What is the composition of unsS31803 pipe?

What is ASTM A790 uns S31803 pipe?

ASTM A790 UNS S31803 is a standard specification for seamless or welded ferritic/austenitic (duplex) stainless steel pipe designed for high-strength, corrosive service. It is commonly known as 2205 duplex or WNR 1.4462, offering roughly twice the yield strength and superior corrosion resistance compared to standard austenitic stainless steels (like 316L).

 

UNS S31803 Stainless Steel Round Pipe Supplier

GNEE supplies UNS S31803 (2205 duplex stainless steel) pipes in strict accordance with ASTM A790 and ASME SA790 standards. Manufactured from ultra-low carbon duplex stainless steel, our products achieve a PREN value of 35–40, delivering corrosion resistance significantly superior to 316L.

 

We offer both seamless and welded pipes (TIG / ERW / LSAW) with an outer diameter range of 6–630 mm and wall thickness from 0.3–50 mm. Our products feature high dimensional accuracy, with OD tolerance of ±0.8% and wall thickness tolerance of +20% / –12.5%. Each batch is supplied with Mill Test Certificates (MTC) and supports SGS / EN 10204 3.2 certification, ensuring full traceability and a clean, defect-free surface finish.

 

Compared with conventional austenitic stainless steels, S31803 duplex pipes allow wall thickness reduction of 30–50%, resulting in lower weight while maintaining strength. At the same time, they offer a service life extended by 3–5 times and maintenance cost reductions of over 50%. These advantages make them ideal for marine engineering, flue gas desulfurization (FGD), oil and gas transmission, and high-pressure heat exchanger applications under severe conditions.

 

What is the difference between S31803 and S32205?

S31803 was the originally established specification; however, the S32205 grade was subsequently introduced to ensure that the material possesses superior corrosion resistance. Today, most high-quality tubular products are "Dual Certified" meaning they meet the standards for both S31803 and S32205,as their chemical composition satisfies the requirements of both grades.

 

ASTM A790 S31803 Pipe Chemical Composition % (max values, unless noted)

UNS Designation[B]	C	Mn	P	S	Si	Ni	Cr	Mo	N
S31803	0.030	2.00	0.030	0.020	1.00	4.5-6.5	21.0-23.0	2.5-3.5	0.08-0.20

 

Mechanical Properties ASTM A790 S31803 Pipe

UNS Designation	Tensile Strength, min,ksi [MPa]	Yield Strength, min, ksi [MPa]	Elongation in 2 in.or 50 mm min,%	Hardness, max
				HBW	HRC
S31803	90 [620]	65 [450]	25	290	30

 

Duplex Steel S31803 Pipe Tolerances

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 Pipe: High Corrosion Resistance

S31803 possesses high strength and resistance to chloride corrosion, making it suitable for harsh environments such as offshore oil and gas extraction or chemical processing; however, SS316 is typically more affordable, easier to weld, and better suited for applications requiring low-temperature toughness (below -50°C) or general corrosion resistance.

 

UNS S31803 Seamless Pipe: High Strength

UNS S31803 seamless pipe (commonly referred to as 2205 duplex stainless steel pipe) is a high-strength stainless steel tubing characterized by a microstructure that combines the features of both ferrite and austenite; its yield strength (> 480 MPa) is approximately double that of standard 300-series stainless steels. This material is particularly well-suited for harsh environments, offering excellent resistance to chloride stress corrosion cracking, pitting, and crevice corrosion.

 

ASTM A790 S31803 Pipe  Applications:

Oil and Gas: Transporting crude oil and natural gas, particularly on offshore platforms.
Chemical Processing: Handling chloride-containing, acidic, and chemical fluids.
Marine & Desalination: Environments with high salt concentrations.
Food Industry: Processing equipment.

 

ASTM A790 S31803 Stainless Steel Pipe Prices (Seamless and Welded)

ASTM A790 S31803 duplex stainless steel pipes generally range from $500 to $8,000 per ton, with prices heavily dependent on whether they are seamless or welded, as well as size and wall thickness. Seamless pipes typically cost more, often ranging between $1,500 and $3,000 per ton, while welded pipes can be found at lower prices.

Click to Get UNS S31803 Stainless Steel Pipe Prices

 

Packaging and Marking

Our ASTM A790 Duplex Steel Tube is packaged to ensure no damage during transit. In the case of export, the standard export packing is in a wooden box. All ASTM A790 Duplex Steel Tube are marked with our grade, batch number, size and mark. We can also do custom branding on our products as per buyer's unique requirements.