Low-Finned Tubes for Condensers – ASME SB111 C68700 Aluminum Brass
Product Overview
Low-Finned Tubes for Condensers, manufactured from ASME SB111 C68700 / UNS C68700 aluminum brass, are designed to increase the external heat-transfer area of condenser tubes while maintaining a compact tube geometry.
C68700, commonly identified as Aluminum Brass B / Arsenical Aluminum Brass, is a copper-zinc alloy containing aluminum and a controlled arsenic addition. ASME SB111 / ASTM B111 recognizes C68700 for seamless condenser, evaporator, and heat-exchanger tube applications.
The low-fin geometry creates a series of integral external fins around the tube surface. Compared with a plain tube of the same nominal diameter, the increased outside surface area can improve heat transfer and provide greater heat-transfer capacity within a given exchanger envelope.
These tubes are particularly suitable for surface condensers, seawater and cooling-water heat exchangers, marine condensers, desalination equipment, and industrial cooling systems where aluminum brass is selected for its combination of thermal conductivity, mechanical strength, and resistance to erosion-corrosion in suitable water-service conditions.
Key Features
- Material: ASME SB111 C68700 / UNS C68700
- Material designation: Aluminum Brass B / Arsenical Aluminum Brass
- Tube type: Seamless low-finned tube
- Application: Condensers and heat exchangers
- Integral low fins increase external heat-transfer surface area
- Suitable for cooling-water and condenser service
- Available in customized fin height, pitch, wall thickness, and length
- Manufactured according to customer drawings and heat-exchanger requirements
- Dimensional and nondestructive inspection available
- Suitable for power generation, marine, desalination, petrochemical, and industrial cooling applications
Typical Applications
1. Surface Condensers
C68700 low-finned tubes can be used in surface condenser systems where steam is condensed on one side of the heat-transfer surface and cooling water flows through the tube.
ASTM B111 specifically identifies C68700 among copper alloys covered for surface condensers, evaporators, and heat exchangers.
2. Power Plant Condensers
The tubes can be considered for condenser and auxiliary cooling equipment in:
- Thermal power plants
- Combined-cycle power plants
- Industrial power-generation facilities
- Cogeneration systems
3. Marine and Seawater Cooling
C68700 is widely associated with condenser and heat-exchanger tube service involving cooling water. The aluminum-brass composition is particularly relevant to marine and seawater-related equipment when the operating chemistry and water velocity are properly controlled.
Typical equipment includes:
- Marine condensers
- Central cooling systems
- Engine coolers
- Offshore cooling equipment
- Shipboard heat exchangers
4. Desalination Equipment
C68700 low-finned tubes can be supplied for heat-transfer equipment used in desalination and seawater treatment systems, subject to the specific water chemistry and design conditions.
5. Industrial Heat Exchangers
Potential applications include:
- Cooling-water heat exchangers
- Process condensers
- Oil coolers
- Water coolers
- Chemical-process heat exchangers
- Industrial circulating-water systems
Typical Size Range
The exact dimensions should be selected according to the condenser design, thermal calculation, tube-sheet configuration, and applicable project specification.
Typical manufacturing ranges can include:
| Parameter |
Typical Range |
| Outside diameter of base tube |
12.7–38.1 mm |
| Base tube wall thickness |
0.8–3.0 mm |
| Overall fin height |
0.5–2.5 mm |
| Fin pitch |
1.5–5.0 mm |
| Tube length |
Up to approximately 18,000 mm |
| Fin type |
Integral low fin |
| Tube form |
Seamless |
| Temper |
Annealed / light-drawn / hard-drawn or project-specified |
ASTM B111/B111M-24 covers seamless condenser tubes up to 3 1/8 in. (80 mm) diameter, although actual low-fin tube dimensions are normally determined by the exchanger design and purchaser specification.
Important: The above dimensional values are typical manufacturing ranges rather than universal ASME SB111 dimensional requirements. Final dimensions, tolerances, fin geometry, temper, and inspection requirements should be confirmed against the purchase specification and applicable edition of the standard.
C68700 Chemical Composition
Typical chemical composition requirements for UNS C68700 aluminum brass include:
| Element |
Typical / Standard Limit, % |
| Copper (Cu) |
76.0–79.0 |
| Aluminum (Al) |
1.8–2.5 |
| Iron (Fe) |
Controlled by specification |
| Zinc (Zn) |
Remainder |
| Arsenic (As) |
0.02–0.06 |
| Lead (Pb) |
Controlled by specification |
C68700 is classified by the Copper Development Association's UNS database as Aluminum Brass, Arsenical, with copper at approximately 76–79%, aluminum at 1.8–2.5%, and arsenic at 0.02–0.06%, with zinc forming the balance.
For contractual supply, the applicable ASME/ASTM edition and purchase specification take precedence over generalized composition tables.
Mechanical Properties
Mechanical properties depend on the tube temper and applicable dimensional range. ASME SB111/ASTM B111 provides requirements according to the specified temper rather than treating all C68700 tubes as having one universal mechanical-property value. ASTM B111 recognizes conditions including annealed, light-drawn, hard-drawn, and hard-drawn/end-annealed.
