What are heat exchanger pipes made of?

Material Overview

Heat exchanger pipes are designed to transfer heat efficiently while withstanding high temperature, pressure, and corrosive working environments. They are manufactured from a range of metals and alloys depending on application requirements:

• Copper: Excellent thermal conductivity, commonly used in refrigeration, air conditioning, and small-scale heat exchangers.

• Stainless Steel (304, 316, etc.): High corrosion resistance, ideal for food processing, chemical, and power plant applications.

• Aluminum: Lightweight with good thermal conductivity, widely applied in automotive and HVAC systems.

• Titanium: Outstanding corrosion resistance, especially in seawater environments; used in marine and desalination plants.

• Carbon Steel: Cost-effective and strong, suitable for industrial cooling and heating systems where corrosion risk is lower.

• Cupronickel (Copper-Nickel Alloys): Combines good thermal conductivity and excellent seawater resistance, widely applied in marine heat exchangers.

Manufacturing Process of Heat Exchanger Pipes

1. Raw Material Preparation

• Selection of suitable base material (copper, stainless steel, aluminum, titanium, carbon steel, etc.) according to application.

• Chemical composition and physical property inspection to ensure compliance with standards.

2. Pipe Forming

• Billet Preparation: Raw metal billets are cast and prepared for extrusion.

• Extrusion / Piercing / Rolling: Billets are pierced and hot-extruded or rolled into hollow tubes.

• Cold Drawing: Pipes are drawn through precision dies to achieve required dimensions and tighter tolerances.

• Cold/Hot Rolling: Enhances surface finish and dimensional accuracy.

3. Heat Treatment

• Annealing: Relieves internal stresses after cold working and improves ductility.

• Solution Treatment (for stainless steel and titanium): Improves corrosion resistance and restores toughness.

4. Surface Treatment

• Pickling and Passivation: Removes oxides and enhances corrosion resistance.

• Polishing: Provides smoother internal/external surface to reduce flow resistance and improve heat transfer efficiency.

5. Pipe Forming & Welding

• Bending: CNC or mandrel bending machines shape tubes to design requirements.

• Welding: Tube-to-tube sheet joints and headers are welded by TIG/MIG methods to ensure leak-tight construction.

6. Testing and Inspection

• Hydrostatic Pressure Test: Ensures pipe integrity and leak-proof performance under pressure.

• Non-Destructive Testing (NDT): X-ray, ultrasonic, or eddy current testing for weld and material quality.

• Dimensional & Surface Inspection: Verifies compliance with specifications and absence of surface defects.

7. Protective Treatment

• Coatings (Epoxy, Polyurethane, etc.) for enhanced corrosion protection in harsh environments.

• Passivation (for stainless steel) to further increase surface resistance to corrosion.

8. Final Assembly & Packaging

• Pipes are assembled into tube bundles or heat exchanger cores according to design.

• Final quality check is performed before packaging and shipping.

Key Features of Heat Exchanger Pipes

• High thermal conductivity for efficient heat transfer.

• Corrosion resistance to withstand aggressive environments (seawater, chemicals, etc.).

• Strength and durability under high pressure and high temperature.

• Precision dimensions ensuring tight fit and efficient operation.