ASTM A312 / ASME SA-312
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. produces heavy thickness stainless steel pipe at its Ban Bueng, Chonburi mill, with quotations handled by its office in Bang Phli, Samut Prakan. The program covers Sch 80S, Sch 160 and XXS walls for steam, hydraulic and process lines that need a thick wall. Typical line-list entries are UNS S31603 heavy wall pipe and WNR 1.4301 heavy wall pipe, both made to ASTM A312 within our stainless steel seamless pipes range.
Heavy Thickness Stainless Steel PipesASTM A312 / ASME SA-312
EN 10204 3.1 certificate / 3.2 on request
Order by NPS and schedule or by outside diameter and wall thickness, and state whether the wall is nominal (average) or minimum. Each grade is fixed on the order by its TP designation and UNS number. The table sets out our heavy-wall production envelope.
Each ASME SA-312 heavy wall pipe we ship is made to ASTM A312, with dimensions, tolerances and test methods taken from the general requirements of ASTM A999. Every length is seamless pipe, which A312 defines as pipe made by a process that involves no welding at any stage of production. Each length carries the SML marking together with its heat number, size and schedule or wall.
Every length is either hydrostatically tested or given a nondestructive electric test, eddy current or ultrasonic, at our option unless your order names the method. Tension tests are taken per lot and flattening tests on lengths drawn from each lot. Results are reported on a mill test certificate to EN 10204 3.1 (3.2 on request), and third-party inspection is available on request.
Carbon level and stabilization matter as much as corrosion resistance when you choose the grade of a thick wall stainless steel pipe that will be welded into the line. We produce the five grades below in heavy walls, and each links to its full grade page.
TP304 is the most common chromium-nickel grade for general duty and welds by all standard fusion methods. Heavy-section welds in 304 carry a sensitization risk, so ASTM A312 TP304 heavy wall pipe suits lines with little heavy welding. Order it as UNS S30400 heavy wall pipe, detailed on our 304 seamless pipe page.
TP304L has restricted carbon, which reduces sensitization and intergranular corrosion after welding compared with standard 304. It is the preferred grade for heavy-section welded fabrications that will not be annealed after welding. Lengths meeting both grades' chemistry and properties can be dual certified to 304 and 304L. See our 304L seamless pipe page.
TP316 adds molybdenum to the chromium-nickel base, which improves resistance to pitting and crevice corrosion in chloride-containing environments. Often called the marine grade, it also offers good tensile and creep strength, a useful pairing for heavy walls in seawater cooling and chloride-bearing process lines. Full data is on our 316 seamless pipe page.
TP316L combines the molybdenum of 316 with low carbon, so thick joints resist sensitization after welding and keep their pitting resistance. ASTM A312 TP316L heavy wall pipe suits chloride service with welded joints. Drawings often list it as WNR 1.4404 heavy wall pipe. See our 316L seamless pipe page.
TP321 is titanium-stabilized, and the titanium reduces sensitization and intergranular corrosion after welding. For heavy walls, A312 sets separate, lower strength minimums for seamless TP321. Order it as UNS S32100 heavy wall pipe or WNR 1.4541 heavy wall pipe, and find chemistry and sizes on our 321 seamless pipe page.
The table gives nominal wall thickness in mm for our three heavy schedules from NPS 1-1/2 to NPS 24, so every listed wall sits inside the 5 to 65 mm range. Sch 80S walls follow ASTM A312 Table X1.1. Sch 160 and XXS walls are produced under the A312 provision for pipe of other dimensions, and such pipe must meet every other requirement of the specification.
| NPS | OD (mm) | Sch 80S wall (mm) | Sch 160 wall (mm) | XXS wall (mm) |
|---|---|---|---|---|
| 1-1/2 | 48.3 | 5.08 | 7.14 | 10.15 |
| 2 | 60.3 | 5.54 | 8.74 | 11.07 |
| 2-1/2 | 73.0 | 7.01 | 9.53 | 14.02 |
| 3 | 88.9 | 7.62 | 11.13 | 15.24 |
| 3-1/2 | 101.6 | 8.08 | - | - |
| 4 | 114.3 | 8.56 | 13.49 | 17.12 |
| 5 | 141.3 | 9.53 | 15.88 | 19.05 |
| 6 | 168.3 | 10.97 | 18.26 | 21.95 |
| 8 | 219.1 | 12.70 | 23.01 | 22.23 |
| 10 | 273.1 | 12.70 | 28.58 | 25.40 |
| 12 | 323.9 | 12.70 | 33.32 | 25.40 |
| 14 | 355.6 | 12.70 | 35.71 | - |
| 16 | 406.4 | 12.70 | 40.49 | - |
| 18 | 457 | 12.70 | 45.24 | - |
| 20 | 508 | 12.70 | 50.01 | - |
| 24 | 610 | 12.70 | 59.54 | - |
Swipe sideways to see the full table.
