Ct20 Gost Flange Manufacturer
Ct 20 is known as a low-carbon, non-alloy structural steel accoriding to Gost standard,used widely in the production of pipes, fittings, machinery parts, and pressure vessels. It is also called St 20, It’s known for its good ductility, weldability, and machinability, making it ideal for both mechanical and pipeline applications.
GOST flanges made of St20 are high-quality pipe flanges manufactured according to Russian GOST standards using carbon steel grade 20 (Сталь 20). These flanges are widely used in low- to medium-pressure piping systems for oil and gas, water supply, heating, chemical, and mechanical engineering applications.
St 20 steel is a high-grade unalloyed steel used in metal structures and components operating in temperatures of -40°С to +450°С. Hot-rolled and forged long products made from 20 steel conform to the DSTU 7809 and GOST 1050 standards.
Ct20 according to GOST 1050
SIZED BARS MADE OF HIGH-QUALITY STRUCTURAL CARBON STEEL WITH A SPECIAL SURFACE FINISH
Ct 20 Flanges are made of Ct20 round bar according to GOST 1050-2013
Ct 20 Chemical composition
Chemical composition in % for grade Ct 20 ( 20 )
C | Si | Mn | Ni | S | P | Cr | Cu | As |
0.17 – 0.24 | 0.17 – 0.37 | 0.35 – 0.65 | max 0.3 | max 0.04 | max 0.035 | max 0.25 | max 0.3 | max 0.08 |
Mechanical property of Ct20

Ct20 Analogues Equivalent grade Material
US | 1020, 1023, 1024, G10200, G10230, H10200, M1020, M1023 |
Japan | S20C, S20CK, S22C, STB410, STKM12A, STKM12A-S, STKM13B, STKM13B-W |
EU | 1.1151, 2C22, C20E2C, C22, C22E |
China | 20, 20G, 20R, 20Z |
Sweden | 1450 |
Australia | 1020, M1020 |
Switzerland | Ck22 |
South Korea | SM20C, SM20CK, SM22C |
Gost Flange Standards:
- GOST 12820-80 – Flat flanges (plain)
- GOST 12821-80 – Weld neck flanges
- GOST 12822-80 – Loose flanges
- GOST 12815-80 – General flange connection requirements
Pressure Ratings: From PN 6 to PN 40 (PN6, PN10, PN16, PN25, PN40)
Nominal Diameters: DN10 to DN1000 (and more upon request)
Applications of Gost Ct20 Flanges
- Water and heating systems
- Steam pipelines
- Oil and gas infrastructure
- Mechanical equipment connections
- Boiler and pressure vessel systems
Gost Flange Documentation & Compliance
- Supplied with mill test certificates (MTC) and GOST compliance
- Available with passport and quality certificates
- Optional 3.1 or 3.2 EN certificates for international projects