Duplex / Super Duplex Pipes, Fittings & Flanges Supplier
Overview
Sagiant Piping Industries supports enquiries for duplex and super duplex stainless steel pipes, tubes, fittings, flanges and forgings — the two-phase (austenite + ferrite) alloys that combine roughly twice the yield strength of 304/316 with strong chloride pitting and stress-corrosion-cracking resistance. Coverage spans lean duplex (2101/2304), standard duplex (S31803 and S32205 — supplied as separate acceptance records), and super duplex (2507, S32760 / ZERON 100, S32550 / Ferralium 255). Grade, UNS, brand requirement, product form, condition, testing and certification are confirmed with the quotation — availability is not implied for every grade or size.
Duplex & super duplex grades, chemistry, standards and RFQ reference data
Lean, standard and super duplex grades by product form and condition, with chemistry, PREN, mechanical, corrosion-test and dimensional references. Values carry a basis label (specification / producer / nominal); because full current licensed standards were not available, confirm the adopted ASTM edition, grade/UNS, brand requirement and product form on the material certificate.
Technical Specification
| Parameter | Specification |
|---|---|
| Product Forms | Seamless & welded pipe, seamless tube, BW & forged fittings, flanges, forgings, plate/sheet, bar; cast grades where offered |
| Grades | Lean 2101 (S32101) / 2304 (S32304); standard S31803 & S32205 (2205); super 2507 (S32750), S32760 / ZERON 100, S32550 / Ferralium 255. Hyper (2707/3207 HD) reviewed against actual supply. |
| Size Range | Pipe from 1/2" NPS; tube by OD × wall; bar and plate per product form — confirmed with quotation |
| Wall / Schedule / Class | ASME B36.19 S schedules; B36.10 walls where ordered; flanges B16.5 / B16.47 — separate designations |
| Standards | ASTM A790 (seamless/welded pipe), A928 (EFW), A789 (tube), A815 (BW fittings), A182 (forgings/flanges), A240 (plate), A276/A479 (bar), A1082 (bolting) where offered |
| Testing & Docs | Chemistry/PMI, tensile, hardness, ferrite, G48/CPT, A923/A1084 intermetallic screening, Charpy where ordered, MTC EN 10204 3.1/3.2 — coordinated per scope |
Chemical Composition (wt %)
| Grade | UNS | C max | Mn max | Si max | P max | S max | Cr | Ni | Mo | N | Cu / W | PREN (nom.) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2101 (lean) | S32101 | 0.04 | 4.0–6.0 | 1.0 | 0.040 | 0.030 | 21.0–22.0 | 1.35–1.70 | 0.10–0.80 | 0.20–0.25 | Cu 0.10–0.80 | ~26 |
| 2304 (lean) | S32304 | 0.030 | 2.50 | 1.0 | 0.040 | 0.030 | 21.5–24.5 | 3.0–5.5 | 0.05–0.60 | 0.05–0.20 | Cu 0.05–0.60 | ~25 |
| S31803 (2205) | S31803 | 0.030 | 2.0 | 1.0 | 0.030 | 0.020 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | 0.08–0.20 | — | ~34 (min limits) |
| S32205 (2205) | S32205 | 0.030 | 2.0 | 1.0 | 0.030 | 0.020 | 22.0–23.0 | 4.5–6.5 | 3.0–3.5 | 0.14–0.20 | — | ~35 |
| 2507 (super) | S32750 | 0.030 | 1.2 | 0.8 | 0.035 | 0.020 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 | Cu ≤0.5 | ~41 (≥38 at min limits) |
| S32760 / ZERON 100 | S32760 | 0.030 | 1.0 | 1.0 | 0.030 | 0.010 | 24.0–26.0 | 6.0–8.0 | 3.0–4.0 | 0.20–0.30 | Cu 0.5–1.0, W 0.5–1.0 | ~40 (W formula) |
| S32550 / Ferralium 255 | S32550 | 0.04 | 1.5 | 1.0 | 0.040 | 0.030 | 24.0–27.0 | 4.5–6.5 | 2.9–3.9 | 0.10–0.25 | Cu 1.5–2.5 | ~38 |
S31803 and S32205 are separate records — S32205 has the narrower, more consistently corrosion-resistant chemistry; a heat certified to one is not automatically dual-certified. Ranges are specification limits (not "typical" chemistry); heat vs product analysis and footnotes need the adopted edition. PREN is nominal, computed as Cr + 3.3Mo + 16N (W-bearing grades use Cr + 3.3(Mo + ½W) + 16N) — it is an empirical index, not a guaranteed CPT, crevice threshold or seawater rating. The lower composition limits give lower PREN (e.g. S32750 minimums ≈ 37.7, not 42), so any minimum PREN must be separately ordered. Generic UNS is not the branded product: ZERON 100 (S32760) and Ferralium 255 / SD50 (S32550) carry tighter producer requirements. Final chemistry is on the heat-wise MTC.
