ASTM A790 UNS S31803, ASME B36.19,Duplex Seamless Steel Pipe
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) deliversdouble 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
1.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 per cent | 22.0-23.0 per cent | 24.0-26.0 per cent |
Mo Content | 2.5-3.5 per cent | 3.0-3.5 per cent | 3.8-4.5 per cent |
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)
by 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.
