ASTM A789 / ASME SA-789 / EN 10204 3.1
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. offers ASTM A789 / ASME SA-789 super duplex steel seamless tubes produced at its Ban Bueng, Chonburi plant for acid process coolers, seawater-cooled exchangers and hydraulic control lines offshore. The range covers UNS S32750 (WNR 1.4410), UNS S32760 (WNR 1.4501), UNS S32550 (WNR 1.4507) and UNS S32950. Each tube starts as a solid round billet that is heated, pierced, cold worked and heat treated. Quotations and order documents come from our Bang Phli, Samut Prakan office.
Super Duplex Steel seamless tubeASTM A789 / ASME SA-789
EN 10204 3.1 certificate / 3.2 on request
All four grades share the production range below. Each order line is defined by its UNS grade, actual outside diameter, wall thickness on an average or minimum basis, length and quantity.
Under ASTM A789, ferritic-austenitic tubing is specified for general corrosive service in which stress corrosion cracking resistance matters most, and an order placed as ASME SA-789 super duplex seamless tube is held to the same requirements. Exchanger specifications prepared in Europe cite EN 10216-5 numbers instead, in which seamless WNR 1.4410 tube corresponds to UNS S32750 and seamless WNR 1.4501 tube to UNS S32760. Likewise, seamless WNR 1.4507 tube is cross-referenced to UNS S32550. ASTM A790 governs the connecting process piping, which we supply as super duplex steel seamless pipes.
Testing runs at two levels. At tube level, A789 lets the manufacturer prove each length either hydrostatically or by nondestructive electric examination (eddy current, flux-leakage or ultrasonic), with the purchase order free to fix the method. At lot level, tension, flaring and hardness specimens are taken for each heat, so every super duplex stainless steel seamless tube in a mixed-heat lot is covered by results from its own heat. Each heat's chemistry sits beside its test values on the EN 10204 3.1 (3.2 on request) certificate, and PMI or third-party inspection can be ordered as extras.
ASTM A789 gives each of the four grades its own chemistry, strength and heat treatment limits, so the UNS number on the order decides what the mill makes. Where a datasheet names a standard duplex grade instead, our duplex steel seamless tubes in UNS S31803 and UNS S32205 cover it.
Saltwater service, chemical plant exchangers and offshore hydraulic control lines are typical duties for UNS S32750, the grade ASTM names 2507. Its nitrogen-rich chemistry needs no tungsten, and A789 sets its tensile minimum above the rest of the family. Europe lists it as seamless WNR 1.4410 tube; full limits sit with UNS S32750 seamless tube.
Sour-system chemical injection lines, oil and gas extraction equipment and seawater cooler bundles call for UNS S32760, the only grade of the four with a specified tungsten range, together with a copper addition. In Europe it is seamless WNR 1.4501 tube; chemistry and strength limits are listed for UNS S32760 seamless tube.
Sulfuric acid service, industrial scrubbers and marine equipment exposed to abrasion or erosion suit UNS S32550, known in ASTM as type 255, whose copper range is set well above the other grades. The European equivalent, seamless WNR 1.4507 tube, is shared with another chemistry, so order lines name UNS S32550 seamless tube.
UNS S32950 stands apart twice over: A789 has it air cooled after heat treatment, and its chromium range sits above the other three while its nickel and molybdenum sit below. Because it lacks a WNR equivalent, the UNS number is the only identity a UNS S32950 seamless tube carries on the order, stencil and certificate.
We make super duplex seamless tubing from 6 to 720 mm OD, with walls of 1 to 65 mm and lengths up to 22 m. Because a seamless super duplex steel tube is bought by actual OD rather than nominal size, the OD and cut-length tolerances in ASTM A789 Table 5 apply band by band:
| OD band (mm) | OD tolerance (mm) | Cut length tolerance (mm) |
|---|---|---|
| Under 38.1 | ±0.13 | +3 / -0 |
| 38.1 to under 88.9 | ±0.25 | +5 / -0 |
| 88.9 to under 139.7 | ±0.38 | +5 / -0 |
| 139.7 to 203.2 | ±0.76 | +5 / -0 |
These cut-length values hold for cuts no longer than 7.3 m; longer cuts take an extra 3 mm of plus tolerance per additional 3 m or part of 3 m, to a maximum increase of 13 mm. Wall thickness is held on the average or minimum basis stated on the order, and the marking on each length, or on the bundle tag for small bore, states that basis.
