange with a thickness of 2 to 3 times the inner diameter of the flange, then spot-welded to the pipeline. For horizontal pipes, the flange should be spot-welded from above, then checked and corrected for its position with a 90-degree angle ruler from different directions to ensure that the sealing surface is perpendicular to the centerline of the pipeline, and the second spot weld is correct.
3. Check and correct the flange position from left and right directions with a 90-degree angle ruler, spot weld the third and fourth points after passing through, to complete the spot welding and fixing of the flange.
4. Regarding the assembly of flange discs, the bolt holes for installing the flange should align with the corresponding bolt holes of the fixed flange, and be parallel to the fixed flange. The deviation should not be less than 1.5% of the outer diameter of every thousand flanges, and not more than 2mm.
5. When selecting matching flanges for equipment or valve components, attention should be paid to whether the flanges of the original equipment or valve components are consistent with the flange connection sizes used in the pipeline.
Common Gasket Materials for Flanges
Rubber sheets and rubberized asbestos sheets are commonly used gasket materials for flanges.
1. Industrial Rubber Sheet
Industrial rubber sheets, also known as industrial vulcanized rubber sheets or rubber sheets.
2. Rubberized Asbestos Sheet
Rubberized asbestos sheets, generally used as gaskets for sealing equipment and pipe flanges. Media can include water, steam, air, various gases, ammonia solution, alkali solution, and oil, etc.
Flange Connection
1. Flange connections should be kept on the same axis, and the deviation of the bolt hole center should not exceed 5% of the aperture, and the bolts should pass freely. The connecting bolts of the flange should have the same specifications, the installation direction should be the same, and the bolts should be symmetrically and evenly tightened.
2. Different thickness inclined washers should not be used to compensate for the non-parallelism of the flange. Double washers should not be used. When large-diameter washers need to be spliced, they should not be docked with flat ports, but should be in the form of oblique lap or labyrinth.
3. For the convenience of installing and disassembling flanges, the distance between fastening bolts and flange faces should not be less than 200 mm.
4. When tightening bolts, it should be symmetrical and intersecting to ensure that the gaskets are uniformly stressed.
5. Bolts and nuts should be coated with molybdenum disulfide, graphite oil, or graphite powder for subsequent removal: stainless steel, alloy steel bolts and nuts; pipelines designed for temperatures at or below 100°C or 0°C; outdoor facilities; atmospheric corrosion or corrosive media.
6. Metal washers such as copper, aluminum, and soft steel should be annealed before installation.
7. Direct burial of flange connections is not allowed. Flange connections for buried pipelines should have inspection wells. If burial is necessary, corrosion protection measures should be taken.
