Basic Introduction
ASTM A790 UNS S31803 (also known as 2205 duplex steel, EN 1.4462, GB 022Cr22Ni5Mo3N) seamless pipe is austenitic-ferritic duplex stainless steel tubular product manufactured per ASTM A790/ASME SA790 standard for high-pressure, chloride-corrosion service. Balanced dual-phase microstructure (~50% ferrite + 50% austenite) delivers double yield strength vs 316L austenitic steel, outstanding resistance to pitting, crevice corrosion and chloride stress corrosion cracking (SCC). Widely recognized as cost-effective duplex material for medium-to-severe corrosive industrial environments.
Full Technical Parameters
1. Chemical Composition (Weight %, ASTM A790 Standard)
| Element | C | Si | Mn | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|---|
| Min | - | - | - | - | - | 21.0 | 4.5 | 2.5 | 0.08 |
| Max | 0.03 | 1.0 | 2.0 | 0.03 | 0.02 | 23.0 | 6.5 | 3.5 | 0.20 |
2. Mechanical Properties (Solution Annealed Delivery State)
| Property | Standard Minimum Value |
|---|---|
| Tensile Strength (UTS) | ≥620 MPa |
| Yield Strength (Rp0.2) | ≥450 MPa |
| Elongation (A) | ≥25% |
| Max Hardness (HB) | ≤290 HB |
| Impact Toughness (-50℃) | ≥100 J |
| Critical Pitting Temperature (CPT) | ~35℃ |
3. Production & Dimension Specifications:
- Manufacturing Process: Hot extrusion + cold drawing seamless forming
- Standard: ASTM A790 / ASME SA790, EN 10216-5, GB/T 22270
- Outer Diameter (OD): 6mm – 720mm
- Wall Thickness (WT): 1mm – 65mm
- Length: Fixed length 6m/12m, random length 1–18m, customized U-bend available
- Surface Finish: Pickled white, bright annealed, polished
- Pipe End: Plain end, beveled end, threaded end
- Heat Treatment: Solution annealing 1020–1100℃, rapid water/air cooling
- Tolerance: Strict per ASTM A790 & ASME B36.19 seamless pipe tolerance
- Certification: EN10204 3.1 / 3.2, SGS, TUV, DNV, PED, ISO9001, ABS, NACE MR0175
4. Packaging & Shipment
Bundle with steel straps, plastic end caps for inner protection
Wrapped waterproof plastic film, plywood pallet / wooden case for sea transport
Marking: Grade, standard, OD×WT, length, heat number, batch number, manufacturer logo
Shipment: FCL 20GP/40HQ, break bulk vessel, LCL consolidation
Main Application Fields
- Oil & Gas Upstream & Downstream
Offshore platform piping, subsea auxiliary pipelines, sour service gathering lines, refinery heat exchanger tubes, separator piping (NACE sour gas service)
- Marine & Seawater Desalination
Seawater intake pipes, reverse osmosis desalination equipment, marine cooling circulation pipelines, shipboard fluid piping
- Chemical & Petrochemical Plants
Dilute acid transport pipelines, reactor cooling tubes, brine processing equipment, fertilizer production piping
- Pulp & Paper Industry
Bleaching process pipelines, black liquor conveying tubes, high-chloride process equipment
- Energy & Environmental Protection
Geothermal fluid pipes, flue gas desulfurization (FGD) pipelines, waste water treatment high-chloride piping
- Food & Light Industry
Saline food processing equipment, brine circulation pipelines, beverage anti-corrosion delivery pipes
Duplex Steel Grade Comparison: S31803 vs S32205 vs S32750
| Comparison Item | UNS S31803 (2205 Base Duplex) | UNS S32205 (Standard 2205) | UNS S32750 (Super Duplex 2507) |
|---|---|---|---|
| PREN Value | 32–35 | ≥35 | ≥42 |
| Cr Content | 21.0–23.0% | 22.0–23.0% | 24.0–26.0% |
| Mo Content | 2.5–3.5% | 3.0–3.5% | 3.8–4.5% |
| Min Yield Strength | 450 MPa | 550 MPa | 550 MPa |
| CPT Corrosion Temp | ~35℃ | ~40℃ | >50℃ |
| Chloride Resistance | Medium chloride ≤1000ppm | Medium-high chloride | Ultra-high chloride, seawater long-term immersion |
| Cost Level | Lowest (Cost-effective) | Medium | Highest |
| Typical Scenarios | General chemical, moderate marine, inland brine | Offshore auxiliary, desalination main pipeline | Deep sea subsea, high-acid high-chloride severe corrosive environment |
| Advantages | Low raw material cost, stable supply, mature Chinese production | Balanced strength & corrosion resistance, most global standard duplex | Top-tier anti-corrosion, replaces nickel alloy in extreme conditions |
| Disadvantages | Narrower alloy range, slightly unstable corrosion performance vs S32205 | Slightly higher price than S31803 | High alloy cost, limited domestic large-diameter production |
