ASTM A179 Seamless Cold-Drawn Mild Steel Heat Exchanger & Condenser Tubes
ASTM A179 covers seamless cold-drawn low-carbon steel tubes specifically manufactured for heat exchangers, condensers, and similar heat transfer equipment. These are precision tubes optimized for thermal efficiency, not general piping.
Key Features
| Feature | Description |
|---|---|
| Material | Low-Carbon Mild Steel (Killed Steel) |
| Process | Seamless & Cold-Drawn |
| Condition | As-drawn or annealed |
| Primary Use | Heat transfer surfaces in condensers, heaters, economizers |
Why A179?
Excellent Heat Transfer: Cold drawing creates smooth ID/OD surfaces
Precision Dimensions: Tight tolerances for reliable tube-to-tubesheet fit
Good Formability: Easily expanded/rolled into tubesheets without cracking
Cost-Effective: Most economical option for non-corrosive heat transfer
Chemical Composition
| 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) |
Killed Steel Advantage: Minimizes porosity, ensures uniform properties.
Mechanical Properties
| Property | Requirement |
|---|---|
| Tensile Strength, min | 325 MPa (47,000 psi) |
| Yield Strength, min | 180 MPa (26,000 psi) |
| Elongation, min | 35% |
| Hardness, max | 72 HRB |
Manufacturing Process
Production Sequence:
text
Hot-rolled seamless tube → Pickling/Cleaning → Cold Drawing → [Optional: Annealing] → Straightening/Cutting → Testing
Cold Drawing Benefits:
Smooth surface finish (Ra 1.6-3.2 µm typical)
Tight dimensional control (±0.10 mm OD typical)
Improved mechanical properties through work hardening
Superior straightness
Applications
Power Generation:
Surface condensers (steam to water)
Feedwater heaters
Closed cooling water heat exchangers
Auxiliary coolers
HVAC & Refrigeration:
Chiller tubes
Evaporator/condenser coils
Heat recovery units
Process Industries:
Shell & tube heat exchangers
Reboilers
Process coolers
Marine condensers
Typical Service Conditions
| Parameter | Typical Range |
|---|---|
| Temperature | Up to ~400°C (750°F) |
| Pressure | Moderate (shell & tube design pressures) |
| Media | Treated water, steam condensate, refrigerants |
| Velocity | < 2 m/s (to prevent erosion) |
Testing Requirements
| Test | Requirement | Purpose |
|---|---|---|
| Hydrostatic Test | Mandatory (every tube) | Pressure integrity |
| Flattening Test | Required | Ductility verification |
| Flaring Test | Required | Expandability into tubesheets |
| Hardness Test | Optional | Material verification |
| Visual Inspection | 100% | Surface defect detection |
Hydrostatic Test Pressure:
text
P = 2St/D (minimum 70 bar/1000 psi) S = 60% of specified minimum yield strength
Dimensional Specifications
Common Sizes:
| Parameter | Typical Range |
|---|---|
| Outside Diameter | 3/16" to 3" (4.8-76.2 mm) |
| Wall Thickness | 0.035" to 0.165" (0.9-4.2 mm) |
| Length | Up to 24 m (custom lengths available) |
Special Features Available:
U-bends for heat exchanger bundles
Extended surfaces (finned tubes)
Special ID/OD finishes
Close tolerance versions
Comparison with Related Standards
| Standard | Key Difference from A179 |
|---|---|
| ASTM A214 | Electric Resistance Welded (not seamless) |
| ASTM A192 | For high-pressure boiler tubes |
| ASTM A199 | Alloy steel for higher temperatures |
| ASTM A556 | For feedwater heater applications |
Fabrication & Installation
Tube-to-Tubesheet Joints:
Rolling/Expanding: Standard method
Welding: May be used for stronger joints
Packing: For removable bundles
U-Bend Requirements:
Minimum bend radius: Typically 1.5 × OD
Annealing after bending often required for tight bends
Special testing of bent sections may be specified
⚠️ Important Limitations
NOT for These Services:
High-temperature (>400°C) - Use alloy steels
Corrosive fluids without proper treatment
High-velocity erosive services
Pressure piping systems - Use A106 for piping
Corrosion Considerations:
Susceptible to oxygen pitting - requires proper water treatment
Galvanic corrosion when coupled with dissimilar metals
Erosion-corrosion at tube inlets with high velocity
Ordering Information
Typical Specification:
text
ASTM A179 Tubes 19.05 mm OD × 2.11 mm Wall × 6,096 mm Length Annealed condition Square cut ends, deburred For condenser service
Required Details:
Quantity (length or number of tubes)
Dimensions: OD × Wall × Length
Condition: As-drawn or annealed
End preparation
Special tolerances (if needed)
Testing requirements beyond standard
Maintenance & Life Expectancy
| Service Condition | Expected Life |
|---|---|
| Clean treated water | 20-30 years |
| Moderate fouling | 10-20 years |
| Brackish water | 5-15 years |
| Abrasive service | 3-10 years |
Common Failure Modes:
Pitting corrosion (most common)
Erosion at tube inlets
Fouling/deposit buildup
Stress corrosion cracking (rare)
International Equivalents
| Region | Equivalent Standard |
|---|---|
| Europe | EN 10216-2 P195GH |
| Japan | JIS G3461 STB340 |
| China | GB 5310 20G |
| ISO | ISO 2937 |
Cost Considerations
Price Factors:
Cold drawing adds ~15-25% to hot-finished tube cost
Annealing adds additional cost
Special tolerances/finishes increase price
Quantity discounts significant for large orders
Value vs Alternatives:
vs Cupronickel: 60-70% lower cost
vs Stainless Steel: 50-60% lower cost
vs Titanium: 80-90% lower cost
In summary: ASTM A179 is the standard specification for seamless cold-drawn carbon steel heat exchanger and condenser tubes, offering optimal thermal performance, reliability, and cost-effectiveness for non-corrosive or properly treated fluid services. Its smooth surfaces and precise dimensions make it ideal for efficient heat transfer in power plants, refineries, HVAC systems, and industrial processes.
