GNEE supplies ASTM B111 C68700 Aluminum Brass Tubes for critical applications including heat exchangers, condensers, evaporators, and desalination plants.
C68700 is an aluminum brass alloy containing 76-79% copper and 1.8-2.5% aluminum, with arsenic addition for dezincification resistance. These tubes offer excellent corrosion resistance in seawater and brackish water environments.
The outstanding characteristic of C68700 Aluminum Brass is its high resistance to impingement attack – a critical factor for tube longevity in high-velocity seawater applications. This alloy effectively resists the corrosive action of high-velocity salt and brackish water and develops a protective self-healing film on its surface.
Key Specifications
| Parameter | Details |
|---|---|
| Standard | ASTM B111 / ASME SB111 |
| UNS Number | C68700 |
| Material | Aluminum Brass |
| Temper | O61 (Annealed) |
| OD Range | 6.35mm – 101.6mm |
| Wall Thickness | 0.89mm – 5.0mm |
| Length | Up to 6 meters (custom available) |
| Manufacturing Type | Seamless |
Available Standard Sizes
| OD (mm) | Wall Thickness (mm) | Length (mm) |
|---|---|---|
| 6.35 | 0.89 | 6000 |
| 9.52 | 1.22 | 6000 |
| 12.70 | 1.63 | 6000 |
| 15.88 | 1.63 | 6000 |
| 19.05 | 1.65 | 6000 |
| 25.40 | 1.65 | 6000 |
| 31.75 | 2.11 | 6000 |
| 38.10 | 2.11 | 6000 |
| 50.80 | 2.77 | 6000 |
C68700 Chemical Composition
| Element | Weight % |
|---|---|
| Copper (Cu) | 76.0 – 79.0 |
| Aluminum (Al) | 1.8 – 2.5 |
| Arsenic (As) | 0.02 – 0.06 |
| Lead (Pb) | 0.07 max |
| Iron (Fe) | 0.06 max |
| Zinc (Zn) | Remainder |
Mechanical Properties (O61 Temper)
| Property | Value |
|---|---|
| Tensile Strength (min) | 345 MPa (50 ksi) |
| Yield Strength (min) | 125 MPa (18 ksi) |
| Elongation | 25-45% |
| Hardness (HV5) | 150 min |
| Grain Size | 0.010 – 0.045 mm |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.33 g/cm³ (0.301 lb/in³) |
| Thermal Conductivity | 58.0 BTU·in/hr·ft²·°F (100.4 W/m·K) |
| Electrical Conductivity | 23% IACS @ 68°F |
| Modulus of Elasticity | 16000 ksi |
| Melting Point | 1710-1780°F (932-971°C) |
Equivalent Grades
| Standard | Designation |
|---|---|
| ASTM B111 | C68700 |
| BS 2871 | CZ110 |
| DIN 1785 | CuZn20Al2 |
| JIS H3300 | C6870 |
| EN | CW702R |
| GB/T 8890 | HAL77-2 |
Applications
| Industry | Application |
|---|---|
| Power Generation | Condensers, cooling systems |
| Desalination | Evaporators, distiller tubes |
| Marine | Seawater piping, heat exchangers, shipbuilding |
| Petrochemical | Refineries, process equipment |
| HVAC | Heat exchangers, refrigeration |
| Offshore | Oil rigs, FPSO cooling systems |
FAQ
Q1: What is ASTM B111 C68700?
A: ASTM B111 C68700 is an aluminum brass alloy (76-79% Cu, 1.8-2.5% Al) used for seamless condenser and heat exchanger tubes in seawater applications.
Q2: What is the tensile strength of C68700?
A: UNS C68700 in annealed O61 temper has minimum tensile strength of 345 MPa (50 ksi) and yield strength of 125 MPa (18 ksi) .
Q3: What is the purpose of arsenic in C68700?
A: Arsenic (0.02-0.06%) prevents dezincification – selective zinc leaching in seawater – extending tube life to 10+ years.
Q4: What is the difference between C68700 and C44300?
A: C68700 (Aluminum Brass) handles high-velocity seawater (up to 3 m/s). C44300 (Admiralty Brass) fails at velocities above 2 m/s.
Q5: What sizes are available for C68700 tubes?
A: ASTM B111 C68700 tubes are available in OD from 6.35mm to 101.6mm and wall thickness from 0.89mm to 5.0mm.
Q6: What are the equivalent grades of C68700?
A: UNS C68700 equivalents are BS CZ110, DIN CuZn20Al2, JIS C6870, EN CW702R, and GB HAL77-2.
