304 Stainless Steel Capillary Tube 1.0mm 1.2mm 1.3mm 1.4mm 1.5mm 1.6mm Stainless Steel Precision Tube
321 stainless steel pipe (UNS S32100) is a titanium-stabilized austenitic stainless steel pipe derived from 304 stainless steel, with titanium added to suppress intergranular corrosion caused by chromium carbide precipitation. It excels in high-temperature resistance, corrosion resistance, and mechanical stability, making it a preferred choice for harsh-environment applications such as industrial high-temperature pipelines and chemical processing equipment. Below is a detailed breakdown:
1. Core Product Overview & Standards
Key Grades
321 (UNS S32100): Standard grade with a maximum carbon content of 0.08%, optimized for general high-temperature and corrosion-resistant scenarios.
321H (UNS S32109): High-carbon variant (carbon content 0.04-0.10%) designed for enhanced creep resistance and strength at temperatures above 537°C (1000°F).
Dual certification is common for both grades due to their similar chemical compositions.
International Standards
Complies with multiple global standards, ensuring broad applicability across industries:
ASTM/ASME: A312/SA312 (seamless/welded stainless steel pipes), B36.10M/B36.19M (dimensional specifications)
DIN: 1.4541 (equivalent material number)
JIS/SUS, GB, AISI (regional mainstream standards)
2. Key Technical Parameters
Chemical Composition (Weight %)
The addition of titanium (Ti ≥ 5×(C+N)) is the core modification, preventing intergranular corrosion by forming titanium carbides instead of chromium carbides:
| Element |
C |
Si |
Mn |
Cr |
Ni |
S |
P |
Ti |
Fe |
| 321 |
≤0.08 |
≤0.75 |
≤2.0 |
17.0-19.0 |
9.0-12.0 |
≤0.03 |
≤0.045 |
5×(C+N)-0.70 |
Balance |
| 321H |
0.04-0.10 |
≤0.75 |
≤2.0 |
17.0-19.0 |
9.0-12.0 |
≤0.03 |
≤0.045 |
5×(C+N)-0.70 |
Balance |
Mechanical Properties (Annealed State)
| Grade |
Tensile Strength (MPa, min) |
Yield Strength (σ0.2, MPa, min) |
Elongation (δ5, %, min) |
Hardness (max) |
| 321 |
520 |
205 |
40 |
187 HB / 90 HRB / 200 HV |
| 321H |
520 |
205 |
40 |
217 HB |
Physical Properties
Density: 7.93 g/cm³ (0.286 lbm/in³)
Operating Temperature Range: -270°C (cryogenic) to 816°C (oxidation-resistant up to 1500°F)
Thermal Expansion Coefficient: 9.2×10/°C (68-212°F)
Modulus of Elasticity: 200 GPa (28×10 psi) at 20°C
Dimensional Specifications
| Type |
Outer Diameter (OD) |
Wall Thickness |
Length |
End Types |
| Seamless Pipe |
6 mm - 914.4 mm |
2.5 mm - 30 mm |
6-12 m (customizable) |
Plain end, beveled end, threaded |
| Welded Pipe (ERW/SAW) |
9.5 mm - 1200 mm |
0.3 mm - 40 mm |
6-12 m (customizable) |
Plain end, butt weld end |
| Shapes |
Round, square, rectangular, hexagonal, U-shaped |
- |
- |
- |
| Schedules |
Sch 5, Sch 10, Sch 40, Sch 80, Sch 160, XXS, etc. |
- |
- |
- |
3. Core Performance Advantages
Superior High-Temperature Stability: Resists oxidation at 816°C and offers better creep (high-temperature deformation resistance) and stress rupture properties than 304/304L.
Intergranular Corrosion Resistance: Titanium stabilization prevents chromium depletion in the 427-816°C range, avoiding intergranular corrosion even after welding or heat treatment.
Broad Corrosion Resistance: Comparable to 304 in general corrosion resistance; suitable for dilute organic acids, pure phosphoric acid (low temperature), and 10% dilute acid solutions (high temperature). Resists polythionic acid stress corrosion cracking in hydrocarbon environments.
Excellent Toughness: Maintains good low-temperature toughness (down to cryogenic levels) and formability, enabling bending, welding, and punching without cracking.
4. Typical Applications
Widely used in industries requiring high-temperature resistance, corrosion resistance, and structural stability:
Aerospace: Aircraft piston engine manifolds, exhaust stacks.
Petrochemical & Refining: Heat exchangers, furnace parts, refinery pipelines, expansion joints, and hydrocarbon processing equipment.
Chemical Industry: High-temperature chemical process equipment, pipelines for dilute acids (excluding chlorides/sulfuric acid).
Energy & Power: Thermal oxidizers, boiler tubes, and high-temperature flue gas pipelines.
Food & Pharmaceutical: Food processing equipment, brewery pipelines, and pharmaceutical machinery (hygienic and corrosion-resistant).
Mechanical Engineering: Auto parts, structural components, and furniture/kitchenware (durable and decorative).
5. Limitations & Selection Notes
Chloride Sensitivity: Not suitable for chloride-rich environments (e.g., seawater, salt sprays) or sulfuric acid solutions, as it may suffer pitting corrosion.
Machinability: Titanium addition reduces machinability compared to 304; use specialized tools and cutting parameters for processing.
Grade Selection: Choose 321 for temperatures ≤537°C; opt for 321H for long-term service above 537°C (enhanced creep resistance).
Certifications: Prioritize products with ISO, SGS, or BV certifications to ensure compliance with ASTM/ASME standards.
6. Manufacturing & Quality Control
Processes: Hot rolling, cold rolling (seamless), electric resistance welding (ERW), submerged arc welding (SAW) for welded pipes.
Surface Treatments: Black oxide, pickling, polished (No.4/BA), satin, mirror finish, electropolishing.
Mandatory Inspections: Hydrostatic pressure testing (leakage), non-destructive testing (ultrasonic/ radiographic testing), chemical composition analysis, and mechanical property testing.
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A: Yes. Please feel free to contact us for more details.
Q3:What is your terms of payment?
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30% T/T and balance against copy of documents.
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Q5: Can you provide sample?
A: Yes. Sample is free for regular sizes, but the buyer needs to pay freight cost.
Q6: How long is your delivery time?
A: Regular lead time is 15 to 30 days after receiving deposit.
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321 stainless steel pipe (UNS S32100) is a titanium-stabilized austenitic stainless steel pipe derived from 304 stainless steel, with titanium added to suppress intergranular corrosion caused by chromium carbide precipitation. It excels in high-temperature resistance, corrosion resistance, and mechanical stability, making it a preferred choice for harsh-environment applications such as industrial high-temperature pipelines and chemical processing equipment. Below is a detailed breakdown:
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