API 6A Wellhead Flanges & Equipment
API 6A Wellhead Flanges : Specifications | Materials | Dimensions | Weight Chart | Tolerances | FAQ
Top-Grade API 6A Wellhead Flanges & Equipment – Manufactured for Global Oil & Gas Needs – PSL 1 to PSL 3, Sizes 2”–36” – Available in India, Saudi Arabia, Singapore, Australia & UK.
Best Export Prices: sales@midlandforgefittings.com
Midland Forge Fittings is a leading manufacturer and supplier of API 6A – Wellhead Flanges, committed to delivering high-quality solutions to industries worldwide, including oil & gas, petrochemical, power, and industrial piping sectors. With a strong emphasis on precision, reliability, and innovation, we have established ourselves as a trusted partner for clients seeking durable and high-performance forged components.
Driven by a skilled team and state-of-the-art manufacturing processes, we operate with a focus on quality, operational excellence, and customer satisfaction. Our vision is to be recognized as a global leader in forged fittings, while our mission is to consistently provide superior, standards-compliant solutions that enhance efficiency, safety, and long-term value for our clients.
API 6A – Wellhead Flanges & Equipment are critical components in the oil and gas industry, designed to provide safe and reliable connections at the wellhead. These flanges and associated equipment, including valves, adapters, and spools, are engineered to withstand extreme pressure, high temperature, and corrosive environments encountered in upstream drilling and production operations. Their precise design ensures leak-proof sealing, structural integrity, and operational safety, which are essential for controlling wellbore fluids and maintaining pressure containment during drilling, completion, and production activities.
Manufacturing of API 6A equipment involves high-grade alloy steels and carbon steels, subjected to forging, machining, heat treatment, and surface finishing processes to achieve the required strength and dimensional accuracy. Each component is tested rigorously under hydrostatic, mechanical, and non-destructive inspections to meet the strict API 6A standards. This rigorous manufacturing and testing process ensures that the wellhead flanges and equipment can reliably perform under demanding conditions, preventing failures that could lead to operational downtime, environmental hazards, or safety risks.
With a strong global presence, We exports its API 6A Flanges to countries including India, UAE, Saudi Arabia, Germany, Malaysia, and Brazil. We are committed to delivering reliable and timely solutions that meet international standards, fostering long-term partnerships with clients across diverse industrial sectors.
High-Pressure Wellhead Flanges
Wellhead Flanges & Equipment - Materials, Grades & Standards
| Material Type | Grades / Standards | Notes |
|---|---|---|
| Carbon Steel | API 6A PSL1 / PSL2, ASTM A105, A350 LF2 | Suitable for standard pressure and temperature applications |
| Alloy Steel | ASTM A182 F11, F22, F91 | High-temperature, high-pressure, and corrosion-resistant |
| Stainless Steel | ASTM A182 F304/F304L, F316/F316L, F321, F347 | Corrosion-resistant, used in subsea and chemical service |