A dash marks a size with no wall listed for that schedule. An XXS stainless steel pipe is listed up to NPS 12, while a Schedule 160 stainless steel pipe runs through NPS 24. On nominal-wall orders the A312 wall tolerance applies. From NPS 3, every Sch 160 and XXS wall in the table falls in its row for walls that are thick relative to the outside diameter, which pairs a tighter plus limit with the same minus limit.
Each heavy wall stainless steel pipe starts as a solid billet that is heated and pierced into a hollow shell. Hot extrusion then develops the heavy wall, and cold drawing improves dimensional accuracy and surface quality. After solution annealing, the pipe is pickled and straightened before it goes to testing. Ends are finished plain, beveled or threaded as ordered. For lighter schedules from Sch 40S upward and the test of each length in detail, see our stainless steel high pressure pipe range.
An SS heavy wall pipe goes where a line must carry high pressure or resist slow material loss over a long service life.
Main steam and feedwater lines, high-pressure steam transmission, and superheater and reheater connections take heavy walls, because the thick wall adds strength and slows material degradation in harsh service.
High-pressure hydraulic oil lines use heavy walls for pressure capacity, while the smooth internal surface of the pipe limits scaling and buildup that would otherwise obstruct the flow of oil.
Reactor inlet and outlet lines, corrosive fluid circulation and acid and alkali transport need the right grade and a thick wall for service life; WNR 1.4404 heavy wall pipe suits chloride-bearing streams.
Downstream refinery process lines, injection and discharge lines, wellhead and gathering lines and high-pressure oil and gas transmission use heavy walls, stepping from Sch 80S to Sch 160 or XXS as pressure rises.
Industrial water supply, pump station lines and wastewater treatment plant lines specify an ASTM A312 TP304 heavy wall pipe where general corrosion resistance and long, low-maintenance service are needed.
Ballast water systems, seawater cooling lines, offshore platform process lines and splash-zone sections face constant chloride exposure, so molybdenum-bearing ASTM A312 TP316L heavy wall pipe is the grade specified for them.
Each consignment is packed and marked as follows:
Packing
Bundles with protective wrapping and woven bags, or wooden and plywood cases, with seaworthy packing on request.
Marking
Heat number, grade, specification, size and schedule or wall on each length; custom marking on request.
End protection
Plastic end caps on beveled, plain and threaded ends.
Trade terms
FOB, CIF or CFR.
Destinations
Delivery across Thailand and export to Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
Our range runs from WNR 1.4301 heavy wall pipe for water and general process lines to UNS S32100 heavy wall pipe for stabilized service. Each heavy thickness stainless steel pipe is produced to order at our factory, 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Quotations and documents come from our office at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand.
Sch 80S, Sch 160 and XXS, within walls of 5 to 65 mm. An XXS stainless steel pipe is not always the heaviest: it carries the thicker wall through NPS 6, but from NPS 8 the Sch 160 wall is heavier, for example 23.01 mm against 22.23 mm at NPS 8.
Order on minimum wall when your design calculation already uses the minimum thickness. Under ASTM A999 a minimum-wall order allows no under-tolerance, so every length meets the figure you calculated. A nominal-wall order accepts the A312 minus tolerance, which your designer must then deduct before checking the pipe.
Walls up to 65 mm and outside diameters up to 1016 mm, in lengths up to 18 m. Within that envelope we make NPS and schedule sizes or the OD and wall from your drawing. The heaviest schedule wall in our table is Sch 160 at NPS 24, 59.54 mm.
ASTM A312 ties the tensile and yield minimums of seamless TP321 to wall thickness. Above a defined nominal wall the lower heavy-wall values apply, and most Sch 160 and XXS walls in our table fall in that row. Each lot's tension test on those walls is judged against the heavy-wall minimums.
Beveled ends are the usual choice for butt-welded heavy walls, and we prepare the bevel to the detail on your drawing or welding procedure. Plain ends suit lines joined by other methods, and threaded ends are available on these heavy schedules. State the end type for each line item, since one order can mix them.
Match the grade to the medium and the welding plan. Choose UNS S31603 heavy wall pipe for chloride-bearing media and 304L for general duty, or titanium-stabilized WNR 1.4541 heavy wall pipe where a stabilized grade is specified. UNS S30400 heavy wall pipe remains an option where joints are annealed after welding.
It records grade, size, schedule or wall, heat number and the tension, flattening and hydrostatic or electric test results, issued to EN 10204 3.1 (3.2 on request). Each length is marked with its heat number, which ties it to the certificate. Third-party inspection is available on request.
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