Grade Directory — UNS, Forging Grades & Related Designations
| Grade | UNS | Forging (A182) | EN (comparison only) | Character & typical service |
|---|---|---|---|---|
| Lean 2101 | S32101 | — | 1.4162 | Low-nickel lean duplex for cost-sensitive structural and moderate-chloride service. |
| Lean 2304 | S32304 | F52 | 1.4362 | Low-molybdenum lean duplex bridging 304/316 and 2205 (no deliberate substantial Mo addition). |
| Duplex 2205 | S31803 | F51 | 1.4462 | Standard 22Cr duplex, broader historical chemistry range. Do not merge with S32205. |
| Duplex 2205 | S32205 | F60 | 1.4462 | Standard 22Cr duplex, narrower modern chemistry. F51 and F60 are not collapsed. |
| Super 2507 | S32750 | F53 | 1.4410 | 25Cr super duplex for seawater, subsea, desalination and qualified sour service. |
| ZERON 100 | S32760 | F55 | 1.4501 | Cu/W-bearing super duplex; branded product has tighter requirements than generic S32760. |
| Ferralium 255 | S32550 | F61 | 1.4507 | Copper-bearing super duplex (also SD50 producer variant); high strength for marine/chemical service. Distinguish from S32520. |
EN numbers are related designations for comparison, not exact replacements — sharing a material number does not prove dual certification. An A182 F grade is for forgings, not plate or pipe. Hyper duplex (S32707 / 2707 HD, S33207 / 3207 HD) and cast grades (A995/A890) are separate advanced/product families supplied only where offered. Resolve every UNS/brand identifier against the adopted standard before relying on it.
Mechanical Properties (solution-annealed, specified minima)
| Grade | Tensile min MPa | 0.2% yield min MPa | Elong. min % | Hardness max | Basis |
|---|---|---|---|---|---|
| 2205 (S31803 / S32205) | 620 | 450 | 25 | 293 HBW / 30.5 HRC | A790 pipe / A240 plate |
| 2507 (S32750) | 795 | 550 | 15 | 310 HBW / 32 HRC | A790 pipe |
| S32760 (ZERON 100) | 750 | 550 | 25 | ≤28 HRC (product-dependent) | A790 / branded |
| S32550 (Ferralium 255) | 760 | 550 | 15 | 302 HBW | A479 bar / producer |
| Lean 2101 (S32101) | 650 | 450 | 30 | 290 HBW | A240 plate |
| Lean 2304 (S32304) | 600 | 400 | 25 | 290 HBW | A790 / A240 |
Values are specified minima for solution-annealed product on the stated basis — they are not universal across every form, size or condition. Pipe (A790), plate (A240), bar (A479), forging (A182) and cold-worked products have their own tables; do not apply one row to all. S31803 and S32205 share A790 mechanical minima but differ in chemistry. Elongation depends on specimen, gauge length and orientation. Do not overwrite independently stated SI requirements with converted inch-pound values.