| Nickel Alloys | Inconel, Monel, Hastelloy | Extreme temperature and highly corrosive environments |
| Duplex / Super Duplex | UNS S31803, UNS S32750 | Excellent corrosion resistance & strength for harsh service |
| Forged Steel | API 6A PSL1 / PSL2 Forgings | Used for high-pressure wellhead flanges and components |
API 6A Wellhead Flanges – Dimensions
| Flange Type |
NPS (in) |
Pressure Class (psi) |
Outside Diameter OD (mm / in) |
Bolt Circle Diameter BCD (mm / in) |
Number of Bolts |
Bolt Size | Face Thickness (mm / in) |
|---|---|---|---|---|---|---|---|
| RF / RTJ | 2½” | 2,000 | 127 / 5.0 | 89 / 3.5 | 4 | ¾” | 25 / 0.98 |
| RF / RTJ | 2½” | 5,000 | 140 / 5.5 | 100 / 3.94 | 4 | 7/8” | 30 / 1.18 |
| RF / RTJ | 2½” | 10,000 | 152 / 6.0 | 114 / 4.49 | 8 | 1” | 38 / 1.50 |
| RF / RTJ | 2½” | 15,000 | 165 / 6.5 | 127 / 5.0 | 8 | 1¼” | 45 / 1.77 |
| RF / RTJ | 3½” | 2,000 | 140 / 5.5 | 100 / 3.94 | 4 | ¾” | 25 / 0.98 |
| RF / RTJ | 3½” | 5,000 | 152 / 6.0 | 114 / 4.49 | 4 | 7/8” | 30 / 1.18 |
| RF / RTJ | 3½” | 10,000 | 165 / 6.5 | 127 / 5.0 | 8 | 1” | 38 / 1.50 |
| RF / RTJ | 3½” | 15,000 | 178 / 7.0 | 140 / 5.51 | 8 | 1¼” | 45 / 1.77 |
| RF / RTJ | 4½” | 2,000 | 165 / 6.5 | 127 / 5.0 | 4 | ¾” | 30 / 1.18 |
| RF / RTJ | 4½” | 5,000 | 178 / 7.0 | 140 / 5.51 | 8 | 7/8” | 38 / 1.50 |
| RF / RTJ | 4½” | 10,000 | 190 / 7.48 | 152 / 5.98 | 8 | 1” | 45 / 1.77 |
| RF / RTJ | 4½” | 15,000 | 203 / 8.0 | 165 / 6.5 | 12 | 1¼” | 50 / 1.97 |
| RF / RTJ | 6½” | 2,000 | 190 / 7.48 | 152 / 5.98 | 8 | 7/8” | 38 / 1.50 |
| RF / RTJ | 6½” | 5,000 | 203 / 8.0 | 165 / 6.5 | 8 | 1” | 45 / 1.77 |
| RF / RTJ | 6½” | 10,000 | 216 / 8.5 | 178 / 7.0 | 12 | 1¼” | 50 / 1.97 |
| RF / RTJ | 6½” | 15,000 | 229 / 9.0 | 191 / 7.52 | 12 | 1¼” | 55 / 2.16 |
| RF / RTJ | 8½” | 2,000 | 216 / 8.5 | 178 / 7.0 | 8 | 7/8” | 38 / 1.50 |
| RF / RTJ | 8½” | 5,000 | 229 / 9.0 | 191 / 7.52 | 12 | 1” | 45 / 1.77 |
| RF / RTJ | 8½” | 10,000 | 241 / 9.5 | 203 / 8.0 | 12 | 1¼” | 50 / 1.97 |
| RF / RTJ | 8½” | 15,000 | 254 / 10.0 | 216 / 8.5 | 16 | 1¼” | 60 / 2.36 |
| RF / RTJ | 10½” | 2,000 | 241 / 9.5 | 203 / 8.0 | 8 | 7/8” | 45 / 1.77 |
| RF / RTJ | 10½” | 5,000 | 254 / 10.0 | 216 / 8.5 | 12 | 1” | 50 / 1.97 |
| RF / RTJ | 10½” | 10,000 | 267 / 10.5 | 229 / 9.0 | 12 | 1¼” | 55 / 2.16 |
| RF / RTJ | 10½” | 15,000 | 279 / 11.0 | 241 / 9.5 | 16 | 1¼” | 65 / 2.56 |
| RF / RTJ | 13½” – 24” | 2,000 – 15,000 | 305 – 610 / 12 – 24 | 254 – 580 / 10 – 22.8 | 12 – 24 | 1 – 1½” | 55 – 150 / 2.16 – 5.9 |
Wellhead Fittings & Flanges - Weight Chart as per API 6A
| Flange Type | NPS (in) | Pressure Class (psi) | Approx. Weight (kg / lb) |
|---|---|---|---|
| RF / RTJ | 2½” | 2,000 | 15 / 33 |
| RF / RTJ | 2½” | 5,000 | 18 / 40 |
| RF / RTJ | 2½” | 10,000 | 25 / 55 |
| RF / RTJ | 2½” | 15,000 | 35 / 77 |
| RF / RTJ | 3½” | 2,000 | 17 / 37 |
| RF / RTJ | 3½” | 5,000 | 20 / 44 |
| RF / RTJ | 3½” | 10,000 | 28 / 62 |
| RF / RTJ | 3½” | 15,000 | 38 / 84 |
| RF / RTJ | 4½” | 2,000 | 20 / 44 |
| RF / RTJ | 4½” | 5,000 | 28 / 62 |
| RF / RTJ | 4½” | 10,000 | 38 / 84 |
| RF / RTJ | 4½” | 15,000 | 50 / 110 |
| RF / RTJ | 6½” | 2,000 | 35 / 77 |
| RF / RTJ | 6½” | 5,000 | 45 / 99 |