Most of these tubes go into two kinds of equipment: bundles that exchange heat between seawater or acid streams and process fluid, and narrow lines that carry hydraulic fluid or injected chemicals under pressure.
Coastal plants and offshore platforms cool process streams with seawater. Their cooler bundles use super duplex stainless steel seamless tube in UNS S32750 or UNS S32760 to resist chloride stress corrosion cracking.
Offshore hydraulic control lines and umbilicals run in small-bore seamless super duplex steel tube, while chemical injection lines serving sour systems are made in seamless 1.4501 super duplex tube.
High-pressure reverse osmosis sections in seawater desalination plants are tubed with ASTM A789 super duplex seamless tube to handle seawater and brine under pressure.
Reactors and heat exchangers on phosphoric and sulfuric acid units take seamless 1.4507 super duplex tube for its copper-bearing chemistry, while mixed acid and chloride streams are also tubed in seamless 1.4410 super duplex tube.
Power stations clean their flue gas in desulfurization scrubbers, and the heat-transfer and process lines serving those units use seamless super duplex stainless steel tube to carry the scrubber liquids.
Bleach plants and liquor systems in pulp and paper mills expose tube to bleaching chemicals, and seamless 1.4507 super duplex tube serves their heat exchangers and process lines.
Packing units
Wooden crates for heavy-wall and large-OD tube, strapped and wrapped bundles for small bore, with one UNS grade per bundle.
Traceability
Heat number, UNS grade, OD, wall and its average or minimum basis stenciled on each length, with small-bore tube also identified on the bundle tag.
Tube ends
Closed with plastic caps at both ends of each length.
Long lengths
Tube approaching 22 m rides on open-top or flat-rack equipment, while shorter cuts go in standard containers.
Sea freight
Arranged on FOB, CFR or CIF terms, whichever your contract specifies.
Markets served
Thailand, Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
Billet heating, piercing, cold working, heat treatment and testing of every super duplex steel seamless tube take place at our mill, 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Inquiries, quotations and shipping documents are managed at our office, 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand.
For flue gas desulfurization and flue gas cleaning, UNS S32750 seamless tube and seamless 1.4501 super duplex tube (UNS S32760) are both used. Bleach plant and liquor duty in pulp and paper mills is served by S32550, S32750 and S32760, so the choice follows the chemistry the mill specifies.
Only UNS S32750 and UNS S32760. A789 sets an index floor for both, worked out from chromium, molybdenum and nitrogen, with tungsten added to the molybdenum term for S32760. UNS S32550 and UNS S32950 have none, so a datasheet asking for a pitting index on those two grades needs the value agreed before ordering.
Yes. The tests and their frequency are identical for all four grades; only the acceptance limits change, because A789 sets chemistry, tensile, yield, elongation and hardness values grade by grade. Each certificate is therefore judged against the limits of the UNS grade ordered, which is why mixed-grade orders keep every line separately identified.
No. For tube, A789 sets the hydrostatic pressure from the specified wall and OD alone, using one fixed stress figure rather than each grade's yield strength, so all four grades see the same pressure at the same size. The same upper limit applies to every grade, and a nondestructive electric test remains the alternative.
Check the marking first: each length, or the bundle tag for small bore, shows the UNS grade and heat number, and the heat number ties the tube to its certificate chemistry. Positive material identification can be ordered to separate grades with overlapping chemistry, such as super duplex 2507 seamless tube and S32760, in a mixed delivery.
The EN 10204 3.1 (3.2 on request) certificate for every heat in the consignment, a packing list keyed to the bundle tags, the commercial invoice and a certificate of origin. Any inspection reports your order calls for are added to the same document set.
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