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Duplex Steel Flanges

API 6A Type 6BX 3000 PSI Blind Flanges

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Duplex Flanges Overview

Duplex flanges are made from duplex stainless steel material that combines the best properties of austenitic & ferritic steels. This unique microstructure of duplex flanges has features like excellent corrosion resistance, high strength & good weldability. These flanges are magnetic, work hardenable & are used in high-pressure, high-temperature industrial applications such as chemical plants, offshore oil rigs & marine systems.

There are several types of duplex flanges available, including:

  • Slip-On Flanges – Allow pipes to slide in for easy alignment and welding.
  • Blind Flanges – Used to close off pipe ends securely.
  • Spectacle Blind Flanges – Used for maintenance and flow control.
  • Welding Neck Flanges – Suitable for high-stress applications.

Duplex steel flanges typically conform to standards like ASTM A182 , ANSI B16.5 with pressure ratings & sizes ranging from NPS ½ to NPS 24. The material offers a minimum yield strength of 450 MPA & tensile strength of 620 MPa. Duplex steel flanges should be used at temperatures below 570°F to avoid embrittlement. Due to their lightweight design, precise dimensions & reliable performance, they are used in valve fittings, shafts, couplings & pressure vessels.

Duplex Steel Flanges Manufacturer & Supplier

Kalpataru Piping Solutions is a trusted manufacturer and supplier of Duplex Steel Flanges offering precision engineered solutions for high performance piping systems. Our duplex flanges are known for their excellent mechanical strength, superior resistance to corrosion & long service life. Our Duplex Flanges are designed to perform in highly demanding applications including offshore structures, petrochemical plants, desalination facilities & chemical processing units. With a balanced microstructure of dual material, duplex steel delivers enhanced durability under both mechanical & chemical stress. 

We offer different types of duplex steel  like Slip-On, Blind  (BLRF), Weld Neck, Socket Weld Flanges, Spectacle Blind, Ring Type Joint (RTJ)  & many more. We supply flanges in accordance with global standards such as ASTM A182, ASME B16.5 & DIN or EN specifications covering grades like UNS S31803, S32205, S32750 & S32760. Each product undergoes rigorous quality checks including destructive & non-destructive tests to ensure dimensional accuracy & long-lasting performance under pressure & temperature variations. We maintain a ready stock of Duplex and Super Duplex Flanges to ensure quick delivery, competitive pricing & global supply capability.

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Grades of Duplex Flanges

Kalpataru Piping Solutions offers Duplex Flanges in premium grades like UNS S31803, S32205 and many more. These grades deliver superior strength, corrosion resistance & reliability for critical industrial and offshore applications.

Duplex Steel UNS S31803 Flanges

Duplex Steel UNS S31803 Flanges

Duplex Steel UNS S31803 Flanges

Duplex Steel UNS S32205 Flanges

Duplex Flanges Specification

Explore Duplex Flanges with high strength, corrosion resistance, and durability. Available in ASTM A182 standards, sizes from ½” to 24”, and types like Slip-On, Blind, Weld Neck & Socket Weld for high-pressure industrial applications.

Size 1/8″ NB TO 24″ NB
Standard ANSI Flanges, ASME Flanges, BS Flanges, DIN Flanges, EN Flanges, etc.
Designation ANSI B 16.5, BS 1560. BS 10, IS 6392, B-2.1 NPT, API, DIN, JIS. MSS SP 44
Grade ASTM A182 / ASME SA182 F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61, UNS S31803, UNS S32205.
Class 150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS
Flange Face Type Flate Face (FF), Raised Face (RF), Ring Type Joint (RTJ)

Duplex Steel Flanges Chemical Composition

Understanding chemical composition of Duplex Steel Flanges includes chromium, nickel, molybdenum, and nitrogen – key elements that provide excellent corrosion resistance, high strength, and durability for critical industrial applications.

Grade C Mn Si P S Cr Mo Ni N Fe
S31803 0.030 max 2.00 max 1.00 max 0.030 max 0.020 max 22.0 – 23.0 3.0 – 3.5 4.50 – 6.50 0.14 – 0.20 63.72 min
S32205 0.030 max 2.00 max 1.00 max 0.030 max 0.020 max 21.0 – 23.0 2.50 – 3.50 4.50 – 6.50 0.8 – 0.20 63.54 min

Mechanical Properties of Duplex Flanges

Get detailed insights into the mechanical properties of Duplex Flanges including density and melting point, along with equivalent grades like Duplex 2205 (UNS S31803/S32205, Werkstoff Nr. 1.4462) used for high-strength, corrosion-resistant applications.

