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ASTM A178 vs A179 vs A192 – Which Boiler Tube Standard Do You Need?
Created on 05.03
ASTM A178 vs A179 vs A192 – Which Boiler Tube Standard Do You Need?
A Complete Comparison for Power Generation & Heat Transfer Applications
Introduction
When specifying steel tubes for boilers, heat exchangers, condensers, and superheaters, three ASTM standards frequently appear:
- ASTM A178
– ERW Welded Boiler Tube
- ASTM A179
– Seamless Cold-Drawn Heat Exchanger Tube
- ASTM A192
– Seamless Carbon Steel Boiler Tube
Choosing the wrong standard can lead to premature failure, safety risks, or unnecessary costs. This article compares these three standards across manufacturing process, mechanical properties, applications, and cost to help you make the right decision.
Quick Comparison Table
Parameter | ASTM A178 | ASTM A179 | ASTM A192 |
Manufacturing | ERW Welded | Seamless – Cold Drawn | Seamless – Cold Drawn / Hot Finished |
Primary Application | Boilers, Superheaters | Heat Exchangers, Condensers | High-Pressure Boilers |
OD Range | 1/2″ – 5″ (12.7-127mm) | 1/8″ – 3″ (3.2-76.2mm) | 1/8″ – 7″ (3.2-177.8mm) |
Wall Thickness | 0.035-0.360″ (0.9-9.1mm) | 0.5-3mm (thin wall) | 1-15mm (medium to heavy) |
Pressure Rating | Medium | Low to Medium | High |
Cost | Low (most economical) | Medium | Medium to High |
Grades | A, C, D | One grade only | One grade only |
Detailed Breakdown by Standard
1. ASTM A178 – ERW Welded Boiler Tube
Overview:
ASTM A178 covers electric-resistance-welded (ERW) carbon steel tubes for boilers, boiler flues, superheater flues, and safe ends. Tubes are heat treated after welding to ensure weld integrity.
Key Features:
- ERW manufacturing –
lowest cost among the three
- Grades A, C, D for different strength levels
- Heat treated after welding for stress relief
- Minimum-wall-thickness design
Best Applications:
- General boiler service (Grade A)
- High-temperature boilers (Grade C)
- Demanding superheater service (Grade D)
- Cost-sensitive projects
Limitations:
- Not suitable for the highest pressure applications
- Weld seam requires careful inspection
- Grade C & D not recommended for safe-ending for forge welding
2. ASTM A179 – Seamless Heat Exchanger Tube
Overview:
ASTM A179 covers seamless cold-drawn low-carbon steel tubes for heat exchangers, condensers, and similar heat transfer apparatus. The cold-drawing process provides tight tolerances and smooth surfaces.
Key Features:
- Seamless construction –
no weld seam
- Low carbon content – excellent ductility
- Tight dimensional tolerances
- Smooth internal/external surface for optimal heat transfer
- 100% hydrostatic and eddy current tested
Best Applications:
- Shell and tube heat exchangers
- Condensers
- Feedwater heaters
- Low-pressure boilers
- HVAC systems
Limitations:
- Not designed for high pressure
- Thin wall thickness only (typically 0.5-3mm)
- Lower strength than A192
3. ASTM A192 – Seamless High-Pressure Boiler Tube
Overview:
ASTM A192 covers seamless carbon steel tubes for high-pressure service in boilers, superheaters, and heat exchangers. It offers higher strength than ASTM A179.
Key Features:
- Seamless construction – no weld seam
- Higher strength than A179
- Designed for elevated pressure and temperature
- Available in larger diameters (up to 7″)
- Heavier wall thickness capability (1-15mm)
Best Applications:
- High-pressure steam boilers
- Superheaters and reheaters
- Industrial power generation
- Marine high-pressure boilers
Limitations:
- Higher cost than A178
- More expensive than A179 for heat exchanger use
Mechanical Properties Comparison
Property | ASTM A178 (Grade C) | ASTM A179 | ASTM A192 |
Tensile Strength (MPa) | ≥415 | ≥325 | ≥325 |
Yield Strength (MPa) | ≥255 | ≥180 | ≥180 |
Elongation (%) | ≥30 | ≥35 | ≥35 |
Hardness (HRB) | — | ≤72 | ≤77 |
📌 Note: ASTM A178 Grade D offers even higher strength (≥485 MPa tensile, ≥275 MPa yield).
