ASTM A790 / ASME SA-790
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. manufactures ASTM A790 / ASME SA-790 duplex steel seamless pipes in Ban Bueng, Chonburi, Thailand, for high-pressure oil and gas, petrochemical and seawater service where standard austenitic grades pit and crack in warm chlorides. Our office is in Bang Phli, Samut Prakan. We produce UNS S31803 and UNS S32205, both Duplex 2205 (EN 1.4462), and hyper duplex UNS S32707, all as ferritic-austenitic lengths with no longitudinal weld.
Duplex Steel seamless pipeASTM A790 / ASME SA-790
EN 10204 3.1 certificate / 3.2 on request
The table below sets out the production envelope for our seamless duplex steel pipe. You can order by outside diameter and wall thickness, or by NPS and schedule, and each grade is fixed on the order by its UNS number rather than by trade name.
Alongside ASTM A790, we produce to European, Japanese and Chinese standards, because a single project package in Southeast Asia often mixes them. EN 10216-5 is the European pressure standard for seamless stainless grades including duplex, and it is the usual route when a data sheet calls for seamless WNR 1.4462 pipe. JIS G3459 governs stainless steel seamless pipe on Japanese specifications, and GB/T 21833 covers austenitic-ferritic seamless product on Chinese ones. For the tube form, ASTM A789 / ASME SA-789 applies, and we make that product as duplex steel seamless tubes.
Each ferritic-austenitic stainless steel seamless pipe we release carries a mill test certificate to EN 10204 3.1 (3.2 on request), recording heat number, grade, standard, size and test results against the ordered grade. We also provide raw material certificates, positive material identification (PMI) of every pipe, heat treatment charts, third-party inspection reports, surface roughness and size measurement, and a laboratory test certificate from a government-approved lab.
Chloride level and temperature decide the grade. For chloride duty beyond UNS S32205, our super duplex steel seamless pipes take over, and hyper duplex UNS S32707 sits above every standard super duplex grade.
A balanced ferrite-austenite structure gives our three duplex grades far higher yield strength than 316L seamless pipes, so a given pressure rating needs a thinner wall.
UNS S31803 is the original Duplex 2205 grade. It balances strength with resistance to localized corrosion, which makes it a cost-effective choice for high-pressure lines carrying chloride-bearing fluids, and many older plant specifications still name it. Full grade data, sizes and testing for UNS S31803 seamless pipe are on its own page.
UNS S32205, the refined Duplex 2205 grade, has tighter minimum chromium, molybdenum and nitrogen than S31803 for more consistent corrosion resistance. It is approved for sour service under NACE MR0175 / ISO 15156, within its hardness and environmental limits. Chemistry, mechanical values and sizes for UNS S32205 seamless pipe are on the grade page.
Hyper duplex UNS S32707 is the most highly alloyed grade in our duplex range. Supplied as seamless WNR 1.4658 pipe, it is made for warm seawater, hot chloride and sour service, with typical use in deep-water risers, seawater cooling systems and heat exchangers handling aggressive brine.
Within the envelope in the specification table, we make seamless duplex steel pipe to NPS sizes and schedules under ASME B36.19M and B36.10M, or to the outside diameter and wall thickness on your drawing. Imperial and metric dimensions are both given below, since specifications across Southeast Asia routinely mix the two on a single isometric. Calculated weight per meter is provided with the quotation.
Schedule fixes the wall thickness for a given outside diameter, and on a duplex steel seamless pipe it decides both pressure rating and pipe weight. We produce the full ladder from SCH 5S at the thin-wall end, where the higher yield strength of duplex is most useful, through 40S/STD and 80S/XS for general process duty, up to SCH 160 and XXS for high-pressure sections.
| Schedule | Typical use |
|---|---|
| 5S, 10S | Thin-wall service where duplex strength allows weight and cost reduction against austenitic wall |
| 40S / STD | General process and utility duty; the most widely specified wall |
| 80S / XS | Higher pressure, corrosive or erosive service |
| 100, 120, 160, XXS | High-pressure and high-duty sections, small and medium bore |
Nominal wall thickness in mm by NPS, per ASME B36.19M / B36.10M:
| NPS (in) | OD (mm) | Sch 10S | STD | XS | Sch 160 |
|---|---|---|---|---|---|
| 1/2 | 21.3 | 2.11 | 2.77 | 3.73 | 4.78 |
| 3/4 | 26.7 | 2.11 | 2.87 | 3.91 | 5.56 |
| 1 | 33.4 | 2.77 | 3.38 | 4.55 | 6.35 |
| 1-1/4 | 42.2 | 2.77 | 3.56 | 4.85 | 6.35 |
| 1-1/2 | 48.3 | 2.77 | 3.68 | 5.08 | 7.14 |
| 2 | 60.3 | 2.77 | 3.91 | 5.54 | 8.74 |
| 2-1/2 | 73.0 | 3.05 | 5.16 | 7.01 | 9.53 |
| 3 | 88.9 | 3.05 | 5.49 | 7.62 | 11.13 |
| 3-1/2 | 101.6 | 3.05 | 5.74 | 8.08 | - |
| 4 | 114.3 | 3.05 | 6.02 | 8.56 | 13.49 |
| 5 | 141.3 | 3.40 | 6.55 | 9.53 | 15.88 |
| 6 | 168.3 | 3.40 | 7.11 | 10.97 | 18.26 |
| 8 | 219.1 | 3.76 | 8.18 | 12.70 | 23.01 |
| 10 | 273.1 | 4.19 | 9.27 | 12.70 | 28.58 |
| 12 | 323.9 | 4.57 | 9.53 | 12.70 | 33.32 |
| 14 | 355.6 | 4.78 | 9.53 | 12.70 | 35.71 |
| 16 | 406.4 | 4.78 | 9.53 | 12.70 | 40.49 |
| 18 | 457.2 | 4.78 | 9.53 | 12.70 | 45.24 |
| 20 | 508.0 | 5.54 | 9.53 | 12.70 | 50.01 |
| 22 | 558.8 | 5.54 | 9.53 | 12.70 | 53.98 |
| 24 | 609.6 | 6.35 | 9.53 | 12.70 | 59.54 |
Swipe sideways to see the full table.
