ASTM A213 Stainless Steel Heat Exchanger Tube Corrosion Resistant U Bend Pipe
U-bend stainless steel heat exchanger tubes are seamless or welded tubes precision-formed into a U-shape, designed specifically for shell and tube heat exchangers. This U-configuration allows the tube bundle to expand and contract freely under thermal stress while eliminating the need for a second tube sheet, making the entire heat exchanger more compact, cost-effective, and easier to maintain.
Manufactured from high-quality austenitic stainless steel grades such as 304, 304L, 316, and 316L, U-bend tubes offer exceptional resistance to corrosion, high temperatures, and pressure. They are widely used in petrochemical plants, power generation facilities, HVAC systems, food processing, and pharmaceutical industries, where efficient heat transfer and equipment reliability are critical.
The cold-bending process is carefully controlled to ensure uniform wall thickness, no visible flattening or wrinkling, and complete stress relief annealing to restore mechanical properties. Each tube undergoes rigorous non-destructive testing to guarantee long-term performance in demanding service conditions.
Why Choose U-bend stainless steel heat exchanger tubes?
- Eliminates one tube sheet, reducing heat exchanger weight and cost
- Allows unrestricted thermal expansion of individual tubes
- Simplifies cleaning and maintenance – the tube bundle can be easily removed
- Compact design saves valuable floor space
- Ideal for high-temperature differential applications
Specifications
| Parameter | Details |
|---|---|
| Product Name | U-Bend Stainless Steel Heat Exchanger Tube |
| Tube Type | Seamless / Welded and drawn |
| Grades | 304, 304L, 316, 316L, 321, 347, Duplex 2205, 904L |
| Outer Diameter (OD) | 6.35 mm – 50.8 mm (1/4″ – 2″) |
| Wall Thickness | 0.5 mm – 3.0 mm (0.020″ – 0.120″) |
| Straight Leg Length | 500 mm – 12,000 mm (custom available) |
| Bend Radius (R) | 1.5 * OD – 5 * OD (custom radii available) |
| Bend Angle | 180° (U-shape) standard; other angles on request |
| Tolerance – OD | ±0.1 mm (for OD < 25.4 mm); ±0.15 mm (for OD ≥ 25.4 mm) |
| Tolerance – Wall Thickness | ±10% |
| Surface Finish | Annealed and pickled / Bright annealed / Polished |
| Standard | ASTM A213, ASTM A249, ASTM A269, ASTM A789, ASME SA213, EN 10216-5, EN 10217-7 |
Chemical Composition (Typical Values, % by weight)
| Grade | C max | Mn max | P max | S max | Si max | Cr | Ni | Mo | Others |
|---|---|---|---|---|---|---|---|---|---|
| 304 | 0.08 | 2.00 | 0.045 | 0.030 | 0.75 | 18.0–20.0 | 8.0–10.5 | — | — |
| 304L | 0.03 | 2.00 | 0.045 | 0.030 | 0.75 | 18.0–20.0 | 8.0–12.0 | — | — |
| 316 | 0.08 | 2.00 | 0.045 | 0.030 | 0.75 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| 316L | 0.03 | 2.00 | 0.045 | 0.030 | 0.75 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| 321 | 0.08 | 2.00 | 0.045 | 0.030 | 0.75 | 17.0–19.0 | 9.0–12.0 | — | Ti ≥5*C |
| 347 | 0.08 | 2.00 | 0.045 | 0.030 | 0.75 | 17.0–19.0 | 9.0–13.0 | — | Nb ≥10*C |
| Duplex 2205 | 0.03 | 2.00 | 0.030 | 0.020 | 1.00 | 22.0–23.0 | 4.5–6.5 | 3.0–3.5 | N 0.14–0.20 |
| 904L | 0.02 | 2.00 | 0.045 | 0.035 | 1.00 | 19.0–23.0 | 23.0–28.0 | 4.0–5.0 | Cu 1.0–2.0 |
Mechanical Properties
| Grade | Tensile Strength min (MPa) | Yield Strength min (MPa) | Elongation min (%) | Hardness max (HRB) |
|---|---|---|---|---|
| 304 | 515 | 205 | 35 | 90 |
| 304L | 485 | 170 | 35 | 90 |
| 316 | 515 | 205 | 35 | 90 |
| 316L | 485 | 170 | 35 | 90 |
| 321 | 515 | 205 | 35 | 90 |
| 347 | 515 | 205 | 35 | 90 |
| Duplex 2205 | 620 | 450 | 25 | — |
| 904L | 490 | 215 | 35 | — |
Physical Properties (Typical for 304/316):
| Property | Value |
|---|---|
| Density | 7.9 – 8.0 g/cm³ |
| Modulus of Elasticity | 193 – 200 GPa |
| Thermal Conductivity (100°C) | 16.2 W/(m·K) |
| Specific Heat (0-100°C) | 500 J/(kg·K) |
| Electrical Resistivity | 720 μΩ·m |
| Melting Range | 1370 – 1400°C |
U-bend stainless steel heat exchanger tubes Manufacturing Process
Our U-bend tubes are produced following strict quality control procedures:
| Step | Description |
|---|---|
| 1. Tube Selection | Straight seamless or welded tubes are inspected for dimensional accuracy |
| 2. Tube Preparation | Cleaned, cut to precise leg length, ends deburred |
| 3. Cold Bending | CNC mandrel bending machine with controlled radius, no wrinkling or flattening |
| 4. Stress Relief Annealing | Heat treatment at 1010°C – 1120°C to eliminate residual stress |
| 5. Pickling & Passivation | Removes heat tint and restores corrosion resistance |
| 6. Dimensional Inspection | Check bend radius, leg length, ovality, and wall thickness reduction |
| 7. Non-Destructive Testing | 100% eddy current or ultrasonic testing |
| 8. Hydrostatic Test | Pressure test per customer requirement |
| 9. Final Cleaning & Packaging | Oil-free cleaning, plastic end caps, wooden crates |
Dimensional Tolerances
| Parameter | Tolerance |
|---|---|
| Outside Diameter (OD) | ±0.1 mm (OD < 25.4 mm); ±0.15 mm (OD ≥ 25.4 mm) |
| Wall Thickness | ±10% |
| Straight Leg Length | ±1.5 mm/meter |
| Bend Radius (R) | ±1.5 mm (R < 100 mm); ±2.0 mm (R ≥ 100 mm) |
| Center-to-Center Leg Distance | ±1.5 mm |
| Ovality after Bending | ≤ 10% of OD |
| Wall Thinning after Bending | ≤ 15% of original wall thickness |
| End Squareness | ≤ 1° |
| Burr Removal | ≤ 0.2 mm |
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