ASME SA179 L Type Finned Tube with Al1060 Fins For Air Cooled Heat Exchangers

ASME SA179 L Type Finned Tube with Al1060 Fins For Air Cooled Heat Exchangers

In simple terms, ASME SA179 L Type Finned Tube with Al1060 Fins is a high-efficiency heat exchanger tube. It combines the strength and pressure-handling capability of a carbon steel core tube with the superior heat transfer properties of aluminum fins.

Here are some detailed breakdowns:

1. Core Tube: ASME SA179 seamless base tubes

Material: Low-carbon steel

(1) Chemical Composition

The chemical composition for SA179 steel is defined by a maximum percentage for each element. This ensures the steel remains a low-carbon, "mild" steel with good ductility and weldability.

The requirements are typically given as follows (values are in weight %, maximum unless a range is shown):

Note on Silicon: While the base SA179 standard may not specify a silicon range, the material is often supplied as "silicon-killed" steel, meaning silicon was used to deoxidize it. This results in a finer grain structure and better surface quality. Other common grades like SA214 (which is similar but for higher temperatures) are explicitly for silicon-killed steel.

(2) Mechanical Properties

The mechanical properties are the minimum values that the material must meet after being cold-drawn and stress-relieved (a heat treatment to relieve internal stresses from the drawing process).

Important Notes on Mechanical Properties:

• Cold Working Effect: The cold-drawing process significantly increases the tensile and yield strength of the steel compared to its hot-rolled state. The values listed are the minimums after this process.
• Elongation is Critical: The exceptionally high elongation requirement (≥35%) is what makes SA179 tubes so suitable for tube rolling, bending, and flaring operations during the fabrication of heat exchangers.
• Hardness: While not always a required test, the typical hardness for SA179 tubes falls in the range of 72 to 85 HRB (Rockwell B Scale).

2. Fin Type: "L" Type

Key Characteristics:

• Excellent Corrosion Resistance: Very high resistance to atmospheric corrosion, which is crucial for applications like air-cooled heat exchangers.
• High Thermal Conductivity: Among the highest of all aluminum alloys, making it an ideal choice for transferring heat to or from the air.
• High Formability and Ductility: Makes it easy to roll and form into the "L" shape during the finning process.
• Lower Strength: Its softness is not a major drawback for fins, as their primary job is to dissipate heat, not withstand pressure.

3. Why This Combination is Popular:

• Cost-Effectiveness: Carbon steel (SA179) is less expensive than copper or stainless steel, and the L-type finning process is efficient.
• Performance: It leverages the best properties of both materials: the strength of steel and the light weight, high thermal conductivity, and corrosion resistance of aluminum.
• Reliability: The seamless core tube and robust mechanical bond ensure a long service life in demanding environments.

Detailed Breakdown of Applications

Here is a categorized list of its most common uses across various industries:

1. Power Generation

• Air-Cooled Condensers (ACC): In power plants located in water-scarce regions, these large banks of finned tubes use ambient air to condense the steam exiting the turbine back into water, creating a vacuum and completing the thermodynamic cycle.
• Radiation Coolers: For closed-loop cooling water systems that cool various auxiliary equipment in the plant.
• Lube Oil Coolers: Cooling the lubricating oil for large turbines, generators, and other critical machinery.

2. Hydrocarbon & Chemical Processing Industries (CPI)

• Process Air Coolers (Fin-Fan Exchangers): These are the iconic, large, fan-forced units seen in refineries and chemical plants. They cool process streams (like distilled hydrocarbons, reactor feed, or intermediate products) before storage or the next processing step.
• Compressor Aftercoolers: Cooling the hot, compressed air or gas from an air compressor to condense out moisture and increase efficiency.
• Sample Coolers: Reducing the temperature of high-pressure process fluid samples to a safe level for analysis and monitoring.

3. Industrial Machinery & Engines

• Charge Air Coolers (CAC / Intercoolers): Used on turbocharged or supercharged diesel engines in trucks, ships, locomotives, and stationary power generators. They cool the compressed intake air, making it denser for more efficient combustion and increased power output.
• Hydraulic Oil Coolers: Essential for maintaining the temperature of hydraulic fluid in heavy machinery like excavators, presses, and injection molding machines, preventing overheating and viscosity breakdown.
• Radiators for Heavy Equipment: While often using different fin types, the same principle applies for cooling engine coolant in large off-road vehicles.

4. Heating, Ventilation, Air Conditioning & Refrigeration (HVAC&R)

• Dry Coolers: Used in chilled water systems or process cooling where using a cooling tower (which evaporates water) is not desirable. The fluid is cooled directly by the air passing over the finned tubes.
• Fluid Coolers: Similar to dry coolers but can also involve some evaporative cooling.
• Condensers for Refrigeration Plants: In large industrial refrigeration systems, these tubes can act as the condenser, rejecting heat from the refrigerant to the outside air.