Phosphoric Acid Heat Exchangers
Reactor coolers and shell-and-tube exchangers in phosphoric acid production use S32550 bundles, which carry hot process acid on one side of the tube wall and cooling water on the other.
ASTM A789 / ASME SA-789 / UNS S32550 / W.Nr. 1.4507
Super Duplex Steel UNS S32550 Seamless Tubes Manufacturer in Thailand
From its Ban Bueng, Chonburi mill in Thailand, Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. produces UNS S32550 super duplex steel seamless tubes to ASTM A789 for phosphoric and sulfuric acid heat exchangers, scrubber systems and seawater desalination units. Of the four grades in our super duplex steel seamless tubes range, it is the one specified with 1.50 to 2.50% copper. Its European cross-reference is 1.4507 (X2CrNiMoCuN25-6-3), while pricing and order paperwork are handled by our Bang Phli, Samut Prakan office.
Super Duplex Steel UNS S32550 seamless tubeUNS S32550 / W.Nr. 1.4507
- 6 to 720 mmOutside diameter
- 1 to 65 mmWall thickness
- Up to 22 mLength
- EN 10204 3.1Test certificate
EN 10204 3.1 certificate / 3.2 on request
ASME SA-789 S32550 Seamless Tube Specifications
Our S32550 drawing range is listed below. The wall basis you choose, average or minimum, decides which ASTM A789 tolerance column applies to your order, so state it with each size.
- Standard
- ASTM A789 / ASME SA-789
- Grade
- UNS S32550
- Outside Diameter
- 6 to 720 mm
- Wall Thickness
- 1 to 65 mmaverage or minimum wall
- Length
- Up to 22 mor cut to your length
- Form
- Seamlessround
- End Type
- Plain end or beveled end
- Production Route
- 1Heated solid billet pierced at high temperature
- 2Then precision cold drawn and rolled
- Heat Treatment
- 1040 °C (1900 °F) minimum, rapid cooling in water or by other means
- Test Certificate
- EN 10204 3.13.2 on request
- Testing
- Every tube: hydrostatic or nondestructive electric test. Every lot: tension, flaring and hardness tests
Chemistry, heat treatment, mechanical tests, dimensional limits and marking for every ASTM A789 UNS S32550 seamless tube follow that standard and SA-789, its ASME twin. A789 covers tubing for general corrosion resistance where stress corrosion cracking is the chief concern, and it flags a risk of embrittlement after long exposure to elevated temperatures. On European drawings, the counterpart call-out is seamless WNR 1.4507 tube to EN 10216-5. Piping runs sized by NPS and schedule are covered by our UNS S32550 seamless pipes, made to ASTM A790.
Release of every tube depends on one of two ASTM A789 checks, a hydrostatic test or a nondestructive electric test. Lot testing then covers tension (one tube for lots of up to 50, two above that), flaring of one tube end per lot to at least 10% inside-diameter expansion, and Brinell or Rockwell hardness on two tubes, with the set repeated for every heat in a mixed-heat lot. Our EN 10204 3.1 (3.2 on request) certificate records each result, and an independent inspector can witness the tests on request.
Chemical Composition of Seamless S32550 Super Duplex Steel Tube
Copper at 1.50 to 2.50% is the defining addition in S32550 and improves its resistance to sulfuric acid; carbon may reach 0.04%, slightly above the 0.030% set for S32750, S32760 and S32950. ASTM A789 sets the limits below (percent; single figures are maxima), and the heat analysis on the certificate of every seamless S32550 super duplex steel tube has to sit within them:
- CrChromium, 24.0 to 27.0
- NiNickel, 4.5 to 6.5
- MoMolybdenum, 2.9 to 3.9
- CuCopper, 1.50 to 2.50
- MnManganese, 1.50 max
UNS S32550S32550
| Element | UNS S32550, ASTM A789 (%) |
|---|---|
| C (Carbon) | 0.04 max |
| Mn (Manganese) | 1.50 max |
| P (Phosphorus) | 0.040 max |
| S (Sulfur) | 0.030 max |
| Si (Silicon) | 1.00 max |
| Ni (Nickel) | 4.5 to 6.5 |
| Cr (Chromium) | 24.0 to 27.0 |
| Mo (Molybdenum) | 2.9 to 3.9 |
| N (Nitrogen) | 0.10 to 0.25 |
| Cu (Copper) | 1.50 to 2.50 |
Super Duplex Steel S32550 Seamless Tube Mechanical Properties
Super Duplex Steel UNS S32550 Seamless Tubes are supplied heat treated, and ASTM A789 sets the minimums below for that condition. They match the ASTM A790 values for the same grade, so one set of design figures serves a mixed tube and pipe package.
| Property | Requirement under ASTM A789 |
|---|---|
| Tensile Strength, min | 760 MPa (110 ksi) |
| Yield Strength, min | 550 MPa (80 ksi) |
| Elongation in 50 mm (2 in.), min | 15% |
| Hardness, max (Brinell) | 297 HBW |
| Hardness, max (Rockwell) | 31 HRC |
| Hardness, max (Vickers) | 295 HV |
Because the yield floor sits at 550 MPa, a pressure calculation in this grade usually returns a lighter wall than austenitic stainless steel needs for the same rating, trimming bundle weight. For tube under 12.7 mm OD, elongation is judged on strip specimens.
