ASME SA789 UNS S32506 Duplex Stainless Steel Tube

ASME SA-789 / SA-789M places seamless and welded duplex stainless tubing for general service in Section II Part A. UNS S32506 is a tungsten-bearing 25Cr duplex with chromium 24.0–26.0%, nickel 5.5–7.2%, molybdenum 3.0–3.5%, nitrogen 0.08–0.20%, and tungsten 0.05–0.30% at carbon ≤0.030%. This series titles it Duplex (not Super Duplex) per the QUEUE family word.

SHH STEEL can produce and supply ASME SA789 UNS S32506 duplex stainless steel tube in seamless and welded (no filler metal) forms, in typical heat-exchanger OD × wall sizes, with EN 10204 3.1 certificates covering ladle chemistry including tungsten, the 90/65 ksi tensile pair with 18% elongation minimum, and Table 2 heat treatment. Dual SA-789/A789 marking is available when the PO asks for both names; this page stays ASME-first.

Compare SA789 S31260 for another W-bearing 25Cr duplex with higher tensile; SA789 S32205 for mainstream 22Cr; SA789 S32750 / SA789 S32760 for PREN ≥40 super duplex. Plate: A240 / SA240. Hub: SA789/SA789M.

Table 1 of ASME SA-789 fixes the heat analysis for S32506. 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 ≈25, Mo ≈3.25, N ≈0.14 gives PREN ≈ 38.0 from %Cr + 3.3×%Mo + 16×%N. Tungsten may be credited partially in some mill PREN practices, but SA-789 does not define a W term for this grade — treat any W-adjusted figure as a trade estimate only. Sulfur is tight at 0.015% max.

Table 4 sets tensile and hardness requirements for S32506 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 90 ksi [620 MPa] min, yield 65 ksi [450 MPa] min, elongation 18% min — lower than the 25% common on many sister duplex rows — and hardness max 302 HBW / 32 HRC / 300 HV. Source: ASME BPVC.II.A-2023 SA-789 Table 4. Design allowables remain in Section II Part D.

ASME SA-789 allows S32506 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 S32506 routes and records them on stencil and EN 10204 3.1 MTC.

Order ASME SA789 S32506 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 S32506 enquiry.

ASME SA-789 UNS S32506 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.

Spell the UNS number and ASME SA789 on the purchase order rather than relying on a shop nickname alone.

Table 2 requires S32506 solution treatment at 1870–2050 °F [1020–1120 °C] followed by rapid cooling in air or water. The top of the band (2050 °F / 1120 °C) sits above S32205’s 2010 °F maximum.

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 S32506 only heat-treated per Table 2, with the record on the MTC.

Estimated PREN near 38.0 places S32506 in the upper standard-duplex window from Cr+Mo+N, helped by ~3% Mo and tungsten. It lacks the PREN ≥40/41 footnotes written for S32760/S32750. For seawater PREN ≥40 duty use SA789 S32750 or SA789 S32760.

Observe SA-789’s elevated-temperature embrittlement warning and the 475 °C ferrite-embrittlement mechanism known in duplex practice. Keep continuous-service temperature inside engineering limits.

S32506 is specified when a 25Cr duplex with intentional tungsten is written into the datasheet for process exchangers and corrosive general service. Select by UNS, not by informal 25Cr duplex language alone.

If Cu+W and higher tensile are needed, compare SA789 S31260; if PREN ≥40, compare SA789 S32760.

Fabrication welds use matching duplex fillers under a qualified WPS; the mill welded SA-789 product stays autogenous with no filler in the seam. Molybdenum and tungsten increase sigma risk if the HAZ cools slowly, so heat input and interpass temperature need careful control on S32506 tube-to-tubesheet work.

SHH STEEL can discuss filler families used with this grade; the Code-stamped fabricator owns the WPS/PQR under the applicable vessel or piping Code.

Standard delivery for SA789 S32506 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 S32506.

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.

S32506 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.

SHH STEEL produces and supplies ASME SA789 UNS S32506 as manufactured tungsten-bearing duplex Code Book tube, reporting W on the heat analysis and meeting the 18% elongation minimum on the EN 10204 3.1 MTC. We do not omit tungsten or substitute a non-W 25Cr heat against this UNS.

If PREN ≥40 is required, we quote SA789 S32750 or SA789 S32760. Dual SA-789/A789 marking is available on request.

SHH STEEL can produce and supply ASME SA789 UNS S32506 against the edition, route, and finish on your enquiry. Capability and Stock / Available sizes follow.

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 S32506, seamless or welded, OD × wall, wall basis, length, and quantity on the enquiry.

ASME SA789 UNS S32506 is supplied by SHH STEEL as seamless and welded (no filler metal) 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.