ASME SB111 C68700 Low Finned Tubes for Shell-and-Tube Heat Exchangers
Product Overview
ASME SB111 C68700 Low Finned Tubes are premium enhanced-surface heat transfer tubes manufactured from Aluminum Brass (UNS C68700) seamless tubing and engineered specifically for high-efficiency shell-and-tube heat exchangers. The low-fin geometry is mechanically formed from the base tube wall, creating an integral fin structure that significantly increases the external heat transfer area while maintaining excellent thermal conductivity and mechanical integrity.
C68700 Aluminum Brass is widely recognized for its exceptional resistance to seawater corrosion, erosion, impingement attack, and biofouling, making it one of the most widely specified materials for condensers, marine coolers, desalination plants, power stations, and petrochemical heat exchangers.
The combination of Aluminum Brass metallurgy and low-fin enhancement enables designers to achieve higher thermal performance, reduced exchanger size, and lower operating costs compared to conventional plain tubes.
Key Features
- Manufactured from seamless ASME SB111 UNS C68700 Aluminum Brass tubing
- Integral low-fin construction without welding or bonding
- Enhanced external heat transfer surface area
- Excellent resistance to seawater and brackish water corrosion
- High resistance to erosion-corrosion and impingement attack
- Improved heat exchanger efficiency
- Reduced shell size and equipment footprint
- Suitable for condensers, evaporators, and liquid coolers
- Long service life in marine and industrial environments
- Custom fin geometry available to meet thermal design requirements
Typical Applications
Power Generation
- Steam surface condensers
- Feedwater heaters
- Auxiliary cooling systems
Marine Industry
- Seawater coolers
- Central cooling systems
- Engine jacket water coolers
- Offshore platform heat exchangers
Desalination Plants
- Multi-stage flash evaporators
- Brine heaters
- Condensers
Petrochemical & Refining
- Process coolers
- Hydrocarbon condensers
- Heat recovery systems
HVAC & Refrigeration
- Water-cooled condensers
- Chillers
- Heat recovery units
Manufacturing Process
The low fins are formed through a precision cold-working process that displaces material from the tube wall to create continuous helical fins. Since the fins are integral with the tube, there is no metallurgical discontinuity between the fin and the base material.
This manufacturing method provides:
- Maximum heat transfer efficiency
- Excellent fin-to-tube thermal conductivity
- Superior mechanical strength
- Resistance to vibration-induced damage
- Long-term operational reliability
Standard Size Range
| Parameter |
Standard Range |
| Base Tube Outside Diameter |
15.88 mm – 31.75 mm |
| Tube Wall Thickness |
0.70 mm – 3.00 mm |
| Tube Length |
Up to 18,000 mm |
| Fin Height |
0.8 mm – 2.5 mm |
| Fin Pitch |
8 – 26 Fins Per Inch (FPI) |
| Fin Thickness |
0.25 mm – 0.50 mm |
| Finned Length |
As per customer requirements |
| Bare End Length |
50 mm – 300 mm |
| Surface Area Enhancement Ratio |
2 – 4 Times Plain Tube |
Custom dimensions and fin configurations can be produced according to project specifications and thermal design calculations.
Chemical Composition of ASME SB111 C68700 (Aluminum Brass)
| Element |
Composition (%) |
| Copper (Cu) |
76.0 – 79.0 |
| Zinc (Zn) |
Balance |
| Aluminum (Al) |
1.8 – 2.5 |
| Arsenic (As) |
0.02 – 0.06 |
| Iron (Fe) |
0.06 Max |
| Manganese (Mn) |
0.01 Max |
| Nickel (Ni) |
0.50 Max |
| Lead (Pb) |
0.07 Max |
The controlled aluminum addition forms a protective surface film that significantly enhances resistance to seawater corrosion and erosion.
Mechanical Properties
Typical Mechanical Properties (Annealed Condition)
| Property |
Value |
| Tensile Strength |
≥ 360 MPa |
| Yield Strength (0.5% Extension Under Load) |
≥ 125 MPa |
| Elongation |
≥ 30% |
| Hardness |
Typical 70–100 HRB |
| Thermal Conductivity |
Approximately 115–125 W/m·K |
| Density |
Approximately 8.33 g/cm³ |
Values may vary depending on tube dimensions, manufacturing condition, and customer specifications.
Inspection and Testing
Raw Material Verification
- Material certificate review
- Heat number traceability
- Positive Material Identification (PMI) upon request
Dimensional Inspection
- Outside diameter measurement
- Wall thickness verification
- Fin height inspection
- Fin pitch measurement
- Fin thickness verification
- Bare-end dimension checks
- Straightness and length inspection
Mechanical Testing
- Tensile testing
- Flattening test
- Flaring test
- Expansion test
- Hardness testing
Non-Destructive Testing (NDT)
- Eddy Current Testing (ECT)
- Hydrostatic pressure testing
- Air-under-water leak testing
- Ultrasonic testing (UT) when specified
Surface Examination
- Visual inspection
- Surface defect evaluation
- Fin profile verification
- Cleanliness inspection
Documentation Supplied
- EN 10204 3.1 Material Test Certificate
- Dimensional inspection reports
- Mechanical test reports
- NDT reports
- Third-party inspection documentation (TÜV, SGS, BV, DNV, Lloyd's Register) available upon request
Advantages of C68700 Low Finned Tubes
The low-fin profile increases external surface area, resulting in significantly improved thermal efficiency compared to plain tubes.
Aluminum Brass offers excellent protection against seawater corrosion, making it ideal for marine and desalination applications.
Improved heat transfer coefficients allow more compact exchanger designs and reduced material usage.
Excellent resistance to erosion-corrosion and biofouling contributes to lower maintenance costs and extended operational life.
Combines strong thermal performance with durability, reducing total lifecycle costs.
Applicable Standards
Manufacturing and inspection can be performed according to:
- ASME SB111
- ASTM B111
- TEMA Standards
- ASME Boiler & Pressure Vessel Code
- EN 10204
- Customer Project Specifications
Why Choose ASME SB111 C68700 Low Finned Tubes?
ASME SB111 C68700 Aluminum Brass Low Finned Tubes provide an ideal combination of heat transfer efficiency, seawater corrosion resistance, mechanical reliability, and long-term durability. Their enhanced surface design enables higher thermal performance while maintaining the proven corrosion resistance of Aluminum Brass, making them a preferred choice for shell-and-tube heat exchangers operating in marine, power generation, desalination, HVAC, and petrochemical environments.
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