ASTM A179 Seamless Cold-Drawn Low-Carbon Steel Tubes for Economizers
What is ASTM A179 Tube?
ASTM A179 (ASME SA179) is the standard specification for seamless cold-drawn low-carbon steel tubes used in tubular heat exchangers, condensers, economizers, and similar heat-transfer equipment.
These tubes are widely used in power plants, industrial boilers, petrochemical facilities, and refinery systems because of their excellent thermal conductivity, dimensional accuracy, and formability.
According to ASTM standards, ASTM A179 covers:
"Seamless cold-drawn low-carbon steel tubes for tubular heat exchangers, condensers, and similar heat-transfer apparatus."
Source:
ASTM A179/A179M
ASME SA179
Why ASTM A179 Tubes Are Used for Economizers
An economizer is a heat recovery component that transfers heat from boiler flue gases to feedwater in order to improve thermal efficiency and reduce fuel consumption.
ASTM A179 tubes are commonly selected for economizer service because they provide:
1. Excellent Heat Transfer Performance
The low-carbon steel composition provides high thermal conductivity, allowing efficient heat exchange between flue gas and boiler feedwater.
2. High Dimensional Accuracy
The cold-drawn manufacturing process improves:
Wall thickness uniformity
Outer diameter tolerance
Surface smoothness
This helps reduce fouling and improves flow efficiency inside the tubes.
3. Good Bending and Fabrication Properties
Economizer coils often require:
U-bending
Serpentine bending
Expansion into tube sheets
ASTM A179 tubes offer excellent ductility and formability, reducing the risk of cracking during fabrication.
ASTM A179 Chemical Composition
|
Element |
Content |
|
Carbon (C) |
0.06% – 0.18% |
|
Manganese (Mn) |
0.27% – 0.63% |
|
Phosphorus (P) |
≤ 0.035% |
|
Sulfur (S) |
≤ 0.035% |
Mechanical Properties of ASTM A179
|
Property |
Value |
|
Tensile Strength |
≥ 325 MPa (47,000 psi) |
|
Yield Strength |
≥ 180 MPa (26,000 psi) |
|
Elongation |
≥ 35% |
|
Hardness |
Maximum 72 HRB |
The relatively low hardness improves vibration resistance and fabrication performance in boiler systems.
Manufacturing Process
ASTM A179 tubes are produced using a seamless cold-drawn process:
Steel Billet → Piercing → Seamless Tube → Cold Drawing → Heat Treatment → Testing
After final cold drawing, the tubes are heat-treated to improve ductility and mechanical stability.
Inspection and Testing Requirements
To ensure safe operation under thermal cycling and pressure conditions, ASTM A179 tubes undergo several mechanical and non-destructive tests.
Flattening Test
Verifies the tube can withstand deformation without cracking.
Flaring Test
Ensures the tube can be expanded for tube-to-tube-sheet applications.
Hardness Test
Confirms the material remains sufficiently ductile and is not excessively brittle.
Hydrostatic Test
Each tube is pressure tested to verify leak-tightness and pressure integrity.
Non-Destructive Testing (NDT)
Alternative NDT methods may include:
Eddy Current Testing
Ultrasonic Testing (UT)
Electromagnetic Testing
These inspections help detect internal or surface defects without damaging the tube.
ASTM A179 vs ASTM A192
|
Item |
ASTM A179 |
ASTM A192 |
|
Manufacturing |
Cold-drawn only |
Hot-finished or cold-drawn |
|
Main Application |
Heat exchangers and economizers |
High-pressure boiler tubes |
|
Pressure Service |
Low to medium pressure |
High pressure |
|
Surface Finish |
Higher precision |
Standard boiler finish |
|
Typical Use |
Economizers, condensers |
Boilers, superheaters |
ASTM A179 is generally preferred for heat-transfer efficiency and precision, while ASTM A192 is commonly used in higher-pressure boiler systems.
Typical Applications of ASTM A179 Tubes
ASTM A179 tubes are widely used in:
Boiler economizers
Heat exchangers
Surface condensers
Feedwater heaters
Petrochemical heat-transfer systems
Power plant boiler systems
Maintenance Considerations for Economizer Tubes
To improve service life in economizer applications, operators commonly implement:
Oxygen Control
Proper feedwater deaeration helps reduce internal corrosion and pitting.
Soot Blowing
Periodic cleaning removes ash and flue gas deposits that may accelerate external corrosion.
Wall Thickness Monitoring
Ultrasonic thickness (UT) inspection during maintenance shutdowns helps monitor erosion and corrosion rates.
A179 Pipe process line
A179 Cold drawn Pipe test equipments
Frequently Asked Questions
Is ASTM A179 Seamless?
Yes. ASTM A179 is a seamless cold-drawn low-carbon steel tube specification.
Is ASTM A179 Carbon Steel or Stainless Steel?
ASTM A179 is a low-carbon steel tube specification, not stainless steel.
What is ASTM A179 Tube Used For?
It is mainly used in economizers, heat exchangers, condensers, and boiler heat-transfer systems.
What is the Difference Between ASTM A179 and A192?
ASTM A179 is primarily used for heat-transfer applications with higher dimensional precision, while ASTM A192 is designed for high-pressure boiler service.
Reference Standards
ASTM A179/A179M
ASME SA179
EN 10204
ASME Boiler and Pressure Vessel Code