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Duplex Stainless Steel Pipe

Duplex Stainless Steel is a type of austenitic stainless steel that comprises of nickel and chromium majorly, along with other elements like nitrogen and molybdenum.

It provides great strength and resistance to corrosive environments. It is used in desalination plants, heat exchangers, and marine processes.

This stainless steel alloy offers good resistance to localized as well as to uniform corrosion. The duplex microstructure of the alloy contributes to the high strength and high resistance to stress corrosion cracking. It has good weld ability and offers many beneficial properties of ferritic and austenitic steels combined.

Duplex Stainless Steel gives very good resistance to pitting and crevice corrosion and has high resistance to stress corrosion cracking and corrosion fatigue. It displays high mechanical strength and also provides good abrasion and erosion resistance. It is used in chemical, Oil and gas and marine industries. Other uses if the duplex stainless steel is in pollution control equipments, pulp & paper manufacturing, seawater desalination plants and in flue-gas cleaning to name a few.

Typical Properties:

  • Low cost
  • Alternative to high nickel based alloys
  • High strength
  • Corrosion resistant
  • Very hard machining

Specification:

  • ASTM A789/SA789 – Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service
  • ASTM A790/SA790 – Standard Specification for Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe
  • ASTM A928 – Standard Specification for Ferritic/Austenitic (Duplex) Stainless Steel Pipe Electric Fusion Welded with Addition of Filler Metal

Chemical Composition

Grade Chemical Composition
C (max) Si (max) Mn (max) P (max) S (max) Cr Ni Mo N Cu
S32750 0.030 0.8 1.2 0.030 0.015 24.0-26.0 6.8-8.0 3.0-5.0 0.24-0.32 0.5 max
S13803 0.030 1.0 2.0 0.030 0.020 21.0-23.0 4.50-6.50 2.50-3.50 0.08-0.20

Physical Propertie

Grade Physical Propertie
Y.S. MPa (min) T.S. MPa (min) Elongation % Hardness HRC
S32750 550 800 15 31
S13803 450 620 25 31

Size range for duplex pipes
W.T. 1.0 1.2 1.5 1.65 2.0 2.11 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
15
16
18
19.05
22
25.4
31.8
35
38.1
42
45
50.8
55
60
65
70
75
80
90
101.6
114.3
121
127
133
141.3
159
168.3

Note: For sizes other than given, please check with our office for further confirmation.

Duplex stainless steel

Steel No. Standard No. Type Chemical composition Other
C Si S P Mn Cr Ni Mo Other ób ós δ5 HB
0Cr26Ni5Mo2 GB1220 Bar 0.08 1 0.03 0.035 1.5 23-28 3-6 1-3 590 390 18 277 ψ%:40
0Cr26Ni5Mo2 GB4237 Plate 0.08 1 0.03 0.035 1.5 23-28 3-6 1-3 590 390 18 277
0Cr26Ni5Mo2 GB/T14976 Pipe 0.08 1 0.03 0.035 1.5 23-28 3-6 1-3 590 390 18
00Cr18Ni5Mo3Si2 GB1220 Bar 0.03 1.3-2 0.03 0.035 1.2-1.6 18-19.5 4.5-5.5 2.5-3 590 390 20 ψ%:40
00Cr18Ni5Mo3Si2 GB4237 Plate 0.03 1.3-2 0.03 0.03 1.2-1.6 18-19.5 4.5-5.5 2.5-3 N:0.1 590 390 20
HDR Q/SJB11-99 Pipe 0.03 1 0.03 0.035 2 23-26 4.5-7.5 2-3 650 450 27

Duplex stainless steels possess a mixed microstructure of ferrite and austenite. They contain a high chromium content of 22 wt.% – 25 wt.%, a molybdenum content of up to 5 wt.% and a low nickel content.

Duplex stainless steels exhibit roughly twice the strength of austenitic stainless steels and possess greater resistance to chloride stress corrosion cracking compared to austenitic stainless steels, albeit less so than ferritic. They exhibit toughness between that of ferritic and austenitic.

Examples & applications of duplex stainless steels

Due to these properties, duplex stainless steels are ideal for demanding environments where good mechanical properties are required in addition to good corrosion resistance. Common examples of duplex stainless steels include:

  • 2205, used in chemical processing, oil and gas processing equipment, marine and other high chloride environments, effluent scrubbing systems, pulp and paper industry, cargo tanks for ships and trucks, food processing equipment, biofuels plant.
  • 2304, used in chloride containing environments, welded pipe systems, transportation, heat exchanger tubes, construction, pressure vessels, caustic solutions and the food industry.
  • 2507, used in oil and gas industry equipment, offshore platforms, chemical process industries, desalination plants, mechanical and structural components and power industry FGD systems.

Delivery requirment:

  • 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

Material stainless steel grades

Also known as “marine grade” stainless steel due to its increased ability to resist saltwater corrosion compared to type 304. SS316 is often used for building nuclear reprocessing plants.