GOST 33259 Flange Dimensions & Pressure Ratings: Complete Specification Guide for Kazakh & Russian Buyers (2026)

Zhejiang Jiaji Forging Co., Ltd., a leading ISO-certified flange manufacturer in China, supplies GOST 33259 flanges to oil & gas operators in Kazakhstan, Russia, and the Caspian region. With multi-standard capabilities covering EN 1092-1, ASME B16.5, and GOST 33259-2015, Jiaji Forging provides certified forged flanges for major projects including Tengizchevroil (TCO), NCOC (Kashagan), and SOCAR.

Quick Answer: What Is GOST 33259?

Introduction: GOST 33259 for Caspian Region Buyers

The Caspian region—Kazakhstan, Azerbaijan, Turkmenistan—is undergoing a massive pipeline expansion. KazMunayGas’s 2025-2030 plan adds 1,200 km of new pipelines, while SOCAR’s petrochemical complex expansion in Azerbaijan demands EN 1092-1 PN40/PN63 duplex steel flanges. For these projects, GOST 33259-2015 remains the mandatory standard for domestic procurement. However, many international operators also require ASME B16.5 or EN 1092-1 compliance for cross-border equipment.

Jiaji Forging bridges this gap by manufacturing flanges to GOST 33259, EN 1092-1, and ASME B16.5 simultaneously, ensuring seamless integration for Tengizchevroil (TCO) expansion and NCOC Kashagan operations.

GOST 33259 vs EN 1092-1 vs ASME B16.5: Key Differences

Buyers must understand these three standards to avoid costly mismatches:

• Pressure Rating: GOST uses PN (PN 1.0 to PN 250); EN 1092-1 uses PN; ASME B16.5 uses Class (150, 300, 600, etc.). PN 40 ≈ Class 300, but bolt circles differ.
• Bolt Dimensions: GOST specifies metric bolt diameters (M16, M20, M24); ASME uses inch-based bolts. EN 1092-1 also uses metric but with different pitch.
• Face Dimensions: GOST flanges have different raised face heights and gasket seating widths compared to ASME. For example, a GOST PN 40 DN 100 flange has a 102 mm raised face diameter vs ASME Class 300’s 107.9 mm.
• Materials: GOST 33259 specifies steel grades like 09G2S, 20, 12Kh18N10T (Russian equivalents to ASTM A105, A182 F304). Stainless steel vs carbon steel flanges selection depends on corrosion resistance requirements.

For projects requiring dual certification, Jiaji Forging supplies flanges stamped with both GOST 33259 and ASME B16.5 markings, verified by third-party inspection.

GOST 33259 Pressure Ratings & Dimensions (PN Series)

GOST 33259 defines flanges for PN 1.0, PN 2.5, PN 6.3, PN 10, PN 16, PN 25, PN 40, PN 63, PN 100, PN 160, and PN 250. Key dimensions include:

• DN 15 to DN 600: Standard sizes for PN 16 and PN 40. For example, a GOST PN 40 DN 100 flange has an outer diameter of 220 mm, bolt circle of 180 mm, and 8 bolt holes (M20).
• DN 700 to DN 1400: Large-diameter flanges for pipeline tie-ins, commonly used in KazMunayGas projects.
• Facing Types: Flat face (FF), raised face (RF), tongue-and-groove (TG), and ring-joint (RJ). Large-diameter flanges often use RJ facing for high-pressure gas services.

Materials for GOST 33259 Flanges

Common materials under GOST 33259 include:

• Carbon steel: 20 (analogous to ASTM A105), 09G2S (A350 LF2). Used for general-purpose pipelines.
• Stainless steel: 12Kh18N10T (A182 F304), 08Kh17N15M3T (A182 F316). Carbon steel vs stainless steel flanges selection depends on sour service (NACE MR0175).
• Duplex stainless steel: 2205 (F51), 2507 (F53) for high-strength, corrosion-resistant applications. SOCAR’s petrochemical complex requires duplex steel flanges for chloride environments.
• Nickel alloys: Inconel 625, Incoloy 825 for extreme temperature and corrosive conditions. Duplex steel flange suppliers like Jiaji Forging offer certified materials with traceable heat numbers.

