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.

Specifications of Duplex Pipes

Standard

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 (ASME SA928)

Standard Specification for Ferritic/Austenitic (Duplex) Stainless Steel Pipe Electric Fusion Welded with Addition of Filler Metal

Duplex 2507 (UNS S32750)

Steel Grade

Duplex 2507 (UNS S32750) 

is a super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel designed.

Duplex 2205 (UNS S31803)

or Avesta Sheffield 2205 is a ferritic-austenitic stainless steel.

SUPER DUPLEX UNS S32760

is a super duplex stainless steel, so-called due to its higher Chromium and Molybdenum content.

ASTM Referenced Standards

A450 A450M

Specification for General requirements for carbon, Ferritic Alloy, and Austenitic alloy steel tubes.

A480 A480M

Specification for general requirements for flat-rolled stainless and heat-resisting steel plate, sheet, and strip.

A941 

 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys.

E527 

 Practice for numbering metals and alloys (UNS).

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.

List Of Duplex Pipe Types

Duplex Pipe Composition Standard

Steel designation

Number

C, max

Si

Mn

P, max

S, max.

N

Cr

Cu

Mo

Ni

Other

X2CrNiN22-2

1.4062

0.03

≤1.00

≤2.00

0.04

0.010

0.16 to 0.28

21.5 to 24.0

-

≤0.45

1.00 to 2.90

-

X2CrCuNiN23-2-2

1.4669

0.045

≤1.00

1.00 to 3.00

0.04

0.030

0.12 to 0.20

21.5 to 24.0

1.60 to 3.00

≤0.50

1.00 to 3.00

-

X2CrNiMoSi18-5-3

1.4424

0.03

1.40 to 2.00

1.20 to 2.00

0.035

0.015

0.05 to 0.10

18.0 to 19.0

-

2.5 to 3.0

4.5 to 5.2

-

X2CrNiN23-4

1.4362

0.03

≤1.00

≤2.00

0.035

0.015

0.05 to 0.20

22.0 to 24.5

0.10 to 0.60

0.10 to 0.60

3.5 to 5.5

-

X2CrMnNiN21-5-1

1.4162

0.04

≤1.00

4.0 to 6.0

0.040

0.040

0.20 to 0.25

21.0 to 22.0

0.10 to 0.80

0.10 to 0.80

1.35 to 1.90

-

X2CrMnNiMoN21-5-3

1.4482

0.03

≤1.00

4.0 to 6.0

0.035

0.030

0.05 to 0.20

19.5 to 21.5

≤1.00

0.10 to 0.60

1.50 to 3.50

-

X2CrNiMoN22-5-3

1.4462

0.03

≤1.00

≤2.00

0.035

0.015

0.10 to 0.22

21.0 to 23.0

-

2.50 to 3.50

4.5 to 6.5

-

X2CrNiMnMoCuN24-4-3-2

1.4662

0.03

≤0.70

2.5 to 4.0

0.035

0.005

0.20 to 0.30

23.0 to 25.0

0.10 to 0.80

1.00 to 2.00

3.0 to 4.5

-

X2CrNiMoCuN25-6-3

1.4507

0.03

≤0.70

≤2.00

0.035

0.015

0.20 to 0.30

24.0 to 26.0

1.00 to 2.50

3.0 to 4.0

6.0 to 8.0

-

X3CrNiMoN27-5-2

1.4460

0.05

≤1.00

≤2.00

0.035

0.015

0.05 to 0.20

25.0 to 28.0

-

1.30 to 2.00

4.5 to 6.5

-

X2CrNiMoN25-7-4

1.4410

0.03

≤1.00

≤2.00

0.035

0.015

0.24 to 0.35

24.0 to 26.0

-

3.0 to 4.5

6.0 to 8.0

-

X2CrNiMoCuWN25-7-4

1.4501

0.03

≤1.00

≤1.00

0.035

0.015

0.20 to 0.30

24.0 to 26.0

0.50 to 1.00

3.0 to 4.0

6.0 to 8.0

W 0.50 to 1.00

X2CrNiMoN29-7-2

1.4477

0.03

≤0.50

0.80 to 1.50

0.030

0.015

0.30 to 0.40

28.0 to 30.0

≤0.80

1.50 to 2.60

5.8 to 7.5

-

X2CrNiMoCoN28-8-5-1

1.4658

0.03

≤0.50

≤1.50


0.035

0.010

0.30 to 0.50

26.0 to 29.0

≤1.00

4.0 to 5.0

5.5 to 9.5

Co 0.50 to 2.00

X2CrNiCuN23-4

1.4655

0.03

≤1.00

≤2.00

0.015

0.015

0.05 to 0.20

22.0 to 24.0

1.00 to 3.00

0.10 to 0.60

3.5 to 5.5

-

Duplex Pipes Mechanical properties

Grade

Tensile strength, min., ksi [MPa]

Yield strength, min., ksi [MPa]

Elongation in 2 in., or 50mm, min, %

Hardness, MaxBrinell

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

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