ASTM A790 / ASME SA-790 / EN 10204 3.1
Manufactured in Ban Bueng, Chonburi, Thailand, super duplex steel seamless pipes from Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. are made to ASTM A790 / ASME SA-790 for offshore, seawater, firewater and chemical process piping where high pressure meets chloride attack. Engineering queries and offers are answered from our Bang Phli, Samut Prakan office. Our four grades are UNS S32750 (EN 1.4410), UNS S32760 (EN 1.4501), UNS S32550 (EN 1.4507) and UNS S32950, each pierced from a solid billet with no weld seam.
Super Duplex Steel seamless pipeASTM A790 / ASME SA-790
EN 10204 3.1 certificate / 3.2 on request
The table lists what our mill makes in this family: dimensions, finish, heat treatment, tests and paperwork. Quote the UNS number on every line item, because an EN number alone does not identify every grade in this family.
Every ASME SA-790 super duplex seamless pipe we produce is made to ASTM A790 / ASME SA-790, a ferritic/austenitic specification for general corrosive service whose chief aim is resistance to stress corrosion cracking. Appendix X1 sets out NPS and schedule dimensions after ANSI B36.19, yet non-tabulated sizes are acceptable when every other A790 clause is met. Wall and OD tolerances sit in ASTM A999, the general requirements standard that A790 calls up. The 1.4410, 1.4501 and 1.4507 grades are cross-referenced to EN 10216-5 where a European data sheet governs, while exchanger and instrument lines sized by exact OD move to ASTM A789 and our super duplex steel seamless tubes.
ASTM A790 subjects every length of super duplex stainless steel seamless pipe to a hydrostatic test or, as the alternative, to ultrasonic or eddy current examination under ASTM E213 or E309; where the purchase order is silent, we choose. Tension, flattening and hardness specimens are cut lot by lot. Product analysis and PMI reports can be added, third-party inspection is available on request, and the heat analysis, with the figures from every lot test, is reported on the EN 10204 3.1 (3.2 on request) material test certificate.
Super duplex grades take over when seawater, warm chlorides, sour gas or line pressure exceed what our duplex steel seamless pipes are chosen to handle. The four grades below share the A790 tolerances and test plan, yet their chemistry and heat treatment differ, so each one has its own grade page.
Seawater, firewater and offshore process lines suit UNS S32750 seamless pipe, the grade ASTM A790 lists under the type name 2507. Among these four grades it has the highest minimum tensile strength, and A790 requires its chromium, molybdenum and nitrogen content to meet a minimum pitting resistance index.
Tungsten and copper, added to a chromium, molybdenum and nitrogen base, distinguish UNS S32760, and A790 counts the tungsten in its pitting resistance index. It also carries the highest minimum elongation among the four. We supply UNS S32760 seamless pipe for deep-water oil and gas, sour gas lines and seawater piping.
Copper sets UNS S32550 (ASTM type 255) apart: it carries the highest copper range of the four grades, an addition that improves resistance to sulfuric acid. Acid process lines, reactor manifolds and seawater handling in marine engineering all suit UNS S32550 seamless pipe.
The fourth grade, UNS S32950, has higher chromium with lower nickel and molybdenum, and its minimum strength falls below that of S32750, S32760 and S32550. A790 also has it air cooled, never quenched, even straight after hot forming. With no EN number, UNS S32950 seamless pipe is ordered by UNS designation alone.
Inside an envelope of 1 to 65 mm wall thickness and 6 to 720 mm OD, each seamless super duplex steel pipe follows an NPS and schedule or the OD and wall shown on your isometric. ASTM A790 Appendix X1 tabulates four stainless schedules, and the table shows how far each one runs within our OD limit.
| Schedule | NPS range (A790 Appendix X1) | Nominal wall (mm) | End finish |
|---|---|---|---|
| 5S | 1/2 to 24 | 1.65 to 5.54 | Plain or beveled |
| 10S | 1/8 to 24 | 1.24 to 6.35 | Plain or beveled |
| 40S | 1/8 to 12 | 1.73 to 9.52 | Plain, beveled or threaded |
| 80S | 1/8 to 12 | 2.41 to 12.70 | Plain, beveled or threaded |
Swipe sideways to see the full table.
