INOX STEEL INDIA is one of India’s most trusted suppliers of Duplex (S31803/S32205) and Super Duplex (S32750/S32760) Welded Tubes, engineered for environments where chlorides, pressure, temperature and corrosive chemicals can destroy standard stainless steel.
Designed for offshore structures, desalination plants, refineries, chemical reactors, seawater systems and high-pressure heat exchangers, our Duplex & Super Duplex welded tubes offer superior strength, outstanding chloride resistance and long-term stability.
All tubes are manufactured, welded, solution annealed, pickled, tested and certified as per ASTM A789 / ASTM A790.
Duplex stainless steels are 50% ferrite + 50% austenite, giving them:
Super Duplex grades (S32750 / S32760) offer even higher chromium, molybdenum and nitrogen levels — delivering PREN > 40–45, ideal for the most severe corrosive conditions.
These welded tubes undergo TIG / Plasma / Laser welding, bead control, full solution annealing, pickling & passivation, 100% PMI and NDT (EC/UT/PT/RT) to ensure corrosion stability and weld soundness.
Best for:
Benefits:
Best for:
Benefits:
| Parameter | Duplex 2205 | Super Duplex 2507 |
| PREN | 35–38 | >40–45 |
| Strength | High | Very High |
| SCC Resistance | High | Excellent |
| Seawater Corrosion | Good | Excellent |
| Cost | Moderate | Higher |
| OD (mm) | WT (mm) | Applications |
| 6 – 12.7 | 1.0 – 1.6 | Instrumentation |
| 12.7 – 25.4 | 1.0 – 2.0 | Chemical injection |
| 25.4 – 50.8 | 1.5 – 4.0 | Heat exchangers |
| 50.8 – 114 | 2.0 – 6.0 | Process piping |
| 114 – 254 | 2.0 – 12.7 | Offshore & desalination |
| Grade | INR/Kg | USD/Kg |
| Duplex S31803 / S32205 | ₹650 – ₹1,100 | $8 – $14 |
| Super Duplex S32750 | ₹1,100 – ₹1,850 | $14 – $23 |
| Super Duplex S32760 | ₹1,250 – ₹2,200 | $15 – $27 |
| Finish | Applications |
| Pickled & Passivated | Process piping |
| Bright Annealed | Heat exchangers |
| Polished | Marine / architectural |
| Cleaned & Degreased | Offshore / subsea |
Pitting Resistance Equivalent Number: Higher PREN = better seawater resistance. Duplex → ER2209 Super Duplex → ER2594 / ER2553 Yes — solution annealing is mandatory to maintain phase balance. ASTM A789 / A790 for duplex & super duplex tubes. Yes — fully certified with PMI, NDT & solution annealing charts. What is the difference between Duplex 2205 and Super Duplex 2507?
What is PREN value in duplex?
What filler wire is used for duplex & super duplex welding?
Do welded duplex tubes require heat treatment?
Which ASTM standard applies?
Do you supply Super Duplex 2507 according to ASTM A790 S32750?