ASTM A790 UNS S31803 Welded Duplex Stainless Steel Pipe Duplex 2205 Welded Pipe

 ASTM A790 UNS S31803 Duplex Stainless Steel Pipe Duplex Steel Welded Pipe 

ASTM A790 UNS S31803 Welded Duplex Stainless Steel Pipe is a welded stainless steel pipe manufactured according to ASTM A790/A790M from UNS S31803 duplex stainless steel, commonly known as 2205 duplex stainless steel. It has a two-phase microstructure of ferrite + austenite, typically about 50/50, which gives it higher strength and better resistance to chloride stress corrosion cracking than common austenitic stainless steels such as 304/316. Choose UNS S31803 only if the project specifically requires it or if dual-certified S32205 is not available. For critical corrosive service, always verify the actual chloride level, temperature, pH, H₂S content, and applicable code before finalizing the material.

Corrosion Resistance of UNS S31803 / 2205 duplex stainless steel:

• High resistance to chloride pitting and crevice corrosion

• Excellent resistance to chloride stress corrosion cracking

• High strength compared with 304/316 stainless steel

• Good resistance to many acids and corrosive environments

• Good fatigue and erosion resistance

Chemical Composition of ASTM A790 UNS S31803 Welded Duplex Stainless Steel Pipe Duplex Steel Welded Pipe

Welded Pipe Manufacturing

ASTM A790 welded duplex pipe is generally made as follows:

1. Forming – Duplex stainless steel strip or plate is formed into a tubular shape.

2. Welding – The seam is welded by an automatic process. In ASTM A790, welded pipe is normally made without filler metal. If filler metal is required, ASTM A928 may be applicable.

3. Weld seam treatment – The weld seam may be rolled, cold-worked, or otherwise treated.

4. Solution annealing – The pipe is normally solution annealed at about 1020–1100°C / 1870–2010°F, then rapidly cooled/quenched.

5. Finishing – Pickling, passivation, straightening, cutting, beveling, and marking.

6. Testing – Hydrostatic test, ultrasonic test, eddy current test, radiographic test, or other NDT as specified.

The solution annealing step is important because it restores the ferrite–austenite balance and avoids harmful phases such as sigma phase.

Application

• Oil and gas pipelines, flowlines, and risers

• Chemical and petrochemical processing

• Heat exchangers and condensers

• Desalination and seawater cooling systems

• Pulp and paper industry

• Flue gas desulfurization

• Marine and offshore structures

• Pressure vessels and storage tanks