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GOST Flanges

GOST Standard Flange: Specifications | Materials | Dimensions | Weight Chart | Tolerances | FAQ

GOST Flanges Manufacturer and Supplier in Russia, USA, Germany, UAE, India, and South Korea, offering Weld Neck, Slip-On, Blind, Threaded, and Lap Joint flanges in Carbon Steel, Stainless Steel, and Alloy Steel as per GOST 12820-80, GOST 12821-80, and GOST 12822-80 standards for industrial, oil & gas, petrochemical, chemical, and power plant piping systems.

GOST 12822-80 Flanges Manufacturer and Supplier

Best Export Prices: sales@midlandforgefittings.com

Midland Forge Fittings is a leading manufacturer and global supplier of precision-engineered GOST Standard Flanges. With a commitment to quality and innovation, we specialize in delivering high-performance flanges, forged fittings, and piping solutions that meet stringent international standards. Our manufacturing processes integrate advanced forging and machining technologies, ensuring consistent dimensional accuracy, mechanical strength all products.

Backed by decades of industry expertise, We serves critical sectors including oil & gas, petrochemical, chemical, power generation, and industrial process systems. Our team emphasizes meticulous quality control, full traceability, and timely delivery, making us a trusted partner for complex pipeline projects worldwide.

Our GOST 12820-80 flanges are manufactured strictly according to GOST 12820-80, 12821-80, and 12822-80 standards, ensuring high accuracy in dimensions, bolt alignment, and pressure containment. Available in Weld Neck, Slip-On, Blind, Threaded, and Lap Joint types, these flanges are suitable for high-pressure and high-temperature industrial applications, including oil & gas, petrochemical, chemical, and power plant pipelines.

Slip-On GOST Flanges from Midland Forge Fittings are offered in Carbon Steel, Stainless Steel, and Alloy Steel, providing superior strength, corrosion resistance, and durability. Each flange undergoes strict dimensional inspection, material verification, and tolerance checks, ensuring leak-proof connections and long-term operational reliability in demanding piping systems.

We are dedicated to innovation and customization, offering tailor-made solutions that cater to specific client requirements. Our focus on precision, reliability, and compliance with global standards positions Midland Forge Fittings as a preferred choice for engineering and industrial enterprises demanding excellence in piping components.

GOST 12820-80

Threaded GOST Flanges - Specifications

Size Range

15 mm (1/2") to 1200 mm (48")

Pressure Ratings

pressure class range from PN 6, PN 10, PN 16, PN 25, PN 40

Facing Type

Raised Face (RF), Flat Face (FF), Tongue & Groove (T&G)

Connection

Butt Weld, Slip-On, Threaded, Lap Joint

Flange Types

Weld Neck (WN), Slip-On (SO), Blind (BL), Threaded (TH), Lap Joint (LJ)

Material Grades

Carbon Steel (S235JR, S275JR, S355JR, P265GH, P355GH), Stainless Steel (12X18H10T / 1.4301, 08X17H13M2 / 1.4404), Alloy Steel (15CrMo, 10CrMo9-10)

Surface Finish

Machined finish Ra 3.2 μm or as per customer requirement

Dimensional Standards

GOST 12820-80, GOST 12821-80, GOST 12822-80

Manufacturing Method

hot forging, precision CNC machining, and strict quality inspection to ensure dimensional accuracy, mechanical strength, and pressure integrity.

Certification

Material Test Certificate (MTC), Dimensional Inspection Report, Traceability to Raw Material Batch
GOST 12821-80

Lap Joint GOST Flanges - Materials, Grades & Standards

Material GOST / EN Equivalent Grade / Specification Applications
Carbon Steel GOST 1050, 20, 09G2S S235JR, S275JR, S355JR,
P265GH, P355GH		 General industrial, oil & gas,
chemical, power plants
Stainless Steel 12X18H10T, 08X17H13M2 EN 1.4301, EN 1.4404 Corrosive environments, chemical,
food, marine applications
Alloy Steel 15CrMo, 10CrMo9-10 GOST / EN
Alloy Steel Grades		 High temperature & pressure applications
in refineries, power plants
Low Alloy Steel 20Cr, 35CrMo EN 1.7709, EN 1.7225 Critical pipelines with high stress
and fatigue resistance
Duplex / Super Duplex 1.4462, 1.4501 EN 1.4462, EN 1.4501 Highly corrosive environments,
offshore, chemical industries
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Industrial Piping GOST Flanges – Dimensions

