Seamless Super Duplex Stainless Steel Pipe

Super duplex and high-alloy duplex stainless steel seamless pipe is selected for chloride-bearing and other corrosive piping service where 300-series stainless steel or 22Cr duplex may not provide sufficient resistance. This category covers UNS S32550, S32750, S32760 and S32950. Pipe is supplied to ASTM A790/A790M or ASME SA790 when specified; EN 10216-5 applies only when it is named in the purchase order and supported by the supplied grade and product form.

Grade selection must be based on the service environment and the purchase specification. S32550 is a copper-bearing 25Cr grade. S32750 is the widely used 2507 grade, also designated EN 1.4410. S32760, EN 1.4501, adds copper and tungsten. S32950 is a high-chromium duplex grade whose corrosion performance must be stated from the actual heat analysis rather than a blanket PREN claim. Available dimensions depend on grade, standard and order. Send the UNS grade, standard edition, OD or NPS, wall thickness or schedule, length, quantity, finish, NDT, certificate and delivery destination for confirmation.

Choose the grade

Super duplex seamless pipe — ASTM A790 / ASME SA790 (general requirements ASTM A999 / ASME SA999). 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 A790 / A789	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 A790 / A789	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, offshore
S32760 (EN 1.4501)	Super duplex, Cu + W	ASTM A790 / A789	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 A790 / A789	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

Pipe in this category is ordered to ASTM A790/A790M or ASME SA790, with the general requirements of ASTM A999 / ASME SA999. Typical order testing: hydrostatic, eddy-current or ultrasonic examination per the named edition, plus corrosion testing where specified. Dimensions and tolerances follow the pipe standards above — tube tolerance tables do not apply. EN 10204 3.1 mill test certificate is standard; 3.2 or third-party witnessing on request.

Looking for the other form? See the Seamless Super Duplex Stainless Steel Tube category.