Chemical Composition Comparison
Element | ASTM A178 Grade C | ASTM A179 | ASTM A192 |
Carbon (C) | ≤0.35% | ≤0.25% | 0.06-0.18% |
Manganese (Mn) | ≤0.80% | 0.27-0.63% | 0.27-0.63% |
Phosphorus (P) | ≤0.035% | ≤0.035% | ≤0.035% |
Sulfur (S) | ≤0.035% | ≤0.035% | ≤0.035% |
Application Selection Guide
Choose ASTM A178 when:
Condition | Reason |
Budget is a primary constraint | Lowest cost option |
Pressure requirements are moderate | ERW sufficient for medium pressure |
You need Grade D high strength | Higher strength than A192 |
Welded tube is acceptable | No requirement for seamless |
Choose ASTM A179 when:
Condition | Reason |
Application is heat exchange | Optimized for heat transfer |
Smooth surface is critical | Cold-drawn for clean ID/OD |
Tight tolerances required | Precision cold-drawn process |
Pressure is low to medium | Not designed for high pressure |
Choose ASTM A192 when:
Condition | Reason |
Service is high pressure | Designed for high-pressure boilers |
Temperature is elevated | Heat resistant for superheater service |
Seamless required | No weld seam for safety |
Larger diameter needed | Up to 7″ OD available |
Cost Comparison
Standard | Relative Cost | Value Proposition |
ASTM A178 | $ (Lowest) | Best for budget-conscious boiler projects |
ASTM A179 | $$ (Medium) | Best for heat transfer efficiency |
ASTM A192 | $$ – $$$ (Medium-High) | Best for high-pressure safety |
Common Mistakes to Avoid
Mistake | Consequence | Solution |
Using A179 for high-pressure boiler | Tube failure, safety risk | Use A192 instead |
Using A178 when seamless is specified | Non-compliance, rejection | Use A179 or A192 |
Using A192 for thin-wall heat exchanger | Higher cost, over-engineering | Use A179 for heat transfer |
Ignoring Grade variations in A178 | Wrong strength level | Specify Grade A, C, or D correctly |
Industry Standards Cross-Reference
ASTM Standard | ASME Equivalent | Commonly Used With |
A178 | SA178 | A106, A53 |
A179 | SA179 | A179 tubes often bundled with A179 heads |
A192 | SA192 | A106, A213 |
Frequently Asked Questions
Q1: Can I use ASTM A179 instead of ASTM A192?
A: No. A179 has lower strength and is not designed for high-pressure boiler service. Using A179 in high-pressure applications risks tube failure.
Q2: Is ASTM A178 seamless or welded?
A: Welded (ERW). ASTM A178 is electric-resistance-welded, not seamless.
Q3: Which standard is most commonly used for heat exchangers?
A: ASTM A179 is the industry standard for heat exchangers and condensers due to its tight tolerances and smooth surface.
Q4: Which standard offers the highest strength?
A: ASTM A178 Grade D (≥485 MPa tensile) offers higher strength than A179 and A192. However, A192 is preferred for seamless high-pressure applications.
Q5: Can ASTM A178 be used for superheater service?
A: Yes. ASTM A178 specifically includes superheater flues as an intended application, especially Grade C and D.
Q6: Do all three standards require hydrostatic testing?
A: Yes. All three require 100% hydrostatic or nondestructive electric testing.
Conclusion
Your Need | Recommended Standard |
Most economical boiler tube | ASTM A178 Grade A or C |
Best heat transfer performance | ASTM A179 |
Highest pressure boiler service | ASTM A192 |
Superheater with cost constraint | ASTM A178 Grade C or D |
Cryogenic / low-temperature | ASTM A334 (not covered here) |
About Our Products
We supply all three ASTM standards with:
✅ 100% hydrostatic or NDT testing
✅ Mill test certificates (EN 10204 3.1 or 3.2)
✅ Factory direct pricing
✅ Fast delivery from stock or custom production
✅ Third-party inspection available (SGS, BV, TUV)
Contact Us
Need help selecting the right standard for your project?
📧 Email: yjhtrade@gmail.com
📞 WhatsApp: +86 15106174543
🌐 Website: www.wuxihengzhihui.com
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