ASTM A790 UNS S31803 Duplex Steel Pickled Annealed Pipe

Why do piping and process systems-even when specifically designed to utilize stainless steel materials-still occasionally suffer from Stress Corrosion Cracking (SCC), pitting corrosion, or unexpected mechanical failures? The root cause of the problem often lies in the material's microstructure, its delivery condition, and the manufacturing processes employed.

We manufacture ASTM A790 UNS S31803 duplex stainless steel pipes, available in both seamless and welded forms. UNS S31803 seamless pipes are typically produced via cold drawing or hot rolling processes, followed by solution annealing and pickling treatments to ensure a uniform microstructure and superior corrosion resistance. UNS S31803 welded pipes (EFW/ERW) are manufactured using longitudinal welding techniques and are widely utilized in structural components and fluid conveyance systems.

ASTM A790 UNS S31803 stainless steel tubular products feature excellent resistance to pitting corrosion (PREN ≥ 32) and exceptionally high mechanical strength; their yield strength typically reaches ≥ 450 MPa, and tensile strength ≥ 620 MPa-values ​​that are nearly double those of conventional 304/316 stainless steel grades.

ASTM A790 UNS S31803 piping is frequently supplied in the "Pickled and Annealed" (AP) condition, ensuring that the pipe surface is clean, free of residual scale, and possesses a stable internal microstructure. Our product range is extensive, covering outer diameters from 6 mm to 720 mm and wall thicknesses from 1 mm to 65 mm, thereby fully meeting the diverse requirements of a wide variety of projects.

 

Specification asme sa 790 uns s31803 material pipe

ASTM Specification	ASTM A790/ASME SA790
Standard	NF, JIS, GB, EN, AISI, ASTM, TOCT, SAE, DTD, DS, ASME, DIN, AMS,
Seamless Wall thickness	Wall thickness.: 0.05- 20 milimeter Customizable
Seamless Tube Size	3.35 milimeter To 101.6 milimeter OD
Length	Standard & Cut length , Single Random, Double Random Pipe
Finish	AP (Annealed & Pickled), BA (Bright & Annealed), NO.1, 2B, Polished, MF, HL, NO.4, Mirror finish, BA, 8K etc
End	Plain End, Beveled End, Treaded Pipe, Screwed ends
Form	Hydraulic, Rectangular, Coiled, Square, Hollow, Round, Straight Pipes/tubes, "U" Shape, Coils, Boiler etc.
Application	Dairy Pipe, Oil Pipe/tube, Gas Pipe/tube, Fluid Pipe/tube, Boiler Tube, Heat exchanger Tube

 

Chemical Composition of of ASTM A790 Duplex Stainless Steel Pipes

Grade	C max	Si max	Mn max	P max	S max	Cr	Ni	Mo	N
UNS S31803	0.030	1.0	2.0	0.020	0.020	21.0-23.0	4.5-6.5	2.5-3.5	0.08-0.20
UNS S31500	0.030	1.0	1.2-2.0	0.030	0.030	18.0-19.0	4.5-5.5	2.5-3.5	0.05-0.10

Physical Properties of ASTM A790 Duplex Stainless Steel Pipes

Grade	Y.S.MPa min	T.S.Mpa min	Elongation %	Hardness HRC
UNS S31803	450	620	25	20
UNS S31500	440	630	30	20

 

astm a790 uns s31803 duplex seamless pipe Heat Treatment

Solution temperature is around 1100°C, and rapid cooling.

UNS Designation	Temperature	Quench
S31803	1870-2010 °F [1020-1100°C]	Rapid Cooling In Air Or Water

 

ASME SA790 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)

 

HS Code Table for ASTM A790 UNS S31803 Pipe

Product Category	Manufacturing Process	Universal HS Code (First 6 Digits)	China HS Code (Example)	US HTS Code (Example)
Seamless Pipe	Cold-drawn / Cold-rolled	7304.41	7304.4110	7304.41.30
Seamless Pipe	Hot-finished	7304.49	7304.4910	7304.49.00
Welded Pipe	Circular Cross-section	7306.40	7306.4000	7306.40.50
Welded Pipe	Large Diameter (>406.4mm)	7305.11	7305.1100	7305.11.10

 

 

ASTM A790 Stainless Steel Pipe Testing

Tensile Testing: To determine yield strength.
Flattening Testing: To ensure material ductility and weld integrity.
Hardness Testing: To ensure that hardness does not exceed the specified upper limit.
Hydrostatic Testing: A standard inspection procedure designed to ensure the pipe is leak-free.
Eddy Current Testing or Ultrasonic Testing (UT): Used for non-destructive testing to verify the internal soundness of the material.

 

ASTM A790 UNS S31803 Duplex Steel Pickled and Annealed Pipe Supplier

Our annual production capacity for duplex and super duplex stainless steel reaches up to 5,000 tons. The company operates eight advanced cold rolling/cold drawing production lines, as well as three continuous solution annealing furnaces. Furthermore, we maintain a standing inventory of 1,500 tons of duplex steel billets to ensure continuous and smooth production operations.

Standard stock items can be shipped within 7 to 10 days, while the production lead time for standard orders is 25 to 35 days. For urgent repair projects, we offer a specialized "Fast Track" service, guaranteeing production completion within 15 days. Regarding packaging, we utilize heavy-duty, fumigated wooden crates that comply with the international ISPM 15 standard; additionally, all pipe ends are fitted with high-quality plastic caps designed to protect the pipe's inner surface and prevent damage to the bevels.

 

 

 

FAQ

Q: Why is S31803 often called "Duplex 22Cr"?
A: S31803 contains approximately 22% Chromium, which is the primary element providing its high corrosion resistance. Because of this 22% Cr content, it is commonly referred to in the industry as "22Cr Duplex."

 

Q: Is S31803 the same as S32205?
A: They are very similar, but S32205 is a higher-specification version of S31803 with more strictly controlled Nitrogen, Molybdenum, and Chromium. Most high-quality mills today produce "Dual Certified" pipes that meet the requirements of both S31803 and S32205 to ensure superior pitting resistance (PREN ≥ 35).

Q: How does S31803 perform against Chloride Stress Corrosion Cracking (SCC)?
A: Superiorly. While standard austenitic steels (like 316L) often fail due to SCC in warm, chloride-rich environments (like seawater), the ferritic structure in S31803 provides exceptional resistance to this type of failure, making it ideal for offshore and desalination plants.