Choose the manufacturing route, end preparation and length from the options in the specification table; fixing these turns a grade selection into a quotable line item. The delivery condition is fixed by the specification. Solution annealing followed by water quenching restores the ferrite-austenite phase balance after hot or cold work, and ASTM A790 requires it, so every ASTM A790 duplex seamless pipe we release is supplied in this condition.
Chloride-bearing, high-pressure service is where duplex earns its place: oil and gas, petrochemical processing, seawater desalination, marine systems, heat exchangers, and pulp and paper.
Flowlines, manifolds and water injection systems carry high pressure, so the strength of duplex keeps walls and weights manageable offshore and onshore. On deep-water risers, seamless 1.4658 hyper duplex pipe adds fatigue resistance.
Process lines, transfer piping and acid or brine circuits in petrochemical plants use duplex stainless steel seamless pipe where an austenitic grade would risk chloride stress corrosion cracking.
Feed and brine reject lines in desalination plants run seawater at high pressure, which calls for duplex strength and seawater resistance. The most heavily loaded sections take seamless 1.4658 hyper duplex pipe.
Weight counts aboard vessels and offshore structures. Ballast, firewater, cargo and seawater cooling systems in seamless 1.4462 duplex pipe run thinner walls than an austenitic design, cutting topside and onboard mass.
Heat exchanger and condenser circuits carrying cooling water, brine or process fluid go through repeated thermal cycles. Seamless WNR 1.4462 pipe handles that cycling duty while resisting pitting.
Pulp mill digester and liquor lines run hot and caustic, and bleach plant sections add chlorides. Duplex 2205 seamless pipe handles both duties, from digester circuits to bleach washers.
Each consignment is packed and marked as follows:
Packing
Steel-strapped bundles or ISPM-15 compliant wooden cases, with dunnage for container loading.
Marking
Heat number, grade, specification and size stenciled on each length; custom marking on request.
End protection
Plastic end caps on bevels and bores.
Shipment
FCL containers for standard consignments, break-bulk for large-diameter or over-length material.
Trade terms
FOB, CIF or CFR.
Destinations
Delivery across Thailand and export to Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
We deliver from stock or to production schedule, confirmed with the quotation. Our factory at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand, produces the full range, from seamless 1.4462 duplex pipe to hyper duplex UNS S32707. Our office is at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand.
Choose UNS S32205 for new designs. It is the tighter version of Duplex 2205, with higher minimum chromium, molybdenum and nitrogen, so corrosion resistance is more consistent from heat to heat. UNS S31803 seamless pipe suits plant specifications that still name the original grade, and most S31803 production also meets the S32205 composition.
Specify it for the most aggressive chloride service, where Duplex 2205 and the higher-alloyed grades above it fall short, such as subsea flowlines, high-pressure desalination piping, chlor-alkali lines and mining autoclaves. UNS S32707 seamless pipe is made to ASTM A790, and seamless WNR 1.4658 pipe is produced up to 457 mm OD.
Yes. Duplex 2205 has a far higher minimum yield strength than 316L, so the same design pressure is met with a lighter wall, which also cuts installed weight. The exact saving comes from your design code calculation at the operating pressure and temperature, and we quote the resulting wall or schedule.
Usually not. Most applications use the pipe as welded, under a qualified procedure with matching filler (ER2209 for UNS S31803 and UNS S32205), limited heat input and interpass temperature below 150 °C to hold the ferrite-austenite balance. Post-weld solution annealing may be required for critical applications, so state it on the order when your code calls for it.
Yes, UNS S32205 is approved for sour service under NACE MR0175 / ISO 15156, within the hardness and environmental limits of that standard. Compliance depends on the exact grade, hardness, heat treatment and microstructure, never on the grade name alone, so state the sour-service requirement on the order and we confirm the supporting tests and documentation.
Standard NPS sizes and schedules to ASME B36.19M or B36.10M are produced within 6 to 720 mm OD and 1 to 65 mm wall, from SCH 5S up to SCH 160 and XXS, in lengths up to 18 m or cut to length. We also make drawing-based OD and wall sizes.
Every heat ships with a mill test certificate to EN 10204 3.1 (3.2 on request). Reported tests can include hydrostatic, eddy current, ultrasonic, flattening, impact, hardness and pitting corrosion testing, and duplex orders can add ferrite content measurement to ASTM E562 and detrimental-phase screening to ASTM A923.
Request a Quote for Duplex Steel Seamless Pipes
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