Introduction to flange types and models

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This post was last edited by Cuaili Yisu on 2018-12-1 at 11:09. Introduction to Flange Types and Models: Flanges are a commonly used method for pipe connection, but depending on the pressure conditions under which they are used, the types of flanges and their sealing surfaces vary. Below is a brief introduction to the different types and models of flanges. I. Classification of flanges 1. Classified according to chemical industry standards: Integral flange (IF), Threaded flange (Th), Plate flat welding flange (PL), Welding neck flange (WN), Socket weld flange (SO), Slip-on welding flange (SW), Ring joint loose-flange (PJ/SE), Flat welding ring loose-flange (PJ/RJ), Lined flange cover (BL(S)), Flange cover (BL). 2. Classified according to petrochemical industry standards: threaded flanges (PT), butt-welded flanges (WN), socket-welded flanges (SO), slip-welded flanges (SW), loose-flange type flanges (LJ); flange covers (not specified). 3. Classified according to mechanical industry standards: integral flanges, butt-welded flanges, plate-type socket weld flanges, butt-welded ring plate-type loose flanges, plate-type socket weld ring plate-type loose flanges, flanged ring plate-type loose flanges, and flange covers. Flat welding steel flanges: Suitable for connecting carbon steel pipelines with a nominal pressure not exceeding 2.5 MPa. The sealing surfaces of flat welding flanges can be designed in three types: smooth, ribbed, and tongue-and-groove. Smooth flat welding flanges are the most widely used; they are employed in situations where the medium conditions are relatively mild, such as low-pressure, unpurified compressed air or low-pressure circulating water. Their advantage is their relatively low cost ； Butt-welded steel flanges: Used for welding flanges to pipes; they have a rational structure, high strength and stiffness, can withstand high temperatures and pressures as well as repeated bending and temperature fluctuations, and offer reliable sealing performance. Butt-welded flanges with a nominal pressure of 0.25–2.5 MPa feature male-female type sealing surfaces. Socket-welded flanges: Commonly used in pipes with PN≤10.0 MPa and DN≤40 ； Loose-flange: Also known as a flexible flange, loose-flanges are divided into weld-ring type flexible flanges, flanged-type flexible flanges, and butt-welded flexible flanges. They are commonly used in situations where the temperature and pressure of the medium are not high, but the medium has strong corrosive properties. When the medium is highly corrosive, the part of the flange that comes into contact with the medium (the flanged stub) is made of corrosion-resistant high-grade materials such as stainless steel, while the outer portion is secured using lower-grade materials such as carbon steel flange rings to achieve sealing ； Integral flange: The flange is often integrated with equipment, pipes, fittings, valves, etc.; this type is commonly used on equipment and valves.