API 6A Flanges Suppliers

Type 6B/6BX Flanges

API 6A Flanges Suppliers

API 6A Standard Flanges: Dimensions | Specifications | Material Grade | Standards | About API 6A | All Product Types

API 6A flanges are high-performance, pressure-rated components used in wellhead systems, Christmas Tree assemblies, and other critical equipment in upstream oil and gas production. These flanges are designed to meet the rigorous requirements of the API 6A standard, which governs wellhead and tree equipment. At Nutech, we manufacture and export API 6A flanges that conform to the latest edition of the specification, including Type 6B and Type 6BX flanges, supporting pressure classes from 2,000 psi to 20,000 psi.

Our product range includes weld neck, blind, companion, and studded flanges for various wellhead configurations. These are manufactured in compliance with PSL 1 to PSL 4 (Product Specification Levels) and tested as per PR1 and PR2 requirements. We also supply EE and FF designated flanges with metal-to-metal sealing suitable for sour service environments and NACE MR0175/ISO 15156 compliance.

API 6A Type 6B flanges are bolted with ring gaskets and are widely used in upstream pipelines and manifolds, while Type 6BX flanges are compact, high-pressure-rated, and feature a gasket-less metal seal for critical pressure applications such as blowout preventers (BOPs) and Xmas Tree assemblies.

Each flange is forged from high-strength alloy steel and undergoes rigorous non-destructive testing, including hydrostatic testing, ultrasonic inspection, and hardness checks. Material traceability and certification as per EN 10204 3.1/3.2 are provided.

As a reputed API 6A flange manufacturer and exporter, Nutech supplies equipment to global markets including USA, Saudi Arabia, UAE, Qatar, Iraq, Indonesia, and Europe, supporting oilfield service contractors, EPC firms, and rig OEMs with custom machining, fast lead times, and strict adherence to API standards.

API 6A Flange Types, Pressure Ratings, and Applications – Manufactured by Nutech for Wellhead and Xmas Tree Equipment Worldwide.

For complete technical details, including dimensions, pressure rating classes, weight charts, sizes, tolerances, and material specifications of our API 6A Standard Flanges, please download the full Catalog PDF below.

Explore API 6A Type 6B and 6BX Flanges Rated for 2,000 to 20,000 PSI in Critical Oilfield and Drilling Systems

Technical Specifications of API 6A Standard Flange

Specification Details
Standard API 6A
Flange Types Type 6B, Type 6BX, Weld Neck, Blind, Companion, Studded Face Flanges
Pressure Ratings 2,000 psi to 20,000 psi (Class 2000 – 20000)
Size Range 1 13/16″ to 26 3/4″
Product Specification Levels PSL 1, PSL 2, PSL 3, PSL 3G, PSL 4
Material Classes AA, BB, CC, DD, EE, FF, HH (NACE-compliant grades available)
Temperature Ratings Grades L, P, R, S, T, U, V, X (as per API 6A Annex)
Testing Levels PR1 and PR2 (Performance Rating Levels)
Sealing Type Metal-to-Metal Seal (for 6BX), Ring Joint (for 6B)
Surface Finish As per API 6A requirements – Stock Finish, Spiral Serrated
Applications Wellhead Assemblies, Christmas Tree Equipment, Blowout Preventers (BOP), Choke & Kill Manifolds, Subsea Equipment
Documentation EN 10204 3.1 / 3.2, NACE MR0175 / ISO 15156, Mill Test Certificates
Application Industries Oil & Gas, Petrochemical, Power Generation, Water Treatment, Food & Beverage, Fire Protection Systems, Pulp & Paper, Shipbuilding, HVAC, Offshore
Origin Made in India (by Nutech Overseas)
Export Network USA, Europe, and Middle East

