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ASTM B111 C68700 Copper-Alloy Seamless Tube For Condenser and Heat Exchanger Tube Bundle
ASTM B111 C68700 is a high-performance arsenical aluminum brass (CuZn20Al1As) seamless tube specifically engineered for critical heat transfer applications in condensers, heat exchangers, and other thermal systems. This alloy combines copper (Cu), zinc (Zn), aluminum (Al), and a controlled arsenic (As) addition to achieve superior corrosion resistance, erosion resistance, and thermal conductivity, particularly in marine, power plant, and industrial cooling systems.
1.Chemical & Mechanical Properties
| ASTM B111 C68700 Chemical Composition (%) |
| Cu |
Al |
Fe |
Zn |
As |
Mo |
| 76.0-79.0% |
1.8-2.5% |
≤0.06% |
REM |
0.02-0.06% |
/ |
Mechanical Properties
| Property |
Standard Value (Annealed) |
| Tensile Strength |
≥ 380 MPa |
| Yield Strength |
≥ 140 MPa |
| Elongation |
≥ 30% |
| Hardness (Brinell) |
≤ HRB 65 |
2. Key Adventages
- Superior Corrosion Resistance
Dezincification Resistance: Arsenic (As) addition prevents dezincification in seawater and aggressive cooling media.
Erosion-Corrosion Resistance: Aluminum (Al) oxide layer resists impingement attack in high-velocity flows (>3 m/s).
-
Excellent Thermal Conductivity
Thermal conductivity ~100 W/m·K, close to pure copper, far surpassing stainless steel (15 W/m·K) and titanium (22 W/m·K).
Smooth seamless interior minimizes fouling, ensuring sustained heat transfer efficiency.
-
High Strength & Fabrication Flexibility
Cold-work hardening: Tensile strength can reach 650 MPa (hard temper) via cold drawing.
Annealed temper (O61) allows tube bending/flaring for complex heat exchanger layouts.
-
Long Service Life & Low Maintenance
Service life exceeds 20 years in seawater (3~5x longer than carbon steel).
No need for cathodic protection or coatings, reducing lifecycle costs.
3. Key Applications
Thermal power plant condensers: Resists high-pressure steam, ammonia attack, and sulfide corrosion
Nuclear plant heat exchange systems: Used in secondary cooling loops, resists chloride-induced corrosion
- Marine & Offshore Engineering
Marine central coolers: Resists seawater corrosion and biofouling, reduces maintenance
Desalination plants: Withstands high-salinity media, maintains heat transfer performance
Refinery heat exchangers: Resists H₂S and acidic fluid corrosion
LNG liquefaction equipment: Maintains ductility in cryogenic conditions (above -40°C)
- Industrial Refrigeration & HVAC
Industrial chillers: High thermal conductivity reduces energy consumption
Lithium bromide absorption chillers: Resists LiBr solution corrosion, service life >15 years
| Performance |
C68700
(Arsenical Aluminum Brass)
|
C71500
(Cu-Ni 70/30)
|
C70600
(Cu-Ni 90/10)
|
C44300
(Admiralty Brass)
|
| Composition |
Cu-Zn20-Al1-As0.04 |
Cu-30Ni-0.7Fe |
Cu-10Ni-1.4Fe |
Cu-Zn28-Sn1-As0.04 |
| Thermal Conductivity (W/m·K) |
100 |
29 |
50 |
110 |
| Seawater Corrosion Resistance |
★★★★★
(anti-dezincification)
|
★★★★★
(all-round)
|
★★★★☆
(better than 90/10)
|
★★★☆☆
(requires inhibitor)
|
| Acid Resistance |
★★★☆☆ (pH≥6) |
★★★★★
(resists H₂S/CO₂)
|
★★★★☆ |
★★☆☆☆ |
| Erosion-Corrosion Resistance |
★★★★☆
(Al oxide layer)
|
★★★★★ |
★★★★☆ |
★★☆☆☆ |
| Max Operating Temp (°C) |
200 (short-term 260) |
300 |
260 |
150 |
| Low-Temperature Toughness |
Good above -40°C |
Stable at -196°C |
Stable at -100°C |
Good above -40°C |
| Cost Index |
$$$ (moderate) |
$$$$$ (highest) |
$$$$ |
$$ (lowest) |
| Typical Applications |
Seawater condensers, marine heat exchangers |
Offshore platforms, LNG equipment |
Desalination plants, chemical exchangers |
Freshwater coolers, HVAC |
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