Corrosion & Phase-Quality Testing
| Test / data | What the requirement must state |
|---|---|
| PREN | Formula used, chemistry basis (actual / nominal / limit), tungsten treatment, and any separately ordered minimum PREN. It is an index, not a service guarantee. |
| G48 pitting | Method (A/B/…), test temperature, duration, specimen preparation, whether welds are included, and mass-loss / pitting acceptance — with the source specification. |
| CPT / CCT | Method (e.g. specific G48 or G150 procedure), solution, specimen finish and criterion. Laboratory critical temperatures are not universal service limits. |
| Intermetallic phase | ASTM A923 (its own methods) or A1084 as applicable — grade-specific; do not treat them as interchangeable with generic IGC testing. |
| Ferrite | Base / weld / HAZ, volume fraction vs ferrite number, method/calibration, sampling and the ordered acceptance range (a producer target is not automatically the acceptance range). |
| Charpy impact | Temperature, orientation, specimen size, average and individual energies, and subsize rules. |
| PMI / chemistry | Handheld XRF does not establish carbon or nitrogen, so it cannot verify complete duplex grade identity on its own. |
| Sour service | The relevant ISO 15156-3 table/qualification route, environment (H₂S, chloride, pH, temperature), material condition and hardness — not a blanket "NACE compliant" label. |
Physical Properties (representative)
| Property | Approximate value | Basis |
|---|---|---|
| Density | ≈ 7,800 kg/m³ (7.8 g/cm³) | weight-estimation assumption — varies by grade |
| Young's modulus (ambient) | ≈ 200 GPa | room temperature reference |
| Magnetic response | Ferromagnetic (from the ferrite phase) | magnetism does not mean it is not stainless steel |
| Thermal conductivity / expansion / heat capacity vs temperature | Grade- and temperature-dependent — use a producer dataset | withheld: not verified per grade |
Representative reference values, not acceptance limits. Duplex has lower thermal expansion and higher conductivity than austenitic grades, but publish grade- and temperature-specific values (with mean vs instantaneous expansion stated) only from a verified producer source.
Standards & Product Forms
| Product | Material / product specification | Separate dimensional / other basis |
|---|---|---|
| Seamless / welded pipe | ASTM A790 (grade, process, condition) | ASME B36.19 / B36.10; product tolerances |
| EFW welded pipe | A928 (class + filler-metal / examination) — not a generic A790 welded entry | Class-dependent radiography & testing |
| Seamless tube | A789 | OD × wall, min/nominal wall, length, tube tests |
| Butt-weld fittings | A815 (grade / class / construction / exam) | ASME B16.9; B16.25 weld ends |
| Forged fittings & flanges | A182 (F51/F53/F55/F60/F61) | B16.11 fittings; B16.5 / B16.47 flanges (size / class / series) |
| Plate / sheet | A240 with general requirements | Thickness, finish, condition, tolerance |
| Bar | A276 / A479 (grade, condition, section) | Diameter / section, testing |
| Bolting | A1082 (finished duplex bolting) where applicable — not A276/A479 alone | Grade/condition, diameter, thread, tensile/proof/hardness |
| Castings | A995 / A890 (where cast products supplied) | Casting grade & heat treatment — not a wrought UNS renamed |
Material, dimensional, design-code and testing standards are distinct. A276/A479 are bar requirements, not a finished-fastener specification — use A1082 (or the ordered bolting standard) with grade, condition, thread and acceptance tests. For offshore, NORSOK M-630 (exact MDS/edition/product) and M-650 (manufacturer/process qualification) apply within their essential-variable scope; distinguish MR0175/ISO 15156-3 (production) from MR0103/ISO 17945 (refining).
Pipe Schedules, Tube Sizes & Flange Classes
| Concept | Correct treatment |
|---|---|
| S schedules | ASME B36.19 S schedules (5S/10S/40S/80S) differ from B36.10 wall designations. XXS is not an S schedule and not a universal Sch 160 equivalent. |
| Schedule vs pressure | Schedule / wall is not a pressure rating; required wall comes from the design-code calculation. |
| Tube | Ordered by OD × wall (A789), not NPS/schedule. |
| B16.5 flanges | NPS ½–24, Classes 150–2500 (Class 2500 through NPS 12). It is not a 48-inch flange standard, and material rating coverage must be checked. |
| B16.47 flanges | Large-diameter NPS 26–60, Series A/B — confirm class/series in the ordered edition. |
For full dimensional data see the Pipe Schedule Chart. NPS/DN are nominal — not the measured ID (ID = OD − 2 × wall). Every advertised size/grade/process combination needs confirmation with the quotation.
