Duplex UNS S31803 seamless pipe is a duplex stainless steel pipe that combines the advantages of both austenitic and ferritic microstructures. Duplex UNS S31803 seamless steel pipe is a duplex stainless steel pipe that combines the advantages of both austenitic and ferritic microstructures, and is widely used in high-corrosion, high-strength environments such as petroleum and natural gas, chemical, and marine engineering industries.
UNS S31803, also known as 2205 duplex stainless steel, is currently the most widely used duplex stainless steel grade. Its microstructure consists of approximately 50% ferritic and 50% austenitic phases.
In the vast field of metallic materials, S31803 duplex stainless steel has secured a significant position in numerous industrial applications due to its unique properties. This tubing combines the advantages of austenitic and ferritic stainless steels, demonstrating exceptional corrosion resistance, high strength, and excellent machinability, making it an ideal choice for many industries. It is widely used in high-corrosion, high-strength environments such as the petroleum and natural gas, chemical, and marine engineering industries.
Specification of ASTM A790 UNS S31803 Pipe
ASTM A790 pipe specifications are mainly applicable to sizes ranging from 1/8” to 30” (DN6 to DN750). The wall thickness of these steel pipes must comply with ASME B36.19 standards, and the wall thickness grades are SCH 10, SCH 20, SCH 40, STD, XS, SCH 100, SCH 120, SCH 160, XXS.
| Processing Method | Seamless and Welded |
| Size Range | 1/8” – 30” / DN6 – 750 |
| Thickness Schedule | SCH10 SCH20 STD SCH40 SCH60 SCH80 SCHXS SCH100 SCH120 SCH140 SCH160 SCHXXS |
| Length | 6m or 12 m or Random |
| Standard | ASME B36.19,ASTM A789, ASTM A790, ASTM A928, ASME SA789, |
| Surface Treatment | Polish , Mirror , Epoxy Powder FBE, 2PE, 3PE Coating |
| Material Grade | ASTM A790 S32205, S31803, 32750, 32760, S32550 |
| Pipes Ends | Plain Ends / Beveled Ends |
Advantages of Seamless Pipe
Seamless pipe is manufactured by piercing and rolling solid steel billets, resulting in a product with no internal welded seams. Compared to welded tubing, seamless pipe offers higher pressure-bearing capacity and structural integrity, making it the preferred choice for critical applications requiring high safety and reliability.
Duplex UNS S31803 seamless pipe combine the superior properties of the material itself with the advantages of seamless manufacturing, making them an ideal choice for transporting fluids in high-pressure, highly corrosive environments.
ASTM A790 Duplex Steel S31803 Seamless Pipe Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo | N |
| ASTM A790 S31803 | MIN | 4.5 | 21.00 | 2.50 | 0.08 | |||||
| MAX | 0.03 | 2.00 | 0.03 | 0.02 | 1.00 | 6.5 | 23.00 | 3.50 | 0.20 |
Duplex Steel S31803 Pipe Mechanical Properties
| MATERIAL | T.S (MPA) | Y.S (MPA) | EL % | HARDNESS |
| ASTM A790 S31803 | 620min | 450min | 25min | 290max |
Physical Properties of UNS S31803 Duplex Stainless Steel Seamless Pipes
| Grade | Density (kg/m3) | Elastic Modulus(GPa) | Mean Co-eff of Thermal | Thermal | Specific | Electrical | |||
| Expansion (μm/m/°C) | Conductivity (W/m.K) | Heat | Resistivity | ||||||
| 0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | 0-100°C( J/kg.K) | (nΩ.m) | |||
| UNS S31803 | 782 | 190 | 13.7 | 14.2 | – | 19 | – | 418 | 850 |
Duplex Stainless Steel Seamless Pipes Dimension
| Stainless Steel Pipe (ASME B 36.19M) | ||||||||||
| Nominal Size | OD | Sch5s | Sch10s | Sch40s | Sch80s | |||||
| DN | NPS | 0 | T | kg/m | T | kg/m | T | kg/m | T | kg/m |
| 6 | 1/8 | 10.3 | 1.24 | 0.28 | 1.73 | 0.37 | 2.41 | 0.47 | ||
| 8 | 1/4 | 13.7 | 1.65 | 0.49 | 2.24 | 0.63 | 3.02 | 0.8 | ||
| 10 | 3/8 | 17.1 | 1.65 | 0.63 | 2.31 | 0.84 | 3.2 | 1.1 | ||
