The international pipe flange standard mainly has two systems, 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 in petrochemical installations generally only used for public works, and the international impact is small. The pipe flanges of various countries are introduced below:

1, to Germany and the former Soviet Union as the representative of the European system pipe flange
2. American system pipe flange standard, represented by ANSIB16.5 and ANSIB16.47
3, British and French pipe flange standards, two countries each have two pipe flange standards.
To sum up, the international standard of pipe flanges can be summarized as two different and not interchangeable pipe flange systems: a European pipe flange system represented by Germany; Another is the American pipe flange system represented by the United States.
Ios7005-1 is a standard promulgated by the International Organization for Standardization in 1992, the standard is actually the United States and Germany two series of pipe flanges merged into the pipe flange standard.