DN /
NB		 Flange
Type		 Outside
Diameter
(OD mm)		 Flange
Thickness
(mm)		 Bolt Circle
Diameter
(BCD mm)		 Number of
Bolt Holes		 Bolt Hole
Diameter
(mm)		 Face
Type		 PN Rating
15 (1/2″) WN, SO, BL, TH, LJ 95 14 65 4 14 RF / FF PN 6–PN 40
20 (3/4″) WN, SO, BL, TH, LJ 105 16 75 4 14 RF / FF PN 6–PN 40
25 (1″) WN, SO, BL, TH, LJ 115 16 85 4 14 RF / FF PN 6–PN 40
32 (1 1/4″) WN, SO, BL, TH, LJ 140 18 100 4 14 RF / FF PN 6–PN 40
40 (1 1/2″) WN, SO, BL, TH, LJ 150 18 110 4 14 RF / FF PN 6–PN 40
50 (2″) WN, SO, BL, TH, LJ 165 20 125 4 18 RF / FF PN 6–PN 40
65 (2 1/2″) WN, SO, BL, TH, LJ 185 20 145 4 18 RF / FF PN 6–PN 40
80 (3″) WN, SO, BL, TH, LJ 200 22 160 8 18 RF / FF PN 6–PN 40
100 (4″) WN, SO, BL, TH, LJ 220 24 180 8 18 RF / FF PN 6–PN 40
150 (6″) WN, SO, BL, TH, LJ 285 28 240 8 22 RF / FF PN 6–PN 40
200 (8″) WN, SO, BL, TH, LJ 340 32 295 12 22 RF / FF PN 6–PN 40
250 (10″) WN, SO, BL, TH, LJ 405 34 355 12 26 RF / FF PN 6–PN 40
300 (12″) WN, SO, BL, TH, LJ 465 36 410 12 26 RF / FF PN 6–PN 40
400 (16″) WN, SO, BL, TH, LJ 585 42 525 16 30 RF / FF PN 6–PN 40
500 (20″) WN, SO, BL, TH, LJ 705 48 645 20 30 RF / FF PN 6–PN 40
600 (24″) WN, SO, BL, TH, LJ 840 54 770 24 34 RF / FF PN 6–PN 40
800 (32″) WN, SO, BL, TH, LJ 1040 70 950 28 36 RF / FF PN 6–PN 40
1000 (40″) WN, SO, BL, TH, LJ 1250 80 1140 32 39 RF / FF PN 6–PN 40
1200 (48″) WN, SO, BL, TH, LJ 1450 90 1320 36 42 RF / FF PN 6–PN 40

GOST 12822-80 Flanges - Weight Chart

DN / NB Flange Type PN Rating Approx. Weight (kg)
15 (1/2″) WN, SO, BL, TH, LJ PN 6–PN 40 1.5 – 2.5
20 (3/4″) WN, SO, BL, TH, LJ PN 6–PN 40 1.8 – 3.0
25 (1″) WN, SO, BL, TH, LJ PN 6–PN 40 2.0 – 3.5
32 (1 1/4″) WN, SO, BL, TH, LJ PN 6–PN 40 2.5 – 4.0
40 (1 1/2″) WN, SO, BL, TH, LJ PN 6–PN 40 3.0 – 4.5
50 (2″) WN, SO, BL, TH, LJ PN 6–PN 40 5 – 8
65 (2 1/2″) WN, SO, BL, TH, LJ PN 6–PN 40 7 – 10
80 (3″) WN, SO, BL, TH, LJ PN 6–PN 40 9 – 14
100 (4″) WN, SO, BL, TH, LJ PN 6–PN 40 15 – 25
150 (6″) WN, SO, BL, TH, LJ PN 6–PN 40 28 – 45
200 (8″) WN, SO, BL, TH, LJ PN 6–PN 40 50 – 80
250 (10″) WN, SO, BL, TH, LJ PN 6–PN 40 80 – 120
300 (12″) WN, SO, BL, TH, LJ PN 6–PN 40 120 – 180
400 (16″) WN, SO, BL, TH, LJ PN 6–PN 40 200 – 300
500 (20″) WN, SO, BL, TH, LJ PN 6–PN 40 350 – 500
600 (24″) WN, SO, BL, TH, LJ PN 6–PN 40 500 – 750
800 (32″) WN, SO, BL, TH, LJ PN 6–PN 40 1000 – 1500
1000 (40″) WN, SO, BL, TH, LJ PN 6–PN 40 1800 – 2500
1200 (48″) WN, SO, BL, TH, LJ