 

Grades Density (g/cm 3) Density (lb/in 3) Melting Point (°C) Melting Point (°F)
S31803 / S32205 7.805 0.285 1420 – 1465 2588 – 2669

Duplex Stainless Steel Flanges Equivalent Grades

Duplex Stainless Steel Flanges are available in equivalent grades like Duplex 2205, with Werkstoff Nr. 1.4462 and UNS S31803/S32205, offering a balanced combination of strength and corrosion resistance for diverse industrial uses.

STANDARD WERKSTOFF NR. UNS
Duplex 2205 1.4462 S31803 / S32205

Size Chart for Duplex Steel Flanges

Duplex Steel Flanges are available in a wide range of sizes to meet various industrial piping requirements. The chart below provides standard flange sizes, suitable for high-pressure and high-corrosion applications.

Nominal Pipe Size (NPS) Flange Outer Diameter (mm) Bolt Circle Diameter (mm) Number of Bolts
½” 90 60.3 4
1” 110 73.0 4
2” 150 120.7 4
3” 190 152.4 4
4” 230 190.5 8
6” 280 241.3 8
8” 345 298.5 8
10” 405 362.0 12
12” 485 431.8 12
16” 650 603.2 16

Duplex Steel Flanges Temperature Rating

Duplex SS Flanges offer excellent performance up to 570°F (300°C), with a melting point range of 1420–1465°C. Ideal for high-pressure, corrosive environments, but prolonged exposure to elevated temperatures should be avoided to prevent embrittlement.

ASME/ANSI B 16.5 Welding Neck Flanges, Socket Weld Flanges, Slip on Flanges, Blind Flanges, Lap Joint Flanges, Threaded Flanges, High Hub Blind Flanges, Ring Type Joint Flanges
PRESSURE CLASS 150, 300, 400, 600, 900, 1500, 2500
ASME/ANSI B 16.36 Threaded Flanges, Welding Neck Flanges, Slip on Flanges (SORF)
PRESSURE CLASS 300, 400, 600, 900, 1500, 2500
ASME/ANSI B 16.47 Weld Neck Flanges, Blind Flange [Series A & B]
PRESSURE CLASS 75, 150, 300, 400, 600, 900
BS 4504 SEC 3.1 Hubbed Threaded Flanges, Welding Neck Flanges, Blank Flanges, Hubbed Slip on Flanges, Lapped Pipe End Flanges, Plate Flanges, Loose Plate Flanges, Loose Plate With Weld Neck Flanges
PRESSURE CLASS PN 2.5 TO PN 40
BS 1560 BOSS Slip-On Flanges, Welding Neck Flanges, Socket Welding Flanges, Blind Flanges, Lapped Flanges, Screwed Boss Flanges
PRESSURE CLASS 150, 300, 400, 600, 900, 1500, 2500
BS10 Blind Flanges, Welding Neck Flanges, Plate Slip-On Flanges, Screwed Boss Flanges, Slip-On Boss Flanges
TABLE D, E, F, H
DIN FLANGES DIN 2527, 2566, 2573, 2576, 2641, 2642, 2655, 2656, 2627, 2628, 2629, 2631, 2632, 2633, 2634, 2635, 2636, 2637, 2638, 2673
PRESSURE CLASS PN 6 TO PN 100
BS 4504[PART 1] Loose Plate With Weld On Plate Collar, Welding Neck Flanges, Hubbed Slip-On Hubbed Threaded, Plate Flanges, Blank Flanges
PRESSURE CLASS PN 2.5 TO PN 400

Duplex Flanges Weight Chart

Get accurate weight details of Duplex Steel Flanges based on size, type, and pressure class. Our weight chart helps in selecting the right flange for efficient handling, installation, and cost estimation in industrial piping systems.