| 15 | 1/2 | 21.3 | 1.65 | 0.82 | 2.11 | 1 | 2.77 | 1.27 | 3.73 | 1.62 |
| 20 | 3/4 | 26.7 | 1.65 | 1.04 | 2.11 | 1.28 | 2.87 | 1.69 | 3.91 | 2.2 |
| 25 | 1 | 33.4 | 1.65 | 1.33 | 2.77 | 2.09 | 3.38 | 2.5 | 4.55 | 3.24 |
| 32 | 1 1/4 | 42.2 | 1.65 | 1.68 | 2.77 | 2.7 | 3.56 | 3.39 | 4.85 | 4.47 |
| 40 | 1 1/2 | 48.3 | 1.65 | 1.95 | 2.77 | 3.11 | 3.68 | 4.05 | 5.08 | 5.41 |
| 50 | 2 | 60.3 | 1.65 | 2.44 | 2.77 | 3.93 | 3.91 | 5.44 | 5.54 | 7.48 |
| 65 | 2 1/2 | 73.0 | 2.11 | 3.77 | 3.05 | 5.26 | 5.16 | 8.63 | 7.01 | 11.41 |
| 80 | 3 | 88.9 | 2.11 | 4.6 | 3.05 | 6.45 | 5.49 | 11.29 | 7.62 | 15.27 |
| 90 | 31/2 | 101.6 | 2.11 | 5.29 | 3.05 | 7.4 | 5.74 | 13.57 | 8.08 | 18.63 |
| 100 | 4 | 114.3 | 2.11 | 5.96 | 3.05 | 8.36 | 6.02 | 16.07 | 8.56 | 22.32 |
| 125 | 5 | 141.3 | 2.77 | 9.67 | 3.4 | 11.57 | 6.55 | 21.77 | 9.53 | 30.97 |
| 150 | 6 | 168.3 | 2.77 | 11.55 | 3.4 | 13.48 | 7.11 | 28.26 | 10.97 | 42.56 |
| 200 | 8 | 219.1 | 2.77 | 15.09 | 3.76 | 19.96 | 8.18 | 42.55 | 12.7 | 64.64 |
| 250 | 10 | 273.1 | 3.4 | 23.08 | 4.19 | 27.78 | 9.27 | 60.31 | 12.7 | 96.01 |
| 300 | 12 | 323.9 | 3.96 | 31.89 | 4.57 | 36 | 9.53 | 73.88 | 12.7 | 132.08 |
| 350 | 14 | 355.6 | 3.96 | 35.06 | 4.78 | 41.3 | ||||
| 400 | 16 | 406.4 | 4.19 | 42.41 | 4.78 | 47.29 | ||||
| 450 | 18 | 457.2 | 4.19 | 47.77 | 4.78 | 53.26 | ||||
Tolerances of UNS S31803 Seamless Pipe
| NPS Designator | Permissible Variations in Outside Diameter | |
| Over In. | Under In. | |
| 1/8 to 1-1/2, incl | 1/64 (0.015) | 1/32 (0.031) |
| Over 1-1/2 to 4, incl | 1/32 (0.031) | 1/32 (0.031) |
| Over 4 to 8, incl | 1/16 (0.062) | 1/32 (0.031) |
| Over 8 to 18, incl | 3/23 (0.093) | 1/32 (0.031) |
UNS S31803 Duplex Stainless Steel Pipe Corrosion Resistance
One of the most notable properties of Duplex UNS S31803 seamless pipe is its exceptional corrosion resistance. In corrosive environments, the high chromium content rapidly forms a dense and stable oxide layer on the surface of the pipe. This oxide layer acts as a robust shield, effectively blocking the corrosion caused by various corrosive media, including seawater, brine, sulfuric acid, acetic acid, and various organic acids.
In harsh environments containing chloride ions, S31803 demonstrates significantly superior resistance to stress corrosion cracking compared to traditional 304 and 316L stainless steels. Chloride ions are common corrosion factors in many industrial and marine environments, often leading to stress corrosion cracking in metallic materials and causing pipeline failure. However, S31803 can effectively resist chloride ion corrosion, significantly enhancing its service life and safety in such environments.
UNS S31803 Duplex Stainless Steel Pipe Machining
Duplex UNS S31803 seamless pipe offer significantly improved mechanical strength. The yield strength of S31803 pipe is more than twice that of ordinary austenitic stainless steel, which means it can meet thinner wall requirements, reducing the weight of piping systems and lowering material costs. Furthermore, its excellent toughness ensures reliable operation under extreme conditions such as low temperature, high pressure, and high impact, minimizing the risk of brittle fracture.
You can get an offer for products in below material forms:
-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)
-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )
-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)
-Round bar , Billet (ASTM A276, ASTM A479)
– Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)
-Bolting, Nuts（ASTM A193, A194, A320）
Applications of Duplex Stainless Steel Pipe
Chemical processing, transportation, and storage
Oil and gas exploration and offshore drilling platforms
Oil and gas refining
Marine environments
Pollution control equipment
Pulp and paper manufacturing
Chemical processing plants