GOST 12821-80 Weld Neck Flange

Butt-Welded Steel Flange | PN 0.6–2.5 MPa

GOST 12821-80 weld neck flanges are butt-welded steel flanges designed for low to medium pressure piping systems.
Manufactured in accordance with the Russian standard GOST 12821-80, these flanges feature a tapered hub and butt-weld connection, providing improved strength and stress distribution compared with flat welded flanges.

GOST 12821-80 weld neck flanges are widely used in oil & gas pipelines, water supply systems, heating networks, chemical plants, and general industrial applications across Russia and CIS countries.

What Is GOST 12821-80?

GOST 12821-80 is a Russian standard specifying requirements for steel weld neck flanges (butt-welded type) used in pipelines operating at nominal pressures from PN 0.6 MPa to PN 2.5 MPa.

We are the profession manufacturer of weld neck flange, butt welded flanges by GOST 12821-80. 

GOST 12821-80 Flange （Dowload the GOST 12821-80 standard in PDF)

The standard defines:

• Flange dimensions and tolerances

• Pressure ratings

• Material requirements

• Marking and inspection rules

GOST 12821-80 is commonly used together with:

• GOST 12820-80 (Slip On / Flat Welded Flanges)

Flange Design & Features

• Flange Type: Weld Neck (Butt-Welded)

• Connection: Butt-welded to pipe

• Design Feature: Tapered hub for smooth stress transition

Advantages of GOST 12821-80 weld neck flanges:

• Higher strength than slip on flanges

• Better fatigue and pressure resistance

• Suitable for pipelines with temperature and pressure fluctuations

Pressure Rating

Nominal Pressure Range:

• PN 0.6 MPa

• PN 1.0 MPa

• PN 1.6 MPa

• PN 2.5 MPa

(Comparable to PN 6 / PN 10 / PN 16 / PN 25 in EN standards.)

Materials

Common materials for GOST 12821-80 weld neck flanges include:

• Carbon Steel:

  • St20

  • St3

  • 09G2S

  • 10Г2, 15Х5М, 12Х18Н10Т,gost CT20

• Low-Temperature / Alloy Steel:

  • Available upon request

Material selection depends on design pressure, temperature, and service medium.

Dimensions & Size Range

• Standard: GOST 12821-80

• Nominal Diameter (DN): DN 10 – DN 2000

• Facing Type: Flat Face (FF)

• Bolt Holes: As specified in GOST 12821-80

GOST/ГОСТ 12821 welding neck flange dimensions PN10 1.0Mpa

GOST /ГОСТ 12821 Welding neck flange Dimensions PN16 1.6Mpa

GOST /ГОСТ 12821 Welding neck flange Dimensions PN25 2.5Mpa

GOST /ГОСТ 12821 Welding neck flange Dimensions PN40 4.0Mpa

GOST /ГОСТ 12821 Welding neck flange Dimensions PN63 6.3Mpa

GOST /ГОСТ 12821 Welding neck flange Dimensions PN100 10Mpa

Inspection & Quality Control

GOST 12821-80 weld neck flanges are supplied with standard quality control, including:

• Dimensional inspection

• Visual examination

• Material verification

• Weld inspection

• Marking and traceability

Certification options:

• Manufacturer Test Certificate

• EN 10204 2.1 / 2.2 / 3.1 (on request)

Applications

• Oil & gas transmission pipelines

• Water supply and distribution systems

• Heating and district heating networks

• Chemical and industrial pipelines

• Power and utility infrastructure

GOST 12821-80 weld neck flanges provide a strong, reliable, and cost-effective solution for low to medium pressure piping systems.
With butt-welded design, wide size availability, and compliance with Russian standards, these flanges are widely trusted in industrial and infrastructure projects throughout Russia and CIS regions.

Recommended Related Products

• GOST 12820-80 Slip On Flanges

• GOST Carbon Steel Pipe Fittings

• EN 1092-1 Weld Neck Flanges

• ASME B16.5 Weld Neck Flanges

Gost flange is a flange system from Russia, include Plate Flanges(GOST12820-80),Blind Flanges(GOST12836-67),Welding neck Flanges(GOST12821-80), Steel Butt-Welded Flanges GOST12821-80 etc., size from DN10 to DN1600, Plate flange, welding neck flange, slip on welding plate flange.