ASTM B983 / UNS N07718 / W.Nr. 2.4668
Solution annealed and precipitation hardened before dispatch, Inconel 718 seamless tubes from Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. are produced to ASTM B983 at our Ban Bueng, Chonburi mill. Every length is UNS N07718 (W.Nr. 2.4668), the age-hardenable member of our Inconel seamless tubes range, chosen for hydraulic, fuel and control lines designed on a high yield minimum. Drawings sent for review, quotations and export paperwork are handled in Bang Phli, Samut Prakan, where our office is based.
Inconel 718 seamless tubeUNS N07718 / W.Nr. 2.4668
EN 10204 3.1 certificate / 3.2 on request
ASTM B983 has tube ordered on its outside diameter, a minimum or an average wall, and a length; our quotations use the same basis. The table sets out the UNS N07718 range we produce, the condition it is delivered in, and the checks completed before release.
Tube in this grade is made to one product standard only: ASTM B983, Standard Specification for Precipitation Hardened or Cold Worked, Seamless Nickel Alloy Pipe and Tube. B983 ties its chemistry, strength and hardness limits for this alloy to the UNS number N07718, so an ASTM B983 Inconel 718 seamless tube is certified under that number, whichever commercial name appears on the drawing. Lines specified by pipe size and schedule are covered by our Inconel 718 seamless pipes, made under the same standard.
Every tube passes one of two release tests before it leaves the mill: hydrostatic pressure, or nondestructive electric examination. Chemistry and tensile properties are checked once per lot, the tensile specimen being cut after the final heat treatment and pulled along the direction of fabrication. The results appear on an EN 10204 3.1 (3.2 on request) certificate, and a third-party inspector named on the order can witness them.
Iron makes up the balance of UNS N07718 seamless tube once the other elements are met. Six elements carry both a lower and an upper limit, nickel at 50.0 to 55.0% and chromium at 17.0 to 21.0% among them, and eight more are capped at a maximum only.
UNS N07718718
| Element | ASTM B983 Limit, % |
|---|---|
| Ni (Nickel) | 50.0 to 55.0 |
| Cr (Chromium) | 17.0 to 21.0 |
| Fe (Iron) | Remainder |
| Nb (Niobium) | 4.75 to 5.50 |
| Mo (Molybdenum) | 2.80 to 3.30 |
| Ti (Titanium) | 0.65 to 1.15 |
| Al (Aluminum) | 0.20 to 0.80 |
| Co (Cobalt) | 1.0 max |
| C (Carbon) | 0.08 max |
| Mn (Manganese) | 0.35 max |
| Si (Silicon) | 0.35 max |
| P (Phosphorus) | 0.015 max |
| S (Sulfur) | 0.015 max |
| B (Boron) | 0.006 max |
| Cu (Copper) | 0.30 max |
Columbium is the label B983 prints on the niobium row, and boron, at 0.006% maximum, is the tightest cap in the table. The certificate reports the heat analysis against every row.
B983 Table 3 gives N07718 one row: three minimums for strength and ductility plus one maximum for hardness, all for seamless nickel alloy 718 tube in its solution annealed plus precipitation hardened state.
| Property | ASTM B983 Requirement |
|---|---|
| Condition | Solution annealed plus precipitation hardened |
| Tensile Strength, min | 150 ksi (1034 MPa) |
| Yield Strength, min | 125 ksi (862 MPa) |
| Elongation in 2 in. (50 mm) or 4D, min | 20% |
| Hardness, max | Rockwell C 40 |
Hardness appears in Table 3 as a maximum rather than as a test schedule: B983 fixes lot frequencies for chemistry and tension only and attaches no sampling rule to the Rockwell C 40 figure.
Drawings from Europe, Japan and China often name the alloy by a national number instead of its UNS designation. The rows below line those numbers up with N07718 for cross-reference only; B983 itself prints the UNS number alone and implies no conformity to the other systems.
Seamless Inconel 718 tube leaves our mill in one condition: solution annealed, then precipitation hardened. B983 lets its alloys be supplied cold worked, or cold worked and aged, as well, but Table 3 gives N07718 properties only after the full solution-and-age sequence. Heat-treatment scale is removed before dispatch unless the furnace atmosphere was controlled, the one case in which B983 lets descaling be skipped.
B983 gives solution and aging cycles only in its heat-treatment table, under columns headed Recommended, so the cycle itself is not an acceptance point. Acceptance rests on the tube: in the condition it arrives in, it must reach the Table 3 minimums and stay at or below the Rockwell C 40 ceiling.
We produce seamless WNR 2.4668 tube in outside diameters of 6 to 257 mm, wall thicknesses of 1 to 35 mm and single lengths reaching 22 m. Each size is quoted to OD and to either minimum or average wall, the two wall bases ASTM B983 recognizes for tube.
Clause 14.1 of ASTM B983 applies the standard's own Table 4 to hot-finished tube. Because our seamless 718 tube is delivered precipitation hardened, clause 14.2 can instead place it under a separate set of cold-worked limits that also govern straightness and ovality, so Table 4 is not the only possible regime and every quotation line names the one it is offered against. The two Table 4 bands that cover the upper part of our tube range are:
| Nominal OD, in. (mm) | OD Tolerance, in. (mm) | Nominal Wall | Minimum Wall |
|---|---|---|---|
| Over 4 (102) to 9 1/4 (235), incl. | +0.062 (1.6) / -0.031 (0.8) | ±12.5% | +28.5% / 0 |
| Over 9 1/4 (235) to 12 (305), incl. | ±0.110 (2.8) | ±12.5% | None listed |
Swipe sideways to see the full table.