June 2026 Actual Export Price & Main Export Markets
1. June 2026 FOB China Export Price (UNS S31803 ASTM A790 Seamless Pipe)
Price term: FOB Tianjin / FOB Shanghai, based on standard pickled surface, normal wall thickness, MOQ ≥5 tons
Small diameter thin-wall tubing (OD 6–114mm, WT 1–6mm): USD 5,300 – 6,100 / MT
Medium diameter general pipe (OD 114–325mm, WT 6–20mm): USD 4,700 – 5,400 / MT
Large diameter thick-wall industrial pipe (OD 325–720mm, WT 20–65mm): USD 4,400 – 5,000 / MT
Premium polished / U-bend customized pipe: +USD 400–800 / MT extra processing fee
Price fluctuation factor: Nickel raw material spot price, order quantity, third-party inspection requirement, delivery port
2. Global Main Export Markets (2026 H1, S31803 Duplex Pipe)
》Middle East (Largest Market, ~42% Total Export Volume)
Core Countries: UAE, Saudi Arabia, Kuwait, Oman, Bahrain
Demand Driver: Offshore oil & gas pipeline, seawater desalination infrastructure, refinery expansion; buyers prefer thick-wall NACE-certified S31803 pipe, high unit price orders, stable long-term contracts
》Southeast Asia (~15% Export Volume)
Core Countries: Singapore, Malaysia, Indonesia, Thailand, Vietnam
Demand Driver: Coastal chemical plants, offshore minor oilfields, municipal seawater treatment; dominated by small & medium diameter tubing, price-sensitive bulk orders
》3. Latin America (~13% Export Volume)
Core Countries: Chile, Brazil, Ecuador, Peru
Demand Driver: Offshore petroleum, mining brine processing, coastal desalination projects; growing demand year-on-year under Belt & Road cooperation
》4. Europe (~12% Export Volume)
Core Countries: Germany, Netherlands, Spain, Norway
Demand Driver: Chemical process equipment, North Sea auxiliary marine piping; strict PED & 3.2 inspection certification requirements
》5. Central Asia & Africa (~18% Export Volume)
Core Countries: Kazakhstan, Uzbekistan, Nigeria, Egypt
Demand Driver: Land-based sour gas pipelines, saline water resource treatment, fertilizer chemical factories; cost-effective S31803 replaces expensive S32205 for inland medium-corrosion projects
FAQ
Q1: What is the difference between UNS S31803 and S32205? Can they replace each other?
A: S32205 has tighter chemical control with higher Mo & N content, better consistent corrosion resistance. S31803 is cost-effective for medium chloride environments. They can partially replace each other for low-risk service; high-chloride offshore projects recommend S32205 for long-term stability.
Q2: Does S31803 seamless pipe need post-weld heat treatment?
A: Normally not required. Only for ultra-thick wall (>40mm) pipe under ultra-low temperature service, low-temperature stress relief annealing can be conducted at 800–900℃.
Q3: What test certificates can you provide for export?
A: Standard MTC EN10204 3.1; third-party 3.2 certification by SGS, TUV, DNV upon buyer request; PMI test, hydrostatic test, UT/RT non-destructive test report, NACE MR0175 compliance certificate.
Q4: What is the minimum order quantity?
A: Stock standard sizes MOQ 1 MT; customized non-standard OD/WT MOQ 5 MT; mixed specifications consolidated order acceptable.
Q5: What is the standard production lead time?
A: Stock items: 7–10 working days; regular customized size: 15–25 days; large-diameter thick-wall special production: 30–40 days.
Q6: Can S31803 be used in seawater immersion environment?
A: Suitable for intermittent seawater contact, cooling circulation with chloride ≤1000ppm. Permanent full seawater subsea service is recommended to upgrade to S32750 super duplex for longer service life.
Q7: What payment terms do you support for export orders?
A: T/T (30% advance deposit, balance against copy of B/L), Irrevocable L/C at sight
Q8: What is the service temperature range of S31803 pipe?
A: Continuous service temperature: -50℃ ~ 280℃; long-term service over 300℃ will reduce duplex phase stability and corrosion performance.
Q9: Is S31803 magnetic?
A: Yes, slightly magnetic due to ferrite phase, which is normal duplex steel characteristic, not material quality defect.
Q10: What's the HS code for export customs clearance?
A: HS Code: 73044190 – Seamless duplex stainless steel pipe, can provide customs declaration documents as requested.
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