ASTM A789 UNS S32750 Super Duplex Stainless Steel Tube

ASTM A789 / A789M covers seamless and welded ferritic/austenitic stainless steel tubing for general corrosion service with particular emphasis on stress corrosion cracking resistance. UNS S32750 — the 2507-class workhorse super duplex — has heat limits of carbon ≤0.030%, chromium 24.0–26.0%, nickel 6.0–8.0%, molybdenum 3.0–5.0%, nitrogen 0.24–0.32%, and copper 0.50% max in A789/A789M-24 Table 1. Footnote C of that table requires PREN = %Cr + 3.3×%Mo + 16×%N ≥ 41 for this grade, which is the contractual corrosion floor many seawater and chloride specs rely on.

SHH STEEL can produce and supply ASTM A789 UNS S32750 super duplex stainless steel tube as seamless and welded product (welded without filler metal) in the usual heat-exchanger and process OD × wall / BWG band, with EN 10204 3.1 mill test certificates that report ladle chemistry (including a PREN check when requested) and tensile plus hardness. Dual A789/SA789 marking only when both standards are named on the order. Hub: A789/A789M.

2507, 1.4410, and S32750 super duplex are common shop names. Compare with W-bearing A789 S32760, hyper duplex A789 S32707 / A789 S33207, and standard duplex A789 S32205. Plate: A240.

Heat analysis must meet A789/A789M-24 Table 1. Product analysis follows A480/A480M annex tolerances when ordered.

A789 footnote C mandates PREN ≥41 using Cr + 3.3Mo + 16N — verify on every heat certificate. Mid-range chemistry (Cr 25, Mo 4.0, N 0.28) screens about PREN ≈ 43. Cu is a maximum only. Supplier web tables sometimes disagree on hardness (300 vs 310 HBW); this pack uses 300 HBW / 32 HRC from the inmoteh older Table 4 reprint.

Tensile and hardness floors come from older A789 Table 4 reprints; the public A789/A789M-24 sample did not include that table. Reconfirm on the PO edition.

15% elongation in older copies — plan U-bends accordingly. Soft disagree: some supplier pages list 310 HBW for S32750; we cite 300 HBW from the more complete Table 4 reprint and note the conflict.

A789 Section 5 allows seamless or welded manufacture with no filler metal added. Seamless S32750 tube is typically hot-finished then cold-drawn to final OD and wall; welded tube is roll-formed from matching strip and autogenously welded, then usually cold-worked and re-annealed so the seam meets parent-metal heat treatment and mechanical floors.

Seamless lots take a flaring test (minimum 10% inside-diameter expansion); welded lots take a flange test plus a reverse flattening test on a specimen from each 1500 ft [450 m] of finished tubing. Tension and hardness sampling apply to both routes. SHH STEEL produces and supplies both seamless and welded A789 S32750 against the route named on the enquiry, with EN 10204 3.1 coverage of chemistry and mechanicals.

Average wall is the default under A789; specify minimum wall on the order when that is the design basis. Outside diameter and wall are ordered as tube sizes (metric or inch OD × wall / BWG). General dimensional requirements sit in Specification A1016/A1016M unless A789 states otherwise.

When converting a pipe schedule into tube wall, state clearly whether acceptance is average or minimum wall — the two are not interchangeable on the mill ticket. SHH STEEL confirms OD × wall, length, and finish before the heat is reserved.

UNS S32750 maps to EN 1.4410 (X2CrNiMoN25-7-4) and the 2507 trade family.

Dual A789/SA789 on request. Hub: A789/A789M.

A789/A789M-24 Table 2 lists UNS S32750 at 1880–2060 °F [1025–1125 °C] with rapid cooling in water or by other means unless Table 2 states otherwise. Seamless tube may be quenched directly after hot forming while at or above the minimum solution temperature where that alternate is allowed.

Rapid cooling limits time in the sigma-forming window (roughly 700–1000 °C), which is especially important for highly alloyed duplex and super duplex. A789’s scope warns that these steels are susceptible to embrittlement if used for prolonged periods at elevated temperatures, including 475 °C (885 °F) ferrite embrittlement. SHH STEEL supplies S32750 solution-annealed and quenched per Table 2.

