Pipe flanges are essential connecting components widely used in pipeline systems, to link pipes, valves, pumps and other process equipment. Proper flange standard selection guarantees assembly compatibility, sealing safety and long-term stable operation. There are four common types of pipe flange standards applied globally: ASME B16.5 (American standard), EN 1092-1 (European standard), GB/T (Chinese national standard), and JIS B2220 (Japanese standard).

1. ASME B16.5 (American Standard)

ASME B16.5 is the most popular international flange standard issued by the American Society of Mechanical Engineers. It specifies dimensions, pressure-temperature ratings, materials, marking and inspection requirements for steel pipe flanges and flanged fittings.

Size range: NPS 1/2” ~ 24”; large-size flanges over 24 inches adopt ASME B16.47

Pressure marking: Class 150, 300, 400, 600, 900, 1500, 2500

Unit: Imperial inch system

Main applications: Oil & gas, petrochemical, power plants, international EPC projects, North America, Middle East and global high-pressure industrial pipelines

Common flange types: Weld neck, slip-on, blind, threaded, socket weld, lap joint

2. EN 1092-1 (European Standard)

EN 1092-1 is the current unified European steel flange standard, which inherits and replaces the old DIN 2501 German standard. It adopts metric DN & PN marking system.

Size range: DN10 ~ DN4000

Pressure marking: PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN400

Unit: Metric millimeter

Main applications: EU countries, Africa, many Asia-region projects following European PED pressure equipment directive

Multiple flange form types, supporting flat face, raised face and other sealing surface forms

3. GB/T Chinese National Standard

GB/T 9112~9124 is China’s national standard for steel pipe flanges, widely adopted in domestic chemical, water treatment, power and municipal pipeline engineering. HG/T 20592~20635 (HG standard) is also widely used in Chinese petrochemical industry, aligned with EN system.

Size range: DN10 to DN2000 and above

Pressure marking: PN series metric pressure grades

Unit: Metric system

Main applications: Domestic industrial projects, China-based engineering contractors and equipment export projects designed to Chinese specifications

Covers weld neck, slip-on, blind, plate flanges and full range of sealing face options

4. JIS B2220 (Japanese Standard)

JIS B2220 is the Japanese industrial pipe flange standard, widely used in Japan, South Korea, Southeast Asia and Japanese-invested factories worldwide.

Pressure marking: K class (5K,10K,16K,20K,30K,40K,63K)

Unit: Metric

Main applications: Japanese equipment, semiconductor plants, water supply, general chemical pipelines and Japanese-funded industrial projects