ASTM A179 / SA179 Seamless Steel Pipe (Tube)
Basic Overview
A standard specification for seamless cold-drawn low-carbon steel tubes for heat exchangers and condensers. A179 is the most common grade for small-diameter heat exchanger, condenser, and feedwater heater tubes where excellent heat transfer and clean internal surface are critical.
Clarification: This is a tube standard, not a pipe standard. It is a cold-drawn product for precision applications.
Name Explanation
| Part | Meaning |
|---|---|
| ASTM / SA | ASTM International / ASME Boiler Code |
| A179 / SA179 | Standard for seamless cold-drawn low-carbon steel heat exchanger tubes |
| Seamless | No longitudinal weld seam |
| Process | Cold-drawn for precise dimensions and smooth surface |
Key Features of A179
| Feature | Description |
|---|---|
| Material Type | Low-Carbon Steel |
| Manufacturing | Cold-drawn – provides smooth surface & tight tolerances |
| Primary Use | Heat exchanger, condenser, and feedwater heater tubes |
| Key Advantage | Excellent internal surface for heat transfer & fouling resistance |
| Temperature Limit | ~425°C (800°F) max (similar to other carbon steels) |
Chemical Composition
| Element | Content (%) | Purpose |
|---|---|---|
| Carbon (C) | 0.06 - 0.18 | Low carbon for maximum ductility |
| Manganese (Mn) | 0.27 - 0.63 | Basic strength |
| Phosphorus (P) | 0.035 max | Impurity control |
| Sulfur (S) | 0.035 max | Impurity control |
| Silicon (Si) | 0.10 - 0.35 | Deoxidizer (narrower range than A192) |
Mechanical Properties
| Property | Requirement |
|---|---|
| Tensile Strength | 325 MPa (47,000 psi) min |
| Yield Strength | 180 MPa (26,000 psi) min |
| Elongation | 35% min (on 2-inch gauge length) |
| Hardness | 72 HRB max (Rockwell B Scale) |
Comparison Table: A179 vs. A192 & A210
| Aspect | ASTM A179 | ASTM A192 | ASTM A210 A-1 |
|---|---|---|---|
| Primary Standard | Heat Exchangers & Condensers | High-Pressure Boiler Tubes | General Boiler Tubes |
| Manufacturing | Cold-Drawn | Usually Hot-Finished | Hot-Finished or Cold-Drawn |
| Key Focus | Surface Finish & Dimensional Precision | Pressure Containment with Ductility | Balanced Strength & Cost |
| Typical Use | Condenser tubes, feedwater heaters | Water wall tubes, risers | Boiler generating tubes |
| Internal Surface | Very Smooth (drawn finish) | Standard Mill Finish | Standard Mill Finish |
| Strength | Same as A192 | Same as A179 | Higher |
Common Applications
Surface condenser tubes (most common use)
Feedwater heater tubes
Heat exchanger tubes for liquid-to-liquid service
Compressor intercooler and aftercooler tubes
Hydraulic and instrumentation tubing
Process cooler tubes
Critical Technical & Design Notes
1. The "Heat Transfer Efficiency" Material
A179 is engineered for optimal thermal performance:
Cold-drawn process creates a smooth internal surface that:
Reduces frictional resistance to fluid flow.
Minimizes fouling and scaling buildup.
Improves heat transfer coefficient.
Precise dimensions ensure consistent tube-to-tubesheet joints and flow characteristics.
2. When to Select A179
Choose A179 when the application is a shell-and-tube heat exchanger or condenser and:
Heat transfer efficiency is a primary design goal.
Fouling control is important (smooth surfaces foul slower).
Tube vibration is a concern (consistent dimensions help).
High water velocity is used (smooth surface reduces erosion).
Do NOT choose A179 for:
Fired heater tubes (use A192/A210).
Superheater tubes (use alloy steels).
Structural applications.
3. Fabrication & Installation
Excellent for tube expanding into tube sheets – its primary installation method.
Can be bent, but cold-drawn material may require annealing after severe bending.
Good weldability due to low carbon content.
Not typically welded into headers like boiler tubes; instead, they are rolled (expanded) into tube sheets.
4. Corrosion Considerations
Not corrosion-resistant – for corrosive environments, admiralty brass, cupronickel, stainless steel, or titanium tubes are used.
Common in freshwater cooling systems for power plants and industrial processes.
For seawater condensers, cupronickel (ASTM B111) is standard; A179 is used for freshwater side or mild services.
Industry Role
A179 is the default carbon steel tube for non-fired, liquid-cooled heat exchangers in the power and process industries. It is the standard of comparison for surface finish and dimensional control in carbon steel heat exchanger tubing.
Typical System Flow (Power Plant):
Steam Condenser: A179 tubes (cooling water inside, steam outside).
Feedwater Heater: A179 tubes (extraction steam outside, feedwater inside).
Boiler: A192/A210 tubes (water/steam inside, fire/flue gas outside).
Key Takeaway: ASTM A179 is the cold-drawn, low-carbon steel heat exchanger tube material. It is specified when surface finish, dimensional precision, and heat transfer efficiency are critical, primarily for condensers and liquid-to-liquid heat exchangers operating below 425°C (800°F). Its mechanical properties are identical to A192, but its manufacturing process and application focus are entirely different.
