ASTM A789 UNS S32304 Lean 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 S32304 — often called 2304 — is a lean duplex with heat limits of carbon ≤0.030%, chromium 21.5–24.5%, nickel 3.0–5.5%, molybdenum 0.05–0.60%, nitrogen 0.05–0.20%, and copper 0.05–0.60% in A789/A789M-24 Table 1. Low Mo and moderate Ni keep alloy cost below 2205 while duplex strength and SCC resistance stay well above 304/316, which is why water, pulp, and light process buyers specify 2304 by name.

SHH STEEL can produce and supply ASTM A789 UNS S32304 lean duplex stainless steel tube as seamless and welded product (no filler metal on welded) in typical OD × wall / BWG sizes, with EN 10204 3.1 mill test certificates. Dual A789/SA789 marking only when both names are on the order. Hub: A789/A789M.

2304, 1.4362, and S32304 lean duplex are common shop names. Compare with A789 S32101 and Mo-bearing lean A789 S32003, and with A789 S32205 when 3% Mo is required. Plate: A240.

Heat analysis must meet A789/A789M-24 Table 1.

Mid-range PREN = Cr + 3.3Mo + 16N at Cr 23, Mo 0.30, N 0.12 is about PREN ≈ 26 — lean band. Molybdenum is low (0.05–0.60%); copper is part of the lean design. Older Table 4 copies also split mechanical floors by OD (see Mechanical Properties), so size and chemistry both matter on this grade.

Older A789 Table 4 copies split S32304 by outside diameter. Not in the public -24 sample — reconfirm on the PO edition.

Small-OD tube carries higher tensile/yield floors in those older copies. For OD ≤1 in. the hardness columns were shown as ellipses (no requirement listed) in the reprints used here — an honest gap, not an invented number. State OD when citing mechanicals.

A789 Section 5 allows seamless or welded manufacture with no filler metal added. Seamless S32304 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 S32304 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 S32304 maps to EN 1.4362 (X2CrNiN23-4) and the 2304 trade name.

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

A789/A789M-24 Table 2 lists UNS S32304 at 1700–1920 °F [925–1050 °C] with rapid cooling in water or by other means — a relatively low anneal window among A789 duplex grades.

Rapid quench still matters; A789 warns about embrittlement after prolonged elevated-temperature use, including 475 °C ferrite embrittlement. SHH STEEL supplies S32304 solution-annealed and quenched per Table 2.

S32304 offers lean duplex SCC resistance and strength for water and light chloride duty. Mid-range PREN ≈26 is below A789 S32205 and not intended for seawater crevice service written around A789 S32750.

Compared with A789 S32101 it uses more nickel and less manganese; corrosion selection should follow the named UNS and heat certificate, not the shared “lean” label.

Water treatment, pulp-and-paper, light chemical process exchangers, and general industry where 2304 / S32304 is frozen. Wall reduction versus 316L is a common driver.

SHH STEEL produces and supplies A789 S32304 and can quote A789 S32205 when Mo crevice margin is needed.

Autogenous welded tube must meet parent properties. Fabrication typically uses matching lean duplex fillers with controlled heat input. Re-anneal after heavy hot work when required; avoid sigma and 475 °C soaks unless qualified.

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 S32304 (2304) lean duplex tube — coordinating chemistry, the lower 1700–1920 °F anneal window, testing, and EN 10204 3.1 documents to the PO. Production capability, not trader-only.

We call out the OD-split mechanical floors so buyers do not apply the small-OD tensile pair to large-OD tube by mistake.

SHH STEEL can produce and supply ASTM A789 UNS S32304 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 S32304 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 S32101, A789 S32003, and A789 S32205 can be quoted on the same enquiry when the project mixes duplex classes.

ASTM A789 UNS S32304 (2304) is a lean duplex stainless tube grade for water and light process service where duplex strength and SCC resistance are needed without 2205 alloy cost. SHH STEEL produces and supplies seamless and welded S32304 with EN 10204 3.1 documentation. Contact admin@steelspecs.com.