In these sizes the 5 in. (127 mm) mark matters. At or below it, every single reading must fall within the band with ovality counted; above it, the mean diameter must stay inside the band and any one reading may reach double the band. Our 257 mm maximum sits inside the second band, which Table 4 extends to 305 mm.
Inconel 625 seamless tubes come in an annealed Grade 1 and a solution-annealed Grade 2, neither with an aging step nor a hardness limit. Seamless alloy 2.4668 tube is aged to a higher yield minimum and carries the Rockwell C 40 cap. Both grades share our 6 to 257 mm OD and 1 to 35 mm wall range, so strength, not size, usually settles the choice.
Inconel 600 seamless tubes are supplied annealed as condenser and heat-exchanger tube, with a yield minimum of 241 MPa against 862 MPa for aged 718 and no hardness limit. That tube is made up to 457 mm OD and 65 mm wall, beyond the 257 mm and 35 mm we reach in 718.
Alloy 718 seamless tube goes into fluid, fuel, propellant, heat-exchange and well-control lines, each designed around the precipitation-hardened strength row.
Hydraulic and pneumatic lines in aerospace fluid systems call for fracture-resistant tubing, and UNS N07718 seamless tube supplies it in small diameters ordered to minimum wall, so no point falls below the drawing thickness.
Gas turbine fluid systems route fuel and gases through a high-stress zone of the engine in seamless Inconel 718 tube, whose 125 ksi yield minimum is confirmed by a tension test on every lot.
Transfer lines that move liquefied gases, rocket propellant among them, use seamless nickel alloy 718 tube for a strong bore with no weld seam, in single lengths of up to 22 m.
Feed lines controlling the flow of highly reactive propellants depend on the strength and erosion resistance of Alloy 718 seamless tube, supplied descaled and traceable to its heat number.
Exchangers that see large pressure and temperature differences across the tube wall are tubed in seamless 2.4668 tube, held to its OD tolerance so each tube seats correctly in the tubesheet.
Injection and control lines in corrosive, high-pressure oil and gas wells run in seamless alloy 2.4668 tube, which pairs balanced corrosion resistance with the aged strength of the alloy.
Packing
Small-diameter tube in seaworthy wooden cases, larger sizes in wrapped bundles, with plastic caps on every open end.
Identification
Each tube carries its heat number and size beside UNS N07718 and ASTM B983; tubes too small or short to mark are identified by a tag on their bundle.
Paperwork
The invoice and packing list travel with the EN 10204 3.1 (3.2 on request) certificate, all keyed to the same heat numbers.
Trade terms
CFR, CIF or FOB, with the destination port set by you.
Loading
Cases sized for container stowage, with one heat per case when the order asks for separation.
Inconel 718 seamless tube sits in an indicative band of USD 26 to 60 per kg. Movements in the nickel market shift that band most, with niobium and molybdenum behind it; inside the band, a short run of small-OD tube ordered to minimum wall is priced differently from a long run of large sizes, and witnessed or extra testing adds to the figure. A firm price comes as a dated quotation against your size list.
Indicative only. Send your sizes and specification to Thaida for a firm quotation.
Production takes place at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Quotations and shipping documents are prepared at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand. Plants in Thailand receive seamless alloy 2.4668 tube directly, and export consignments go to Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
It means the tube is solution annealed and then aged before dispatch, so it arrives at the ASTM B983 strength row ready to install. If welding or forming comes first, tell us at inquiry, since the standard's nonmandatory appendix links optimum performance to proper heat treatment during or after fabrication and refers you to the manufacturer.
It marks the hard side of the aged condition. Tube that reads above Rockwell C 40 falls outside ASTM B983 however strong it tests, just as tube below the tension minimums does. If your inspection plan includes hardness, list it on the order and we add the measured value to the certificate.
150 ksi (1034 MPa) tensile, 125 ksi (862 MPa) yield and 20% elongation, checked once per lot on a specimen of full tube section where the size permits. If that test fails, two more specimens from different sample pieces are tested, and both must pass before the lot is released.
Over 4 in. (102 mm) to 9 1/4 in. (235 mm), incl., OD may run +0.062 in. (1.6 mm) / -0.031 in. (0.8 mm), with minimum wall available at +28.5% / 0. Over 9 1/4 in. to 12 in. (305 mm), incl., OD is ±0.110 in. (2.8 mm) and no minimum-wall figure exists, so order nominal wall (±12.5%).
Specify 718 when the line is sized on yield strength: 862 MPa minimum in the aged condition, against 414 MPa for 625 Grade 1 and 276 MPa for Grade 2. Elongation favors 625, at 30% minimum against 20% for 718, and 625 needs no aging step. If both could work, name both on one inquiry and we quote each.
Outside diameter 6 to 257 mm, wall 1 to 35 mm and lengths up to 22 m. A line larger than 257 mm OD or heavier than 35 mm wall is quoted as seamless pipe in the same grade, which we produce to 457 mm and 65 mm, ordered by pipe size and schedule.
An EN 10204 3.1 (3.2 on request) certificate reporting heat chemistry, lot tensile results and the pressure or electric test passed by each tube, together with the packing list and invoice. Heat numbers on the certificate match the tube marking, and an inspection report is added when your order names a third-party inspector.
Request a Quote for Inconel 718 Seamless Tubes
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