ASME SB111 UNS C68700 Aluminum Brass Seamless Tube (CuZn20Al2)
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What is ASTM B111 Aluminium Brass Seamless Tube?
ASTM B111 Aluminium Brass Seamless Tubes are made from a combination of aluminum & brass. They have great corrosion resistance because of their high aluminum content in the brass alloy. The seamless construction of the tubes provides a smooth and uniform interior and reduces the risk of corrosion and also makes them easier to clean & maintain.
ASME SB111 UNS C68700 Aluminum Brass Seamless Tubes Supplier
ASME SB111 UNS C68700 Aluminum Brass Seamless Tubes supplied by GNEE contain approximately 2% aluminum, which forms a dense, robust aluminum oxide protective film on the metal surface. Combined with the anti-dezincification properties provided by trace amounts of arsenic (As, approx. 0.02%–0.06%), the tubing demonstrates exceptional resistance to seawater impingement attack and dezincification, withstanding seawater flow velocities up to 2.0–2.5 m/s. Even in high-salinity environments and under heat transfer media temperatures reaching 100°C–150°C, these tubes maintain superior structural integrity and thermal conductivity (thermal conductivity approx. 100 W/m·K), making them widely utilized in coastal power plant condensers, desalination plant evaporators, and offshore platform condenser tubing systems.
To meet the stringent procurement requirements of global heat exchanger manufacturers, GNEE provides a full range of ASME SB111 C68700 seamless tubes with outer diameters (OD) ranging from 6 mm to 88.9 mm and wall thicknesses (WT) from 0.5 mm to 5 mm (common sizes include OD 19.05 mm/25.4 mm; WT 1.24 mm/1.65 mm). Customization options include straight tubes up to 24 meters in length as well as U-bend tubes.
ASTM B111 Aluminum Brass Seamless Tube Specification:
| Specifications | ASTM B111 & Its equivalent ASME, DIN & EN Standard |
| Grades | C68700/CuZn20Al2/CZ110 |
| Type | U-bend & Straight seamless tube |
| Delivery Condition | O61, Annealed |
| Ends | Plain End |
| Other Testing | Product Analysis, Eddy Current Test, Hydrostatic Test, Ultrasonic Test, Flattening Test, Hardness Test, Tensile Test etc. |
| Dimension | All Pipes & Tube Is Manufactured and Inspected / Tested to the Relevant standards including ASTM and ASME |
| Packing | Plywood case |
ASTM B111 C68700 Tube Chemical Composition
| lement | Weight % |
| Copper | 76.0-79.0 |
| Zinc | Reminder |
| Aluminium | 1.8-2.5 |
| Arsenic | 0.02-0.06 |
| Lead | 0.07 |
| Iron | 0.06 max |
Mechanical Properties:
| Grade | Tensile Strength, min, ksi (MPa) |
Yield Strength, min, ksi (MPa) |
Expansion of Tube Outside Diameter, % |
| C68700 | 50(345) | 18(125) | 20 |
What is the equivalent material for UNS C68700?
The international equivalent material for UNS C68700 (Aluminum Brass) is CuZn20Al2As (EN numerical designation CW702R under EN 12451/12452). Older or alternative regional standards also designate it as CZ110 (British Standard / BS) and CuZn20Al (DIN).
| Material Designation | Corresponding Material Symbol | ||||
| GB/T8890 | ASTM B111 | BS2871 | JIS H3300 | DIN1785 | |
| Admiralty Brass | HSn70-1 | C44300 | CZ111 | C4430 | CuZn28Sn1 |
UNS C68700 Aluminum Brass Tube Applications
Condensers and heat exchangers in power plants and ships
Desalination plants
Marine cooling water systems
Oil refinery and process coolers
Our warehouse holds a large inventory of ASME SB 111 standard copper-nickel tubes. Please contact us for free samples and the inventory list. ASTM B111 copper tubes, C44300 copper tubes, C44300 Admiralty brass tubes, C44300 admiralty brass pipes, C68700 copper tubes, C68700 aluminum brass tubes, C68700 aluminum brass pipes, C70600 Copper tubes, C70600 brass pipes, C70400 copper tubes, C70400 Brass tubes and pipes, C70400 Copper-Nickel tubes and pipes. C71500 copper tubes, C71500 Brass tubes and pipes, C71500 Copper-Nickel tubes and pipes, C71640 copper tubes, C71640 Brass tubes and pipes, C71640 Copper-Nickel tubes and pipes.
Please let me know if you need assistance:
Do you require dimensional data (outer diameter and wall thickness),
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Materials and Manufacture:
When specified in the purchase order or contract, the purchaser shall be furnished certification that samples representing each lot have been either tested or inspected as directed in this specification and requirements have been met.
When identified in the ordering information that product is purchased for ASME Boiler and Pressure Vessel Code applications, certification to this specification is mandatory.
Quality Control
All tubes undergo 100% eddy current testing (ET), hydrostatic testing (at pressures of 7–10 MPa or higher), and airtightness testing prior to shipment. Strict control of the annealing process (e.g., O61 temper) ensures optimal performance during bending and tube expansion operations. Each batch is accompanied by traceability certificates compliant with EN 10204 3.1/3.2 standards-including results from seawater corrosion tests and PMI (Positive Material Identification)-guaranteeing long-term, stable operation in high-salinity and high-humidity environments.
Note:
Mill test certificates will be issued
All tubes shall be supplied as per applicable ASTM B111 /B 111M Specification.
Packing and Marking
ASME SB111 UNS C68700 Aluminum Brass Seamless Tubes are carefully packaged to ensure dimensional accuracy and surface protection during international transportation. Each tube is cleaned, inspected, and protected with plastic end caps to prevent damage, contamination, and oxidation. Tubes are bundled with moisture-proof wrapping and securely packed in export-grade plywood wooden cases or steel frames according to project requirements. Clear markings, including material grade (UNS C68700), standard ASME SB111, size, quantity, and heat number, are applied for easy identification and traceability. This packaging method helps maintain tube integrity for critical applications such as heat exchangers, condensers, and marine cooling systems.
FAQ
Q: Why is aluminum added to this type of brass?
A: Aluminum significantly enhances corrosion resistance, particularly against seawater corrosion and impingement corrosion caused by flowing water.
Q: What is the difference between C68700 and C44300?
A: Both C68700 (Aluminum Brass) and C44300 (Naval Brass) are copper-zinc alloys used in heat exchangers. The primary difference lies in their secondary alloying elements: C68700 contains aluminum (1.8%–2.5%) and is designed to withstand high flow velocities and turbulent seawater; C44300 contains tin (approximately 1%) and is primarily used to provide corrosion resistance in milder water conditions with lower flow velocities.
Q: In what condition is C68700 tubing typically supplied?
A: As this material is primarily used for manufacturing condensers, heat exchangers, and desalination equipment, the annealed condition ensures excellent ductility and cold-working properties, facilitating subsequent operations such as tube bending and expansion for installation.