Service, Temperature & Corrosion
| Topic | Guidance |
|---|---|
| Chlorides & seawater | Performance depends on chloride level, temperature, pH, oxidants/chlorination, deposits, crevices, flow, weld quality and finish. High PREN does not confer crevice-corrosion immunity or a fixed seawater temperature limit. |
| Upper-temperature limit | Separate α-prime / 475°C embrittlement from higher-temperature sigma/intermetallic precipitation — different mechanisms and time–temperature behaviour. Duplex is generally limited to roughly ≤ 250–300°C continuous service (grade/code dependent); a metallurgical warning temperature is not one universal maximum. |
| Low-temperature / LNG | Duplex offers good toughness for seawater and cryogenic-adjacent utility duty, but general liquid-LNG suitability is not implied — toughness and code acceptance must be demonstrated for the actual component and temperature. |
| Subsea / cathodic protection | Hydrogen-assisted cracking under cathodic protection needs separate assessment for super duplex subsea components. |
| Sour service | Qualify to ISO 15156-3 for the exact environment; hardness and ferrite checks alone are not sufficient. |
Welding & Fabrication
| Item | Guidance |
|---|---|
| Procedure & phase balance | Qualified WPS/PQR/personnel, grade-appropriate over-alloyed filler, and controlled heat input and interpass temperature to keep the austenite/ferrite balance and limit nitrogen loss. No universal heat-input figure. |
| Shielding / backing | Correct shielding and backing gas (often N₂-bearing) to protect root passes and phase balance. |
| Heat treatment | Full solution treatment with rapid cooling is a distinct, grade-specific process — ordinary carbon-steel-style stress relief can damage duplex and is inappropriate. Separate mill delivery treatment from fabrication practice. |
| Weld/HAZ quality | Verify weld/HAZ corrosion and toughness and intermetallic freedom by the ordered tests; define repair limits. |
| Forming / finishing | Higher forming loads and springback; control work hardening, cleanliness, iron-contamination prevention, heat-tint removal, pickling/passivation and final surface inspection. |
Applications, Industries & Grade Guidance
| Family | Representative grades | Considered for / limitations |
|---|---|---|
| Lean duplex | 2101, 2304 | Cost-sensitive structural, storage, moderate-chloride water — not equivalent to 316L in every chloride environment. |
| Standard duplex | S31803 / S32205 (2205) | Chemical process, pressure vessels, chloride and SCC service — the general workhorse. |
| Super duplex | 2507, S32760, S32550 | Seawater, subsea, desalination, aggressive/qualified sour service — subject to temperature, crevice and CP limits. |
| Hyper duplex | 2707 HD, 3207 HD (if offered) | The most aggressive high-chloride/high-strength duties — separate advanced family. |
Candidate families for enquiry — not substitutions or material-selection approvals. Exact selection is set by the environment and design code, not by a PREN number.
Available Forms, Sizes & Dimensions
Supplied as seamless and welded pipe, seamless tube, butt weld and forged fittings, flanges, forgings, plate/sheet and bar; cast grades where offered. Share grade/UNS, brand requirement, NPS/OD, schedule or wall and standard for confirmation. For full dimensional data see the Pipe Schedule Chart.
| Form | Size Range | Wall / Thickness / Class | Standard |
|---|---|---|---|
| Seamless pipe | 1/2" – 24" NPS | Sch 10S–XXS | ASTM A790 |
| Welded / EFW pipe | 1/2" – 48" NPS | per class | ASTM A790 / A928 |
| Seamless tube | by OD × wall | nominal / minimum wall | ASTM A789 |
| BW fittings | 1/2" – 36" | Sch / grade-class | ASME B16.9 / A815 |
| Flanges | 1/2" – 24" (B16.5); 26"+ (B16.47) | Class 150–2500 (per series) | ASME B16.5 / B16.47 / A182 |
| Bar | 10 – 300 mm | solution-annealed | ASTM A276 / A479 |
Dimensional coverage is standard-based; the confirmed supply range is stated with the quotation. B16.5 covers ½–24"; larger flanges use B16.47 Series A/B — a 48-inch flange is not B16.5.
Frequently Asked Questions
Are S31803 and S32205 the same?
Both are "2205", but S32205 has narrower, more consistently corrosion-resistant chemistry (higher minimum Cr/Mo/N). They are separate acceptance records; a heat certified to one is not automatically dual certified to the other without documentary evidence.
Does PREN 40 guarantee seawater resistance?
No. PREN is an empirical composition index, not a guaranteed critical pitting/crevice temperature or a seawater approval. Real performance depends on temperature, chlorination, crevices, flow and the actual environment.
Does all S32750 have PREN ≥ 42?
Not from the composition limits alone — the lower limits compute to about 37.7. A minimum PREN (or an actual mill-heat value / producer guarantee) must be separately ordered and reported.
Does duplex need post-weld heat treatment?
