Introduction
This article explains ASME SB111 and ASTM B111 C44300 copper seamless tube for condensers. Admiralty brass, designated C44300, is a copper-zinc-tin alloy developed for seawater and brackish-water heat exchange service. Small additions of tin and arsenic suppress dezincification, which is the common failure mode of plain brasses in chloride-bearing water.
Composition
Admiralty brass contains 70.0 to 73.0 percent copper, 0.9 to 1.2 percent tin and 0.02 to 0.10 percent arsenic with the balance zinc. The tin strengthens the alloy and moves the corrosion mechanism away from selective leaching, while the arsenic addition further blocks the dezincification reaction at the grain boundaries. Common international equivalents include CuZn28Sn1 under EN standards and CZ111 under British designations.
Why It Resists Seawater
In plain brass, chloride water attacks the zinc-rich phase and leaves a porous copper deposit, a process called dezincification. The tin and arsenic in admiralty brass inhibit that reaction, which is why the alloy passes dezincification testing per ASTM B858 and gives decades of service in condensers cooled with clean or moderately polluted seawater.
| Element | Typical Range |
|---|---|
| Copper | 70.0 - 73.0% |
| Tin | 0.9 - 1.2% |
| Arsenic | 0.02 - 0.10% |
| Zinc | Balance |
Properties
Admiralty brass tube combines a thermal conductivity of about 109 to 111 W/(m·K) with tensile strength of roughly 330 to 380 MPa annealed and elongation above 40 percent. Density is about 8.53 g/cm3. The alloy resists corrosion by seawater, brine and non-oxidizing acids, and it has practical immunity to stress-corrosion cracking in the annealed condition.
Applications and Standards
The main use is condenser and heat exchanger tubing in power plants, desalination plants, ships and refinery coolers. Tube is supplied to ASTM B111, with size and temper tolerances per the same standard, and the material is also available as sheet, strip, rod and pipe.
Verification
Confirm the copper, tin and arsenic ranges on the mill certificate, check the dezincification test requirement, and verify the tube dimensions and temper against ASTM B111 before acceptance.
