API 605 Large Diameter Flanges
API 605 Flanges: Specifications | Materials | Dimensions | Weight Chart | Tolerances | FAQ
API 605 Large Diameter Flanges Manufacturer and Supplier in USA, Germany, UAE, India and South Korea providing high strength flanges from sizes 26 inches to 60 inches for heavy duty piping systems.
Best Export Prices: sales@midlandforgefittings.com
Midland Forge Fittings is a globally recognized manufacturer and supplier of high-performance API 605 – Large Diameter Flanges designed for demanding industrial applications. With a strong foundation in engineering excellence, we combine advanced manufacturing processes with stringent quality control systems to deliver products that consistently meet international standards.
Our work structure is built around precision, efficiency, and reliability. Every stage of production, from raw material selection to final inspection, is carefully monitored to ensure compliance with client specifications and industry regulations. Our in-house facilities are equipped with modern machining, heat treatment, and testing capabilities, enabling us to maintain a seamless flow from design to dispatch.
API 605 Large Diameter Flanges are specifically designed for heavy-duty piping systems where strength, durability, and precise dimensional accuracy are critical. These flanges are manufactured for large bore pipelines, typically in sizes ranging from 26 inches to 60 inches, and are engineered to handle high pressure and high temperature applications in oil, gas, chemical, and power industries.
Produced in accordance with the API 605 standard, these flanges feature accurate bolt hole alignment, robust wall thickness, and superior sealing surfaces to ensure leak-proof connections under extreme operating conditions. They are manufactured from high-grade forged steel to enhance mechanical strength, resistance to stress, and corrosion durability, making them suitable for both onshore and offshore installations.
We follow a client-centric approach by providing tailored solutions for diverse sectors such as oil and gas, petrochemicals, power generation, marine, and construction. With a skilled workforce, robust logistics network, and a commitment to innovation, Midland Forge Fittings has established itself as a trusted partner for both domestic and international projects.
Large Diameter Flanges - Specifications
ASME B16.47 Large Diameter Flanges - Materials, Grades & Standards
| Material Type | Grades / Standards | Notes |
|---|---|---|
| Carbon Steel | ASTM A105, ASTM A350 LF2, ASTM A694 F42–F70 | Suitable for standard pressure, temperature, and high-yield pipeline applications |
| Alloy Steel | ASTM A182 F1, F5, F9, F11, F22, F91 | Designed for high-temperature, high-pressure, and steam service conditions |
| Stainless Steel | ASTM A182 F304 / F304L, F316 / F316L, F321, F347 | Corrosion-resistant and ideal for chemical, refinery, and subsea environments |
| Duplex / Super Duplex | ASTM A182 F51 (UNS S31803), F53, F55 (UNS S32750) | Excellent strength and resistance to stress corrosion cracking in harsh service |
| Nickel Alloys | Inconel, Monel, Hastelloy | Suitable for extreme temperature fluctuations and highly corrosive media |
| Forged Steel | API 605 / ASME B16.47 Forgings | Used for large bore, high-pressure flanges requiring superior mechanical strength |
API 605 / ASME B16.47 Large Bore Flanges – Dimensions
| NPS (inches) |
Outside Diameter (OD, mm) |
Bolt Circle Diameter (mm) |
Number of Bolt Holes |
Bolt Size | Raised Face (RF) / Flat Face (FF) / RTJ |
|---|---|---|---|---|---|
| 26 | 660 | 600 | 24 | 2.5” | RF / FF / RTJ |
| 28 | 711 | 648 | 28 | 2.5” | RF / FF / RTJ |
| 30 | 762 | 690 | 28 | 2.5” | RF / FF / RTJ |
| 32 | 813 | 732 | 32 | 2.5” | RF / FF / RTJ |
| 34 | 864 | 780 | 32 | 2.5” | RF / FF / RTJ |
| 36 | 914 | 828 | 36 | 2.5” | RF / FF / RTJ |
| 38 | 965 | 876 | 36 | 2.5” | RF / FF / RTJ |
| 40 | 1016 | 924 | 40 | 2.5” | RF / FF / RTJ |
| 42 | 1067 | 972 | 40 | 2.5” | RF / FF / RTJ |
| 44 | 1118 | 1020 | 44 | 2.5” | RF / FF / RTJ |
| 46 | 1168 | 1068 | 44 | 2.5” | RF / FF / RTJ |
| 48 | 1219 | 1116 | 48 | 2.5” | RF / FF / RTJ |
| 50 | 1270 | 1164 | 48 | 2.5” | RF / FF / RTJ |
| 52 | 1321 | 1212 | 52 | 2.5” | RF / FF / RTJ |
| 54 | 1372 | 1260 | 52 | 2.5” | RF / FF / RTJ |
| 56 | 1422 | 1308 | 56 | 2.5” | RF / FF / RTJ |
| 58 | 1473 | 1356 | 56 | 2.5” | RF / FF / RTJ |
| 60 | 1524 | 1404 | 60 | 2.5” | RF / FF / RTJ |