Complete Material Grade Chart - API 6A Flange

Material Category API 6A Flange Grades
Stainless Steel API 6A Flange ASTM A182 F304 / F304L / F304H, F316 / F316L / F316Ti, F310, F309S, F317 / F317L, F321 / F321H, F347 / F347H, F904L, ASTM A351 CF3 / CF3M / CF8 / CF8M / CF8C, DIN 1.4301, 1.4306, 1.4307, 1.4311, 1.4401, 1.4404, 1.4408, 1.4409, 1.4541, 1.4571, 1.4550, 1.4435, 1.4539
Duplex Steel API 6A Flange ASTM A182 F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61, UNS S31803 / S32205
Super Duplex Steel API 6A Flange ASTM A182 F53 / F55 / F57 / F59 / F60 / F61, UNS S32750 / S32760
Carbon Steel API 6A Flange ASTM A105 / A105N, ASTM A350 LF2, ASTM A694 F52 / F56 / F60 / F65 / F70 / F80, ASTM A216 WCB, DIN 1.0460 / 1.0402 / 1.0619, Die Steel, Mild Steel
Alloy Steel API 6A Flange ASTM A182 F5 / F9 / F11 / F12 / F22 / F91, AISI 4130 / 4140
Nickel Alloy API 6A Flange Nickel 200 / 201, ASTM B564
Monel API 6A Flange Monel 400 (UNS N04400), Monel K500 (UNS N05500), ASTM B564
Inconel API 6A Flange Inconel 600 / 601 / 625 / 690 / 718 / 783 / X750, ASTM B564
Incoloy API 6A Flange Incoloy 800 / 800H / 800HT (UNS N08800), Incoloy 825 (UNS N08825), Incoloy 925, ASTM B564
Hastelloy API 6A Flange Hastelloy C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X, ASTM B564
Alloy 20 API 6A Flange Alloy 20 / 20Cb-3, Carpenter® 20, ASTM B462
254 SMO API 6A Flange SMO 254 / 6Mo, UNS S31254, DIN 1.4547, ASTM A182
Copper Nickel API 6A Flange Copper Nickel 90/10 (C70600), 70/30 (C71500), UNS C71640, ASTM B61 / B62 / B151 / B152
Copper API 6A Flange TP1, TP2, T1, T2, C10100–C12300, C14200–C17200, C21000–C71520, including C10930, C11000, C11400, C12000, C12200, C26000, C28000, C33000, C44300, C70600, etc.
Brass API 6A Flange Grades 3602, 2604, H59, H62, etc.
Aluminium API 6A Flange Aluminium Grades 5052, 6061, 6063, 2017, 7075, etc.
Titanium API 6A Flange ASTM B381 Gr.1 / Gr.2 / Gr.4 / Gr.5 / Gr.7, UNS R50250 / R50400 / R50550 / R50700 / R52400 / R53400 / R56320 / R56400
Other Special Grades Al6XN, Tin Bronze, Aluminium Bronze, Lead Bronze, Nimonic 75 / 80A / 90

International Flange Standards We Manufacture & Supply

What is the difference between API 6A Type 6B and Type 6BX flanges?

The key differences between API 6A 6B and 6BX flanges lie in their design, sealing mechanism, and pressure ratings:

Type 6B Flanges:

  • Use Ring Type Joint (RTJ) gaskets
  • Typically rated for pressures up to 5,000 psi
  • Compatible with standard API 6A stud bolts
  • Have flat face or raised face sealing surfaces

Type 6BX Flanges:

  • Feature metal-to-metal sealing (no gasket)
  • Designed for higher pressure ratings, up to 20,000 psi
  • Require special bolting and torque control
  • Do not permit the flange face to extend past the hub — offering flush face contact

In general, 6BX flanges are more compact and robust, making them suitable for critical pressure systems like subsea trees, BOPs, and kill lines.

What are Product Specification Levels (PSL) in API 6A flanges, and why are they important?

Product Specification Levels (PSL) in API 6A flanges define the technical and quality requirements for materials, testing, and documentation based on the intended application’s severity. They are critical in oil & gas to ensure performance, traceability, and safety.

