Super Duplex Pipes & Tubes
Giriraj Impex stocks, supplies and exports super duplex pipes and tubes in UNS S32750 (2507) and UNS S32760 to ASTM A790 for pipe, ASTM A789 for tubing and ASTM A928 for electric fusion welded pipe. We supply super duplex pipes and tubes from approved mills, seamless and welded, solution annealed and pickled, with mill test certificates showing composition, PREN and mechanical properties.
Super duplex pipe is specified for seawater and other high-chloride service where even duplex 2205 is not enough: seawater injection and firewater systems, cooling water, desalination high-pressure lines, offshore process piping and subsea equipment.
Specifications
| Item | Details |
|---|---|
| Standards | ASTM A790 / ASME SA790 (pipe); ASTM A789 / ASME SA789 (tubing); ASTM A928 (EFW pipe) |
| Grades | UNS S32750 (2507), UNS S32760 |
| Pipe dimensions | ASME B36.19M and B36.10M; schedules 10S, 40S, 80S and heavier |
| Tube dimensions | OD and wall in mm, inches or BWG |
| PREN | Minimum 40 is commonly specified (and required for S32760) |
| Condition | Solution annealed and rapidly cooled; pickled and passivated |
| Optional tests | Ferrite count, impact test, ASTM A923, ASTM G48 at specified temperature |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Composition
Super duplex grades raise chromium to 24–26%, nickel to 6–8% and nitrogen to 0.20–0.32%, with molybdenum, giving a PREN of 40 or more. S32760 also contains copper and tungsten.
| UNS | Grade | C | Mn | P | S | Si | Cr | Ni | Mo | N | Other elements |
|---|---|---|---|---|---|---|---|---|---|---|---|
| S31803 | 2205 | 0.030 | 2.00 | 0.030 | 0.020 | 1.00 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | 0.08–0.20 | – |
| S32205 | 2205 | 0.030 | 2.00 | 0.030 | 0.020 | 1.00 | 22.0–23.0 | 4.5–6.5 | 3.0–3.5 | 0.14–0.20 | – |
| S32750 | 2507 | 0.030 | 1.20 | 0.035 | 0.020 | 0.80 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 | Cu 0.50 |
| S32760 | Zeron 100 type | 0.030 | 1.00 | 0.030 | 0.010 | 1.00 | 24.0–26.0 | 6.0–8.0 | 3.0–4.0 | 0.20–0.30 | Cu 0.50–1.00, W 0.50–1.00 |
S32760 also requires a minimum PREN of 40. Footnotes as given in the standards.
Mechanical properties
| UNS | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) | Elongation in 50 mm, % |
|---|---|---|---|
| S31803 | 620 (90) | 450 (65) | 25 |
| S32205 | 655 (95) | 485 (70) | 25 |
| S32750 | 800 (116) | 550 (80) | 15 |
| S32760 | 750 (109) | 550 (80) | 25 |
Hardness limits as given in the standard.
With a minimum yield of 550 MPa, super duplex pipe can be designed with considerably thinner walls than austenitic stainless pipe for the same pressure, which saves weight offshore.
S32750 or S32760?
Both are super duplex grades with similar strength and pitting resistance, and both are widely used for seawater systems. S32750 (2507) is the more common general designation. S32760 adds copper and tungsten and carries a specified minimum PREN of 40; it is known under the trade name Zeron 100 and is specified by name in some oil and gas projects. Where a project names one of them, the other is not normally accepted as a substitute without approval, so the UNS number should be stated on every order.
Quality checks
Super duplex is more sensitive than 2205 to the formation of brittle intermetallic phases during processing, so mills control solution annealing and quenching closely and buyers commonly specify ASTM A923 testing, Charpy impact tests at low temperature, ferrite measurement and ASTM G48 pitting tests at an agreed temperature. The PREN is calculated from the actual composition on the mill test certificate. Pipes can be supplied to NACE MR0175 / ISO 15156 on request, and third-party inspection is available. We verify each consignment against the certificate and the order before dispatch.
Fabrication and ordering
Welding super duplex needs well-controlled heat input and interpass temperature, over-alloyed filler metal and nitrogen-bearing shielding or backing gas where specified, with procedures qualified by ferrite, impact and corrosion tests. Hot bending requires re-annealing. Please give the standard and UNS grade, size and schedule or OD and wall, length, seamless or welded, quantity, minimum PREN and the supplementary tests and inspection required.
Seawater systems in super duplex
Seawater systems are among the most corrosive services in an oil and gas or power plant: warm, oxygenated, chlorinated seawater attacks crevices at flanges and under deposits, and austenitic stainless steels are not normally used. Super duplex is widely specified for these systems because, with a PREN of 40 or more, it resists pitting and crevice corrosion up to temperatures set by the project materials specification, while its strength keeps the piping light. Design limits on seawater temperature and chlorination levels are part of that specification and should be followed in operation.
Applications and related products
Super duplex pipes and tubes are used for offshore seawater, firewater and produced-water systems, water injection, subsea flowlines and umbilical tubing, desalination high-pressure piping, seawater-cooled heat exchangers and chemical service with high chloride content. They are installed with super duplex pipe fittings, super duplex flanges and super duplex fasteners. We also supply super duplex sheets and plates and super duplex round bars. Grade guidance is on the duplex and super duplex steel page, and other seamless materials on the seamless pipes and tubes page.
Frequently Asked Questions
Super duplex pipe is made from duplex stainless steels with higher chromium, molybdenum and nitrogen, such as UNS S32750 and S32760. They have a PREN of 40 or more and are used for seawater and high-chloride service.
ASTM A790 covers seamless and welded super duplex pipe, ASTM A789 covers tubing, and ASTM A928 covers electric fusion welded pipe.
2507 is UNS S32750. Zeron 100 is a trade name for UNS S32760, which adds copper and tungsten and has a specified minimum PREN of 40. Both are super duplex grades for seawater service.
Under ASTM A790, both S32750 and S32760 pipe have a minimum yield strength of 550 MPa (80 ksi), much higher than austenitic stainless steels.
ASTM A923 for intermetallic phases, Charpy impact tests, ferrite measurement and ASTM G48 pitting tests at a set temperature are commonly specified, especially for oil and gas projects.
Yes. Super duplex pipes and tubes can be supplied to NACE MR0175 / ISO 15156 on request, with the hardness and testing the standard requires.
Request a Quote for Super Duplex Pipes & Tubes
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Zeron® 100 is a trademark of Rolled Alloys.