How Do I Choose the Correct Flange Dimensions?

The national standard law ^[1] blue means that the material and workmanship of the flange meet national standards. National standard flange English (National standard flange) refers to the flange plate produced in accordance with the national standard of the People's Republic of China "GB / T 9112 ~ 9124-2010 steel pipe flange".

GB flange

National standard

Forged steel, WCB

The GB flange connection is to fix two pipes, pipe fittings or equipment to a flange plate, and then add flange pads between the two flange plates and fasten them with bolts. connection. Some pipe fittings and equipment already have flanges, which are also flange connections. Flange connection is an important connection method for pipeline construction. The flange connection is easy to use and can withstand large pressures. The flange connection is widely used in industrial pipelines. In the home, the pipe diameter is small and the pressure is low, so the flange connection is not visible. If in a boiler room or production site, flanged pipes and equipment are everywhere.
1. According to the connection method, the flange connection types can be divided into: plate-type flat welding flanges, flat neck welding flanges with necks, butt welding flanges with necks, socket welding flanges, threaded flanges, flange covers, and neck pairs Welded ring loose sleeve flange, flat welded ring loose sleeve flange, ring groove surface flange and flange cover, large diameter flat flange, large diameter high neck flange, blind figure, butt welding ring loose flange .

GB series (GB / T9119-2010 national standard)

JB series (machinery department)

HG series (HG20592 standard of Ministry of Chemical Industry)

ASME B16.5 (American Standard)

BS4504 (British Standard)

DIN (German Standard)

JIS (Japanese Standard)

CBM (ship mark)

There are two main international pipe flange standards, namely the European pipe flange system represented by German DIN (including the former Soviet Union) and the American pipe flange system represented by American ANSI pipe flange. In addition, there are Japanese JIS pipe flanges, but they are generally only used for public works in petrochemical plants, and have a small international impact. The pipe flanges of various countries are introduced below:

1. European system pipe flanges represented by Germany and the former Soviet Union.

2. American system pipe flange standards, represented by ANSI B16.5 and ANSI B 16.47.

3. British and French pipe flange standards, each country has two casing flange standards.

In summary, the internationally accepted standard for pipe flanges can be summarized as two different and non-interchangeable pipe flange systems: one is the European pipe flange system represented by Germany; the other is the United States. American tube flange system.

IOS7005-1 is a standard promulgated by the International Organization for Standardization in 1992. This standard is actually a pipe flange standard combining two sets of pipe flanges from the United States and Germany. The pipe flange connections of the two systems have different safety dimensions and cannot be mutually matched.

The pipe flanges of the two systems are most appropriately distinguished by pressure level, that is, the European system is 0.25, 0.6, 1.0, 1.6, 2.5, 4.0, 6.3, 10.0, 16.0, 25.0, 32.0, 40.0MPa, and the American system is 1.0, 2.0. , 5.0, 11.0, 15.0, 26.0, 42.0 MPa.

The production process is mainly divided into forging, casting, cutting, and rolling.

Cast and forged flanges

The cast flange has accurate blank shape and size, small processing volume and low cost, but has casting defects (porosity, cracks, inclusions); the internal organization of the casting is less streamlined (if it is a cutting part, the streamlined shape is worse);

Forged flanges generally have lower carbon content than cast flanges and are less prone to rust. The forgings are streamlined, the structure is denser, and the mechanical properties are better than those of the cast flanges. Improper forging processes can also cause large or uneven grains, hardening cracks, and forging Higher than the cast flange.

Forgings can withstand higher shear and tensile forces than castings.

The advantages of castings are that they can produce more complex shapes and lower costs;

The advantage of forging is that the internal structure is uniform, and there are no harmful defects such as pores and inclusions in the casting;

The difference between cast flanges and forged flanges from the production process, such as centrifugal flanges are a type of cast flanges.

The centrifugal flange belongs to the production flange of the precision casting method. This type of casting has a much finer structure and a lot of quality improvement than ordinary sand mold casting, and it is not easy to have problems such as loose tissue, porosity and trachoma.

First of all, we need to understand how centrifugal flanges are produced and made by centrifugal casting.

National standard: GB / T9112-2000 (GB9113 · 1-2000 GB9123? 4-2000)
Ministry of Chemical Industry Standards: HG5010-52 HG5028-58, HGJ44-91 HGJ65-91, HG20592-2009 series, HG20615-2009 series Machinery Department standards: JB81-59 JB86-59, JB / T79-94 JB / T86 -94, JB / T74-1994 pressure vessel standards: JB1157-82 JB1160-82, JB4700-2000 JB4707-2000 B16.47A / B B16.39 B16.