Here’s a breakdown:

  1. PSL 1: Basic level — minimum testing and documentation. Suitable for less critical services.
  2. PSL 2: Includes all PSL 1 requirements + additional chemical analysis, NDE (non-destructive testing), and mechanical tests.
  3. PSL 3 & PSL 3G: Advanced levels — for high-risk operations like deep wells or sour service; require full traceability, full-length NDE, hardness testing, and impact testing.
  4. PSL 4: Most stringent level, typically used in critical offshore or high-pressure HPHT environments.

Choosing the correct PSL is vital to ensure long-term reliability of flanged connections under extreme pressure and temperature variations.

Which pressure classes are available in API 6A flanges, and how are they selected?

API 6A flanges are designed for high-pressure wellhead and Xmas tree equipment, and their selection depends on operating pressure, temperature, and service conditions.

The available pressure ratings (classes) under API 6A are:

  • 2,000 psi
  • 3,000 psi
  • 5,000 psi
  • 10,000 psi
  • 15,000 psi
  • 20,000 psi

Selection Criteria:

  • Well depth & pressure zones: Deeper wells or HPHT conditions typically require 10K, 15K, or 20K flanges.
  • Application area: For choke & kill manifolds, blowout preventers (BOPs), and subsea Christmas trees, higher pressure ratings are mandatory.
  • Safety factors: Always chosen based on required design pressure + safety margins.

API 6A strictly regulates these pressure classes, ensuring flanges are matched correctly with other equipment such as valves and connectors.

What materials are commonly used in the manufacturing of API 6A flanges?

API 6A flanges are manufactured using strictly controlled material grades, defined by Material Class Codes such as AA, BB, DD, EE, and so on. These classes indicate mechanical strength, corrosion resistance, and NACE compliance.

Here are the commonly used material classes:

  1. AA / BB – Carbon Steel (non-sour service, general use)
  2. CC / DD – Low Alloy Steel (for higher strength or moderate sour service)
  3. EE / FF – Corrosion-resistant alloys (CRA) for H2S environments (NACE MR0175)
  4. HH – High Nickel-based alloys like Inconel or CRA cladding for extreme sour service

These materials are tested to meet:

  • API 6A hardness limits
  • Impact testing requirements
  • NDE and heat treatment standards

Nutech offers full traceability and documentation for all materials, compliant with PSL levels and application requirements.

Where are API 6A flanges commonly used in oil & gas systems?

API 6A flanges are engineered for use in high-pressure, high-risk environments typically found in upstream oil & gas operations. Their robust design, PSL classifications, and sealing types make them suitable for:

Primary Applications:

  1. Wellhead Assemblies – connecting casing heads, tubing spools, and hangers
  2. Christmas Tree Systems – for flow control at the surface
  3. Blowout Preventers (BOP) – as part of pressure control equipment
  4. Choke & Kill Manifolds – where accurate pressure control is required
  5. Mudline Suspension Systems
  6. Subsea Equipment – like subsea trees and control modules

These flanges are selected for their sealing integrity under cyclic pressure, corrosion resistance, and API 6A standardization, which ensures interoperability across OEM components.

In critical zones like offshore rigs, desert fields, and sour service reservoirs, API 6A flanges are essential for system safety and performance.

Which countries does Nutech export API 6A flanges to?

We are a trusted manufacturer and global exporter of high-performance API 6A flanges, catering to the stringent requirements of the oil & gas, drilling, and offshore sectors across continents.

Key Export Destinations Include:

  • United Arab Emirates (UAE)
  • Saudi Arabia
  • Oman
  • Qatar
  • Kuwait
  • USA
  • Canada
  • Mexico
  • Brazil
  • United Kingdom (UK)
  • Germany
  • Italy
  • Indonesia
  • Malaysia
  • Vietnam
  • Nigeria
  • South Africa

With on-time delivery, PSL-certified documentation, and tailored packaging, Nutech ensures its API 6A flanges meet global project specifications for both onshore and offshore installations.

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