Sulfuric Acid Heat Exchangers
Chemical plants fit the tube in heat exchangers and acid coolers that run sulfuric acid streams, and in the transfer lines and pickling circuits feeding them, relying on copper and molybdenum for acid resistance.
ASTM B729 / UNS N08020 / W.Nr. 2.4660
Nickel Alloy 20 Seamless Tubes Manufacturer in Thailand
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. offers Nickel Alloy 20 seamless tubes produced at its Ban Bueng, Chonburi plant to ASTM B729, in UNS N08020 (W.Nr. 2.4660), for heat exchangers, condensers and feedwater heaters in corrosive service. Within our nickel alloy seamless tubes range the grade is a niobium-stabilized nickel-iron-chromium-molybdenum-copper alloy, one of three iron-bearing nickel alloys. Each tube is cold drawn to the ordered OD and wall, and our Bang Phli, Samut Prakan office prepares quotations, test plans and certificates.
Nickel Alloy 20 seamless tubeUNS N08020 / W.Nr. 2.4660
- 6 to 457 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
ASTM B729 Alloy 20 Seamless Tube Specifications
Every tube line under ASTM B729 is written as an outside diameter with an average or a minimum wall, followed by length and quantity. The table gives the range we quote and the condition, tests and documents that go with each tube.
- Standard
- ASTM B729
- Grade
- Alloy 20 (UNS N08020)
- Outside Diameter
- 6 to 457 mm
- Wall Thickness
- 1 to 65 mm
- Length
- Up to 22 mcut to length or random
- Ordering Basis
- Outside diameter and average or minimum wall thickness
- Manufacturing Route
- 1Seamless
- 2Hot extruded from billet and cold drawn
- Delivery Condition
- Stabilized-annealed
- Ends
- Plaincut and deburred; other end preparation when the order gives the details
- Testing
- Hydrostatic or nondestructive electric test on each tube
- Chemical analysis and tension test per lot
- Certification
- Manufacturer's certification and test report with every order
- Test Certificate
- EN 10204 3.13.2 on request
ASTM B729 is the seamless pipe and tube standard for UNS N08020 and two related alloys, covering cold-worked or hot finished product intended for general corrosive service. It names the grade by UNS number only, so UNS N08020 is what the tube marking and the certificate carry, with Alloy 20 kept as the commercial name. Nickel Alloy 20 seamless pipes share the same chemistry and strength rules but are ordered by NPS and schedule rather than by tube dimensions.
The same standard makes a manufacturer's certification and a report of the test results mandatory on every order. We issue them together as an EN 10204 3.1 (3.2 on request) material test certificate for each ASTM B729 Alloy 20 seamless tube consignment. Witness points at our mill go on the purchase order test by test, and independent third-party inspection is available on request.
Hydrostatic or Electric Test on Every UNS N08020 Seamless Tube
ASTM B729 requires each seamless Alloy 20 tube in a lot to pass either a hydrostatic test or a nondestructive electric test. The method is chosen by the manufacturer unless the purchase order names it, while chemical analysis and the tension test are made once per lot.
Hydrostatic Test With Full-Length Leak Examination
The tube is pressurized to 1000 psi (6.9 MPa), or to a lower pressure where that figure would exceed the allowable fiber stress for the alloy, and the pressure is held for at least 5 s. Visual examination is made while the tube is under pressure, and its full length must be examined for leaks.
Nondestructive Electric Test
When the electric test is the method used, each tube is examined by eddy current or by ultrasonic testing, two methods that stand as equal options. It takes the place of the hydrostatic test for that tube, and its result goes into the test report delivered with the order.
Chemical Composition of Seamless Nickel Alloy 20 Tube
Table 1 of ASTM B729 fixes the limits below for UNS N08020, with iron as the remainder. One chemical analysis is made for each lot, and the result on the certificate is read against these values.
- FeIron, Remainder (by difference)
- NiNickel, 32.00 to 38.00
- CrChromium, 19.00 to 21.00
- NbNb + Ta (Niobium plus Tantalum), 8 x C min, 1.00 max
- CuCopper, 3.00 to 4.00
UNS N0802020
| Element | Limit per ASTM B729 (%) |
|---|---|
| C (Carbon) | 0.07 max |
| Mn (Manganese) | 2.00 max |
| P (Phosphorus) | 0.045 max |
| S (Sulfur) | 0.035 max |
| Si (Silicon) | 1.00 max |
| Ni (Nickel) | 32.00 to 38.00 |
| Cr (Chromium) | 19.00 to 21.00 |
| Mo (Molybdenum) | 2.00 to 3.00 |
| Cu (Copper) | 3.00 to 4.00 |
| Nb + Ta (Niobium plus Tantalum) | 8 x C min, 1.00 max |
| Fe (Iron) | Remainder (by difference) |
Niobium plus tantalum is set against the carbon content: at least eight times the carbon, with 1.00% as the ceiling. That addition is what makes the alloy niobium-stabilized.
