ASME SA789 UNS S32950 Super Duplex Stainless Steel Tube

ASME SA-789 / SA-789M lists UNS S32950 as a high-chromium super duplex tubing grade with chromium 26.0–29.0%, nickel 3.5–5.2%, molybdenum 1.00–2.50%, nitrogen 0.15–0.35%, carbon ≤0.030%. Lower nickel than 2507 and an air-cool heat-treatment row distinguish it among Super Duplex titles on this series.

SHH STEEL can produce and supply ASME SA789 UNS S32950 super duplex stainless steel tube in seamless and welded (no filler metal) forms, with EN 10204 3.1 MTCs reporting chemistry, the 100/70 ksi tensile pair with 20% elongation, and Table 2 heat treatment at 1820–1880 °F with air cool. Dual marking is available when requested.

Compare SA789 S32906 for higher Cr/N and wall-dependent tensile; SA789 S32750 for Mo-rich PREN ≥41; SA789 S32205 for standard duplex. Plate: A240 / SA240. Hub: SA789/SA789M. Keep the ASME designation on Code purchase orders even when dual ASTM marking is also requested for documentation convenience.

Table 1 of ASME SA-789 fixes the heat analysis for S32950. Product analysis applies when Section 8 or the purchase order invokes it through A1016/A1016M, using A480/A480M tolerances. SHH STEEL reports actual ladle values on the EN 10204 3.1 MTC for every heat.

Mid-range PREN with Cr ≈27.5, Mo ≈1.75, N ≈0.25 gives PREN ≈ 37.3. SA-789 has no PREN footnote for S32950. Nickel 3.5–5.2% is lower than on S32750/S32760.

Table 4 sets tensile and hardness requirements for S32950 after final heat treatment. Lot sampling follows Section 9. Mechanical properties do not apply below 1/8 in. [3.2 mm] OD or 0.015 in. [0.4 mm] wall.

Table 4 requires tensile 100 ksi [690 MPa] min, yield 70 ksi [480 MPa] min, elongation 20% min, hardness max 290 HBW / 30 HRC / 290 HV. Source: ASME BPVC.II.A-2023 SA-789 Table 4.

ASME SA-789 allows S32950 as seamless tube or as welded tube made with no filler metal. After welding, the finished tube is heat-treated under Table 2, and marking must state the manufacture route with average or minimum wall so receiving can match each length to the purchase order and MTC.

Seamless lots take flaring to at least 10% ID expansion on one end of one tube per lot. Welded lots take flange testing plus reverse flattening on each 1500 ft [450 m] of finished tubing. Tension and hardness apply to both routes. SHH STEEL produces both SA789 S32950 routes and records them on stencil and EN 10204 3.1 MTC.

Order ASME SA789 S32950 by OD × wall (average unless minimum is specified) and length in tube / BWG language, not B36.19 pipe schedules first. Table 5 sets OD-group tolerances; clause 12.2 covers thin-wall ovality.

Source: ASME BPVC.II.A-2023 SA-789 Table 5. SHH STEEL quotes average-versus-minimum wall explicitly on every S32950 enquiry. Write average or minimum wall on every line item so Table 5 percentage bands are unambiguous at receiving.

ASME SA-789 UNS S32950 is the governing tubing designation for this article. Approximate wrought names are chemistry-family hints, not automatic Code substitutes on an SA-789 mill test certificate. Confirm the product standard and tensile row before accepting a commercial nickname on the certificate.

Spell the UNS number and ASME SA789 on the purchase order rather than relying on a shop nickname alone. Confirm the product standard and tensile row before accepting a commercial nickname on the certificate.

Table 2 requires S32950 solution treatment at 1820–1880 °F [990–1025 °C] followed by air cool. Air cool after the 1820–1880 °F soak is the Table 2 requirement — distinctive among SA-789 duplex grades.

Seamless tubes may be quenched after hot forming when temperature is not below the minimum solution-treatment temperature. Skipping or under-cooling risks intermetallics and undermines corrosion performance. SHH STEEL delivers SA789 S32950 only heat-treated per Table 2, with the record on the MTC.

