Duplex steel seamless pipe is manufactured from duplex stainless steel featuring a dual-phase microstructure comprising austenite and ferrite phases in approximately equal proportions. This balanced metallurgical structure delivers an optimal combination of high mechanical strength and superior corrosion resistance that significantly exceeds conventional austenitic stainless steel pipes. The seamless construction ensures uniform wall thickness, eliminates potential weld-line weaknesses, and provides enhanced pressure resistance for critical industrial applications.
Compared with standard austenitic grades such as 304 and 316L, duplex stainless steel seamless pipes exhibit approximately twice the yield strength and demonstrate exceptional resistance to chloride-induced stress corrosion cracking, pitting corrosion, and crevice corrosion. These characteristics make duplex seamless pipes indispensable for demanding environments in offshore engineering, chemical processing, oil and gas transmission, and desalination facilities where both structural integrity and long-term durability are paramount.
Huashang Steel manufactures duplex steel seamless pipes in compliance with internationally recognized standards, ensuring material traceability and performance consistency across diverse applications. Our product range covers standard duplex and super duplex grades to meet varied operational requirements.
| Material Grade | UNS Designation | Common Name | Manufacturing Standard |
|---|---|---|---|
| S31803 | UNS S31803 | Duplex 2205 | ASTM A790 / ASTM A789 |
| S32205 | UNS S32205 | Duplex 2205 (Improved) | ASTM A790 / ASTM A789 |
| S32750 | UNS S32750 | Super Duplex 2507 | ASTM A790 / ASTM A789 |
| S32760 | UNS S32760 | Super Duplex Zeron 100 | ASTM A790 / NACE MR0175 |
All pipes are manufactured in accordance with ASTM A790 and ASME SA790 specifications for seamless and welded ferritic/austenitic stainless steel pipe, and ASTM A789 for seamless ferritic/austenitic stainless steel tubing. For sour service environments, our products comply with NACE MR0175 and ISO 15156 standards, ensuring reliable performance in oil and gas applications containing hydrogen sulfide.
Duplex stainless steel seamless pipes from Huashang Steel deliver measurable technical advantages that translate directly into operational cost savings and extended service life in aggressive industrial environments.
The balanced microstructure provides excellent resistance to chloride stress corrosion cracking, a common failure mechanism that affects austenitic stainless steels in marine and industrial water systems. Duplex 2205 seamless pipes demonstrate superior resistance to pitting and crevice corrosion, with a Pitting Resistance Equivalent Number (PREN) exceeding 35, suitable for seawater and chloride-containing process fluids.
With minimum yield strength values ranging from 450 MPa for standard duplex grades to 550 MPa for super duplex variants, these pipes support higher allowable design stresses compared with austenitic alternatives. This strength advantage enables thinner wall construction, reducing material costs and installation weight while maintaining equivalent pressure ratings.
Duplex stainless steel seamless pipes provide corrosion resistance approaching that of expensive nickel-based alloys such as Alloy 625 and Alloy C-276, but at approximately 40-60% lower material cost. For applications with chloride exposure below 10,000 ppm and operating temperatures under 250°C, duplex grades represent an economically optimized material selection.
These pipes maintain stable mechanical properties at service temperatures up to 300°C and demonstrate excellent resistance to thermal fatigue in applications involving frequent temperature fluctuations, such as heat exchangers and thermal process piping in chemical plants and refineries.
Huashang Steel operates a state-of-the-art manufacturing facility with over 15 years of specialized experience in producing high-performance duplex steel seamless pipes. Our integrated production capability ensures complete control over material quality, dimensional precision, and metallurgical properties from raw material selection through final testing.