API 605 Flanges replaced with ASME B16.47 - Weight Chart
| NPS (inches) | OD (mm) | Class 75 (kg) | Class 150 (kg) | Class 300 (kg) | Class 400 (kg) | Class 600 (kg) |
|---|---|---|---|---|---|---|
| 26 | 660 | 420 | 450 | 510 | 580 | 650 |
| 28 | 711 | 470 | 510 | 580 | 650 | 730 |
| 30 | 762 | 520 | 560 | 640 | 720 | 810 |
| 32 | 813 | 580 | 620 | 710 | 800 | 900 |
| 34 | 864 | 640 | 680 | 780 | 880 | 980 |
| 36 | 914 | 700 | 740 | 850 | 960 | 1070 |
| 38 | 965 | 760 | 810 | 930 | 1050 | 1160 |
| 40 | 1016 | 820 | 880 | 1010 | 1140 | 1250 |
| 42 | 1067 | 890 | 960 | 1100 | 1240 | 1350 |
| 44 | 1118 | 960 | 1040 | 1190 | 1340 | 1450 |
| 46 | 1168 | 1030 | 1120 | 1280 | 1440 | 1560 |
| 48 | 1219 | 1100 | 1200 | 1370 | 1550 | 1670 |
| 50 | 1270 | 1180 | 1290 | 1470 | 1660 | 1790 |
| 52 | 1321 | 1260 | 1380 | 1570 | 1770 | 1910 |
| 54 | 1372 | 1340 | 1470 | 1670 | 1880 | 2030 |
| 56 | 1422 | 1420 | 1560 | 1780 | 1990 | 2150 |
| 58 | 1473 | 1510 | 1650 | 1890 | 2110 | 2280 |
| 60 | 1524 | 1600 | 1750 | 2000 | 2230 | 2400 |
Large Diameter Flanges as per API 605 - Tolerances
| Parameter | Tolerance |
|---|---|
| Outside Diameter (OD) | ±1% of nominal OD |
| Bolt Circle Diameter (BCD) | ±0.8% of nominal BCD |
| Bolt Hole Diameter | +0 / -1 mm |
| Number of Bolt Holes | Exact as per specification |
| Flange Thickness / Raised Face Height | ±5% of nominal thickness |
| Face Flatness (RF / FF) | 0.5 mm per 300 mm length |
| Out-of-Roundness | ≤1.5% of nominal OD |
| Angular Alignment of Bolt Holes | ±1° |
What are the key differences between API 605 and ASME B16.47 Series A?
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Standard Evolution: API 605 has been superseded by ASME B16.47 Series A to align flange sizes and pressure ratings with modern large diameter piping requirements.
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Size Range: API 605 covers 26” to 60” NPS, which is retained in ASME B16.47 Series A with minor dimensional adjustments for bolt circle and flange thickness.
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Bolt Circle & Holes: ASME B16.47 standardized the bolt hole dimensions and pattern, improving interchangeability between manufacturers.
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Face Types & Ratings: Raised Face (RF), Flat Face (FF), and Ring Type Joint (RTJ) facings are maintained, but ASME B16.47 adds consistent tolerance limits across classes.
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Pressure Classes: ASME B16.47 specifies flange weights and pressure ratings more comprehensively for Class 75, 150, 300, 400, and 600, ensuring compatibility with large bore pipelines.
How are API 605 flanges manufactured to ensure quality and compliance?
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Forging: Flanges are typically forged from carbon, alloy, or stainless steel to achieve high mechanical strength.
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Heat Treatment: Controlled processes enhance toughness, ductility, and stress relief, especially for high-pressure applications.
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Machining: Precision CNC or lathe machining ensures accurate OD, bolt hole alignment, and face finish.
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Testing & Inspection: Includes Ultrasonic Testing (UT), Magnetic Particle Inspection (MPI), Radiography (RT), Positive Material Identification (PMI), and hydrostatic pressure testing to meet API and ASME standards.
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Tolerances Compliance: Thickness, OD, bolt circle diameter, and face flatness are verified against API 605 / ASME B16.47 tolerances.
Which industries commonly use API 605 / ASME B16.47 Large Diameter Flanges?
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Oil & Gas Pipelines: High-pressure large bore pipelines requiring durable flange connections.
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Petrochemical Plants: Corrosion-resistant alloys for chemical processing pipelines.
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Refineries: Large diameter piping systems with high-temperature steam and process fluids.
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Power Generation: Steam, cooling water, and high-pressure feed lines.
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Offshore & Subsea Projects: Duplex, super duplex, and nickel alloy flanges for corrosion and stress resistance.