Estimated PREN near 37.3 places S32950 in the lower super-duplex / upper high-alloy duplex window — confirm whether the project truly needs PREN ≥40 class like SA789 S32750. High chromium helps; moderate Mo limits the ceiling.

Table 2’s air cool is unusual versus rapid water options on many sisters — follow the Table 2 row exactly. Observe embrittlement warnings. Materials review should precede any attempt to stretch this grade outside its PREN and temperature envelope.

S32950 tube is specified when this high-Cr, lower-Ni super duplex UNS is written for chloride exchangers and process lines. Match fluid chemistry and temperature to the PREN estimate and Table 4 floors before freezing the bill of materials.

If PREN ≥41 is mandatory, prefer SA789 S32750. If higher Cr/N with wall-split tensile is written, compare SA789 S32906. Match fluid chemistry and temperature to the PREN estimate and Table 4 floors before freezing the bill of materials.

Welding needs qualified duplex/super-duplex procedures with controlled heat input. Mill welded SA-789 product stays autogenous. Follow the air-cool heat-treatment identity of the base metal when planning PWHT discussions with the fabricator’s engineer.

SHH STEEL can discuss filler families; the fabricator owns WPS/PQR. Procedure qualification on the actual UNS avoids ferrite and sigma surprises in the heat-affected zone.

Standard delivery for SA789 S32950 is heat-treated and descaled/pickled per Section 13, free of excessive mill scale. Bright anneal or Ra-controlled finishes are agreement items that must appear on the order.

SHH STEEL quotes special finishes against the written enquiry rather than assuming them with the grade stamp for S32950. Call any Ra or bright requirement out on the enquiry so mill routing can include it before the heat is reserved.

Testing covers Table 1 chemistry, Table 4 tension and hardness, flare or flange tests by route, reverse flattening for welded tube, and hydro or NDE on each length using duplex hydrostatic factor 64000 (441.2). Manufacturer chooses hydro versus NDE unless the PO locks the method.

Marking shows seamless or welded and wall basis. SHH STEEL 3.1 MTCs tie heat, chemistry, mechanicals, heat treatment, and test method to each length for receiving clearance. Receiving teams should verify hydro-versus-NDE against the purchase order before releasing tube to fabrication.

S32950 tube ships from SHH STEEL in tagged bundles with end protection matched to length. Tags repeat ASME SA789, grade, route, OD × wall, heat number, and PO reference for export or domestic delivery.

Wrapped bundles or wooden cases are available for bright or small-bore material. Incoterms and MTC flow follow the order acknowledgment. Keep bundle tags legible after ocean transit so port and site receiving can proceed without remarking every length.

SHH STEEL produces and supplies ASME SA789 UNS S32950 as manufactured high-chromium super-duplex Code Book tube, heat-treated in the 1820–1880 °F air-cool band and certified on EN 10204 3.1 MTCs.

If PREN ≥41 2507 is intended, we quote SA789 S32750. Dual marking is available on request. Honest sister-grade advice protects Code stamp integrity when a different UNS would fit the corrosion envelope better.

SHH STEEL can produce and supply ASME SA789 UNS S32950 against the edition, route, and finish on your enquiry. Capability and Stock / Available sizes follow. Clear enquiry data on OD, wall, and route shortens quotation turnaround for export and domestic Code jobs.

Stock / Available sizes — Regular enquiry bands include OD about 12.7–50.8 mm with common BWG / metric walls; larger Table 5 groups by agreement. Cut lengths on request. Send OD × wall, route, and quantity — no invented tonnage lists.

List ASME SA789 UNS S32950, seamless or welded, OD × wall, wall basis, length, and quantity on the enquiry. Clear enquiry data on OD, wall, and route shortens quotation turnaround for export and domestic Code jobs.

ASME SA789 UNS S32950 is supplied by SHH STEEL as seamless and welded (no filler metal) super duplex tubing under the Section II Part A Code Book product standard, heat-treated per Table 2, tested per Section 9, and certified on EN 10204 3.1 MTCs. Confirm OD × wall, wall basis, manufacture route, and any dual SA-789/A789 marking on the purchase order so stencil and certificate match the datasheet. For technical follow-up, contact admin@steelspecs.com.