ASTM A179 / SA179 - Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes
ASTM A179 (SA179) covers seamless cold-drawn low-carbon steel tubes specifically manufactured for heat exchangers, condensers, and similar heat transfer equipment.
Key Characteristics
| Feature | Description |
|---|---|
| Material | Low-Carbon Steel (Killed Steel) |
| Manufacturing | Seamless & Cold-Drawn - Provides smooth surface finish and precise dimensions |
| Condition | As-drawn or Annealed after final cold draw |
| Primary Use | Heat transfer surfaces in condensers, evaporators, heaters, coolers |
Chemical Requirements
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.06 - 0.18 |
| Manganese (Mn) | 0.27 - 0.63 |
| Phosphorus (P), max | 0.035 |
| Sulfur (S), max | 0.035 |
| Silicon (Si) | ≥ 0.13 (deoxidized/killed steel) |
Note: The low carbon content and killed steel practice ensure good weldability and formability.
Mechanical Properties
| Property | Requirement |
|---|---|
| Tensile Strength, min | 325 MPa (47,000 psi) |
| Yield Strength, min | 180 MPa (26,000 psi) |
| Elongation (in 50mm), min | 35% |
| Hardness, max | 72 HRB |
Manufacturing Process
Typical Production Flow:
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Hot-rolled seamless tube → Pickling/Cleaning → Cold Drawing → Final Heat Treatment (if annealed) → Straightening/Cutting → Testing
Key Process Features:
Cold Drawing: Reduces diameter/wall thickness, improves surface finish and dimensional accuracy
Surface Finish: Smooth ID/OD critical for heat transfer efficiency and fouling resistance
Dimensional Tolerances: Tighter than hot-finished tubes (per ASTM A450)
Common Dimensions & Sizes
| Parameter | Typical Range |
|---|---|
| Outside Diameter | 3/16" to 3" (4.8 mm to 76.2 mm) |
| Wall Thickness | 0.035" to 0.165" (0.9 mm to 4.2 mm) |
| Length | Up to 24m (custom lengths available) |
Special Features:
U-bends available for heat exchanger tube bundles
Extended surfaces (finned tubes) when specified
ID/OD specially controlled for tube-to-tubesheet fit
Surface Requirements
| Surface | Requirement |
|---|---|
| Internal | Reasonably smooth, free from scale (pickling removes most scale) |
| External | Smooth finish, free from defects that impair heat transfer |
| Cleanliness | Free from lubricants, oxides, or contaminants |
Testing & Inspection
| Test | Requirement |
|---|---|
| Hydrostatic Test | Mandatory - Test pressure calculated per formula |
| Flattening Test | Required - Tests ductility and weld quality |
| Flaring Test | Required - Tests ability to expand into tubesheet |
| Hardness Test | Optional - Max 72 HRB |
| Nondestructive Test | Optional (eddy current common) |
| Visual Inspection | Mandatory - Surface defects |
Hydrostatic Test Pressure Formula:
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P = 2St/D Where: P = test pressure, S = stress (60% of yield), t = wall thickness, D = OD
Applications
Primary Industries:
| Industry | Specific Applications |
|---|---|
| Power Generation | Surface condensers, feedwater heaters, closed cooling systems |
| Refining & Petrochemical | Heat exchangers, coolers, condensers, reboilers |
| HVAC | Chiller tubes, evaporator tubes, cooling coils |
| Marine | Shipboard condensers, heat exchangers |
| Industrial Processing | Process heaters, coolers, condensers |
Why A179 is Preferred:
Excellent Heat Transfer: Smooth surfaces maximize efficiency
Good Corrosion Resistance: In steam condensate and treated water
Easy to Expand/Roll: Into tubesheets without cracking
Cost-Effective: Compared to alloy/cupronickel alternatives
Comparison with Similar Tube Standards
| Standard | Material | Key Difference from A179 |
|---|---|---|
| ASTM A214 | Low-Carbon Steel | Electric Resistance Welded (not seamless) |
| ASTM A192 | Carbon Steel | For high-pressure boiler tubes, not general heat exchangers |
| ASTM A213 T5/T11 | Alloy Steel | Higher temperature/corrosion resistance |
| B111/B111M C70600 | Copper-Nickel | Superior seawater corrosion resistance |
Design & Fabrication Considerations
1. Tube-to-Tubesheet Joints
Rolling/Expanding: Standard practice for A179 tubes
Welding: Requires proper filler (low carbon equivalent)
Strength Welds: May require post-weld heat treatment
2. U-Bend Requirements
Minimum bend radius typically 1.5 × OD
Annealing after bending may be required for tight bends
3. Fouling Prevention
Smooth ID minimizes deposit buildup
Regular cleaning/maintenance required
Water treatment essential for longevity
4. Corrosion Protection
Water Side: pH control, oxygen scavengers, biocides
Steam Side: Proper venting, amine treatment
Cathodic Protection: For seawater applications
Limitations & Warnings
⚠️ Service Limitations:
NOT for high-temperature service: Max ~400°C (750°F)
NOT for corrosive fluids: Without proper water treatment
Susceptible to erosion: At high velocities (>2 m/s in water)
Vulnerable to oxygen pitting: In untreated water systems
Limited pressure rating: Due to thin walls
Ordering Information
Required Specifications:
Quantity (total length or number of tubes)
Dimensions: OD × Wall Thickness × Length
Condition: As-drawn or Annealed
End Finish: Square cut, deburred, or specific bevel
Tolerances: Standard or special
Testing: Additional tests beyond standard
Certification: MTC (Mill Test Certificate) requirements
Typical Order Example:
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ASTM A179 Tubes, 19.05 mm OD × 2.11 mm wall × 6096 mm length, Annealed condition, square cut ends, with full MTC to include hydrostatic, flattening, flaring test results.
Maintenance & Life Expectancy
| Condition | Expected Service Life |
|---|---|
| Clean treated water | 20-30 years |
| Moderate fouling | 10-20 years |
| Seawater (with protection) | 5-15 years |
| Abrasive service | 3-10 years |
Failure Modes:
Pitting corrosion (most common)
Erosion-corrosion at tube inlets
Stress corrosion cracking (rare)
Fouling/deposit buildup
Industry Standards Reference
| Application | Governing Standard/Code |
|---|---|
| Heat Exchanger Design | TEMA (Tubular Exchanger Manufacturers Association) |
| Pressure Vessels | ASME Section VIII, Division 1 |
| Power Plant Condensers | HEI (Heat Exchange Institute) Standards |
| Inspection | ASME Section V (NDE) |
Bottom Line: ASTM A179 is the standard low-carbon steel tube for efficient, cost-effective heat transfer in condensers and heat exchangers operating with non-corrosive or properly treated fluids. Its cold-drawn manufacturing ensures precise dimensions and smooth surfaces critical for thermal performance and reliable tube-to-tubesheet joints.
