Aircraft Exhaust Manifolds
Aircraft exhaust manifolds are bent and welded from seamless stainless steel 321 pipe, then pass through a heating and cooling cycle every time the engine starts and stops.
ASTM A312 / ASME SA-312 / UNS S32100 / W.Nr. 1.4541
Stainless Steel 321 Seamless Pipes Manufacturer in Thailand
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd. manufactures ASTM A312 TP321 titanium-stabilized seamless pipes at its Ban Bueng, Chonburi works in Thailand for welded lines that pass through the sensitizing range in service. Titanium ties up carbon as titanium carbide, keeping chromium in solution beside every weld, and the grade is identified as UNS S32100 and WNR 1.4541 within our seamless stainless steel pipe family. Line lists sent to our office in Bang Phli, Samut Prakan, are checked against A312 before quoting.
Stainless Steel 321 seamless pipeUNS S32100 / W.Nr. 1.4541
- 6 to 1016 mmOutside diameter
- 1 to 65 mmWall thickness
- Up to 18 mLength
- EN 10204 3.1Test certificate
EN 10204 3.1 certificate / 3.2 on request
Production Range of SS 321 Seamless Pipe
Each SS 321 seamless pipe leaves the mill hot finished or cold finished, solution annealed and rapidly cooled. Check size, ends and finish against your line list.
- Standard
- ASTM A312 / ASME SA-312
- Grade
- TP321 (UNS S32100)
- WNR
- 1.4541 (X6CrNiTi18-10)
- Outside Diameter
- 6 to 1016 mm
- Wall Thickness
- 1 to 65 mm
- Length
- Up to 18 mcut lengths to order
- Dimensions
- NPS 1/8 to 30 to ASME B36.19, Sch 5S, 10S, 40S and 80S as listed for each size, or OD and wall to drawing
- End Type
- Plain endbeveled end; threaded end on Sch 40S and 80S
- Surface Finish
- Pickled and annealed (AP), bright annealed (BA), polished, mirror or brushed
- Form
- Seamlesshot finished or cold finished
- Heat Treatment
- Solution annealed at 1040 °C (1900 °F) minimum, water quenched or rapidly cooled
- Test Certificate
- EN 10204 3.13.2 on request
Heat exchanger bundles and instrument runs that are specified by exact tube OD are made in our stainless steel 321 seamless tubes range.
Production follows ASTM A312 / ASME SA-312. For TP321 it sets the ratio of titanium to carbon plus nitrogen, gives one strength level for walls up to 9.50 mm and a lower one above, and requires every length to be heat treated. Pipe outside the A312 dimension table is made when it meets all other requirements of the standard.
An EN 10204 3.1 (3.2 on request) certificate covers every heat. A312 calls for a tension test on every lot of up to 100 pipes, flattening tests, and a hydrostatic or nondestructive electric test on every length, with the method left to the mill unless the order names one. When your order lists them, we add product analysis under S1 and an ASTM A262 Practice E intergranular corrosion test under S7.
UNS S32100 Seamless Pipe Composition Limits
TP321 is a chromium-nickel austenitic grade with 17.0 to 19.0% chromium and 9.0 to 12.0% nickel. Its titanium must reach at least five times the carbon plus nitrogen content, capped at 0.70%. Heat analysis of every UNS S32100 seamless pipe order must fall within these A312 limits:
- CrChromium, 17.0 to 19.0
- NiNickel, 9.0 to 12.0
- TiTitanium, 5 × (C + N) min, 0.70 max
- MnManganese, 2.00 max
- SiSilicon, 1.00 max
UNS S32100321
| Element | TP321 Limit (%) |
|---|---|
| C (Carbon) | 0.08 max |
| Mn (Manganese) | 2.00 max |
| P (Phosphorus) | 0.045 max |
| S (Sulfur) | 0.030 max |
| Si (Silicon) | 1.00 max |
| Cr (Chromium) | 17.0 to 19.0 |
| Ni (Nickel) | 9.0 to 12.0 |
| Ti (Titanium) | 5 × (C + N) min, 0.70 max |
| N (Nitrogen) | 0.10 max |
How Titanium Protects the Weld Zone
Austenitic steel without a stabilizer loses chromium at its grain boundaries when a weld heat-affected zone, or a line that heats and cools in service, passes through the sensitizing range of 425 to 815 °C. Chromium carbides form there, and the depleted band beside them is the first to corrode. Titanium bonds with carbon before chromium can, which is why grade 321 resists sensitization and intergranular corrosion after welding where 304, with no stabilizer, does not. Check titanium, carbon and nitrogen together on the certificate.
