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ASTM A312 Duplex Stainless Steel Tube High Resistance

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ASTM A312 Duplex Stainless Steel Tube High Resistance

Country/Region	china
City & Province	ningbo zhejiang

Product Details

ASTM A312 S31254 Stainless Steel Seamless Pipe , offshore and platform application

254 SMO is a high-alloy austenitic stainless steel developed for use in seawater and other aggressive chloride-bearing media. The steel is characterized by the following properties:

A.Excellent resistance to pitting and crevice corrosion, PRE = ≥42.5%
B.High resistance to general corrosion
C.High resistance to stress corrosion cracking
D.Higher strength than conventional austenitic stainless steels
E.Good weldability

The PRE is defined as, in weight of content %, PRE = Cr % + 3.3 x Mo % + 16 x N %

Standards

UNS: S31254
EN Number: 1.4547
EN Name: X1CrNiMoCuN20-18-7
W.Nr.: 1.4529
SS: 2378
AFNOR: Z1 CNDU 20.18.06AZ
Product standards
Seamless tube and pipe: ASTM A269, A213, A312, NFA 49-217, EN 10216-5
Norsok MDS R11/R18, IOGP S-563 MDS IR111/111S/IR118/IR118S
Welded tube and pipe: ASTM A249, A269 , A312, A358, A409
Fittings: ASTM A182
Bar: ASTM A276, A479, EN 10088-3
Forged products: ASTM A473

Chemical composition (nominal) %
C	Si	Mn	P	S	Cr	Ni	Mo	N	Cu
≤0.020	≤0.80	≤1.00	≤0.030	≤0.010	20	18	6.1	0.20	0.7

254 SMO Applications:

1. Equipment for handling of seawater, such as, seawater cooling, cooling water pipes, ballast water systems, firefighting systems etc.
2. Hydraulic and instrumention tubing
3. Equipment in pulp bleaching plants
4. Components in gas cleaning systems
5. Tanks and pipelines for chemicals with high halide contents

Stress corrosion cracking tests in boiling 25% NaCl solution, pH=1.5. U-bend specimens.
ASTM TP316	<150 h	Pitting
'904L'	No failure (1000 h)	Crevice corrosion
Sandvik 254 SMO	No failure (1000 h)	No attack

Stress corrosion cracking tests. Drop evaporation method*. Stress: 0.9xRp0.2
Grade	Time to failure hours
ASTM TP316	105
TP904L	225
254 SMO	425

Intergranular corrosion

254 SMO has a very low carbon content. This means that there is very little risk of carbide precipitation during heating, for example when welding. The steel passes the Strauss test (ASTM A262, practice E) even after sensitizing for one hour at 600–1000°C (1110–1830°F).

However, due to the high alloying content of the steel, inter-metallic phases can precipitate at the grain boundaries in the temperature range 600–1000°C (1110–1830°F). These precipitations do not involve any risk of intergranular corrosion in the environments in which the steel is intended to be used. Thus, welding can be carried out without any risk of intergranular corrosion.

Pitting corrosion

The pitting and crevice corrosion resistance of stainless steel is primarily determined by the content of chromium, molybdenum and nitrogen. Manufacture and fabrication, e.g. welding, are also of vital importance for the actual performance in service. A parameter for comparing the resistance to pitting in chloride environments is the PRE number (Pitting Resistance Equivalent). The PRE is defined as, in weight-%, PRE = %Cr + 3.3 x %Mo + 16 x %N

Heat Treatment
The tubes are delivered in heat treated condition. If additional heat treatment is needed due to further processing the following is recommended.
Solution annealing 1150–1200°C (2100–2190°F), quenching in water. Thin-walled tubes min. 1130°C (2060°F), quenching in air/water.

Mechanical Properties

Metric units, at 20°C
Wall thickness	Proof strength		Tensile strength	Elong.		Hardness
	Rp0.2a)	Rp1.0a)	Rm	Ab)	A2"	HRB
mm	MPa	MPa	MPa	%	%
<5	≥310	≥340	675-850	≥35	≥35	≤96
>5	≥310	≥340	655-850	≥35	≥35	≤96

1 MPa = 1 N/mm2

Imperial units, at 68°F
Wall thickness	Proof strength		Tensile strength	Elong.		Hardness
	Rp0.2a)	Rp1.0a)	Rm	Ab)	A2"	HRB
inch	ksi	ksi	ksi	%	%
<0.187	≥45	≥49	98-123	≥35	≥35	≤96
>0.187	≥45	≥49	98-123	≥35	≥35	≤96

a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strength, respectively.
b) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-section area.

Weldding:

Recommended filler metals

TIG/GTAW or MIG/GMAW welding
ISO 18274 S Ni 6625/AWS A5.14 ERNiCrMo-3 (e.g. Exaton Ni60)
ISO 18274 S Ni 6059/AWS A5.14 ERNiCrMo-13 (e.g. Exaton Ni59)

MMA/SMAW welding
ISO 14172 E Ni 6625/AWS A5.11 ENiCrMo-3 (e.g. Exaton Ni60)
ISO 14172 E Ni 6059/AWS A5.11 ENiCrMo-13 (e.g. Exaton Ni59)