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Duplex Steel S31803 Seamless Pipe
Duplex S31803 Seamless Pipe starts as a pierced billet, hot worked over a mandrel, then solution-annealed and quenched. No longitudinal joint runs through the wall, so subsea line classes call for it.
Duplex Steel S31803 Pipe Manufacturer in India
Established in 2008, MLTI Private Limited (Moonlight Tube Industries) is a premier Duplex Steel S31803 Pipe manufacturer, supplier, and exporter operating out of Gujarat, India.
UNS S31803 is the original registration of the 22Cr duplex composition, and pipe in this grade is furnished to ASTM A790 / ASME SA-790, with ASTM A928 governing the electric fusion welded route. SA-790 sets chromium at 21.0 to 23.0%, nickel 4.5 to 6.5%, molybdenum 2.5 to 3.5%, and nitrogen 0.08 to 0.20%, carbon held to 0.030% maximum. A roughly balanced ferrite and austenite structure lifts the certified minima to 620 MPa tensile and 450 MPa yield at 25% elongation. Hardness is capped at 290 HBW and 30 HRC. Our S31803 pipe programme covers 1/8" NB to 10" NB in seamless and welded form. Round pipe in SCH 10S, 40S, and 80S is dimensioned to ASME B36.19M, as is SCH 5S from 1/2" NB upwards; SCH 5S below 1/2" NB; and SCH 20S and the square and rectangular profiles are rolled to agreed dimensions outside that standard. Duplex Steel S31803 Seamless Pipe is pierced from a solid billet and solution annealed, leaving no weld or heat-affected zone to handle extreme pressure. S31803 Duplex Steel Welded Pipe is formed from flat annealed plate and longitudinally seam-welded by an automatic welding process with no addition of filler metal, as required by ASTM A790 / ASME SA-790. Full-body thin walls and larger profiles cost less this way.
Chloride-bearing duty absorbs most of it: offshore flowlines, chemical process piping, desalination trains and bleach plant headers. Each length ships against in-house PMI, tensile, hardness, and dimensional inspection, ISO 14001 environmental and ISO 45001 occupational health and safety certification, BIS, EIL, IBR, and PED approvals, and an EN 10204 3.1 mill test certificate.
Duplex Steel S31803 Pipe Specifications
This specification table details the standards, grades, sizes, and conditions for A790 S31803 Duplex.
| Parameter | Value |
|---|---|
| Applicable Standards | ASTM A790 / ASME SA-790: Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe ASTM A928: Ferritic/Austenitic (Duplex) Stainless Steel Pipe Electric Fusion Welded with Addition of Filler Metal |
| Dimensional Standard | ASME B36.19M |
| Size range | 1/8" NB to 10" NB (6 mm to 250 mm) |
| Schedule | SCH 5S, SCH 10S, SCH 20S, SCH 40S, SCH 80S |
| Wall thickness | 1.24 mm to 12.70 mm, by bore and schedule |
| Manufacturing Process | Seamless, welded (ERW) |
| Section profile | Round, square, rectangular |
| Supply condition | Solution annealed 1020 to 1100°C, rapid cooling in air or water |
| Length | Single random, double random, cut length |
| End type | Plain end; bevelled to order |
Duplex Stainless Steel S31803 Pipe Chemical Composition
Composition decides phase balance and pitting resistance in equal measure on this grade. Element limits that ASME SA-790 prescribes for UNS S31803 pipe are given in the chemical composition table below, in weight percent.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.030 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.030 max |
| Sulphur (S) | 0.020 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 21.0 to 23.0 |
| Nickel (Ni) | 4.5 to 6.5 |
| Molybdenum (Mo) | 2.5 to 3.5 |
| Nitrogen (N) | 0.08 to 0.20 |
| Iron (Fe) | Balance |
Nitrogen carries more weight than its small band suggests. It stabilises austenite, raises yield strength, and enters the pitting resistance calculation at sixteen times the coefficient given to chromium.
Duplex Steel S31803 Pipe Mechanical Properties
Design wall thickness is set from the certified yield and tensile minima, while elongation and the hardness ceiling are acceptance requirements, all measured to ASTM A370 on solution-annealed material.
| Property | Requirement |
|---|---|
| Tensile strength, min | 620 MPa (90 ksi) |
| Yield strength, 0.2% offset, min | 450 MPa (65 ksi) |
| Elongation in 50 mm, min | 25% |
| Hardness, max | 290 HBW |
| Hardness, max | 30 HRC |
That 450 MPa yield permits a thinner wall than an austenitic grade needs at the same design pressure. Schedule doesn't alter the certified minima: SCH 5S and SCH 80S meet identical values.