Typical properties evaluated for C68700 condenser tubes include:
- Tensile strength
- Yield strength / proof strength where applicable
- Elongation
- Hardness
- Expansion behavior
- Flattening performance
For a commercial product page, it is preferable to state the guaranteed values according to the ordered temper and current ASME SB111 specification, rather than presenting one mechanical-property table that could incorrectly apply to every temper.
Manufacturing Process
Our low-finned C68700 condenser tubes can be manufactured through a controlled sequence such as:
- C68700 alloy billet/tube preparation
- Seamless tube production
- Cold drawing or sizing
- Heat treatment according to required temper
- Straightening
- Precision dimensional control
- Integral low-fin forming
- Fin geometry inspection
- Tube surface cleaning
- Nondestructive and dimensional inspection
- Final marking and packaging
ASTM B111 describes manufacturing routes including casting, extrusion, drawing, annealing, straightening, trimming, and other processes capable of producing seamless tubes in the specified condition.
Inspection and Testing
To ensure suitability for condenser and heat-exchanger service, inspection can include:
Chemical Analysis
Positive material identification or laboratory chemical analysis can be performed to verify the C68700 alloy chemistry.
Dimensional Inspection
Typical dimensional checks include:
- Outside diameter
- Wall thickness
- Tube length
- Fin height
- Fin pitch
- Fin root dimensions
- Straightness
- Ovality
- End condition
Tensile Testing
Tensile testing is performed according to the applicable material specification and ordered temper to verify mechanical performance.
Expansion Test
Expansion testing evaluates the tube's ability to withstand controlled enlargement without unacceptable cracking or failure.
Flattening Test
Flattening testing evaluates tube ductility and material integrity.
Eddy-Current Testing
Eddy-current examination can be used as a nondestructive method for detecting relevant discontinuities in the tube wall.
Hydrostatic Testing
Hydrostatic testing can be performed where specified by the purchase order or applicable standard.
Pneumatic / Air Underwater Testing
Pneumatic leakage testing can also be provided when required by the project specification.
ASTM B111/B111M identifies expansion, flattening and residual-stress testing and also provides for eddy-current, hydrostatic and pneumatic examinations among its testing requirements/options.
Visual and Surface Inspection
The tube surface is inspected for:
- Cracks
- Laminations
- Seams
- Excessive scratches
- Surface defects
- Fin damage
- Deformation
- Corrosion or contamination
Low-Fin Design Advantages
The main purpose of the low-fin configuration is to increase the external heat-transfer area without requiring a proportionally larger base-tube diameter.
Compared with plain condenser tubes, low-finned tubes can offer:
- Increased external heat-transfer area
- Greater heat-transfer capability within a compact exchanger
- Potential reduction in required exchanger surface area
- Efficient use of existing tube-sheet layouts
- A practical solution where the shell-side heat-transfer coefficient is lower than the tube-side coefficient
The actual thermal advantage depends on fin geometry, fluid properties, velocity, fouling, temperature difference, pressure drop, and the complete heat-exchanger design.
Why Choose C68700 Aluminum Brass?
C68700 combines a copper-rich matrix with aluminum and a controlled arsenic addition. Its established use in condenser and heat-exchanger tubing makes it a relevant material option for cooling-water service.
Its principal advantages for condenser applications include:
- Good thermal-transfer capability
- Suitable mechanical strength for tube applications
- Established condenser-tube specification coverage
- Good resistance to erosion-corrosion under appropriate water-service conditions
- Suitability for marine and industrial cooling-water equipment
- Availability in different tube tempers
ASTM B111 specifically identifies C68700 as Aluminum Brass B for seamless condenser tubes, and the current B111/B111M scope includes surface condensers, evaporators, and heat exchangers.
Quality Assurance
Each production batch can be supplied with appropriate quality documentation, such as:
- Material Test Certificate (MTC)
- Chemical composition report
- Mechanical test results
- Dimensional inspection report
- Eddy-current test report
- Hydrostatic test report, when specified
- Heat/lot traceability
- Certificate of conformity
- Third-party inspection documentation when required
Packaging
C68700 low-finned tubes can be supplied in suitable export packaging according to tube length and customer requirements.
Typical protection may include:
- Plastic end caps
- Protective wrapping
- Moisture-resistant packaging
- Bundling with identification tags
- Wooden cases or export-grade packing where required
Each bundle can be marked with material grade, size, length, heat/lot number, quantity, and applicable specification for traceability.
Recommended Product Positioning
ASME SB111 C68700 Low-Finned Tubes for Condensers and Heat Exchangers
This product is particularly suitable for customers looking for aluminum-brass low-finned tubes for:
Surface Condensers | Power Plant Condensers | Marine Heat Exchangers | Seawater Cooling | Desalination Equipment | Industrial Cooling Systems
Product Keywords / Search Terms
- C68700 low finned tube
- ASME SB111 C68700 tube
- aluminum brass condenser tube
- C68700 condenser tube
- low finned tubes for condensers
- aluminum brass heat exchanger tube
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