Wall thickness and OD are held to the ASTM A999 limits for the nominal size, and every cut length is supplied no shorter than ordered, with at most 6 mm overrun. Each grade page tabulates selected NPS sizes with their schedule walls.
Seamless super duplex pipe is chosen where seawater or process chlorides meet high pressure, from offshore platforms to acid plants and flue gas cleaning.
Subsea flowlines, risers, manifolds and topside process piping on platforms and FPSOs run in seamless super duplex stainless steel pipe, which pairs high strength with resistance to chloride stress corrosion cracking.
Seawater intakes, cooling circuits and firewater ring mains in tropical fields carry warm, chloride-rich water. We supply them in super duplex 2507 seamless pipe or, on European data sheets, seamless WNR 1.4410 pipe.
Piping around high-pressure reverse osmosis pumps and membrane housings, together with brine lines, uses seamless 1.4410 super duplex pipe for its strength and chloride resistance at desalination plants.
Reactor feeds, acid manifolds and transfer lines handling hot sulfuric or phosphoric acid with chlorides take seamless WNR 1.4507 pipe, the copper-bearing grade of the family.
Flowlines and process pipework carrying sour gas or crude on deep-water developments are made in seamless WNR 1.4501 pipe, whose tungsten and copper additions are aimed at sour gas service.
Scrubber liquor lines in power plant flue gas desulfurization units, and bleach washer and digester piping in pulp mills, are typical duties for seamless 1.4501 super duplex pipe.
Bundles and cases
Steel-strapped bundles for small bore; ISPM-15 wooden cases for large-bore and thin-wall lengths.
Marking
A stencil line on every length gives the UNS grade, ASTM A790, heat number and size; pipe below NPS 2 may be tagged by bundle or box instead.
End protection
Every open end is capped in plastic, and threaded ends carry screwed thread protectors.
Transport
Containerized freight for standard lengths, flat rack or break-bulk when a length exceeds container size.
Trade terms
FOB, CFR or CIF.
Destinations
Delivery within Thailand and shipments to Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
Our Ban Bueng mill, at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand, takes all four grades from billet piercing through finishing, heat treatment and testing, from seamless 1.4507 super duplex pipe for acid lines to large-bore seamless 1.4410 super duplex pipe for firewater mains. Quotations, inspection slots and export paperwork are arranged by our Bang Phli office at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand.
When seawater, warm chlorides or sour gas exceed the duty of the duplex grade, or when higher strength would allow a lighter wall. ASTM A790 requires UNS S32750 and S32760 to meet a minimum pitting resistance index, which Duplex 2205 is not held to. Thaida makes super duplex steel seamless pipes to the grade your line class names.
UNS S32750 suits both duties, and seamless WNR 1.4410 pipe is the same grade under its EN number. UNS S32760 fits where a project calls for the tungsten-bearing grade, seamless WNR 1.4507 pipe where acids accompany the chlorides, and UNS S32950 where an existing specification already lists it.
We confirm the UNS grade before production starts. A line of seamless WNR 1.4501 pipe is matched to UNS S32760, while a seamless 1.4507 super duplex pipe call-out is queried, because 1.4507 is also cross-referenced to another super duplex chemistry. The agreed UNS number then goes on the stencil and the material test certificate.
No. Under A790, a mechanical test lot is pipe of one nominal size and wall or schedule, from one heat and with the same finishing treatment, so each grade and size in a mixed order of super duplex 2507 seamless pipe and seamless 1.4501 super duplex pipe is tested separately. Lots above 100 pipes give tension specimens from two pipes.
The S schedules come from ANSI B36.19, the stainless steel schedule standard on which A790 Appendix X1 is based. An A790 footnote states that many of these walls, chiefly in 5S and 10S, do not conform to ANSI B36.10, the wrought steel standard, so quote 5S, 10S, 40S or 80S, or an OD and wall, rather than a B36.10 schedule.
Either designation can be used. ASME SA-790 is the ASME equivalent of ASTM A790, and every ASTM A790 super duplex seamless pipe from our mill is produced to meet both. Put the designation your design code uses on the order, together with the UNS grade.
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