The flange manufacturing standards cover multiple systems both domestically and internationally, including national standards (GB), mechanical industry standards (JB), chemical industry standards (HG), American standards (ANSI), Japanese standards (JIS), German standards (DIN), etc. Here are some specific flange manufacturing standards:

1、 Domestic standards

National Standard (GB)

GB/T 9112~9124-2010: Steel pipe flange standard, covering various types and parameters of flanges, integral steel pipe flanges, threaded steel pipe flanges with necks, welded steel pipe flanges, etc.

Pressure marking: divided into PN marking and Class marking. The PN tag has 12 pressure levels, which are PN2.5、PN6、PN10、PN16、PN25、PN40、PN63、PN100、PN160、PN250、PN320、PN400； The Class label has 6 pressure levels, namely Class 150, Class 300, Class 600, Class 900, Class 1500, and Class 2500.

Mechanical Industry Standards (JB)

JB/T 74-1994: Technical Conditions for Pipeline Flanges.

JB/T 75: Types of pipeline flanges.

JB/T 79 series: including convex integral cast steel pipe flanges, concave convex integral cast steel pipe flanges, mortise and tenon integral cast steel pipe flanges and other types.

Chemical Industry Standard (HG)

HG20592-2009 series: Steel pipe flanges, gaskets, fasteners standards, belonging to the European system.

HG20615-2009 series: also belongs to the standard for steel pipe flanges, gaskets, and fasteners, but belongs to the American system.

2、 International standards

American Standard (ANSI)

ANSI B16.5: Standard for Steel Pipe Flanges and Flange Fitting, representing the American system of pipe flanges.

ANSI B16.47: Includes pipe flange standards for multiple pressure levels such as Class 150, 300, 600, 900, 1500, etc.

Japanese Standard (JIS)

JIS 5K, 10K, 16K, 20K: Japanese standard pipe flange standards, generally only used for public works in petrochemical plants, with little international impact.

German Standard (DIN)

DIN2527、 2543, 2545, 2566, 2572, 2573, 2576, 2631, 2632, 2633, 2634, 2638: German standard for pipe flanges, representing the European system of pipe flanges.

3、 Other standards

British Standard (BS)

BS4504、 4506: British pipe flange standard.

Italian Standards (UNI)

UNI2276、 2277, 2278, 6083, 6084, 6088, 6089, 2299, 2280, 2281, 2282, 2283: Italian pipe flange standards.

International Organization for Standardization (ISO) standards

IOS7005-1: A standard issued by the International Organization for Standardization in 1992, which is actually a pipe flange standard that combines two series of pipe flanges from the United States and Germany. But the flange connection sizes of the two systems are completely different and cannot be interchanged.