What are the common flange types and specifications?

Flanges are common connection parts in pipeline engineering, and their types and specifications are diverse. The following are common types and specifications of flanges:

First, the type of flange

Flat welded flange

Plate flat welded flange: convenient materials, simple manufacturing, low cost, but poor rigidity, suitable for low pressure, low temperature occasions. The sealing surface type has plane (FF) and protruding surface (RF).

With neck flat welding flange: the site installation is more convenient, can omit the weld patting kneading process. The neck height is low, which improves the stiffness and bearing capacity of the flange, but the welding workload is large, the electrode consumption is high, and it can not withstand high temperature and pressure, repeated bending and temperature fluctuations.

Butt welded flange

Neck butt welding flange: the connection is not easy to deform, the sealing effect is good, and the application is widely. It is suitable for pipelines with large temperature or pressure fluctuations or pipelines with high temperature, high pressure and low temperature, and also for pipelines with expensive media, inflammable and explosive media and toxic gases. The sealing surface forms are convex surface (RF), concave surface (FM), convex surface (M), tenon surface (T), groove surface (G), and full plane (FF).

Integral flange: also belongs to a neck butt welded steel pipe flange, the material is carbon steel, stainless steel, alloy steel and so on. The sealing surface is generally a sudden surface (RF), and the sealing surface form of the convex and concave surface (MFM) and the mortise and groove surface (TG) can be selected in the flammable, explosive, high and extremely hazardous working conditions.

Socket welding flange

One end is welded to the steel pipe, and the other end is bolted. The sealing surface forms are a convex surface (RF), a concave and convex surface (MFM), a mortise and groove surface (TG), and a ring connection surface (RJ). It is commonly used in pipelines with PN≤10.0MPa and DN≤40.

Threaded flange

The inner hole of the flange is machined into pipe thread, which is connected with the pipe with thread. It is a non-welded flange. It has the characteristics of easy installation and maintenance, and can be used in some pipelines that are not allowed to be welded on site. However, when the temperature of the pipeline changes sharply or the temperature is higher than 260 ° C and lower than -45 ° C, it is not recommended to use threaded flanges to avoid leakage.

Loose sleeve flange

Butt welded ring loose sleeve flange: it is a movable flange, which is generally matched on the water supply and drainage accessories, and is directly connected with the pipe and equipment in the project with bolts. The purpose is to save materials, the structure is divided into two parts, the pipe part and the pipe are connected, one end is made into a butt welding ring, and the flange is made of low grade materials.

Flat welded ring loose sleeve flange: similar to the butt welded ring loose sleeve flange, but the pipe part is made into a flange, and the flange part is set on the flip side.

Flange cover (blind flange)

Flange without hole in the middle for sealing pipe plugs. The sealing surface has a plane (FF), a convex surface (RF), a concave and convex surface (MFM), a mortise and groove surface (TG), and a ring connection surface (RJ).

Reducing flange

Connect two pipes or fittings of different diameters. It has the characteristics of anti-corrosion, acid and alkali resistance, long service life, etc., and is widely used in water conservancy, electric power station, pipeline fittings, industry, pressure vessels and other fields.

Stainless steel flange

The flange made of stainless steel has excellent corrosion resistance and high temperature resistance. Various specifications, high pressure grade, suitable for a variety of corrosive media and high temperature environment.

Vacuum flange

Mainly used in vacuum systems, common types are CF flanges, KF flanges and ISO flanges. With a high degree of tightness and stability, it is suitable for extreme environments such as ultra-high vacuum and high temperature baking.

Second, flange specifications

Flange specifications are usually expressed in nominal diameter (DN) and pressure rating. The following are some common flange specification ranges:

Nominal diameter (DN) : DN10 ~ DN6000, the specific range depends on the type and use of the flange.

Pressure grade: from low pressure to high pressure, such as PN0.25 ~ PN42.0, 0.6MPa ~ 32MPa, 150Lb ~ 2500Lb and so on. The specific pressure level is determined according to the flange material, sealing surface form and working environment.

In addition, the specification of the flange is also related to its manufacturing standards, such as GB series (national standard), JB series (mechanical department), HG series (chemical department), ASME B16.5(US standard), BS4504(British standard), DIN(German standard), JIS(Japanese standard) and so on. Different standard flanges may differ in size, tolerance and performance.

In summary, there are a variety of types and specifications of flanges, and the selection needs to determine the appropriate type and specifications according to the specific working environment and requirements.