NORMALIZED CARBON STEEL TUBESHEET SA516 GR.70N HEAT EXCHANGER COMPONENT

Overview

SA516 Grade 70 tubesheet is typically used in the construction of heat exchangers, pressure vessels, and boilers, where its function is to support the tubes, ensure proper sealing, and manage high-pressure and high-temperature conditions. The tubesheet is a critical component in heat exchangers, as it serves as the interface between the tubes and the shell, facilitating the transfer of heat while maintaining structural integrity.

SA516 Grade 70 tubesheets are a critical component in pressure vessel and heat exchanger construction. Their strength, weldability, and resistance to moderate temperatures and pressures make them ideal for a variety of industrial applications, especially in the chemical, petrochemical, and power generation sectors. However, for more corrosive environments, additional surface treatments or alloys may be necessary to ensure long-term performance and reliability.

Key Features of SA516 Grade 70 Tubesheet:

1. Material Properties:

• Base Material: SA516 Grade 70 is a carbon steel with a relatively low carbon content and good tensile strength. It is commonly used in pressure vessels, and its inclusion in a tubesheet ensures that the structure can withstand high pressures and temperature fluctuations.
• Tensile Strength: 70-90 ksi (485-620 MPa) which provides sufficient strength to handle mechanical stresses in high-pressure systems.
• Yield Strength: ≥ 38 ksi (260 MPa), ensuring the tubesheet can handle substantial loads without permanent deformation.
• Elongation: At least 20% in 8 inches (200 mm), ensuring some degree of flexibility and toughness during operations.
• Hardness: Typically within the range of 138–179 HB (Brinell), offering sufficient hardness to resist wear and impact.

2. Fabrication and Machining:

• Tubesheet Construction: The tubesheet is typically a thick, solid steel plate or a forged part that is drilled or machined to accommodate the tubes. The holes are carefully drilled with precision to ensure proper alignment and to avoid leakage at the tube-to-tubesheet interface.
• Weldability: SA516 Grade 70 is known for its good weldability, which is critical for fabricating tubesheets. The material can be welded using conventional methods such as SMAW (Shielded Metal Arc Welding), SAW (Submerged Arc Welding), and GTAW (Gas Tungsten Arc Welding).
• Heat Treatment: After fabrication, tubesheets are often heat-treated (e.g., normalized or stress-relieved) to reduce internal stresses and improve toughness. This is especially important in high-pressure applications where cracks or defects could lead to failure.

3. Corrosion Resistance:

• While SA516 Grade 70 has some inherent resistance to general corrosion, tubesheets exposed to harsh chemicals or corrosive environments may require additional coatings, linings, or corrosion-resistant alloys for long-term service.
• For applications in environments where corrosion is a concern, additional surface treatments or the use of alloys like Inconel or Hastelloy for the tubes may be necessary.

4. Mechanical Performance Under Pressure:

• High-Pressure Resistance: The tubesheet must withstand the internal pressure of the fluid circulating through the tubes. SA516 Grade 70, with its strong tensile and yield properties, ensures that the tubesheet can withstand significant internal pressure without failure.
• Temperature Resistance: It is suitable for moderate to high-temperature applications, typically in the range of 400°F to 850°F (200°C to 450°C), which is common in heat exchangers and boilers.

5. Design Considerations:

• Thickness: Tubesheets made from SA516 Grade 70 are available in various thicknesses, depending on the pressure requirements and the size of the heat exchanger or pressure vessel. Thickness can range from a few inches to over a foot.
• Hole Patterns: The design of the hole pattern (arrangement of tubes) and hole size is critical to the performance of the tubesheet. Typically, the tubes are arranged in a circular or square pitch, with precise hole diameters to ensure proper fit.
• Sealing Surface: The sealing surface of the tubesheet is typically machined to a smooth finish to prevent leaks and ensure that the tubes are properly sealed. It may also require a gasket or sealing element to prevent leakage between the tubes and the tubesheet.

Mechnical property

Chemical composition

Applications:

• Heat Exchangers: Used in both shell-and-tube and air-cooled heat exchangers where the tubesheet is the critical part holding the tubes in place.
• Pressure Vessels: In pressure vessels, the tubesheet acts as the partition separating different chambers, often used in steam boilers, reactors, and heat exchangers in petrochemical, power generation, and chemical industries.
• Boilers: Tubesheets are vital in steam boilers, where they hold the tube bundle in place while withstanding thermal expansion and pressure from steam generation.