EN12451 Copper and Copper Alloy Seamless Tubes for Heat Exchangers

 1. Scope  

- Applies to seamless tubes made of copper and copper alloys used in heat exchangers, condensers, and similar heat transfer applications.  

- Covers tubes for general industrial use, including refrigeration, petrochemical, and power plants.  

 2. Normative References  

- References related standards (e.g., EN 1173 for material codes, EN ISO 6892-1 for tensile testing).  

 3. Material Codes & Ordering Information  

- Material Designations:  

  - Copper: CW024A (OF-Cu), CW020A (Cu-DHP).  

  - Copper Alloys: CW704R (CuZn30), CW712R (CuNi10Fe1Mn), etc.  

- Ordering Requirements: Buyers must specify:  

  - Standard number (EN 12451).  

  - Material code (e.g., CW024A).  

  - Dimensions (outer diameter, wall thickness, length).  

  - Delivery condition (annealed, hard-drawn, etc.).  

  - Any additional testing (e.g., hydrostatic pressure, eddy current).  

 4. Manufacturing & Chemical Composition  

- Tubes must be seamless, produced by extrusion, drawing, or pilgering.  

- Chemical composition must comply with EN 1173.  

 5. Mechanical Properties  

- Tensile Strength, Elongation, and Hardness requirements vary by material and temper (annealed vs. hard-drawn).  

  - Example: CW024A (annealed) – Tensile strength ≥ 200 MPa, elongation ≥ 40%.  

 6. Dimensional Tolerances  

- Specifies tolerances for:  

  - Outer diameter (±0.1 mm to ±1%, depending on size).  

  - Wall thickness (±10% typically).  

  - Straightness (max deviation per meter length).  

 7. Inspection & Testing Requirements  

- Mandatory Tests:  

  - Dimensional inspection.  

  - Visual examination (surface defects, cracks).  

  - Tensile test (one per batch).  

  - Flattening test or expansion test (material-dependent).  

- Optional Tests (if specified in order):  

  - Hydrostatic pressure test.  

  - Eddy current testing for defects.  

  - Grain size assessment (for annealed tubes).  

 8. Surface Condition & Defects  

- Tubes must be free of scale, cracks, and inclusions.  

- Minor surface imperfections allowed if within dimensional tolerances.  

 9. Marking & Certification  

- Each tube or bundle must be marked with:  

  - Manufacturer’s name/logo.  

  - Material code.  

  - Dimensions.  

  - Heat number.  

- Inspection Certificate 3.1 (EN 10204) provided upon request.  

 10. Packaging  

- Tubes typically supplied in straight lengths or coils, protected against corrosion/damage.  

Main Material Codes in EN 12451 

 1. Pure Copper (Cu)  

- CW004A (Cu-ETP) – Electrolytic Tough Pitch Copper (common for general heat exchangers).  

- CW008A (Cu-OF) – Oxygen-Free Copper (high conductivity, reduced embrittlement risk).  

- CW020A (Cu-DHP) – Phosphorus-Deoxidized Copper (good weldability, corrosion resistance).  

- CW021A (Cu-DLP) – Low-Phosphorus Deoxidized Copper.  

- CW022A (Cu-DHP, variant with tighter impurity control).  

- CW023A (Cu-OF, ultra-high purity).  

- CW024A (Cu-OF, for high vacuum/electronics applications).  

 2. Copper Alloys  

- CW307G (CuZn30, 70/30 brass) – Good corrosion resistance in water.  

- CW500L (CuZn20Al2As) – Arsenical aluminum brass for condenser tubes.  

- CW702R (CuNi10Fe1Mn) – 90/10 Cupronickel (seawater resistance).  

- CW704R (CuNi30Mn1Fe) – 70/30 Cupronickel (superior corrosion/erosion resistance).  

- CW712R (CuNi30Fe2Mn2) – High-strength cupronickel variant.  

 Notes on Material Selection  

- CW004A (Cu-ETP) is widely used but may suffer from hydrogen embrittlement in high-temperature reducing atmospheres.  

- CW020A (Cu-DHP) is preferred for welded heat exchangers due to phosphorus deoxidation.  

- Cupronickels (CW702R, CW704R) are ideal for seawater/brine applications.  

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