What C44300 is
Admiralty brass is a 70/30 copper-zinc brass with about 1% tin for corrosion resistance and a small arsenic addition to stop dezincification. It combines the thermal conductivity of brass with much better resistance to fresh, brackish, and mildly polluted cooling water than plain yellow brass.
It is the default tube for refinery surface condensers, crude unit overhead exchangers, and power station condensers on fresh or brackish water, and it is the alloy that first put Ameritube in front of the oil refining industry.
The 12,000-tube lesson
In 2007 Ameritube drew 12,000 C44300 tubes, 3/4" x .083" and 3/4" x .065" minimum wall, for a heat exchanger builder supplying Exxon Mobil and Petrobras. Each tube took four draws at more than 30% reduction, with a stress relief anneal in between.
The customer rejected none. We rejected over 1,500 in-process, because a 30% draw finds the sub-surface defects that a 10% tube-sheet roll never would. That job is why every tube we sell today is worked hard and tested at 100%, and it is why we moved toward making our own shells instead of trusting someone else's.
Standards we supply to
- ASME SB-111 / ASTM B111, condenser and heat exchanger tube
- ASME SB-395 / ASTM B395, U-bend tube
- ASTM B543 welded equivalent on request
Chemical composition
| Element | Requirement |
|---|---|
| Copper | 70.0 to 73.0% |
| Tin | 0.9 to 1.2% |
| Arsenic | 0.02 to 0.06% |
| Lead | 0.07% max |
| Iron | 0.06% max |
| Zinc | Remainder |
Typical mechanical properties, annealed
| Property | Value |
|---|---|
| Tensile strength | 45,000 psi min (310 MPa) |
| Yield strength | 15,000 psi min (105 MPa) |
| Elongation in 2" | 30% min |
| Density | 0.308 lb/in3 (8.53 g/cm3) |
Where it is used
- Refinery exchangers: crude and vacuum unit overhead condensers, product coolers, reboilers on cooling water.
- Power generation: surface condensers and auxiliary coolers on fresh and brackish water.
- Chemical processing: cooling water exchangers where chlorides are moderate.
- HVAC: large chiller condensers.
When to choose something else
Seawater or heavily polluted water: move to C70600 or C71500 copper-nickel. Ammonia in the cooling water: admiralty is prone to stress corrosion cracking, ask about copper-nickel or stainless. High-velocity seawater: C72200 copper-nickel-chromium.
OD, wall (specify MW minimum wall or AW average wall), temper, length or U-bend schedule, quantity, ASME SB-111 or other governing spec, and whether your customer requires ammonia vapor testing or 3rd-party inspection.