Q7: What testing is done on C68700 tubes?
A: C68700 tubes undergo eddy current, hydrostatic, expansion, flattening, tensile, and grain size tests per ASTM B111.
Q8: What is the thermal conductivity of C68700?
A: C68700 has thermal conductivity of 58.0 BTU·in/hr·ft²·°F (100.4 W/m·K) at 68°F.
Q9: Where are C68700 tubes used?
A: C68700 tubes are used in power plant condensers, desalination evaporators, marine heat exchangers, and petrochemical refineries.
Quality Assurance – Mill Test Certificate (EN 10204/3.1)
GNEE provides EN 10204/3.1 Mill Test Certificates (MTC) with every shipment of ASTM B111 C68700 / EN 12451 CuZn20Al2As aluminum brass tubes.
The certificate below shows actual test results from a recent production batch:
| Test Item | Result | Requirement |
|---|---|---|
| Tensile Strength | 385 MPa | ≥340 MPa |
| Yield Strength | 150 MPa | ≥120 MPa |
| Elongation | 57-58% | ≥55% |
| Expansion Test | 31% | ≥30% |
| Grain Size | 0.025 mm | 0.01-0.05 mm |
| Eddy Current Test | 100% PASS | EN 1971 |
Certificate details:
Standard: EN 12451 (equivalent to ASTM B111)
Material: CuZn20Al2As (UNS C68700 / CZ110 / HAL77-2)
Dimensions: OD 23mm x 1.0mm / OD 25.4mm x 1.24mm
Temper: R340 (O61 annealed)
Certification: PED 97/23 EC approved
Export-Ready Packing – Anti-Rust & Wooden Case
After passing inspection, all tubes are packed according to export standards and customer-specific requirements. The packing process is documented below to ensure traceability and damage-free delivery.
Packing steps shown in video & images:
1. Tube cleaning & drying
2. Plastic end caps on both ends
3. VCI anti-rust paper wrapping
4. Bundle strapping with moisture barrier film
5. Plywood wooden case (ISPM-15 compliant) with foam padding
6. Labeling with ASTM grade, lot number, and inspection stamp
Our Factory & Equipment
All ASTM C68700 tubes are produced and inspected on our in-house equipment, allowing full process control from billet casting to final packing.
Key equipment used for this lot:
• Induction melting furnace – precise alloying (Cu + Zn + Al + As)
• Horizontal continuous casting – uniform billet structure
• Extrusion press (800T / 1630T) – seamless tube forming
• Cold drawing bench (5–40m) – dimensional accuracy to ±0.02mm
• Online eddy current tester (FOERSTER / MAC) – 100% NDT
• Ultrasonic wall thickness gauge – real-time monitoring
• Annealing furnace (controlled atmosphere) – temper O61
In-house metrology: Micrometers, pin gauges, optical comparator, hardness tester (HV/HRB)
All equipment is calibrated quarterly. Production records are traceable by lot number.
Copper & Copper Alloy Products – Supply Range
| Product Form | Common Alloys / Grades | Size Range | Standards | Typical Applications |
|---|---|---|---|---|
| Tube / Pipe | C12200, C11000, C68700, C70600, C71500, C44300, C27000 | OD: 4mm – 219mm Wall: 0.5mm – 20mm Length: up to 15m | ASTM B68, B75, B111, B280, B359, B466 | Heat exchangers, condensers, HVAC, plumbing, oil coolers |
| Plate / Sheet | C11000, C12200, C26000, C26800, C52100, C68700 | Thk: 0.5mm – 50mm Width: up to 1200mm Length: up to 4000mm | ASTM B152, B169, B103, B465 | Electrical parts, roofing, gaskets, industrial panels |
| Rod / Bar | C11000, C26000, C36000, C46400, C48500, C63000 | Dia: 3mm – 120mm Length: 1m – 6m (or custom) | ASTM B16, B124, B138, B150, B453 | Valve stems, shafts, fasteners, machined components |
| Wire | C11000, C16200, C17500, C26000, C52100, C64700 | Dia: 0.1mm – 12mm Coil weight: up to 100kg | ASTM B1, B2, B3, B197, B206, B624 | Welding electrodes, electrical conductors, springs, mesh |
| Strip / Foil | C11000, C19400, C26000, C26800, C52100, C70250 | Thk: 0.05mm – 3.0mm Width: 5mm – 600mm | ASTM B36, B465, B694, B888 | Connectors, terminals, battery tabs, shielding, stamping parts |
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