DSS S31803 Pipe Equivalent Grades
Designations corresponding to duplex UNS S31803 pipe, including UNS, EN, JIS, and more, are set out in the table below.
| Standard | Designation |
|---|---|
| UNS (USA) | UNS S31803 |
| EN (Europe) | EN 1.4462, X2CrNiMoN22-5-3 (also written X2CrNiMoN 22 5 3) |
| Werkstoff / DIN (Germany) | W.Nr. 1.4462, DIN 1.4462 |
| JIS (Japan) | JIS SUS329J3L, SUS 329J3L |
| GB/T (China) | 022Cr22Ni5Mo3N, S22253 (formerly 00Cr22Ni5Mo3N) |
| AFNOR (France) | Z3 CND 22-05 Az |
| SIS (Sweden) | SIS 2377 |
Duplex Steel S31803 Pipe Types & Forms
Five variants share one analysis: two production routes that settle pressure duty and metre rate, and three section profiles that settle how the load is carried. Route and profile are specified independently of the order.
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Duplex Steel S31803 Welded Pipe (ERW)
Duplex Steel S31803 welded pipe is seam-joined by automatic TIG or laser welding without filler metal, then heat-treated per ASTM A790 / ASME SA-790. ERW pipe closes the seam through electric resistance heating, offering consistent wall thickness and lower cost than seamless pipe above a 4-inch bore.
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S31803 Round Pipe
The round section is what ASME B36.19M dimensions, and it spans the whole nominal bore range tabulated further down. Pressure piping, flowlines, and injection headers take round S31803 pipe almost exclusively.
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S31803 Square Pipe
Square pipe in this grade is roll-formed to an agreed side and wall rather than to a schedule, since B36.19M defines no square section. Structural work inside corrosive plant areas uses it.
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S31803 Rectangular Pipe
Rectangular pipe follows the same forming route, to the width, depth, and wall agreed at order. The unequal section resists bending about its major axis, which suits offshore walkway framing and equipment skid bases.
DSS S31803 Pipe Sizes
Sixteen nominal bores and five schedules make up our supply envelope. The chart below gives nominal bore, outside diameter, and wall thickness per schedule for duplex steel S31803 pipe sizes. The SCH 10S, 40S and 80S columns follow ASME B36.19M, as does SCH 5S from 15 mm NB upwards; the SCH 5S walls for 6, 8 and 10 mm NB and the whole SCH 20S column are supplied by agreement.
| NB (mm) | NB (in) | OD (mm) | SCH 5S (mm) | SCH 10S (mm) | SCH 20S (mm) | SCH 40S (mm) | SCH 80S (mm) |
|---|---|---|---|---|---|---|---|
| 6 | 1/8 | 10.3 | 1.24 | 1.24 | 1.50 | 1.73 | 2.41 |
| 8 | 1/4 | 13.7 | 1.24 | 1.65 | 2.00 | 2.24 | 3.02 |
| 10 | 3/8 | 17.1 | 1.24 | 1.65 | 2.00 | 2.31 | 3.20 |
| 15 | 1/2 | 21.34 | 1.65 | 2.11 | 2.30 | 2.77 | 3.75 |
| 20 | 3/4 | 26.7 | 1.65 | 2.11 | 2.55 | 2.87 | 3.91 |
| 25 | 1 | 33.4 | 1.65 | 2.77 | 3.00 | 3.38 | 4.55 |
| 32 | 1 1/4 | 42.2 | 1.65 | 2.77 | 3.00 | 3.56 | 4.85 |
| 40 | 1 1/2 | 48.3 | 1.65 | 2.77 | 3.00 | 3.68 | 5.08 |
| 50 | 2 | 60.3 | 1.65 | 2.77 | 3.00 | 3.91 | 5.54 |
| 65 | 2 1/2 | 73.0 | 2.11 | 3.05 | 4.00 | 5.16 | 7.01 |
| 80 | 3 | 88.9 | 2.11 | 3.05 | 4.00 | 5.49 | 7.62 |
| 100 | 4 | 114.3 | 2.11 | 3.05 | 4.50 | 6.02 | 8.56 |
| 125 | 5 | 141.3 | 2.77 | 3.40 | 5.00 | 6.55 | 9.53 |
| 150 | 6 | 168.3 | 2.77 | 3.40 | 6.35 | 7.11 | 10.97 |
| 200 | 8 | 219.1 | 2.77 | 3.76 | 6.35 | 8.18 | 12.70 |
| 250 | 10 | 273.1 | 3.40 | 4.19 | 6.35 | 9.27 | 12.70 |
Duplex Steel S31803 Pipe Industrial Applications
High-pressure line classes across five major industrial sectors specify ASTM A790 UNS S31803 pipes to prevent chloride stress corrosion cracking, handle acidic liquors, and reduce structural weight.