S32750 is the default super duplex for seawater-influenced and high-chloride duties that require PREN ≥41 and duplex SCC resistance with roughly double austenitic yield strength. Footnote C makes PREN a contractual chemistry requirement, not just a brochure claim.

Choose A789 S32760 when W-bearing chemistry is specified; choose hyper duplex A789 S32707 when PREN must sit well above the 41 floor. Do not substitute A789 S32205 into an S32750 seawater crevice line.

Seawater coolers and heat exchangers, offshore process tube, desalination reject and brine systems, and chemical-process chlorides where 2507 / S32750 is frozen. Higher strength supports thinner walls versus 2205 and 316L.

SHH STEEL produces and supplies A789 S32750 for enquiry sizes and test extras including PREN reporting on the MTC when requested.

Autogenous A789 welded tube must meet parent anneal and mechanicals without filler. Fabrication welds that use filler typically take matching or overalloyed duplex/super duplex consumables with controlled heat input and interpass temperature so ferrite–austenite balance stays qualified. Re-anneal after heavy hot work when required; keep bake and stress-relief cycles out of the sigma nose and the 400–500 °C embrittlement band unless a qualified procedure says otherwise.

Standard delivery is solution-annealed and pickled (or otherwise descaled) so the passive film can form uniformly. Bright-annealed or lightly polished OD/ID finishes are available by agreement when the exchanger or hygienic duty needs a smoother bore. Passivation after pickling or after fabrication welding is good practice in chloride service; remove carbon-steel tooling contamination before commissioning. SHH STEEL states the finish route on the quotation and on the MTC.

Each A789 tube takes either a nondestructive electric test or a hydrostatic test. Mechanical sampling covers tension, hardness, and flaring for seamless or flange plus reverse flattening for welded, with full heat analysis on the mill test certificate. Product analysis and supplementary corrosion or ferrite tests are added when the purchase order asks for them. SHH STEEL issues EN 10204 3.1 as standard and arranges third-party inspection / 3.2 when the enquiry names an agency, with lot identity per A789 Notes 1 and 2.

Tube is typically packed in hexagonal bundles or plywood cases with end protectors and waterproof wrapping for ocean freight, with bundle tags repeating heat number, size, and standard. Cut-to-length exchanger tube may be boxed by length group; U-bends travel in purpose-built crates when ordered. SHH STEEL ships FOB, CFR, CIF, or EXW under the Incoterm on the order, with commercial invoice, packing list, and the EN 10204 3.1 or 3.2 certificate set.

SHH STEEL produces and supplies ASTM A789 UNS S32750 super duplex tube — coordinating PREN≥41 chemistry, tube making, solution anneal, testing, and EN 10204 3.1 documents to the PO. Production capability, not trader-only “2507” of uncertain UNS.

We call out the 15% elongation floor, the PREN footnote, and the hardness-table disagreement across public copies so buyers specify acceptance clearly.

SHH STEEL can produce and supply ASTM A789 UNS S32750 against the edition, size, and finish route named on your enquiry. The capability table below summarizes what we regularly quote, followed by the Stock / Available sizes map.

Stock / Available sizes

SHH STEEL quotes S32750 tube against a practical production-and-stock enquiry range rather than a frozen warehouse SKU list with published tonnages. Availability of any single line on a given week depends on mill drawing and inbound schedule — treat the table as a supply map for enquiry.

When you send an enquiry, include the ASTM edition if known, seamless or welded, OD × wall (avg or min), length, finish, test extras, and destination port. Sister grades such as A789 S32760, A789 S32205, and A789 S32707 can be quoted on the same enquiry when the project mixes duplex classes.

ASTM A789 UNS S32750 is covered on this page as super duplex stainless steel tube under the A789 seamless-and-welded duplex tubing specification. SHH STEEL produces and supplies seamless and welded S32750 to the A789 anneal and test regime with EN 10204 3.1 documentation. For sizes, dual marking, or grade comparisons, contact admin@steelspecs.com.