How to design flange?

Brief introduction of flange

Pipe flange, gasket and fastener are called flange joint. Flange joint is widely used in chemical engineering design, involving a wide range of parts. It is not only an essential part of piping design, pipe fitting and valve, but also an essential component of equipment, equipment parts such as manhole, sight glass, liquid level gauge, etc. In addition, flange joints are often used in other specialties, such as industrial furnace, thermal engineering, water supply and drainage, heating and ventilation, automatic control, etc.

20210324004734 99557 - How to design flange?

How to design flange?

Standard system of pipe flange:

There are mainly two systems of pipe flange standards in the world, namely, the European pipe flange system represented by din of Germany, including the former Soviet Union, and the American pipe flange system represented by ANSI pipe flange of the United States. In addition, there are JIS pipe flanges in Japan, but they are generally only used for public works in petrochemical plants, and have little influence in the world. The pipe flanges of various countries are introduced as follows:

  • 1. European system pipe flange represented by Germany and former Soviet Union.
  • 2. American system pipe flange standards, represented by ANSI B16.5 and ANSI B16.47.
  • 3. British and French pipe flange standards, each of which has two casing flange standards.

To sum up, the internationally accepted pipe flange standards can be summarized as two different and non interchangeable pipe flange systems: one is the European pipe flange system represented by Germany, and the other is the American pipe flange system represented by the United States.
Ios7005-1 is a standard issued by the international organization for Standardization in 1992. This standard is actually a pipe flange standard which combines two series of pipe flanges from the United States and Germany.
The connection dimensions of the two systems are different and cannot be matched with each other
It is most appropriate to distinguish the pipe flange of the two systems by pressure rating, that is, the pressure rating of 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 that of American system is 1.0, 2.0, 5.0, 11.0, 15.0, 26.0, 42.0mpa.

Status quo of pipe flange standards in China

1. Common flange used in petrochemical industry in China.
(1) Piping series GB 9112-9125, SH 3406 in common use in the world.
(2) The connection dimensions of hgj44-76 and JB / t74-90din, which are commonly used in metric pipes in China, are different from those in JB standard. See the table below for details:

Standard Dimension of thread M / hole φ
JB Series 2 M22/φ25 M30/φ34 M36/φ41 M42/φ48 M48/φ54
Whole Part Part Whole Whole
New HGISOJB Series 1BSΓΟCTDIN M24/φ26 M33/φ36 M33/φ36 M39/φ42 M45/φ48 M45/φ48
Measures to be taken when two part flange is used together The screw hole of the first row flange is expanded by 1 mm The screw hole of the first row flange is expanded by 2mm Gasket can be added Gasket can be added Agreement Gasket can be added

Note: “all” in brackets in the table indicates that all fasteners are replaced by fasteners in the second line. “Part” means that some fasteners of this specification have changed, but some fasteners of this specification have not changed, which is consistent.
2. When Hg new standard and JB old standard flange are used together, the following points should be paid attention to:

  • (1) The number of bolts of three flanges is inconsistent, among which two specifications pn0.25/dn500 and pn0.6/dn500 directly affect the fit; the number of pn1.0/dn80hg standard bolts is 8, and the number of JB standard bolts is 4;
  • (2) The screw holes of some old standard flange JB Series 2 should be expanded by 1-2mm, and some can be installed with gaskets.

3. For pn16.0mpa high pressure pipe flange, new HG and JB standard connection dimensions are completely different.

Source: China Flange Manufacturer – Yaang Pipe Industry (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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