S32550 Super Duplex Steel in Other Designation Systems
Data sheets and older drawings may name the grade by any of these designations; our certificates state UNS S32550 and ASTM A789.
- UNSS32550
- ASTM / ASME (tube)ASTM A789 / ASME SA-789
- EN number (WNR)1.4507
- EN steel nameX2CrNiMoCuN25-6-3 (EN 10216-5)
- Common name255
Treat 1.4507 as a pointer rather than a match: Europe assigns the same number to UNS S32520, which A789 lists with its own composition and strength limits. An inquiry for seamless 1.4507 super duplex tube is therefore quoted as UNS S32550 only once you confirm that grade.
When to Specify S32550 Super Duplex Stainless Steel Seamless Tube
Compared with UNS S32750 seamless tubes, S32550 holds less nickel (4.5 to 6.5% against 6.0 to 8.0%) and a narrower molybdenum band (2.9 to 3.9% against 3.0 to 5.0%), but adds copper. Its A789 minimums are 760 MPa tensile and 550 MPa yield, against 800 MPa and 550 MPa for S32750, with hardness capped at 297 HBW against 300 HBW. Specify S32550 super duplex stainless steel seamless tube where your process licensor or materials engineer names it for acid service. S32750, for its part, must meet an A789 pitting-index minimum, Cr + 3.3Mo + 16N of at least 41, which the standard attaches to S32750 but not to S32550.
If the service review clears a 22Cr duplex grade instead, our UNS S32205 seamless tubes offer A789 minimums of 655 MPa tensile and 485 MPa yield at a lower alloy content.
OD, Wall and Length Tolerances for Seamless WNR 1.4507 Tube
ASTM A789 permits the variations below for tube up to 203.2 mm OD. Above that size, up to our 720 mm limit, A789 lists no tolerance row, so state the limits your design needs on the inquiry.
| Group | OD Range, mm (in.) | OD Variation, mm | Average Wall | Minimum Wall | Cut Length, mm |
|---|---|---|---|---|---|
| 1 | Up to 12.7, excl. (1/2) | ±0.13 | ±15% | +30% / 0 | +3 / 0 |
| 2 | 12.7 to 38.1, excl. (1/2 to 1-1/2) | ±0.13 | ±10% | +20% / 0 | +3 / 0 |
| 3 | 38.1 to 88.9, excl. (1-1/2 to 3-1/2) | ±0.25 | ±10% | +20% / 0 | +5 / 0 |
| 4 | 88.9 to 139.7, excl. (3-1/2 to 5-1/2) | ±0.38 | ±10% | +20% / 0 | +5 / 0 |
| 5 | 139.7 to 203.2, incl. (5-1/2 to 8) | ±0.76 | ±10% | +20% / 0 | +5 / 0 |
Swipe sideways to see the full table.
A789's footnotes relax the wall limits in two cases. With a wall of 19 mm or heavier, or a bore of 60% of the OD or less, an average-wall order may vary ±12.5% and a minimum-wall order +25.0% / 0. Tube under 12.7 mm ID that cannot be drawn over a mandrel may vary ±15% on average wall or +30% / 0 on minimum wall.
A tube counts as thin-walled below 1.6 mm wall in group 2, 2.4 mm in group 3 and 3.8 mm in groups 4 and 5. For those tubes A789 tolerates ovality: maximum and minimum diameters at a cross section may stray from nominal by double the table OD variation, while the mean diameter at that section must still meet the table.
Where Seamless 1.4507 Super Duplex Tube Is Used
Our S32550 seamless tubing serves heat transfer and process duty in chemical, pulp, power, desalination and oil and gas plants, wherever acids and chlorides act on the tube together.
Sulfuric Acid Coolers
In sulfuric acid plants, acid coolers are a core duty for this copper-bearing grade, and each new or replacement bundle is drawn to the tube count, OD and wall on its exchanger data sheet.
Wet Scrubber Tubing for Flue Gas Cleaning
Tubing in wet flue gas desulfurization scrubbers meets acidic liquor carrying abrasive solids, and S32550 is chosen for that circuit because it pairs corrosion resistance with resistance to abrasion and erosion.