Jiaji Forging: GOST 33259 Flange Supplier for Kazakhstan & Russia

As a professional flange manufacturer in China, Jiaji Forging supplies GOST 33259 flanges to major Caspian projects:

• Tengizchevroil (TCO) Expansion: Provided carbon steel and stainless steel flanges for Future Growth Project (FGP).
• NCOC Kashagan: Supplied duplex steel flanges for high-pressure gas injection.
• KazMunayGas Pipeline: 1,200 km pipeline expansion requires GOST standard flanges for all domestic sections.
• SOCAR Petchem Complex: EN 1092-1 PN40/PN63 duplex steel flanges for new ethylene cracker.

Jiaji Forging holds ISO 9001, PED 2014/68/EU, and GOST R certifications, ensuring compliance with local regulations. Their custom forging capabilities allow for non-standard dimensions and special materials.

Market Trends: GOST Flange Demand in 2026

The global flanges market is projected to reach $5.82 billion in 2026, with Asia-Pacific holding 40.7% share. Key trends affecting GOST flange buyers:

• EU CBAM: The Carbon Border Adjustment Mechanism, fully effective in 2026, increases demand for flanges made with 30% recycled steel. EU CBAM compliance is now a requirement for exporters to Europe.
• Smart Manufacturing: AI quality inspection reduces detection time from 15 minutes to 2 seconds. Robot welding lowers defect rates by 32%.
• Custom/High-End Flanges: 42% of top-tier export orders now require custom dimensions or special materials. ODM suppliers like Jiaji Forging are growing market share from 19% to 27%.
• LNG Expansion: Cryogenic flanges for LNG terminals require impact testing at -196°C, often specified under GOST or ASME.

How to Choose a GOST 33259 Flange Supplier

Follow this checklist to ensure quality and compliance:

• Certifications to Verify:
  • ISO 9001 quality management system
  • PED 2014/68/EU (Category III/IV) for EU projects
  • GOST R certification for Russian/CIS markets
  • Material test certificates (MTC) per EN 10204 Type 3.1 or 3.2
• Questions to Ask:
  • Can you supply dual-stamped flanges (GOST + ASME)?
  • What is your lead time for custom dimensions (DN 700+)?
  • Do you provide third-party inspection (SGS, Bureau Veritas)?
  • Are heat numbers traceable to mill certificates?
• Price Factors:
  • Material grade (duplex, nickel alloy cost more)
  • Pressure rating (PN 100 vs PN 40)
  • Facing type (RJ facing adds machining cost)
  • Quantity (MOQ of 10 pcs for custom flanges)

Jiaji Forging offers competitive pricing with full traceability, meeting all the above criteria.

FAQ: GOST 33259 Flanges

Q: What is the difference between GOST 33259 and GOST 12820?

A: GOST 33259-2015 supersedes GOST 12820 (steel flanges PN ≤ 2.5) and GOST 12821 (PN ≥ 4.0). It consolidates all PN ratings into one standard with updated dimensions and materials.

Q: Can GOST 33259 flanges be used with ASME B16.5 equipment?

A: Not directly—bolt circles and face dimensions differ. However, Jiaji Forging supplies adapter flanges with dual drilling patterns to bridge GOST and ASME systems.

Q: What material grade is equivalent to ASTM A105 under GOST?

A: Steel grade 20 (St20) per GOST 1050 is the equivalent to ASTM A105. It is used for carbon steel flanges in general pipeline applications.

Q: Are GOST 33259 flanges certified for sour service (NACE MR0175)?

A: Yes, when made from appropriate materials (e.g., stainless steel 12Kh18N10T or duplex) and heat-treated per NACE requirements. Jiaji Forging supplies flanges with NACE compliance documentation.

Q: What is the typical lead time for custom GOST flanges?

A: 4-6 weeks for standard sizes (DN 15-600), 8-12 weeks for large-diameter (DN 700+) or special alloys. Contact Jiaji Forging for expedited options.

References

• ASTM International – Material standards for flanges (A105, A182, A350).
• ASME – B16.5 and B16.47 flange standards.
• API – API 6A and API 6D flange specifications for oil & gas.

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As a professional flange manufacturer, Jiaji Forging provides custom forging solutions for global industries. Contact our engineering team for technical support and quotation.