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The classification of flange types 2021/01/14 21:17:25

EATHU has been engaged in the production of flange pipe fittings for more than 20 years and has rich experience in flange and pipe fitting products. The following is the classification of flange types:


1. Flange types are classified according to the type of use: integral flange, threaded flange, butt welding flange, flat welding flange with neck, socket welding flange with neck, butt welding ring loose flange with neck, plate flat Welding flange, butt-welding ring plate loose flange, flat welding ring plate loose flange, flanged ring plate loose flange, blind flange.


2. Flange types are classified according to chemical industry standards: integral flange (IF), threaded flange (Th), plate flat welding flange (PL), butt welding flange with diameter (WN), flat welding flange with neck (SO), socket welding flange (SW), butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), lining flange cover (BL(S)), Flange cover (BL).


3. Flange types are divided into petrochemical industry standards: threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose flange (LJ) , Flange cover (BL).


4. Flange types are classified according to mechanical industry standards: integral flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flange ring plate loose flange Flange, flange cover.


    Flat-welded steel flanges: suitable for carbon steel pipe connections with a nominal pressure not exceeding 2.5MPa. The sealing surface of flat-welded flanges can be made into three types: smooth, concave-convex and tongue-and-groove types. Smooth flat-welded flanges The application is the largest. It is mostly used when the medium conditions are relatively mild, such as low-pressure non-purified compressed air, low-pressure circulating water, and its advantage is that the price is relatively cheap;


    Butt-welding steel flanges: used for butt welding of flanges and pipes. It has a reasonable structure, high strength and rigidity, can withstand high temperature and pressure, repeated bending and temperature fluctuations, and has reliable sealing. The nominal pressure is 0.25 ~ 2.5MPa Butt welding flange adopts concave and convex sealing surface.


    Socket welding flange: commonly used in pipelines with PN≤10.0MPa and DN≤40;


    Loose flanges: loose flanges are commonly known as loose flanges, sub-welded ring loose flanges, flanged loose flanges and butt welded loose flanges. Commonly used for medium temperature and pressure are not high and the medium is corrosive Stronger situation. When the medium is highly corrosive, the part of the flange contacting the medium (flanging nipple) is made of corrosion-resistant high-grade materials such as stainless steel, and the outside is clamped by low-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.



ASME B16.5   Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 

ASME B16.47  Large Diameter Steel Flanges: NPS 26 Through NPS 60 

ASME B16.48  Line blanks

ASME B16.36  Orifice Flanges

MSS SP-6 Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and Fittings

ASME B16.20  Metallic Gaskets for Pipe Flanges: Ring-Joint, Spiral-Wound, and Jacketed

ASME B16.21  Nonmetallic Flat Gaskets for Pipe Flanges

ASME B18.2.1  Square and Hex Bolts and Screws, (Inch Series)

ASME B18.2.2  Square And Hex Nuts (inch Series)

ASTM A193  Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications

ASTM A194  Standard Specification for Carbon and Alloy Steel Nuts for Bolts for High Pressure or High Temperature Service, or Both


EN 1092 Flanges and their joints — Circular flanges for pipes,valves, fittings and accessories, PN designated —

Part 1: Steel flanges;

Part 2: Cast iron flanges;

Part 3: Copper alloy flanges;

Part 4: Aluminium alloy flanges.


GB/T 9112-2010 Types and parameters for steel pipe flanges 

GB/T 9113-2010 Integral steel pipe flanges 

GB/T 9114-2010 Hubbed screwed steel pipe flanges 

GB/T 9115-2010 Steel pipe welding neck flanges 

GB/T 9116-2010 Hubbed slip-on-welding steel pipe flanges 

GB/T 9117-2010 Hubbed socket welding steel pipe flanges 

GB/T 9118-2010 Loose hubbed steel pipe flanges with welding neck collor 

GB/T 9119-2010 Slip-on-welding plate steel pipe flanges

GB/T 9120-2010 Loose plate steel pipe flanges with weld-neck collar and with weld ring neck 

GB/T 9121-2010 Loose plate steel pipe flanges with weld-on collar 

GB/T 9122-2010 Loose plate steel pipe flanges with lapped pipe end and pressed collar with long neck 

GB/T 9123-2010 Steel pipe blank flanges 

GB/T 9124-2010 Specification for steel pipe flanges

GB/T 13402-2010 Large diameter steel pipe flanges


HG/20592-2009 Steel pipe flanges(PN designated)

HG/20615-2009 Steel pipe flanges(Class designated)

HG/20623-2009 Large Diameter Steel pipe flanges(Class designated)


In use, the type of flange is selected according to the needs of pipeline construction. The most commonly used are slip on flanges and weld neck flanges. If you have any questions about the choice of flange type, you can contact EATHU for technical consultation.


For download the flange standard PDF format, please check from eathu website: www.eathu.com  .


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