Type 329 duplex seamless pipes and tubes (UNS S32900) is an older grade of duplex stainless steel that is still relevant for applications in heat exchanger tubes and similar products. The grade is manufactured according to the standards of ASTM A789/A790 and grade comprises of 23-28% chromium, 2.5-5% nickel and 1-2% molybdenum along with minimum yield strength of about 485 MPa. Its duplex structure provides a useful combination of strength and corrosion resistance for demanding service. Amardeep Steel supplies UNS S32900 seamless pipes and tubes with EN 10204 3.1 mill test certificates and full heat traceability. Compare our UNS S32205 duplex pipes and tubes, see our SS 329 round bars, or browse all duplex steel pipes and tubes.
What Are UNS S32900 Seamless Pipes and Tubes?
Type 329 is a duplex stainless steel with high chromium and a mixed austenite and ferrite structure. It resists chloride stress corrosion cracking far better than 304 and 316, and has about twice their strength. It is kept below about 300°C in service, as with other duplex grades.
Why 329 Is Mostly Supplied Seamless
S32900 allows up to 0.08% carbon and has no nitrogen requirement in ASTM A790. Without nitrogen, the weld and heat affected zone can end up with too much ferrite, which lowers toughness and corrosion resistance. Newer nitrogen alloyed grades such as 2205 weld more reliably, so 329 is mainly bought as seamless tube and bar.
S32900 Seamless Tube Specifications
Parameter | Details |
|---|---|
Grade | Type 329 duplex |
UNS | S32900 |
Standards | ASTM A789 / ASME SA789 (tube), ASTM A790 / ASME SA790 (pipe) |
Type | Seamless, hot finished or cold drawn |
Size Range | Tube and pipe sizes to the purchase specification |
Schedules | SCH 10S, 40S, 80S and specified wall |
Length | Random, fixed and cut lengths, U bends on request |
Ends | Plain end and bevelled end |
Heat Treatment | Solution annealed and rapidly cooled |
Test Certificate | EN 10204 3.1, with 3.2 available on request |
S32900 Chemical Composition
Element | Content (%) |
|---|---|
Carbon (C) | 0.08 max |
Manganese (Mn) | 1.00 max |
Phosphorus (P) | 0.040 max |
Sulfur (S) | 0.030 max |
Silicon (Si) | 0.75 max |
Nickel (Ni) | 2.5 to 5.0 |
Chromium (Cr) | 23.0 to 28.0 |
Molybdenum (Mo) | 1.00 to 2.00 |
S32900 Mechanical Properties
Property | Value |
|---|---|
Tensile Strength, min | 620 MPa (90 ksi) |
Yield Strength (0.2% offset), min | 485 MPa (70 ksi) |
Elongation in 50 mm, min | 20% |
Hardness, max | 271 HBW / 28 HRC |
S32900 Equivalent Grades
Standard | Designation |
|---|---|
UNS | S32900 |
AISI | 329 |
Closest EN grade | 1.4460 (X3CrNiMoN27-5-2), a close match, not identical |
Closest JIS grade | SUS329J1, a close match, not identical |
ASTM pipe / tube | A790 / A789 |
Equivalent grades are close matches, not direct substitutes. Check the drawing before switching standards.
S32900 vs S31803 vs S32205
Property | S32900 (329) | S31803 | S32205 |
|---|---|---|---|
Chromium | 23.0 to 28.0% | 21.0 to 23.0% | 22.0 to 23.0% |
Molybdenum | 1.0 to 2.0% | 2.5 to 3.5% | 3.0 to 3.5% |
Nitrogen | Not specified | 0.08 to 0.20% | 0.14 to 0.20% |
Carbon, max | 0.08% | 0.030% | 0.030% |
Min. yield | 485 MPa | 450 MPa | 450 MPa |
PREN (spec range) | 26.3 to 34.6 | 30.5 to 37.8 | 34.1 to 37.8 |
PREN is worked out as Cr + 3.3 Mo + 16 N, using the minimum and maximum of each specified range. Yield values are ASTM A790 minimums.
For welded duplex pipe or better pitting resistance, see our UNS S32205 duplex pipes and tubes and UNS S31803 duplex pipes and tubes.
Applications of S32900 Seamless Pipes and Tubes
- Heat exchanger and condenser tubes in chloride bearing cooling water; see our heat exchanger tubes
- Petroleum refining and petrochemical process tubing
- Pulp and paper process lines
- Replacement tubing for existing 329 equipment
Testing and Documentation
Every order of S32900 seamless pipe and tube goes through the checks below at our testing facility or approved third party labs.
- Chemical analysis and PMI
- Tension and hardness tests
- Flattening and flaring tests
- Hydrostatic or eddy current test on every length
- Ultrasonic testing on request
- Visual and dimensional inspection
Mill test certificates are issued to EN 10204 3.1, with 3.2 available on request. You can view our approvals on the certificates page.
Packing and Marking
Each length is marked with the standard, UNS S32900, size, heat number and manufacturer name. Ends are capped, and tubes are kept apart from carbon steel and packed in bundles or wooden boxes. Read more about our packing and despatch process.
Request a Quote for UNS S32900 Seamless Pipes & Tubes
Send us the OD, wall thickness, standard, length or U bend details and quantity, and our team will reply with price and delivery. Use the enquiry form or reach us through the contact page.
Frequently Asked Questions
What is UNS S32900?
UNS S32900 (Type 329) is a duplex stainless steel with 23% to 28% chromium, 2.5% to 5% nickel and 1% to 2% molybdenum, covered for tube and pipe by ASTM A789 and A790.
What are the mechanical properties of S32900 pipe?
ASTM A790 sets 620 MPa minimum tensile strength, 485 MPa minimum yield strength, 20% minimum elongation and 271 HBW maximum hardness.
What is the difference between 329 and 2205?
329 has more chromium but less molybdenum, more carbon and no nitrogen requirement. 2205 has better pitting resistance and welds more reliably.
Is S32900 magnetic?
Yes. Its ferrite phase makes Type 329 magnetic.
