Cold Drawn Carbon Steel U Bend Tube For Waste Heat Recovery Boilers (WHRB), Heat Treatment After Bending

Overview of U Bend Tube

U-shaped tubes in industrial boilers are primarily used in applications requiring resistance to drastic temperature fluctuations, significant temperature differentials, and extremely high demands for thermal expansion compensation. The Heat Recovery Steam Generator (HRSG) represents their most typical application domain, especially in high-temperature or large-differential components such as superheaters, reheaters, and economizers. Secondly, they are employed in chemical process waste heat boilers to address issues of corrosion, scaling, and temperature differentials.

Why Carbon Steel is Used for Boiler Tubes:

• Good thermal conductivity

• Cost-effective

• Easily formable into U-bends

• Sufficient for temperatures up to ~425°C (800°F) in low-to-medium duty applications

• Common carbon steel grades: ASTM A179, A192, A210

Advantages of Carbon Steel U-Bend Tubes:

1. Cost-Effective

• Carbon steel is less expensive than stainless steel or alloy steel.

• Ideal for applications where corrosion resistance is not a primary concern.

2. Good Mechanical Strength

• High tensile and yield strength.

• Withstands moderate pressure and temperature, making it suitable for low to medium-pressure boilers and heat exchangers.

3. Thermal Expansion Compensation

• The U-shape design allows for thermal expansion and contraction without introducing significant stress into the tube system.

• Reduces the risk of cracking or leakage over time.

4. Compact Design

• U-bending allows for more tube length in a confined space.

• Helps in designing compact and efficient heat exchanger bundles.

5. Efficient Heat Transfer

• Carbon steel has good thermal conductivity.

• Ensures effective heat exchange when operating within its thermal limits.

6. Ease of Fabrication and Welding

• Carbon steel is easier to bend, form, and weld than many alloy steels.

• Bending and post-bend heat treatment (stress relief) are well-established processes.

7. Wide Availability

• Common grades like ASTM A179, A192, and A210 are readily available worldwide.

• Suitable for standard specifications in power plants, refineries, and industrial facilities.

Key Features of Carbon Steel U-Bend Tubes

Common application of Carbon Steel U Bend Tube

• Shell and Tube Heat Exchangers

• Waste Heat Recovery Boilers (WHRB)

• Fire-Tube Boilers

• Low-Pressure Industrial Boilers

• Water-Tube Boilers (Economizer or Preheater Sections)