Seamless Super Duplex Stainless Steel Tube
Super duplex and high-alloy duplex stainless steel seamless tube is used for heat exchangers, process equipment, instrumentation and other chloride-bearing service that requires high strength and resistance to localized corrosion. This category covers UNS S32550, S32750, S32760 and S32950. Tube is supplied to ASTM A789/A789M or ASME SA789 when specified. ASTM A790 is a pipe standard and should not be used as the default specification for tube.
S32550 contains copper and is selected for defined chemical environments. S32750 is the 2507 grade, also designated EN 1.4410. S32760, EN 1.4501, contains copper and tungsten. S32950 is a high-chromium duplex grade; a minimum PREN or an EN equivalent is stated only when the order and material documentation support it. Available OD, wall thickness and length depend on grade, manufacturing route and purchase specification. State the required NDT, corrosion testing, surface condition and EN 10204 certificate with the inquiry.
Choose the grade
Super duplex seamless tube — ASTM A789 / ASME SA789 (general requirements ASTM A1016 / ASME SA1016M). Requirements below are specification minima; values are per the standard edition shown on each product page.
| Grade | Type | Standard | Composition (key elements, %) | Tensile / Yield, min · Elongation | PREN | Where it fits |
|---|---|---|---|---|---|---|
| S32550 (Ferralium 255) | Copper-bearing 25Cr duplex | ASTM A789 / A790 | Cr 24.0–27.0 · Ni 4.5–6.5 · Mo 2.9–3.9 · N 0.10–0.25 · Cu 1.50–2.50 | TS ≥ 760 · YS ≥ 550 · 15% | Per heat analysis (≈38 typical) | Defined chemical environments, seawater |
| S32750 (2507, EN 1.4410) | Super duplex | ASTM A789 / A790 | Cr 24.0–26.0 · Ni 6.0–8.0 · Mo 3.0–5.0 · N 0.24–0.32 | TS ≥ 800 · YS ≥ 550 · 15% | Per heat analysis (commonly ≈40+) | Severe chloride, seawater, exchangers |
| S32760 (EN 1.4501) | Super duplex, Cu + W | ASTM A789 / A790 | Cr 24.0–26.0 · Ni 6.0–8.0 · Mo 3.0–4.0 · N 0.20–0.30 · Cu 0.50–1.00 · W 0.50–1.00 | TS ≥ 750 · YS ≥ 550 · 25% | Per heat analysis (W-bearing formula) | Offshore, desalination, scrubbers |
| S32950 (7-Mo PLUS) | High-chromium duplex | ASTM A789 / A790 | Cr 26.0–29.0 · Ni 3.5–5.2 · Mo 1.00–2.50 · N 0.15–0.35 | TS ≥ 690 · YS ≥ 480 · 20% | Per heat analysis (≈37 typical) | Economical high-chromium duplex service |
PREN = %Cr + 3.3 × %Mo + 16 × %N (the A789/A790 footnote for tungsten-bearing grades counts W as ½ Mo), calculated from the heat analysis. ASTM A790 / A789 set no blanket PREN guarantee for these grades — state any minimum PREN in the purchase specification. PREN is a screening index, not a corrosion rate or service-life prediction.
Standards and testing
Tube in this category is ordered to ASTM A789/A789M or ASME SA789, by exact outside diameter and wall thickness (state average or minimum wall) plus cut length. Tolerance basis is A789 Table 5 or the edition named in the order; pipe tolerances (A790 + A999) do not apply. Typical testing: hydrostatic, eddy-current or ultrasonic per the ordered edition, with corrosion testing such as ASTM A923 or G48 where specified. EN 10204 3.1 mill test certificate is standard; 3.2 on request.
Looking for the other form? See the Seamless Super Duplex Stainless Steel Pipe category.
Information required for quotation
- Grade and UNS designation (S32550, S32750, S32760 or S32950)
- Governing standard and edition (for example ASTM A789-24 / ASME SA789)
- Outside diameter and wall — state average or minimum wall
- Cut length: fixed, random or mill lengths
- Quantity and required delivery date
- Delivery condition: solution annealed; pickled / passivated as required
- NDT: hydrostatic, eddy-current or ultrasonic testing
- Corrosion testing (for example ASTM A923 or G48) and acceptance criteria
- Certification documents: EN 10204 3.1 as standard; 3.2 on request
- Delivery destination
Minimum order quantity and lead time are confirmed on enquiry against the ordered grade, size and quantity.
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