Duplex Pipes

Duplex pipes are stainless pipes containing the high amount of chromium and minimum amount of nickel.

Duplex stainless steel (DSS) is featured with structure of two phases (α and γ) and has characteristics of both ferritic and austenitic stainless steel. It has good corrosion resistance and high strength. It is alloyed with 18%-28% Cr and 3%-10% Ni in the condition of low C. Some steels also contain the alloy elements such as Mo, Cu, Nb, Ti and N, etc.

Standard:

Steel Grade:

While Duplex 2205 is the most common duplex product we supply, we can also deliver Duplex 2304 and Duplex 2207 with reduced lead times as these alloys are stocked. Alloy 2205 (UNS S32305/S31803) is a 22% chromium, 3% molybdenum, 5-6% nickel, nitrogen alloyed duplex stainless steel pipe with high general, localized, and stress corrosion resistance properties in addition to high strength and excellent impact toughness.

Alloy 2205 provides pitting and crevice corrosion resistance superior to 316L or 317L austenitic stainless steel tube in almost all corrosive media. It also has high corrosion and erosion fatigue properties as well as lower thermal expansion and higher thermal conductivity than austenitic.

ASTM Referenced Standards

ASTM A789 A789M Covers Grades of nominal wall thickness, stainless steel tubing for services requiring general corrosion resistance, with particular emphasis on resistance to stress corrosion cracking. These steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures.

Chemical Composition:

UNS
Designation
Composition, %
C
Max
Mn
max
P
max
S
max
Si
max
Ni Cr Mo N Cu Others
S31803 0.03 2 0.03 0.02 1 4.5-6.5 21.0-23.0 2.5-3.5 0.08-0.20 . . . . . .
S32205 0.03 2 0.03 0.02 1 4.5-6.5 22-23 3.0-3.5 0.14-0.20 . . . . . .
S31500 0.03 1.20-2.00 0.03 0.03 1.40-2.0 4.3-5.2 18-19 2.5-3.0 0.05-0.10 . . . . . .
S32550 0.04 1.5 0.04 0.03 1 4.5-6.5 24-27 2.9-3.9 0.10-0.25 1.50-2.50 . . .
S31200 0.03 2 0.045 0.03 1 5.5-6.5 24-26 1.-2.0 0.14-0.20 . . . . . .
S31260 0.03 1 0.03 0.03 0.75 5.5-7.5 24-26 2.5-3.5 0.10-0.30 0.20-0.80 W 0.10-0.50
S32001 0.03 4.0-6.0 0.04 0.03 1 1.0-3.0 19.5-21.5 0.6 0.05-0.17 1.00 max . . .
S32304 0.03 2.5 0.04 0.04 1 3.0-5.5 21.5-24.5 0.05-0.60 0.05-0.20 0.05-0.60 . . .
S32750 0.03 1.2 0.035 0.02 0.8 6.0-8.0 24-26 3.0-5.0 0.24-0.32 0.50max . . .
S32760 0.05 1 0.03 0.01 1 6.0-8.0 24-26 3.0-4.0 0.20-0.30 0.50-1.00 W 0.50-1.00
S32950 0.03 2 0.035 0.01 0.6 3.5-5.2 26-29 1.0-2.5 0.15-0.35 . . . . . .
S32520 0.03 1.5 0.035 0.02 0.8 5.5-8.0 23-25 3.0-5.0 0.20-0.35 0.8 . . .

Heat Treatment Requirements

UNS
Designation
Temperature Quench
S31803 1870-2010 °F [1020-1100°C] Rapid cooling in air or water
S32205 1870-2010 °F [1020-1100°C] Rapid cooling in air or water
S31500 1800-1900 °F [980-1040°C] Rapid cooling in air or water
S32550 1900 °F [1040°C] min. Rapid cooling in air or water
S31200 1920-2010 °F [1050-1100°C] Rapid cooling in water
S31260 1870-2010 °F [1020-1100°C] Rapid cooling in water
S32001 1800-1950 °F [982-1066°C] Rapid cooling in air or water
S32304 1700-1920 °F [925-1050°C] Rapid cooling in air or water
S32750 1880-2060 °F [1025-1125°C] Rapid cooling in air or water
S32760 2010-2085 °F [1100-1140°C] Rapid cooling in air or water
S32950 1820-1880 °F [990-1025°C] Rapid cooling in water
S32520 1975-2050 °F [1080-1120°C] Rapid cooling in air or water