Mechanical Properties of Seamless Alloy 20 Tube
ASTM B729 prints one row of minimums with no split by condition or outside diameter, so the smallest and the largest seamless nickel alloy 20 tube in our range are read against the same figures.
| Property | Minimum |
|---|---|
| Tensile strength | 80 ksi (550 MPa) |
| Yield strength (0.2% offset) | 35 ksi (240 MPa) |
| Elongation in 2 in. (50.8 mm) or 4D | 30.0% |
Tube is supplied in the stabilized-annealed condition that ASTM B729 requires for UNS N08020. The ksi values are the requirement and the MPa values are conversions for information; the lot tension test on the certificate is read against this single row.
Equivalent Designations of Alloy 20
Alloy 20 reaches exchanger data sheets under its commercial name, its UNS number or its European material number. ASTM B729 lists the alloy by UNS number; the W.Nr. row serves only to read a European callout and states no conformance to a European standard.
- Commercial nameAlloy 20, also written Nickel Alloy 20
- ASTM B729 (USA)UNS N08020
- Europe (W.Nr.)2.4660
A data sheet calling for seamless WNR 2.4660 tube is entered on our order as UNS N08020 to ASTM B729.
Seamless WNR 2.4660 Tube Sizes and Tolerances
We quote seamless WNR 2.4660 tube from 6 mm to 457 mm OD with walls from 1 mm to 65 mm, in lengths up to 22 m, cut to length or random. A tube ordered to nominal (average) wall is held to the plus-and-minus wall column below, and a tube ordered to minimum wall takes the plus-only column.
Nickel Alloy 20 seamless tubes are measured against the permitted variations that apply to ASTM B729 cold-worked tube:
| OD Band, mm (in.) | OD Tolerance (mm) | Average (Nominal) Wall | Minimum Wall |
|---|---|---|---|
| Up to 10 (0.400), incl. | ±0.10 | ±15.0% | +30% / 0 |
| Over 10 to 16 (5/8), excl. | ±0.13 | ±15.0% | +30% / 0 |
| 16 (5/8) to 38 (1 1/2), incl. | ±0.19 | ±10.0% | +22% / 0 |
| Over 38 to 76 (3), incl. | ±0.25 | ±10.0% | +22% / 0 |
| Over 76 to 114 (4 1/2), incl. | ±0.38 | ±10.0% | +22% / 0 |
| Over 114 to 152 (6), incl. | ±0.51 | ±12.5% | +28% / 0 |
| Over 152 to 168 (6 5/8), incl. | ±0.64 | ±12.5% | +28% / 0 |
| Over 168 to 219 (8 5/8), incl. | ±0.79 | ±12.5% | +28% / 0 |
| Over 219 to 356 (14), incl. | +1.57 / -0.79 | +15.0% / -12.5% | +30.0% / 0 |
| Over 356 to 610 (24), incl. | +3.18 / -0.79 | +15.0% / -12.5% | +30.0% / 0 |
Swipe sideways to see the full table.
The limits apply to individual measurements, eccentricity included, and they include ovality except in two cases. Thin-wall tube, with a wall of 3% of OD or less, is judged on its mean OD, and single readings may go 0.5% of the nominal OD beyond the table. Tube above 114 mm OD with a wall over 3% of OD is also judged on its mean OD, with single readings allowed up to twice the table value. Our 457 mm maximum falls inside the last band.
| OD (mm) | Cut Length Tolerance (mm) |
|---|---|
| Under 50.8 | +3.2 / 0 |
| 50.8 and over | +4.8 / 0 |
The cut-length limits hold up to 7.3 m. Each further 3 m, or part of it, adds 3.2 mm to the plus side, to no more than 12.7 mm extra, and random lengths with their variation are agreed on the order.
Seamless 2.4660 Alloy Tube and Related Grades
Seamless 2.4660 alloy tube and Alloy 31 seamless tubes are both iron-bearing nickel alloys, bought under different standards. Alloy 31 is made to ASTM B622, supplied solution annealed and descaled, with minimums of 94 ksi (650 MPa) tensile, 40 ksi (276 MPa) yield and 40% elongation, and its certification applies when the order specifies it. Alloy 31 carries 6.0 to 7.0% molybdenum against 2.00 to 3.00% in Alloy 20, while Alloy 20 holds more copper, 3.00 to 4.00% against 1.0 to 1.4%. For an exchanger that needs no nickel alloy at all, stainless steel 316L seamless tubes are the lower-alloy option under their own stainless tube standard.
Industrial Applications of Seamless N08020 Tube
Seamless 2.4660 alloy tube goes where sulfuric acid, acid cleaning solutions or seawater meet a heat transfer surface: exchangers, condensers, feedwater heaters and coolers in chemical, refining, power, pharmaceutical, marine and food plants.
Alkylation and Refinery Condensers
Refineries and sulfuric acid plants install the tube in alkylation units and condensers, where each bundle is ordered tube by tube to an outside diameter and an average or minimum wall.