Two Strength Levels of Seamless WNR 1.4541 Pipe
A312 gives seamless TP321 two strength levels. Up to 9.50 mm (0.375 in.) nominal wall the full minimums apply; above 9.50 mm, tensile and yield minimums fall to 485 MPa and 170 MPa. The certificate of each seamless 1.4541 stainless steel pipe lot reports its tested values. A312 sets no hardness limit.
| Property | Nominal wall 9.50 mm (0.375 in.) or less | Nominal wall over 9.50 mm |
|---|---|---|
| Tensile Strength, min, MPa (ksi) | 515 (75) | 485 (70) |
| Yield Strength, min, MPa (ksi) | 205 (30) | 170 (25) |
| Elongation in 2 in. or 50 mm (or 4D), min, longitudinal | 35% | 35% |
| Elongation in 2 in. or 50 mm (or 4D), min, transverse | 25% | 25% |
Grade 321 Cross-Reference Designations
Drawings from Europe, Japan, China and Russia name grade 321 by the designations below. Each order is still made to ASTM A312 TP321 under UNS S32100, and the other numbers serve only to match those drawings.
- USA (ASTM / ASME)ASTM A312 / ASME SA-312 TP321
- USA (UNS)UNS S32100
- Europe (EN / WNR)1.4541
- ISOX6CrNiTi18-10
- Japan (JIS)SUS321
- China (GB)S32168 (ISC) / 06Cr18Ni11Ti
- Russia (GOST)08X18H10T
NPS Schedules and OD Limits for Seamless Stainless Steel 321 Pipe
Within our 6 to 1016 mm OD and 1 to 65 mm wall envelope, seamless stainless steel 321 pipe is cut to any length up to 18 m. Expansion joint, exhaust and furnace work often uses the bores below. Nominal walls in mm come from the ASTM A312 dimension table, shown with the OD tolerance for each size:
| NPS | OD (mm) | OD Tolerance (mm) | Sch 5S | Sch 10S | Sch 40S | Sch 80S |
|---|---|---|---|---|---|---|
| 1-1/4 | 42.2 | +0.4 / -0.8 | 1.65 | 2.77 | 3.56 | 4.85 |
| 2-1/2 | 73.0 | +0.8 / -0.8 | 2.11 | 3.05 | 5.16 | 7.01 |
| 5 | 141.3 | +1.6 / -0.8 | 2.77 | 3.40 | 6.55 | 9.53 |
| 10 | 273.1 | +2.4 / -0.8 | 3.40 | 4.19 | 9.27 | 12.70 |
| 14 | 355.6 | +2.4 / -0.8 | 3.96 | 4.78 | 9.53 | 12.70 |
| 18 | 457 | +2.4 / -0.8 | 4.19 | 4.78 | 9.53 | 12.70 |
Swipe sideways to see the full table.
Where the Lower Strength Level Starts
In the table, the 12.70 mm Sch 80S walls at NPS 10, 14 and 18 are clearly above 9.50 mm, so those pipes are tested against 485 MPa tensile and 170 MPa yield, while NPS 10 Sch 40S, at 9.27 mm, keeps the 515 and 205 MPa minimums. The 9.53 mm walls of Sch 80S at NPS 5 and Sch 40S at NPS 14 and 18 sit on the 0.375 in. limit itself. Base pressure design on the level that matches the wall.
Permitted Wall and Length Variation
On every NPS, the wall may be up to 12.5% thinner than nominal. The permitted overage is 20.0% up to NPS 2-1/2; from NPS 3 it is 22.5% where the wall is up to 5% of the OD and 15.0% for heavier walls. Each cut length may exceed the ordered figure by up to 6 mm (1/4 in.) but is never short of it.
Neighboring Grades: 321H, 347 and 316Ti
Three neighboring grades answer different service needs. Our 321H seamless pipes are the H-grade version: carbon between 0.04 and 0.10%, titanium from 4 × (C + N), grain size 7 or coarser, and solution annealing at 1100 °C cold finished or 1050 °C hot finished.
A seamless 347 stainless steel pipe is stabilized with niobium in place of titanium, at no less than ten times the carbon content and no more than 1.00%, and is preferred over 321 for lines that remain in the sensitizing range for long periods. Where chlorides join the heat, 316Ti seamless pipes add molybdenum to the same titanium stabilization.
Exhaust, Bellows and Furnace Uses of 321 Stainless Steel Seamless Pipe
Stainless steel 321 seamless pipes go into welded fabrications that are reheated in service: exhaust systems, expansion joints, furnaces and heat exchangers.
