ASTM A790 UNS S31803 Duplex Stainless Steel Welded Pipe for Corrosive Process & Offshore Applications
High-Integrity Duplex Welded Pipe Manufactured to ASTM A790 / ASME SA790
ASTM A790 UNS S31803 Duplex Stainless Steel Welded Pipe is engineered for pressure piping systems operating in aggressive chloride-containing and corrosive industrial environments. Manufactured with an optimized ferritic-austenitic microstructure, S31803 combines high mechanical strength with excellent resistance to pitting, crevice corrosion and chloride stress corrosion cracking, making it an ideal material for offshore, petrochemical and marine applications.
YUHONG supplies ASTM A790 S31803 welded pipes produced under strict quality control from raw material selection through final inspection. The welding process is qualified according to applicable international standards, followed by solution annealing and pickling to restore corrosion resistance and ensure a balanced duplex structure. Every production batch undergoes comprehensive dimensional, mechanical and non-destructive testing to provide consistent quality for industrial piping projects worldwide.
Technical Specifications
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Item
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Specification
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Product Name
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ASTM A790 UNS S31803 Duplex Stainless Steel Welded Pipe
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Standard
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ASTM A790 / ASME SA790
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Material Grade
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UNS S31803
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Steel Type
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Duplex Stainless Steel
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Manufacturing Process
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Longitudinal Welded
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Heat Treatment
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Solution Annealed
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Outside Diameter
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12.7 mm – 1219 mm
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Wall Thickness
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1.0 mm – 40 mm
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Length
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Up to 12 m or Customized
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Weld Type
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Automatic TIG / Plasma / Laser Welding (According to Size)
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Surface Finish
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Pickled, Passivated or Bright Annealed
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Pipe Ends
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Plain End, Beveled End
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Inspection
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Hydrostatic Test, UT, Eddy Current Test, PMI, Ferrite Test
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Certification
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EN 10204 3.1, Third-Party Inspection Available
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Chemical Composition
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Element
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Content (%)
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Chromium (Cr)
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21.0–23.0
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Nickel (Ni)
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4.5–6.5
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Molybdenum (Mo)
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2.5–3.5
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Nitrogen (N)
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0.08–0.20
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Carbon (C)
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≤0.030
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Manganese (Mn)
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≤2.00
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Silicon (Si)
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≤1.00
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Phosphorus (P)
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≤0.030
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Sulfur (S)
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≤0.020
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Iron (Fe)
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Balance
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Mechanical Properties
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Property
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Minimum Value
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Tensile Strength
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620 MPa
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Yield Strength
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450 MPa
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Elongation
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25%
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Hardness
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According to ASTM A790
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Product Features
- Excellent Resistance to Chloride Corrosion
The duplex stainless steel structure provides superior resistance to chloride-induced pitting, crevice corrosion and stress corrosion cracking, making it suitable for seawater and aggressive process media.
With approximately twice the yield strength of conventional austenitic stainless steels, S31803 allows lighter piping systems while maintaining reliable pressure performance.
Automatic welding procedures combined with solution annealing produce uniform weld integrity and balanced duplex microstructure for demanding industrial applications.
- Reliable Corrosion Performance
Controlled chemical composition, heat treatment and pickling processes help maintain corrosion resistance across both the weld seam and base material.
- Strict Manufacturing Control
YUHONG implements quality control throughout production, from raw material verification to finished product inspection, ensuring dimensional consistency and compliance with ASTM A790 requirements.
Why Choose Duplex S31803 Instead of 316L?
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Property
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S31803 Duplex
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316L Stainless Steel
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Yield Strength
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Approximately 2× Higher
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Standard
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Chloride Pitting Resistance
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Excellent
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Good
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Stress Corrosion Cracking Resistance
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Excellent
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Moderate
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Crevice Corrosion Resistance
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Excellent
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Good
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Typical Service
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Offshore, Chemical, Marine
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General Industrial
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Available Dimensions
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Parameter
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Range
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Outside Diameter
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12.7 mm – 1219 mm
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Wall Thickness
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1.0 mm – 40 mm
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Pipe Length
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Up to 12 m
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Custom Length
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Available
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Cut-to-Length Service
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Available
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Applications
ASTM A790 UNS S31803 Duplex Stainless Steel Welded Pipes are widely used in:
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Offshore Oil & Gas Platforms
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Petrochemical Processing Plants
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Chemical Processing Systems
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Seawater Piping Systems
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Desalination Plants
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Heat Exchangers
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Pressure Piping Systems
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LNG Facilities
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Marine Engineering
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Fire Water Systems
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Pulp & Paper Industry
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Fertilizer Plants
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Industrial Process Pipelines
Inspection and Testing
Every production batch can be supplied with comprehensive inspection according to ASTM A790, project specifications or customer requirements.
Available testing includes:
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Positive Material Identification (PMI)
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Hydrostatic Test
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Ultrasonic Test (UT)
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Eddy Current Test (ECT)
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Ferrite Content Test
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Weld Seam Inspection
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Chemical Composition Analysis
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Mechanical Property Test
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Dimensional Inspection
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Surface Quality Inspection
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Visual Inspection
Why Choose YUHONG
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More than 20 years of experience supplying stainless steel, duplex stainless steel, nickel alloy and special alloy piping materials.
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Integrated supply capabilities covering pipes, tubes, fittings, flanges and forged products for complete project requirements.
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Manufacturing in accordance with ASTM, ASME, EN and DIN standards with full material traceability.
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Comprehensive inspection options including PMI, UT, ECT, hydrostatic testing and third-party inspection.
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Flexible production for customized dimensions, wall thicknesses, lengths and project specifications.
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Export experience supporting EPC contractors, oil & gas companies, power plants, petrochemical facilities and industrial engineering projects in more than 100 countries.
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Responsive technical support and documentation throughout quotation, production and project delivery.
Frequently Asked Questions
1. What is ASTM A790 UNS S31803 welded pipe?
ASTM A790 UNS S31803 welded pipe is a duplex stainless steel pipe designed for pressure service requiring high strength and excellent corrosion resistance in chloride-containing environments.
2. Is S31803 suitable for seawater applications?
S31803 offers excellent resistance to chloride-induced corrosion and is widely used in seawater piping, desalination systems and offshore facilities. Material selection should always consider chloride concentration, operating temperature and flow conditions.
3. Why is solution annealing performed after welding?
Solution annealing restores the duplex microstructure, improves corrosion resistance and helps achieve the mechanical properties required by ASTM A790.
4. What inspection documents are available?
Material Test Certificates (EN 10204 3.1), dimensional reports, NDT reports, PMI reports and third-party inspection documentation can be supplied according to project requirements.
5. Can YUHONG manufacture customized dimensions?
Yes. Outside diameter, wall thickness, pipe length, end preparation, surface finish and inspection requirements can all be customized to meet project specifications.
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