| RF / RTJ | 6½” | 10,000 | 60 / 132 |
| RF / RTJ | 6½” | 15,000 | 75 / 165 |
| RF / RTJ | 8½” | 2,000 | 45 / 99 |
| RF / RTJ | 8½” | 5,000 | 60 / 132 |
| RF / RTJ | 8½” | 10,000 | 75 / 165 |
| RF / RTJ | 8½” | 15,000 | 95 / 210 |
| RF / RTJ | 10½” | 2,000 | 55 / 121 |
| RF / RTJ | 10½” | 5,000 | 70 / 154 |
| RF / RTJ | 10½” | 10,000 | 85 / 187 |
| RF / RTJ | 10½” | 15,000 | 110 / 242 |
| RF / RTJ | 13½” – 24” | 2,000 – 15,000 | 120 – 850 / 265 – 1874 |
API 6A Wellhead Equipment - Tolerances
| Parameter | Tolerance / Specification |
|---|---|
| Outside Diameter (OD) | ±1% of nominal flange OD |
| Bolt Circle Diameter (BCD) | ±0.8% of nominal BCD |
| Number of Bolts | Exact per specification; no tolerance |
| Bolt Hole Diameter | +0.2 mm / 0 mm (+0.008” / 0) |
| Face Flatness (RF / RTJ) | ≤0.05 mm per 25 mm of flange diameter |
| Face Parallelism | ≤0.1 mm between raised face and flange hub |
| Raised Face Height (RF Flanges) | ±0.5 mm |
| Ring Type Joint (RTJ) Groove Depth | ±0.15 mm |
| Flange Thickness / Face Thickness | ±5% of nominal thickness |
| Bolt Hole Position / Spacing | ±0.5 mm |
| Out-of-Roundness | ≤1% of nominal OD |
| Concentricity (Hub / Bore) | ≤0.5% of nominal bore |
| Threaded / NPT Flanges | Threads per ASME B1.20.1, ±0.15 mm tolerance for minor diameter variation |
| Surface Finish | RF: Ra 3.2 µm max; RTJ: Ra 1.6 µm max (for sealing groove) |
| Material / Heat Treatment | Must meet API 6A PSL requirements; hardness variation ≤10% across flange face |
What is API 6A and why is it critical for wellhead flanges?
- API 6A is the American Petroleum Institute standard that governs the design, materials, dimensions, tolerances, testing, and performance of wellhead and Christmas tree equipment.
- It ensures that wellhead flanges can operate safely under high-pressure, high-temperature, and corrosive conditions commonly found in oil and gas wells.
- The standard guarantees interchangeability, leak-proof connections, and reliability, making it the global benchmark for wellhead equipment.
What are the common types of wellhead flanges in API 6A?
- Raised Face (RF) Flanges: Provide a gasket seating surface for leak-proof connections.
- Ring Type Joint (RTJ) Flanges: Metal-to-metal sealing flanges with precision grooves for extreme high-pressure applications.
- Threaded/NPT Flanges: For temporary installations or low-pressure connections.
- Special Flanges: Customized for subsea or high-chloride service, ensuring compatibility with specific wellhead components.
- Selection of flange type depends on service pressure, temperature, and sealing requirements.
How are API 6A wellhead flanges manufactured?
- Forging or Casting: Ensures structural integrity and required mechanical strength.
- Precision Machining: Critical for OD, BCD, bolt holes, face, and RTJ grooves to meet API 6A dimensions.
- Heat Treatment: Achieves required hardness, tensile strength, and impact resistance.
- Non-Destructive Testing (NDT): Ultrasonic, magnetic particle, or radiographic testing detects surface and internal defects.
- Final Inspection: Confirms compliance with API 6A PSL requirements, ensuring each flange meets dimensional, mechanical, and material standards.