ASTM A790 UNS S31803 Duplex Stainless Steel Pipes
Duplex S31803 stainless steels are extremely corrosion resistant, work hardenable alloys. Their microstructures consist of a mixture of austenite and ferrite phases. As a result, duplex stainless steels display properties characteristic of both austenitic and ferritic stainless steels. This combination of properties can mean some compromise when compared with pure austenitic and pure ferritic grades.
S31803 duplex stainless steels are considered resistant to stress corrosion cracking, they are not as resistant to this form of attack as ferritic stainless steels. However, the corrosion resistance of the least resistant duplex stainless steels is greater than that for the most commonly used grades of stainless steels, i.e. 304 and 316.
S31803 has a superior resistance to corrosion than austenitic grades such as Alloy 316L in most environments, including seawater. This grade offers excellent resistance to intergranular corrosion, pitting and crevice corrosion with its resistance to chloride stress corrosion cracking at temperatures up to 150ºC.
Commercial applications for thisASTM A790 UNS S31803 pipes
- Chemical engineering components
- Oil & Gas industry components
- Brewing industry
- Pipework, flanges & manifolds
- Pumps & valves
ASTM A790 S31803 is a specification for seamless and welded ferritic/austenitic stainless steel pipes.
UNS S31803 is a duplex grade with a ferritic-austenitic microstructure. The alloy consists of around 40-50% ferrite in the annealed condition. The duplex microstructure has the high strength of the ferritic grades whilst retaining the corrosion resistance of the austenitic grades. It is not uncommon to see the metal used as a practical solution to chloride-induced stress cracking.
MECHANICAL PROPERTIES
| Alloy | Tensile Strength Minimum (psi) |
Yield Strength Minimum 0.2% offset (psi) |
% Elongation in 2″ Minimum |
| S31803 | 90,000 | 65,000 | 25 |
CHEMICAL PROPERTIES
| Alloy | C | Si | Mn | P | Cr | Ni | S | N | Mo |
| S31803 | 0.03 | 1.0 | 2.0 | 0.035 | 21.0-23.0 | 4.5-6.5 | 0.015 | 0.1-0.22 | 2.5-3.5 |
ASTM A790 UNS31803 Pipe Dimensional Tolerance :
| Nominal pipe size up to 4 = ± 0.79 mm | 5 thru 8 = + 1.58 mm / – 0.79 mm 10 thru 18 = + 2.37 mm / – 0.79 mm | 20 thru 24 = + 3.18 mm / – 0.79 mm |
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| Wall Thickness All Diameters = – 12.5% + tolerance not specified |
Length + 6.40 mm / – 0 mm |
Weight Weight = + 10% / – 1.5% |
- AVAILABLE DIAMETER: 1/8”~24”
- OD:1/2″ NB/3/4″ NB /1″ NB/1-1/4″ /2″ /2-1/2/3″ NB/3-1/2″/4″ NB/5″ NB/6″ NB/8″ NB /10″ NB /12″ NB/16″/18″/20″24″
- AVAILABLE THICKNESS: SCH10S,SCH40, SCH XS, SCH 60,SCH80S,SCH120,SCH1160,SCH XXS
- LENGTH: 6METERS FIXED LENGTH OR BY ORDER
- ANNEALING AND PICKLING
- ENDS: PLAIN ENDS, BEVELED ENDS
- TOLERANCE OF THICKNESS: +10%/-5%
- PACKING: ENDS WITH PLASTIC CAPS, THEN BUNDLES OR WOODEN CASES
- MARKING: LOGO,SMLS,ASTM A790 S31803 OD XXX THK XXX 6METERS LOT