Slip-On GOST Flanges - Tolerances

Parameter Tolerance / Limit Remarks
Outside Diameter (OD) ±1% Ensures proper mating with adjoining flanges
Flange Thickness +12.5% / -0% Maintains minimum wall strength
Bolt Circle Diameter (BCD) ±1% Ensures uniform bolt alignment
Number of Bolt Holes Exact as per standard Proper bolting and load distribution
Bolt Hole Diameter ±0.5 mm Allows smooth bolt insertion
Raised Face (RF) Height ±1 mm Proper gasket sealing
Flatness (Flange Face) ≤0.5 mm Ensures leak-proof connection
Out-of-Roundness ≤1.5% of nominal OD Prevents misalignment and stress concentration
Surface Finish Ra 3.2 μm or as per customer requirement Smooth contact for gaskets
Centering Hole / Bore Diameter ±0.5 mm Ensures correct pipe fit for slip-on connection
What are GOST 12820-80, 12821-80, and 12822-80 Flanges?
1. GOST 12820-80
  • Scope: Applies primarily to Weld Neck (WN) flanges, designed for high-pressure and high-temperature pipelines.
  • Key Features:
    • Provides gradual stress transition from flange to pipe.
    • Suitable for critical industrial applications such as oil & gas, power generation, and chemical transport.
    • Available in DN 15–1200 mm with PN 6–PN 40 pressure ratings.
  • Material Options: Carbon Steel, Stainless Steel, Alloy Steel, and Duplex Steel.
  • Applications: High-pressure, high-temperature systems where leak-proof connections are essential.
2. GOST 12821-80
  • Scope: Covers Blind (BL), Threaded (TH), and specialty flanges.
  • Key Features:
    • Blind flanges: Close the ends of piping systems and allow pressure testing.
    • Threaded flanges: Enable non-welded connections, suitable for low-pressure systems.
    • Specialty flanges: Designed for unique industrial needs.
  • Size & Pressure Ratings: DN 15–1200 mm, PN 6–PN 40.
  • Materials: Carbon Steel, Stainless Steel, and Alloy Steel.
  • Applications: Low-to-high-pressure pipelines, temporary installations, and pipelines requiring future maintenance or testing.
3. GOST 12822-80
  • Scope: Focused on Slip-On (SO) and Lap Joint (LJ) flanges, designed for easy installation and alignment flexibility.
  • Key Features:
    • Slip-On flanges: Slide over pipe and welded at the hub; suitable for low-to-medium pressure systems.
    • Lap Joint flanges: Used with stub ends, allowing rotation for precise alignment.
  • Size & Pressure Ratings: DN 15–1200 mm, PN 6–PN 40.
  • Material Options: Carbon Steel, Stainless Steel, and Alloy Steel.
  • Applications: Industrial pipelines, chemical transport, large-diameter pipelines, and systems requiring frequent dismantling or maintenance.

GOST Flanges come in several types to meet specific operational requirements:

  1. Weld Neck (WN):

    • Designed for high-pressure and high-temperature applications.
    • The long tapered hub allows gradual stress transfer from flange to pipe.
    • Suitable for critical pipelines in oil, gas, and petrochemical plants.

  2. Slip-On (SO):

    • Easier to install than WN, less expensive.
    • Suitable for low-to-medium pressure systems.
    • Installed by sliding over the pipe and welding around the hub.

  3. Blind (BL):

    • Used to close the ends of piping systems.
    • Allows for pressure testing and future expansion or maintenance.

  4. Threaded (TH):

    • Can be connected without welding.
    • Ideal for low-pressure systems, often in gas distribution or small pipelines.

  5. Lap Joint (LJ):

    • Used with stub ends, allows rotation for alignment.
    • Cost-effective in large-diameter pipes and frequent dismantling applications.

  • Standards: GOST follows Russian GOST 12820-80 series, EN flanges follow EN 1092-1, and ASME flanges follow ASME B16.5 / B16.47.

  • Dimensional Differences: Slight variations in OD, BCD, thickness, and PN ratings.

  • Global Usage:

    • GOST: Russia, CIS countries, and select international projects.
    • EN / ASME: Widely used globally in industrial, oil & gas, and power plant systems.
United Arab Emirates (UAE), Saudi Arabia, Oman, Qatar, Kuwait, Bahrain, Iraq, Jordan, Lebanon, Yemen, Iran, Israel, Germany, United Kingdom (UK), Italy, France, Spain, Netherlands, Myanmar, Singapore, Malaysia, Indonesia, Vietnam, South Korea, Philippines, Thailand, Bangladesh, Sri Lanka, Papua New Guinea, United States (USA), Canada, Brazil, Chile, Argentina, Colombia, Russia, Ukraine, Kazakhstan, Poland, Egypt, Algeria, Morocco, Tunisia, Libya, Nigeria, Ghana, Ivory Coast, Senegal, Cameroon, Gabon, Democratic Republic of Congo, Kenya, Tanzania, Uganda, Ethiopia, Rwanda, Zambia, South Africa, Mozambique, Namibia, Botswana