Seamless Manufacturing Process: Hot extrusion or rotary piercing followed by precision cold drawing to achieve specified dimensions and surface finish
Solution Heat Treatment: Controlled annealing at temperatures between 1020-1100°C, followed by rapid water quenching to optimize phase balance and corrosion resistance
Dimensional Precision: Automated cold-rolling equipment and precision sizing ensure tight tolerances on outer diameter (±0.5%) and wall thickness (±10% minimum)
Production Capacity: 30,000 tons annual capacity across 18 seamless production lines and 3 perforation lines, enabling flexible order quantities and reduced lead times
Every duplex steel seamless pipe undergoes rigorous inspection and testing protocols to verify compliance with customer specifications and international standards:
Chemical Composition Analysis: Direct-reading spectrometry and wet chemical analysis to confirm alloy composition within specification limits
Positive Material Identification (PMI): 100% PMI testing using X-ray fluorescence to prevent material mix-ups
Mechanical Property Testing: Tensile testing, hardness testing, and impact testing per ASTM E8, ASTM E18, and ASTM E23 requirements
Non-Destructive Examination: Ultrasonic testing (UT), eddy current testing (ET), and hydrostatic testing to detect internal or surface discontinuities
Dimensional Inspection: Automated measurement systems verify outer diameter, wall thickness, length, and straightness against drawing requirements
Corrosion Resistance Verification: Intergranular corrosion testing (ASTM A262 Practice E) and ferrite content measurement to ensure optimal microstructure
All products are supplied with complete documentation including Mill Test Certificates (MTC 3.1 per EN 10204), material traceability records, and third-party inspection reports from classification societies such as BV, ABS, DNV-GL, Lloyd's Register, and CCS upon request.
Duplex steel seamless pipes are engineered for critical applications where conventional materials prove inadequate due to corrosion, mechanical stress, or combined environmental challenges. Our products serve demanding sectors globally with proven performance records.
High-pressure transmission pipelines, subsea flowlines, and topside process piping benefit from the combination of strength and corrosion resistance. Super duplex grades meet NACE MR0175 requirements for sour service in environments containing H₂S and CO₂.
Seawater cooling systems, ballast piping, fire protection systems, and offshore platform structural components require materials resistant to chloride-induced corrosion. Duplex seamless pipes withstand the aggressive marine environment while reducing maintenance frequency.
Process piping handling corrosive chemicals including sulfuric acid, phosphoric acid, chlorinated hydrocarbons, and organic acids benefit from duplex steel's broad chemical compatibility. Heat exchangers and reactor vessels utilize these pipes for reliable long-term operation.
Both thermal and reverse osmosis desalination plants use duplex stainless steel seamless pipes for brine circulation, seawater intake, and concentrate discharge systems where elevated chloride concentrations and temperatures demand superior corrosion resistance.
Digesters, bleach plant piping, and chemical recovery systems handling alkaline and chlorine-containing process fluids at elevated temperatures rely on duplex materials for extended service intervals and reduced unplanned shutdowns.
Flue gas desulfurization systems, cooling water circuits, and geothermal power plant piping benefit from duplex steel's resistance to chloride stress corrosion cracking and thermal cycling damage.
Huashang Steel has established a reputation as a reliable manufacturer and supplier of premium duplex stainless steel seamless pipes, serving major industry clients including PetroChina and Sinopec with consistent quality and technical support.
Extensive Manufacturing Experience: Over 15 years of specialized expertise in duplex and super duplex stainless steel seamless pipe production, with deep understanding of critical application requirements
Complete Size Range & Custom Solutions: Standard sizes from 6mm to 325mm outer diameter with wall thickness from 0.5mm to 20mm, plus custom dimensions, special lengths up to 12 meters, and cut-to-length services tailored to project specifications
International Standards Compliance: Full compliance with ASTM, ASME, EN, and NACE specifications, certified by ISO 9001:2015 quality management system and recognized by major classification societies
Technical Support & Application Engineering: In-house metallurgical and engineering team provides material selection guidance, corrosion analysis, and application-specific recommendations to optimize performance and lifecycle costs
Global Export Experience: Proven track record supplying duplex seamless pipes to projects across Asia, Middle East, Europe, and Americas with comprehensive export documentation and logistics coordination
Quality Assurance & Traceability: Complete material traceability from heat number to final product, backed by comprehensive testing certificates and third-party verification available through our quality control program
Contact our technical sales team to discuss your project specifications, receive detailed product information, and obtain competitive pricing for UNS S31803, UNS S32205, UNS S32750, and other duplex grades. We provide fast quotations, technical data sheets, and application engineering support to ensure optimal material selection for your specific requirements.
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