What Is TP309 / 309S Stainless Steel Pipe?
ASTM A312 TP309 and TP309S are austenitic stainless steel pipes with a boosted 22-24% chromium and 12-15% nickel chemistry. That extra alloy content is what lets the grade keep its scale-resistant passive film - and its strength - in hot, oxidizing atmospheres where common 304 or 316 pipe would rapidly degrade.
TP309 is the standard-carbon grade (C <= 0.20%); TP309S is the low-carbon version (C <= 0.08%), giving markedly better weldability and resistance to intergranular corrosion after welding. TP309H (C 0.04-0.10%) is the high-carbon option for elevated-temperature pressure service.
Why Choose ASTM A312 TP309/309S Stainless Steel Pipe?
TP309 and TP309S are ideal choices if you require piping that delivers stable, reliable performance under high-temperature conditions. Offering superior heat resistance compared to standard austenitic stainless steels, they are widely used in heater components, heat tr eatment equipment, and petrochemical processing units.
With a maximum carbon content of 0.08%, these grades offer improved weldability and reduced carbide precipitation during welding. This results in cleaner welds and enhanced corrosion resistance in the heat-affected zone, ensuring long-term structural stability for the equipment.
They withstand oxidizing environments at temperatures up to 1900°F (1040°C), outperforming TP304 and TP316. Their mechanical properties remain stable under thermal cycling or prolonged exposure to extreme heat-capabilities that standard stainless steels cannot match.
Product Range & Forms
We supply TP309 / 309S in the full family of product forms to match fabrication and service needs:
|
Form |
Process / Note |
Typical Size |
|
Seamless Pipe |
Hot-finished or cold-drawn, no weld seam |
1/2"-24" NB |
|
Welded Pipe (ERW) |
Longitudinal weld, economical for larger sizes |
1"-48" NB |
|
EFW Pipe |
Electric-fusion-welded, large diameter |
8"-48" NB (to 110") |
|
Heat-Exchanger Tube |
ASTM A213 / A269, BA or AP finish |
OD 6-114 mm |
|
Square / Rectangular |
Structural & furnace framing |
per customer spec |
|
Heavy-Cold-Worked (HCW) |
Higher strength, A312 permitted |
per customer spec |
Technical Specifications
Chemical Composition (%)
|
Element |
TP309 (S30900) |
TP309S (S30908) |
|
Carbon (max) |
0.20 |
0.08 |
|
Manganese (max) |
2.00 |
2.00 |
|
Phosphorus (max) |
0.045 |
0.045 |
|
Sulfur (max) |
0.030 |
0.030 |
|
Silicon (max) |
1.00 |
1.00 |
|
Chromium |
22.0-24.0 |
22.0-24.0 |
|
Nickel |
12.0-15.0 |
12.0-15.0 |
|
Iron |
Balance |
Balance |
Mechanical Properties
|
Property |
Value |
|
Tensile Strength (min) |
>= 515 MPa (75 ksi) |
|
Yield Strength 0.2% (min) |
>= 205 MPa (30 ksi) |
|
Elongation (50 mm, min) |
>= 40% |
|
Hardness (HRB max) |
85 |
|
Hardness (HB max) |
147 |
|
Density |
8.0 g/cm3 |
|
Continuous service temp |
~1038 C (1900 F) |
Where You Can Use These Pipes
Specific operating conditions determine the optimal material selection. ASTM A312 TP309/309S stainless steel pipes deliver outstanding performance in the following scenarios:
- Petrochemical industry: Pipelines for transporting corrosive chemicals under high-temperature conditions
- Power generation: Heat exchanger tubes for evaporators and heat exchangers
- Heat treatment equipment: Heating furnace components and tempering units
- Chemical processing: Piping for reactors and distillation columns
- Oil and gas refining: Piping systems in high-temperature zones of refineries
- Industrial furnaces and kilns: Structural supports and medium transport pipelines
TOM's Distinct Advantages
Sourcing piping materials means partnering with a manufacturer that truly understands your needs. We guarantee that all our products meet technical specifications:
✅ Rigorous Quality Control: Full traceability of raw materials; testing of finished products using specialized equipment; batch-by-batch verification by ISO 17025-certified laboratories.
✅ Comprehensive Documentation: Availability of MTR (3.1/3.2), TPI reports, WPS/PQR, MPS, and UT/RT inspection reports.
✅ Flexible Ordering: Capable of handling everything from small-batch sample orders to full-container orders for large-scale projects, all with consistent quality.
✅ Technical Services: Engineers provide guidance on product selection and application; on-site technical support is available for complex projects.
Standards and Certifications
FAQ
Q: What is the maximum service temperature of 309/309S pipe?
A: Continuous oxidation service up to ~1038 C (1900 F); suitable for intermittent exposure up to ~1093 C (2000 F).
Q: When should I choose 309 instead of 310S?
A: If your operating temperature is below ~1000 C with moderate corrosion, 309/309S gives the best performance-to-cost balance. Above ~1100 C or in harsher oxidation, 310S is preferred.
Q: How weldable is TP309S pipe?
A: Excellent. Its low carbon (<=0.08%) minimizes sensitization; ER309/ER309L filler and standard fusion processes are recommended.
Q: What is the difference between 309 and 309S?
A: 309S is the low-carbon version (C <=0.08% vs 0.20%), giving better weldability and lower risk of intergranular corrosion in welded structures.
Q: Which standards apply?
A: Primarily ASTM A312 / ASME SA312 for pipe; A213/A269 for tubes; A358 for EFW. Confirm with your order technical agreement.
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