ASTM A789 / ASME SA-789 / EN 10204 3.1
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd., based in Ban Bueng, Chonburi, Thailand, produces ASTM A789 / ASME SA-789 duplex steel seamless tubes designed for heat exchangers, coolers and condensers that handle chloride-bearing water and process fluids. Our Bang Phli, Samut Prakan office reviews and answers each tube list. The range covers two grades, UNS S31803 and UNS S32205, each designated WNR 1.4462 in Europe and each made from solid round billet pierced into a hollow shell.
Duplex Steel seamless tubeASTM A789 / ASME SA-789
EN 10204 3.1 certificate / 3.2 on request
Match each line of your tube list against the production range below. Tube is ordered by actual outside diameter and by average or minimum wall, with the UNS number identifying the grade on every line.
ASTM A789 / ASME SA-789 covers ferritic-austenitic tubing for services requiring general corrosion resistance, and it singles out resistance to stress corrosion cracking. Every ASME SA-789 duplex seamless tube we make is produced to it. Its general requirements, including the hydrostatic and flaring test methods, come from ASTM A1016. European data sheets call for seamless WNR 1.4462 tube under EN 10216-5, Japanese specifications use JIS G3463 and Chinese ones GB/T 13296. Piping ordered by NPS and schedule falls under ASTM A790 instead, which we produce as duplex steel seamless pipes.
Each seamless 1.4462 duplex tube goes through a hydrostatic test or an eddy current, ultrasonic or flux leakage examination, with the method left to us unless your order fixes it. Tension, flaring and hardness tests are taken from each lot and repeated for every heat when a lot contains more than one. Results and heat chemistry are reported on an EN 10204 3.1 (3.2 on request) material test certificate; PMI results and heat treatment charts can be added, and third-party inspection is available on request.
Both grades are ferritic-austenitic duplex steels known as Duplex 2205 and supplied as seamless WNR 1.4462 tube, made to the same A789 tolerances and test plan. Where the chloride duty calls for a more highly alloyed grade, our super duplex steel seamless tubes are the next step up.
Many existing exchanger and cooler datasheets name UNS S31803, the original designation for this duplex chemistry, with a wider range of chromium, molybdenum and nitrogen than S32205. It suits like-for-like retubing, chemical tankers and pulp and paper plant. Composition, strength and tolerances for UNS S31803 seamless tube appear on its grade page.
UNS S32205 tightens the chemistry by raising the minimum chromium, molybdenum and nitrogen, and under ASTM A789 it carries higher minimum tensile and yield strength than S31803. That makes it the usual choice for new seawater cooling loops, desalination evaporators and offshore exchangers. The UNS S32205 seamless tube page lists its A789 values and sizes.
Across 6 to 720 mm OD, 1 to 65 mm wall and lengths up to 22 m, each seamless duplex steel tube is made to the OD and wall your drawing calls for, in metric or imperial units. For each ASTM A789 duplex seamless tube, OD is held to the following bands:
| OD range (mm) | OD tolerance (mm) |
|---|---|
| Under 12.7 | ±0.13 |
| 12.7 to under 38.1 | ±0.13 |
| 38.1 to under 88.9 | ±0.25 |
| 88.9 to under 139.7 | ±0.38 |
| 139.7 to 203.2 | ±0.76 |
The wall tolerance follows the basis you order. An average wall may vary to either side of the figure, while a minimum wall is never undercut and may only run over it. A789 sets both OD and wall limits only up to 203.2 mm OD, so for larger tube, state the OD and wall tolerances you need with your inquiry. Band-by-band wall figures appear on each grade page.
Duplex seamless tubing earns its place on the heat-transfer side of a plant, where chloride-bearing cooling water or process streams would put an austenitic tube at risk of stress corrosion cracking.
Oil, gas and chemical plant exchangers and industrial cooling systems run straight-tube bundles in duplex 2205 seamless tube, keeping chloride cooling water on one side and hot process fluid on the other.
Coastal power stations draw seawater through their condensers and cooling circuits, a common duty for UNS S32205 seamless tube, the more highly alloyed of our two duplex grades.
Desalination evaporators and high-pressure seawater systems use seamless duplex stainless steel tube, which combines chloride resistance with enough strength to carry pressure in a comparatively thin wall.
Shell-and-tube exchangers on offshore platforms, hydraulic tubing and flowlines carrying sour gas use duplex stainless steel seamless tube for its stress corrosion cracking resistance in a marine setting.
Coolers and condensers on sulfuric acid and phosphoric acid units, and in plants handling organic acids and chlorides, are tubed with seamless duplex steel tube to resist both acid and chloride attack.
Pulp mill digesters, bleach plant equipment and bleach washers take seamless 1.4462 duplex tube for heat-transfer and process lines exposed to bleaching chemicals.
Bundling
Small-OD tube in strapped bundles, larger sizes in wooden or plywood cases.
Marking
Grade, ASTM A789, heat number, size and wall basis (average or minimum) on each tube.
Bore protection
Each tube is capped at both ends so the bore arrives clean.
Loading
Container shipment for lengths that fit a container, flat rack or break-bulk for longer tube.
Delivery terms
FOB, CFR or CIF, quoted to your port of discharge.
Export markets
Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India, alongside delivery to sites within Thailand.
Every duplex steel seamless tube is pierced, sized, solution annealed and tested at our mill, 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Certificates, export papers and order follow-up come from our office at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand.
UNS S32205, unless the project specification fixes S31803. When retubing a bundle built in UNS S31803 seamless tube, keep the original grade, because a change of grade can mean re-approving the design. If your datasheet leaves the choice open, send it with the tube list and we quote both grades side by side.
Pipe is called up by NPS and schedule under ASTM A790, so its OD is fixed by the nominal size. A789 tube is made to the exact OD on your exchanger drawing, and its lot testing differs: a flaring test, which expands the bore at one tube end, replaces the flattening test used on pipe.
Yes, once the exchanger design is rechecked. Duplex 2205 carries a higher minimum yield than 316L seamless tubes, so the same pressure can often be carried by a thinner wall. The tube-to-tubesheet joint and expansion procedure must be confirmed for the stronger material, so send the datasheet and tubesheet drawing with your inquiry.
The hydrostatic option uses a test pressure set by the ratio of wall thickness to OD, and any tube that leaks is rejected. Electric testing follows ASTM E213, E309, E426 or E570. Where your code also asks for a leak check, an air-underwater pneumatic test can be ordered as supplementary requirement S1.
Yes. ASTM A789 requires every tube to be furnished heat treated, so each length leaves our mill solution annealed and rapidly cooled in water or by other means. The surface is free of excessive mill scale and suitable for inspection, and any further finish is agreed on the order.
Up to 22 m. For tube to 203.2 mm OD, a cut to 7.3 m is never short and may run 3 mm over below 38.1 mm OD, or 5 mm over from 38.1 to 203.2 mm OD. Longer cuts allow 3 mm more per further 3 m or fraction, 13 mm extra at most.
Yes. List the super duplex items alongside your duplex 2205 seamless tube lines, each listed with UNS number, size, length and quantity, and one quotation comes back with production timing per grade. Each line is tested and toleranced to ASTM A789 for its own grade.
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