SA178 GR.A Carbon Steel ERW Boiler Tube For high - temperature condition

Overview

The SA178 ERW (Electric Resistance Welded) tube refers to a type of carbon steel tube manufactured using the electric resistance welding process. This process is commonly used for producing welded tubes, which are typically used in applications such as boilers, heat exchangers, and pressure vessels. These tubes conform to the ASTM A178 specification, which sets the standards for welded carbon steel tubes used in these high-pressure, high-temperature applications.

What is ERW (Electric Resistance Welding)?

• Electric Resistance Welding (ERW) is a welding process where electrical resistance is used to generate heat and join two metal surfaces. In the context of manufacturing tubes, ERW involves:
• Formation of a Steel Strip: A flat steel strip or coil is fed into a tube mill, where it is continuously formed into a cylindrical shape by a series of rollers.
• Electrical Resistance Heating: The edges of the steel strip are heated by electrical resistance as high current is passed through the edges where the two sides of the strip meet.
• Welding: As the steel strip reaches a sufficient temperature (without melting), the edges are pressed together to form a bond, creating a continuous, high-strength weld seam along the length of the tube.
• Cooling and Sizing: The tube is then cooled and passed through sizing rollers to achieve the required diameter and wall thickness.

Key Advantages of SA178 ERW Tubes

1. Cost-Effective: ERW tubes are generally less expensive to manufacture compared to seamless tubes, making them a cost-effective option for many industrial applications.

2. High Strength: The electric resistance welding process produces a strong bond between the steel edges, resulting in a tube with good mechanical properties suitable for high-pressure and high-temperature environments.

3. Good Weld Integrity: With proper welding parameters and quality control, the ERW tube can have a uniform and strong weld seam, making it reliable for critical applications such as boilers and heat exchangers.

4. Customizable Dimensions: ERW allows for flexibility in tube dimensions (diameter and wall thickness), making it suitable for a wide range of applications with specific requirements.

5. Versatility: SA178 ERW tubes are used in various industrial applications, including power generation, heat exchangers, condensers, pressure vessels, and more.

Applications of SA178 ERW Tubes

1. Boilers: SA178 ERW tubes are widely used in the construction of fire-tube boilers, water-tube boilers, and other types of steam generators. The tubes need to withstand high internal pressures and thermal stresses in these applications.

2. Heat Exchangers: The tubes are also used in heat exchangers where heat transfer between different fluids is required. The ability of SA178 ERW tubes to handle high pressure and temperature makes them ideal for such systems.

3. Condensers: In power plants and other industrial applications, these tubes are used in condensers where steam is cooled and condensed into water.

4. Pressure Vessels: SA178 ERW tubes are used in pressure vessels, where the tubes can withstand high pressure and thermal cycling. This includes reactors, storage tanks, and other high-pressure systems.

5. Industrial Piping: These tubes are commonly used in industrial piping systems for carrying fluids, steam, and gases under high-pressure conditions.

Mechanical Properties of SA178 ERW Tubes

SA178 ERW tubes must conform to the mechanical properties specified in the ASTM A178 standard. Some key properties include:

• Tensile Strength: Typically around 40,000 psi (275 MPa) or higher, depending on the exact grade and heat treatment.

• Yield Strength: Typically around 30,000 psi (207 MPa) or higher.

• Elongation: Generally 30% or more in 8 inches (200 mm) for improved ductility.

• Hardness: The tube may have a hardness value that meets the minimum requirements for stress and fatigue resistance.

Summary

The SA178 ERW tube is a type of welded carbon steel tube manufactured using the electric resistance welding (ERW) process. These tubes are widely used in industries requiring high pressure and temperature resistance, such as boilers, heat exchangers, and pressure vessels. The ERW process is cost-effective, reliable, and capable of producing strong, durable tubes that meet the standards for demanding applications.