Standard Class Diameter Bolt Circle Diameter Number of Bolts Bolt Size Diameter of Bolt Hole
AS4087 Flanges PN14 Flanges 95 67 4 M12 14
AS 2129 Flanges Table C Flanges 95 67 4 13 14
Table D Flanges 95 67 4 13 14
Table E Flanges 95 67 4 13 14
Table F Flanges 95 67 4 13 14
Table H Flanges 114 83 4 16 17
Table J Flanges 114 83 4 16 17
ANSI B16.5 Flanges ANSI 150 Flanges 89 60 4 13 16
ANSI 300 Flanges 95 67 4 13 16
ANSI 600 Flanges 95 67 4 13 16
ANSI 900 Flanges 121 83 4 19 22
ANSI 1500 Flanges 121 83 4 19 22
ISO 7005 (DIN) Flanges PN6 Flanges 80 55 4 M10 11
PN10 Flanges 95 65 4 M12 14
PN16 Flanges 95 65 4 M12 14
PN20 Flanges 90 60.5 4 M14 16
PN25 Flanges 95 65 4 M12 14
PN40 Flanges 95 65 4 M12 14

Duplex Steel Flange Thickness Calculation as per ASME B31.3 and UG-34

The wall thickness of these flanges plays a critical role in ensuring structural integrity & safe operation. As per ASME B31.3 Section 304.5.2, the flange thickness can be calculated using guidelines from ASME Section VIII, Division 1, UG-34.

Formula for Minimum Thickness ™:

The minimum required thickness for flat, unstayed circular flanges (blind flanges or covers) is calculated using:

tm = [Formula based on UG-34], where:

  • d = Flange diameter (short span, per UG-34 figure)
  • C = Factor based on attachment type and weld strength (e.g., C = 0.3 for welded designs)
  • hG = Gasket moment arm – radial distance from bolt centerline to gasket reaction line
  • E = Joint efficiency (per ASME Table UW-12)
  • P = Internal design pressure
  • S = Maximum allowable tensile stress (per UG-23 stress tables)
  • W = Total bolt load applicable to circular flanges

The final thickness should include manufacturing tolerances and must not be less than the calculated minimum ™ to ensure compliance and safety under pressure.

Duplex Stainless Steel Flange Pressure Rating

Duplex stainless steel flanges offer high-pressure ratings suitable for demanding applications. They typically conform to ASME standards, handling pressures up to Class 2500 based on size, temperature, and design.

Temperature In °F Working Pressure As per ASME B16.5 Class 150 to 2500 In PSI
CL 150 CL 300 CL 600 CL 900 CL 1500 CL 2500
-20~100 290 750 1500 2250 3750 6250
200 260 745 1490 2230 3720 6200
300 230 665 1335 2000 3335 5560
400 200 615 1230 1845 3070 5120
500 170 580 1160 1740 2905 4840
600 140 555 1115 1670 2785 4640
700 110 540 1085 1625 2710 4520

Thermal Conductivity of Duplex Steel Flanges

Duplex Stainless Steel (DSS) flanges have moderate thermal conductivity, typically around 15 W/m·K. This property balances heat transfer efficiency and resistance to thermal stress in high-temperature industrial systems.

Heat Treatment of Duplex Flanges

TDuplex stainless steels flanges undergo solution annealing between 1020–1100°C followed by rapid cooling. Proper heat treatment enhances corrosion resistance, restores mechanical properties, and prevents intermetallic phase formation.

Frequently Asked Questions About Duplex Flanges

What are duplex flanges & where are they used?

Duplex flanges are pipe connection components made from duplex stainless steel which combines both austenitic and ferritic microstructures. This dual-phase structure offers excellent strength, corrosion resistance & stress resistance.

Applications:

  • Offshore and marine piping
  • Oil and gas refineries
  • Chemical processing plants
  • Power generation systems
  • Desalination and water treatment
What is the cost of duplex steel flanges in India?

The cost in India depends on key factors such as material grade, flange type, size, pressure class & customization needs. Prices may also vary with compliance to ASME/ASTM standards, precision requirement & order volume. For accurate pricing, contact us to get a quick quote.

What are the different types of duplex steel flanges?

Duplex steel flanges are available in multiple types to suit different piping system requirements:

  • Weld Neck Flanges: Ideal for high-pressure and high-temperature applications
  • Slip-On Flanges: Easy to install, used in low-pressure systems
  • Blind Flanges: Seal pipe ends; used in testing and maintenance
  • Socket Weld Flanges: Suitable for small-diameter high-pressure pipes
  • Threaded Flanges: Used in low-pressure, non-welded applications
  • Spectacle Blind Flanges: Provide flow control and maintenance capability
  • Lap Joint & Ring Type Joint (RTJ) Flanges: Allow easy alignment and sealing under pressure

Each type is selected based on pressure class, medium handled, temperature range, and installation method.

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