Offshore, chemical, and desalination piping demand the best. Duplex and Super Duplex buttweld fittings combine the strength of ferritic and corrosion resistance of austenitic stainless — in stock from Mumbai.
Duplex stainless steels have a two-phase microstructure (austenite + ferrite) giving approximately twice the yield strength of standard austenitic grades. Ideal for offshore, chemical processing, and seawater applications.
The most widely used duplex grade globally. 22% Cr, 5% Ni, 3% Mo composition delivers excellent corrosion resistance against chloride pitting and stress corrosion cracking. Twice the strength of SS 316L at comparable corrosion resistance.
25% Cr, 7% Ni, 4% Mo — the premium super duplex grade. PREN >42 ensures outstanding resistance to pitting and crevice corrosion in the most aggressive chloride environments. Specified for deepwater offshore, FPSOs, and subsea applications.
Zeron 100 — tungsten-bearing super duplex with additional copper addition. Very similar to S32750 in performance but with copper improving resistance to sulfuric and hydrochloric acids. Common in North Sea offshore specifications.
Low-Mo lean duplex grade. More economical than 2205 with good strength and corrosion resistance for moderate chloride environments. Used in storage tanks, water treatment, and structural applications where 2205 is over-specified.
| Property | Duplex S31803 / 2205 | SS 316L |
|---|---|---|
| Microstructure | Austenite + Ferrite (50/50) | Fully Austenitic |
| Yield Strength | ~450 MPa (2× higher) | ~220 MPa |
| PREN (Pitting Resistance) | >35 | ~24 |
| Stress Corrosion Cracking | Much better resistance | Susceptible in Cl⁻ |
| Thermal Conductivity | Higher — better heat transfer | Lower |
| Wall Thickness Required | Thinner — weight saving | Thicker |
| Max Service Temp | 300°C (limited by embrittlement) | 870°C |
| Cost vs SS 316L | Higher material cost | Lower |
| Best Application | Offshore, seawater, chemical | General corrosive service |
| Grade | ASTM / ASME | UNS | Cr % | Ni % | Mo % | PREN | Min Yield |
|---|---|---|---|---|---|---|---|
| S31803 / 2205 | A815 WP-S31803 | S31803 | 21–23 | 4.5–6.5 | 2.5–3.5 | >35 | 450 MPa |
| S32205 | A815 WP-S32205 | S32205 | 22–23 | 4.5–6.5 | 3.0–3.5 | >35 | 450 MPa |
| S32750 / 2507 | A815 WP-S32750 | S32750 | 24–26 | 6.0–8.0 | 3.0–5.0 | >42 | 550 MPa |
| S32760 | A815 WP-S32760 | S32760 | 24–26 | 6.0–8.0 | 3.0–4.0 | >40 | 550 MPa |
| S32304 | A815 WP-S32304 | S32304 | 21.5–24.5 | 3.0–5.5 | 0.05–0.6 | >24 | 400 MPa |
| Parameter | Range Available | Notes |
|---|---|---|
| Pipe Size (NPS) | ½" to 24" NB | Larger sizes on request |
| Wall Schedule | Sch 10S, 40S, 80S, 160 | Per ASME B16.9 |
| Fitting Standard | ASME B16.9, MSS SP-43 | EN 10253-4 also available |
| Material Certificate | EN 10204 3.1 MTC | Ferrite content test included |
| Additional Testing | NACE MR0175, HIC, SSCC | On request |
| Impact Test | Charpy at -46°C | Standard for duplex grades |
Every duplex fitting comes with ferrite content test results (20–65% ferrite range). Critical for ensuring the duplex microstructure is correct — wrong ferrite content means loss of the key properties.
All duplex supply can be certified to NACE MR0175 / ISO 15156 for sour service (H₂S-containing) applications in oil and gas. Specify at time of inquiry.
Standard duplex supply includes Charpy V-notch impact testing at -46°C, meeting the requirements of offshore codes (NORSOK, Shell DEP).
We are experienced in supplying to NORSOK, Shell DEP, and ADNOC specifications. Full documentation package including ferrite, NACE, impact, and PMI available.
Duplex and super duplex look identical to stainless steel. PMI (XRF analysis) on every fitting prevents grade mix-up — a critical safety requirement for offshore and chemical projects.
We have supplied duplex fittings to projects in the Middle East, Southeast Asia, and Europe. We understand the documentation requirements and quality expectations.
Send grade (S31803 / S32750), type, size, schedule, quantity, and project standard. We respond within 4 hours.