Tensile Requirements

Grade Tensile strength, min., ksi [MPa] Yield strength, min., ksi [MPa] Elongation in 2 in., or 50mm, min, % Hardness, Max

Brinell

S31803 90 [620] 65 [450] 25 290
S32205 95 [655] 70 [485] 25 290
S31500 92 [630] 64 [440] 30 290
S32550 110 [760] 80 [550] 15 297
S31200 100 [690] 65 [450] 25 280
S31260 100 [690] 65 [450] 25 290
S32001 90 [620] 65 [450] 25 290
S32304 100 [690] 65 [450] 25 290
S32750 116 [800] 80 [550] 15 310
S32760 109 [750] 80 [550] 25 300
S32950 100 [690] 70 [480] 20 290
S32520 112 [770] 80 [550] 25 310

Flange Test (for welded tubes)

Flaring Test

Reverse Flattening Test

Hydrostatic or Nondestructive Testing

Markings

Note:

Applications:

Duplex pipes are stainless pipes containing the high amount of chromium and minimum amount of nickel. Duplex pipes provide great strength and resistance to corrosive environments. Duplex pipes are used in desalination plants, heat exchangers, and marine processes.

The basic idea of duplex is to produce a chemical composition that leads to an approximately equal mixture of ferrite and austenite. This balance of phases provides the following:

The combination of high strength, corrosion resistance and moderate weldability has many benefits but also bring disadvantages and limitations.

High strength is a disadvantage when forming and machining. The higher strength also means that the metal is less ductile than austenitic grades. This means that these steels are not good when the goods being produce require any degree of complex forming.

It is also worth bering in mind that evemn if the item can be formed in duplex steel greater forces are required.

The metallurgy of duplex stainless steels is much more complex than for austenitic or ferritic steels whith the result that they are more complex and therefore expensive to produce. Howver the lower quantity of nickel in them as compared to austenitic grades does help to keep the cost down and reduce price volatility.

Delivery requirment:
Inspection
Inspection
Finished
Finished tubes
Packed in bundles
Packed in bundles
Finished
packing in wooden case
  • Marking: SunnySteel, material grade, standard, specification, heat no.
  • Surface Treatment: Bright annealed, polished outside and inside surface.
  • Package: Each pipe in a PVC bag and caps on both ends then bundled in wood case,
  • Option: Bundle with knitted plastic bag/stee crate.
  • Mill test certificate: according to EN 10204 3.2
  • Inspection: Third party inspection, or by clints
Delivery requirment:
Capped end stainless steel tube
Capped end stainless steel tube
Tubes putted in wooden boxes
Tubes putted in wooden boxes
Stainless Steel Seamless Pipes
the wooden boxes packing for stainless products
Stainless Steel Seamless Pipes
Warehouse
  • Marking: SunnySteel, material grade, standard, specification, heat no.
  • Surface Treatment: Bright annealed, polished outside and inside surface.
  • Package: knitting strip bundle, wooden box or steel box
  • Mill test certificate: according to EN 10204 3.2
  • Inspection: Third party inspection, or by clints

Pipe size range:

  • Outside diameter: range from 6mm to 530mm.
  • Wall thickness: SCH5S, SCH10S, SCH40S, SCH80S, SCH 120S
  • Legnth: unbending length or fix length
Range of Application

Stainless steel pipe (tube) has excellent characteristics of corrosion resistance and smooth finishing. Stainless steel pipe (tube) is commonly used in demanding equipment like automobiles, food processing, water treatment facilities, oil and gas processing, refinery and petrochemicals, breweries and energy industries.

The stainless steel tubing that is supplied by SunnySteel can used in a variety of industries, including:

  • Machinery Parts
  • Pharmaceutical
  • Biotechnology
  • Automotive
  • Oil and Gas
  • Marine
  • Food and Beverage Processing
  • Construction
  • Automotive industries
  • Food processing
  • Water treatment facilities
  • Breweries and energy industries

Considering the importance of outside and inside surface of stainless steel tubes for fluid power industry, Our mills are providing tubes that are free from scale, rust, seams, laps.



SUNNY STEEL

Our team are highly trained and experienced in servicing and producing all types of steel supplies. Whether you've got a large construction project, or need parts for industrial machinery, our team of steel fabrication consultants will ensure that your project is provided with the parts you need, when you need them.

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