Oil and Gas
Offshore gathering lines, produced water injection headers and topside process piping are specified in S31803 because chloride stress corrosion cracking resistance holds where 316L pipe fails. High yield strength also cuts riser wall weight.
Chemical and Petrochemical
Organic acid transfer runs, urea plant piping, and acid cooler circuits use ferritic-austenitic stainless steel pipe in this grade. Chromium at 21.0 to 23.0%, molybdenum at 2.5 to 3.5% and nitrogen at 0.08 to 0.20% together set the pitting resistance, while the balanced ferrite-austenite structure carries the mechanical load.
Desalination and Water Treatment
Reverse osmosis high-pressure feed piping, brine recirculation loops, and evaporator distribution lines take S31803. Ambient seawater sits inside its pitting resistance, and a 450 MPa yield suits the 60 to 80 bar membrane train duty.
Pulp and Paper
Bleach plant washer piping and chlorine dioxide distribution lines carry warm acidic chloride liquor. S31803 pipe resists that combination where 317L thins measurably within a campaign. Digester liquor circuits are built from the same grade.
Marine and Shipbuilding
Cargo lines on chemical tankers, ballast systems and firewater ring mains are fabricated in this grade. Duplex is ferromagnetic, unlike austenitic piping, so compass safe distances need checking at the design stage rather than after installation.
Technical Processing & Thermal Limits for S31803 Pipe
Solution annealing at 1020°C to 1100°C followed by rapid air or water quenching locks the ferrite-to-austenite ratio near 50:50. Precise heat control during welding prevents excess ferrite or intermetallic precipitation. Using the formula , S31803 yields a 30.5 to 37.8 rating (typically 34), providing strong pitting resistance.
Service temperatures must stay between −50°C and 300°C. Above roughly 300°C, the ferrite starts to form alpha prime, the cause of 475°C embrittlement, which runs from about 300°C to 525°C. Sigma phase is a separate reaction, forming between roughly 700°C and 950°C during slow cooling, welding or heat treatment, which is why solution annealing is followed by a rapid quench. Below −50°C, impact toughness falls away as the ferrite passes through its ductile-to-brittle transition.
Duplex Steel S31803 Pipe Shipping and Packaging
As an MLTI Private Limited S31803 Duplex Steel Pipe supplier, we secure every shipment in timber cases after strapping bundles by schedule and capping bore ends.
- Lengths are strapped into bundles by bore and schedule, then timber-cased for export.
- Bore ends are capped, with plastic sleeving applied on request.
- Cargo moves on FOB or CFR terms to Brazil, Turkey, Vietnam, and Europe.
- Cut lengths, bevelled ends and client marking formats precede packing.
Duplex Steel S31803 Pipe Price
Duplex steel S31803 pipe pricing ranges from ₹550–₹850/kg in India ($6.6–$10.2/kg). Small or specialised orders reach ₹1,200–₹1,500/kg ($14–$18/kg), and export FOB rates track the same band at roughly $6.5–$10/kg, depending on bore, wall and tonnage.
Daily fluctuations in nickel and molybdenum raw material markets shift S31803 duplex pipe prices constantly. Seven core parameters drive exact quotes: bore size, wall thickness, schedule, manufacturing process, section profile, order volume, and testing requirements. Standard seamless pipes demand a higher premium over welded options. Because S31803 contains mid-range molybdenum and nitrogen content, it costs less than super duplex grades.
Why Buy Duplex Steel S31803 Pipe From MLTI?
Buyers return to Moonlight Tubes for certified material, approved grades and stock that ships on schedule. Every order is backed by documented quality, a wide size range and delivery commitments we hold to.
Quality Certification
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IBR & EIL Approved
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Why
Choose Us
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Wide Range of Grades & Sizes
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Timely Global Delivery
S31803 Duplex Steel Pipe FAQs
S31803 pipe is a standard duplex grade rather than a super duplex one. Its PREN falls between 30.5 and 37.8 against the SA-790 limits, while SA-790 requires a PREN of at least 41 for super duplex S32750.
ASTM A790 / ASME SA-790 covers Duplex Steel S31803 pipe in seamless and welded form. ASTM A928 UNS S31803 applies only where filler metal is added to the seam.
Certified yield strength is the first reason: 450 MPa against 170 MPa for 316L pipe, so a thinner wall carries the same pressure. Resistance to chloride stress corrosion cracking is the second.
Our S31803 pipe sizes range from 1/8" NB to 10" NB, 10.3 mm to 273.1 mm outside diameter, in SCH 5S, 10S, 20S, 40S, and 80S. Wall thickness spans 1.24 mm to 12.70 mm across that range.
Every consignment leaves with an EN 10204 3.1 mill test certificate reporting heat analysis, tensile results, hardness and dimensional inspection. PMI, tensile, and hardness testing are run in our own laboratory, with NABL-approved external support on request.