Duplex is usually welded with a qualified procedure and no PWHT. Ordinary carbon-steel-style stress relief is inappropriate and can damage properties; full solution treatment with rapid cooling, where required, is a distinct grade-specific process.
Product Range
The duplex and super duplex range can be supplied with related pipes, tubes, butt weld fittings, forged fittings, flanges and forgings where required by the BOQ, with plate, bar and cast items where offered.
Applications
For dimensional references, see the Pipe Schedule & Fittings Guide. For related supply, review Pipes & Tubes, Butt Weld Fittings, Forged Fittings and Flanges. For austenitic grades, see Stainless Steel.
Types of Products
| Type | Description |
|---|---|
| Pipes & Tubes | Seamless & welded A790 pipe and A789 tube |
| Fittings | A815 butt weld and A182 forged fittings |
| Flanges | A182 F-grade forged flanges |
| Plate / Bar / Forgings | A240 plate, A276/A479 bar, forgings — subject to grade and project availability |
Available Forms
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Frequently Asked Questions
Are S31803 and S32205 the same grade?
Both are called "2205", but S32205 has narrower, more consistently corrosion-resistant chemistry (higher minimum chromium, molybdenum and nitrogen) than the older S31803. They are separate acceptance records; a heat certified to one is not automatically dual certified to the other without documentary evidence.
What is the difference between 2205, 2507 and S32760?
2205 (S31803/S32205) is standard 22Cr duplex; 2507 (S32750) and S32760 are 25Cr super duplex with higher chromium, molybdenum and nitrogen for greater pitting resistance and strength. S32760 (ZERON 100) also adds copper and tungsten. Compare the exact grade and product-form requirements, not just the family name.
Does PREN 40 guarantee seawater resistance?
No. PREN is an empirical composition index (Cr + 3.3Mo + 16N), not a guaranteed critical pitting or crevice temperature and not a seawater approval. Actual performance depends on temperature, chlorination, crevices, flow, deposits and the specific environment.
Does all S32750 have PREN ≥ 42?
Not from the composition limits alone — the lower permitted limits compute to about 37.7. A minimum PREN, or an actual mill-heat value / producer guarantee, must be separately ordered and reported on the certificate.
What is the difference between F51 and F60 forgings?
In ASTM A182, F51 is the forging grade for UNS S31803 and F60 is for S32205 — the two "2205" chemistries. They must not be collapsed into one; F53 (S32750), F55 (S32760) and F61 (S32550) are the super-duplex forging grades.
Are branded ZERON 100 and generic S32760 identical purchase specifications?
Not necessarily. The brand owner's manufacturing and property requirements can be tighter than the generic UNS S32760 limits, with specific traceability. Specify whether genuine branded material or generic S32760 is required.
What does a G48 pitting-test report need to state?
The method (A/B or other), test temperature, duration, specimen preparation, whether welds are included, and the mass-loss or pitting acceptance criterion, all against the source specification. A test name without these details is not a purchase requirement.
Does ferrite testing prove the absence of harmful phases?
No. Ferrite measurement checks phase balance, not intermetallic (sigma/chi) precipitation. Intermetallic freedom is verified by grade-specific methods such as ASTM A923 or A1084, with the correct specimen, method and acceptance.
Can duplex be used in sour service or cryogenic LNG?
Only with the right qualification. Sour service must be qualified to ISO 15156-3 for the exact environment, condition and hardness. Duplex offers good toughness for utility duty, but general liquid-LNG suitability is not implied — the toughness and code acceptance must be demonstrated for the actual component and temperature.
Does duplex need post-weld heat treatment?
Usually it is welded with a qualified procedure and no PWHT. Ordinary carbon-steel-style stress relief is inappropriate and can damage duplex properties; full solution treatment with rapid cooling, where required, is a distinct grade-specific process.
Can handheld PMI verify nitrogen and complete grade compliance?
No. Ordinary handheld XRF does not measure nitrogen or carbon, so it cannot confirm complete duplex grade identity on its own. Rely on the material test certificate and the specified chemistry and mechanical tests.
What should a duplex RFQ contain?
State the UNS and any brand requirement, product form, standard and edition, dimensions, condition, service environment (chloride/H₂S/temperature), required testing (G48/CPT, ferrite, A923/A1084, impact), inspection document and destination. Availability and inspection scope are confirmed with the quotation.
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