Chlorine Dioxide Bleaching Stages
Pulp mills run heat exchange and process tubing through chlorine dioxide bleaching stages and liquor systems, where hot, chloride-bearing chemicals call for a high-alloy duplex grade.
Seawater Reverse Osmosis Trains
High-pressure sections of seawater reverse osmosis trains carry pumped seawater into the membrane vessels and pressurized brine out of them, a duty that pairs high chloride levels with sustained pump pressure.
Downhole and Sour Gas Lines
Oil and gas operators run S32550 seamless tubing in downhole equipment and subsea lines carrying sour gas, where high strength and chloride resistance must come from one material.
Crating and Shipment of Seamless S32550 Tube Bundles
Crating
One size per wooden case or strapped lift, with timber spacers supporting the long lengths.
Tube marking
Grade, ASTM A789, heat number, size and the average or minimum wall basis on each super duplex steel S32550 seamless tube, with project tag numbers on request.
Bore protection
A plastic cap is pushed into each tube end before the case is closed.
Paperwork
An EN 10204 3.1 (3.2 on request) certificate per lot, plus the shipping documents your consignee needs for import clearance.
Terms
FOB, CFR or CIF, named in the quotation.
Shipping reach
Any Thai site, plus export consignments to Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
S32550 Super Duplex Seamless Tubing Price per kg
For guidance only, an ASTM A789 UNS S32550 seamless tube order currently falls around USD 9 to 15 per kg. The rate climbs as OD and wall shrink and as quantities get smaller, and it also reflects the wall basis, cut lengths and any testing added to the A789 minimum. Your tube schedule earns a firm figure from Thaida.
Indicative price, Super Duplex Steel UNS S32550 Seamless Tubes
USD 9 to 15 per kg
Indicative only. Send your sizes and specification to Thaida for a firm quotation.
- Outside diameter
- Wall thickness
- Schedule
- Length
- Quantity
- Testing and certification
Ordering from Our Ban Bueng Mill
The mill that pierces, draws and heat treats our Super Duplex Steel UNS S32550 Seamless Tubes stands at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Each tube list is priced, and its order documents issued, at our office at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand. Delivery is quoted size by size, so a mixed tube list shows which items can leave the mill first.
Factory154 Moo.1 Map Phai, Ban Bueng,
Chonburi 20170, Thailand
Chonburi 20170, Thailand
Office89/18 Moo.15 Enterprize Park, Bangna-Trad Road,
Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand
Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand
Exporting to
- Singapore
- Malaysia
- Vietnam
- Indonesia
- Philippines
- India
Frequently Asked Questions on Tolerances, Tests and Retubing
Which OD tolerance applies to S32550 seamless tube between 88.9 and 203.2 mm OD?
Two bands apply under ASTM A789: ±0.38 mm from 88.9 mm up to 139.7 mm OD, and ±0.76 mm from 139.7 to 203.2 mm. For walls under 3.8 mm in those sizes, single readings may reach twice the band while the mean stays inside it, so baffle and tube-sheet drilling should allow for that ovality.
Should S32550 seamless tubing for acid coolers be specified on minimum wall?
Yes, when the cooler design adds a corrosion allowance to a calculated thickness, because a minimum-wall order guarantees that figure: A789 permits 0% under and up to 20% over (30% below 12.7 mm OD). An average-wall order swings ±10% (±15% below 12.7 mm OD) around nominal, so some tubes run thinner than stated.
Does every tube get a hydrostatic test, or can an electric test replace it?
A789 accepts either, and no tube leaves without one; the choice falls to us unless you write one into the order. The electric route means ultrasonic, eddy current or flux leakage examination. A specified hydrostatic test holds P = 441.2 t/D MPa (t wall, D OD) for at least 5 seconds, and never needs to exceed 7 MPa.
How much over the ordered length may a long tube be cut?
None may be short. Up to 7.3 m, ASTM A789 permits +3 mm on tubes below 38.1 mm OD and +5 mm from 38.1 to 203.2 mm OD. For longer tubes, every 3 m beyond 7.3 m, with any remainder treated as a full 3 m, adds 3 mm to that allowance, up to 13 mm extra.
Can you retube an existing exchanger with UNS S32550 seamless tubes?
Yes, once the bundle design or your engineer confirms S32550 for that service. Copy the tube details from the original bundle drawing, including whether the wall was specified as average or minimum, and the new tubes are drawn to those dimensions so they fit the holes already drilled in the tube sheet, in lengths up to 22 m.
Which hardness test applies to small-bore tube in this grade?
Brinell or Rockwell testing on two tubes from each lot, with limits of 297 HBW or 31 HRC. Where the inside diameter is under 9.00 mm or the wall is under 1.65 mm, ASTM A789 allows Vickers testing instead, against a 295 HV maximum. All results appear on the lot certificate.
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or email sales@thaida.co.th