Expansion Joints and Bellows
Connecting ends of expansion joints and bellows are cut from 321 stainless steel seamless pipe and welded to the bellows element, so every joint must resist intergranular attack in the as-welded state.
Furnace Parts
Furnace parts such as radiant tubing and protective sleeves are made from stainless steel 321 seamless pipes, passing through the sensitizing range at every start-up and shutdown of the furnace.
Heat Exchangers
Heat exchangers in high-temperature service are connected with SS 321 seamless pipe, sized by NPS and schedule to mate with the plant piping and welded in place on site.
Shop-Welded Spools for Hot Process Lines
Spools fabricated from ASTM A312 stainless steel 321 seamless pipe serve hot process lines where post-weld heat treatment is not practical, relying on titanium stabilization at every shop weld.
Seamless S32100 Stainless Steel Pipe Packing and Marking
Bundling
Small and mid bores travel in steel-strapped bundles; large bores and polished lengths go in wooden cases.
Marking
ASTM A312 TP321, NPS or OD, schedule or average wall, heat number, SML and the manufacturer's mark are stenciled on each seamless S32100 stainless steel pipe length.
Surface protection
Bright annealed and polished lengths are wrapped before packing so the surface arrives unmarked.
Ends
Beveled and threaded ends are fitted with plastic protectors.
Trade terms
FOB Thailand, or CFR and CIF to the port you name.
Certificates
The EN 10204 3.1 (3.2 on request) certificate is packed with the shipment, its heat numbers matched to the bundle tags.
Indicative Cost of ASTM A312 TP321 Stainless Steel Seamless Pipe
As an indication, ASTM A312 TP321 stainless steel seamless pipe sells at USD 3.5 to 6.5 per kg. Nickel content and the titanium addition set the base, large OD and heavy wall sit toward the top of the band, and quantity, finish, testing and the nickel price on the day fix the final figure. A firm price follows once we have your size list.
Indicative price, Stainless Steel 321 Seamless Pipes
USD 3.5 to 6.5 per kg
Indicative only. Send your sizes and specification to Thaida for a firm quotation.
- Outside diameter
- Wall thickness
- Finish
- Quantity
- Testing and certification
- Nickel price
- Titanium price
Ordering from Our Chonburi Mill
The factory behind every ASTM A312 stainless steel 321 seamless pipe stands at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Our office at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand, prepares quotations, answers technical questions and tracks deliveries. Beyond plants in Thailand, this grade is exported 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
Seamless 1.4541 Stainless Steel Pipe Questions
Does a 9.53 mm wall put seamless TP321 pipe on the lower strength level?
It depends on the unit system of the order. In A312M metric units, 9.53 mm exceeds 9.50 mm, so 485 MPa tensile and 170 MPa yield apply. In inch-pound units the same wall is 0.375 in., which equals rather than exceeds the 0.375 in. limit, so 75 ksi and 30 ksi apply. State the basis on your inquiry.
Can a stabilizing heat treatment be ordered on seamless TP321 pipe?
Yes, as ASTM A312 Supplementary Requirement S6. After solution annealing, the pipe receives a second treatment at a lower temperature agreed between you and Thaida. It applies only when your order names S6, so state it on each line item that needs it.
Is 2B a finish option for SS 321 seamless pipe?
No. 2B is a sheet finish, not a pipe finish. Seamless 321 pipe is delivered pickled and annealed (AP), bright annealed (BA) or polished, and mirror or brushed surfaces can be specified for visible or hygienic sections. Mixed finishes in one order are fine when each item states its own.
Does a hot line in grade 321 call for the H grade instead?
Only when creep governs. A312 states that H grades such as TP321H are intended for service where creep and stress rupture properties are important. If creep is not a design factor and the concern is intergranular corrosion at welds, TP321 is the matching grade.
Can you make seamless S32100 stainless steel pipe smaller than NPS 1/8?
Yes. Our range starts at 6 mm OD, below the 10.3 mm OD of NPS 1/8, and runs to 1016 mm OD with walls of 1 to 65 mm and lengths up to 18 m. Sizes outside the NPS table are ordered by OD and wall and meet every other A312 requirement.
What paperwork comes with a seamless WNR 1.4541 pipe order?
An EN 10204 3.1 (3.2 on request) certificate with heat chemistry and lot tensile results, plus raw material certificates, 100% PMI records, heat treatment charts and surface roughness and size measurements. A government-approved laboratory certificate and third-party inspection are available on request.
Request a Quote for Stainless Steel 321 Seamless Pipes
or email sales@thaida.co.th