Feedwater Heaters and Power Plant Condensers
Power stations specify the alloy for boiler feedwater heaters, condensers and chemical dosing lines, ordering long cut lengths for the exchanger shells and a hydrostatic or electric test on each tube.
Pharmaceutical Heating Loops
Pharmaceutical plants run process lines and heating loops in the tube, along with the acid wash streams that clean their reactors between batches, each tube traceable to its heat number.
Seawater Cooling and Brine Heaters
Marine and coastal plants use the tube in seawater cooling systems, intake lines, brine heaters and heat exchangers, where its molybdenum helps it resist pitting and crevice attack from salt exposure.
Food Plant Heat Exchangers and Wash Circuits
Food processing plants take the tube for heat exchangers, steam lines and wash circuits carrying hot cleaning fluids, with one set of OD and wall tolerances applied across the whole tube set.
Shipping and Packaging of Seamless 2.4660 Tube
Packing
Full-length tubes in strapped bundles, small OD and cut tubes in wooden cases, end caps on every tube.
Marking
Every tube of 19.0 mm OD and larger and longer than 914 mm shows the manufacturer's name or brand, UNS N08020, ASTM B729, the heat number and the nominal size; smaller or shorter tubes are marked on each piece or on a tag fixed to the bundle or box.
Documents
EN 10204 3.1 (3.2 on request) certificate carrying the ASTM B729 test report, with a packing list for every bundle or case.
Terms
FOB, CIF or CFR, with the loading port stated in the offer.
Dispatch
Production slot and shipping date given on the order acknowledgment.
Price per kg of Seamless Alloy 2.4660 Tube
Seamless Alloy 20 tube is indicatively priced at USD 22 to 45 per kg. The figure follows the nickel market first, with molybdenum and copper second. Small outside diameters and thin walls take more cold-drawing passes for each kilogram than heavier sizes, while cut lengths, small lots and the test on each tube move a quote toward the upper end. Send your tube list for a firm price.
Indicative price, Nickel Alloy 20 Seamless Tubes
USD 22 to 45 per kg
Indicative only. Send your sizes and specification to Thaida for a firm quotation.
- Outside diameter
- Wall thickness
- Length
- Testing and certification
- Nickel price
- Molybdenum price
- Copper price
Manufacturing Plant and Sales Office
Nickel Alloy 20 seamless tubes are drawn, tested and packed at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Our sales office at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand, handles quotations, order acknowledgments and export documents. We supply projects across Thailand and export to Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
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
Nickel Alloy 20 Seamless Tube FAQ
Which test should I name on an Alloy 20 order, hydrostatic or electric?
Name one only when your exchanger specification demands it; otherwise ASTM B729 leaves the choice to us. The hydrostatic test proves the full length leak-tight under pressure, while the eddy current or ultrasonic test screens the tube for imperfections. Write the chosen test on each line of the purchase order and we apply it to every tube.
Can Alloy 20 be tested above the standard hydrostatic pressure?
Yes. State the test pressure on the order where it differs from the standard requirement; ASTM B729 also allows tube to be tested to one and one-half times the allowable fiber stress when we agree it with you. Give the exchanger design pressure with your inquiry and we confirm the test pressure for each tube size.
Should I order Alloy 20 to average wall or minimum wall?
Order minimum wall when your design calculation fixes the thinnest acceptable wall, and average wall when the drawing gives a nominal thickness. The tolerance follows the choice: for a tube from 16 to 38 mm OD, an average-wall order may vary by 10.0% either way, while a minimum-wall order allows plus 22% and nothing under.
How are surface marks treated in the electric test of Alloy 20?
They are judged rather than counted as defects automatically. ASTM B729 lists dinges, straightener marks, scratches, steel die stamps and stop marks as imperfections whose test signals may be judged injurious or noninjurious, from a visual check of their severity, from the type of signal they produce on the testing equipment, or from both.
Can a leaking Alloy 20 length be saved after the hydrostatic test?
Only in part. ASTM B729 rejects any tube that leaks under the hydrostatic test, but the leaking area may be cut out and the remaining length retested. The shorter piece must still meet the ordered length: cut lengths carry a plus tolerance only, and random lengths stay within the range agreed on the order.
Is Alloy 20 used in feedwater heaters and condensers?
Yes. In feedwater heaters and condensers the tube resists corrosion from acidic deposits inside the tubing. For these duties send the shell drawing, tube count, OD, wall basis and design conditions, and our offer proposes the test method and cut lengths for each item.
What does the Alloy 20 test certificate report?
It carries the manufacturer's certification that the tube was manufactured, tested and inspected to ASTM B729 and that results on representative samples meet its requirements, with the report of those results: lot chemical analysis, lot tension test and the test on each tube. We issue it as EN 10204 3.1 (3.2 on request), matched to the marked heat number.
Request a Quote for Nickel Alloy 20 Seamless Tubes
or email sales@thaida.co.th