ASME SA789 UNS S32550 Super Duplex Stainless Steel Tube

ASME SA-789 / SA-789M covers seamless and welded duplex tubing in Section II Part A. UNS S32550 is a copper-rich super duplex (Ferralium 255-type family in trade literature) with chromium 24.0–27.0%, nickel 4.5–6.5%, molybdenum 2.9–3.9%, nitrogen 0.10–0.25%, and copper 1.50–2.50% at carbon ≤0.04%. High copper is the defining commercial feature versus 2507-type S32750.

SHH STEEL can produce and supply ASME SA789 UNS S32550 super duplex stainless steel tube in seamless and welded (no filler metal) forms, with EN 10204 3.1 MTCs reporting the copper band, the 110/80 ksi tensile pair with 15% elongation, and Table 2 heat treatment at 1900 °F [1040 °C] minimum. Dual SA-789/A789 marking is available when requested.

Compare SA789 S32520 for another Cu-bearing super duplex; SA789 S32750 for PREN ≥41 2507-type; SA789 S32760 for W-bearing; SA789 S32205 when mid-30s PREN is enough. Plate: A240 / SA240. Hub: SA789/SA789M.

Table 1 of ASME SA-789 fixes the heat analysis for S32550. 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 ≈25.5, Mo ≈3.4, N ≈0.175 gives PREN ≈ 39.5. Copper 1.50–2.50% is required and must appear on the MTC; it is outside the PREN formula but central to this grade’s selection story. Carbon maximum is 0.04%, slightly higher than the 0.030% cap on many sister rows. SA-789 has no PREN footnote for S32550.

Table 4 sets tensile and hardness requirements for S32550 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 110 ksi [760 MPa] min, yield 80 ksi [550 MPa] min, elongation 15% min, hardness max 297 HBW / 31 HRC / 295 HV. Source: ASME BPVC.II.A-2023 SA-789 Table 4.

ASME SA-789 allows S32550 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 S32550 routes and records them on stencil and EN 10204 3.1 MTC.

Order ASME SA789 S32550 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 S32550 enquiry. Write average or minimum wall on every line item so Table 5 percentage bands are unambiguous at receiving.

ASME SA-789 UNS S32550 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 S32550 solution treatment at 1900 °F [1040 °C] min followed by rapid cooling in air or water. Table 2 lists a minimum of 1900 °F [1040 °C] with rapid cooling in air or water rather than a closed upper band.

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 S32550 only heat-treated per Table 2, with the record on the MTC.

Estimated PREN near 39.5 plus intentional high copper places S32550 in super-duplex service for aggressive chlorides and some reducing media where copper helps. Confirm project qualifications rather than relying on PREN alone. Respect elevated-temperature embrittlement and sigma risks on this high-alloy duplex.

For Code PREN ≥41 seawater specs that name 2507, prefer SA789 S32750 unless the datasheet explicitly wants S32550’s copper band. Materials review should precede any attempt to stretch this grade outside its PREN and temperature envelope.

S32550 tube is specified when copper-rich super duplex chemistry is written for process and seawater-leaning exchangers. Match fluid chemistry and temperature to the PREN estimate and Table 4 floors before freezing the bill of materials.

If PREN ≥41 without high Cu is required, use SA789 S32750. If W is required, use SA789 S32760. Match fluid chemistry and temperature to the PREN estimate and Table 4 floors before freezing the bill of materials.

Fabrication welds use matching super-duplex fillers under a qualified WPS; the mill welded product stays autogenous. High Cu, Mo, and Cr raise intermetallic risk — control heat input and cool the HAZ promptly on S32550 joints.

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 S32550 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 S32550. 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.

S32550 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 S32550 as manufactured copper-rich super-duplex Code Book tube, reporting Cu 1.50–2.50% and meeting 110/80 ksi floors on the EN 10204 3.1 MTC.

If the datasheet wants 2507 PREN ≥41 without high copper, 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 S32550 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 S32550, 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 S32550 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.