What ASTM B111 UNS C10300 Copper Pipe Is
ASTM B111 UNS C10300 is a low-oxygen, phosphorized copper grade supplied as seamless tube and pipe for condensers, heat exchangers, refrigeration circuits and general engineering service. The metal contains a minimum of 99.95 % copper with residual phosphorus held at a nominal 0.005 %, a combination that keeps electrical and thermal conductivity high while suppressing hydrogen embrittlement during brazing and welding.
Bright annealing is the final thermal treatment. It runs in a reducing atmosphere, so the tube leaves the line with an oxide-free, mirror-like surface and a fully recrystallised, ductile structure. The result is a tube that can be bent, flared and expanded without the pickling step that open-air annealed material normally requires.
Specifications of Bright Annealed C10300 Copper Tube
| Parameter | Value |
|---|---|
| Base standard | ASTM B111 / ASME SB111 |
| Related standards | ASTM B75, ASTM B280, ASTM B68 and their ASME equivalents |
| Material | Copper UNS C10300, phosphorized low-oxygen copper |
| Outside diameter | 4 mm to 150 mm |
| Wall thickness | 0.25 mm to 8 mm |
| Length | 1 m to 6 m, or cut to order |
| Temper | Light annealed, bright annealed, full annealed, hard drawn |
| Form | Seamless tube, pancake coil, level-wound coil, straight length |
Chemical Composition and Physical Properties
| Property | Typical Value |
|---|---|
| Cu, min | 99.95 % |
| P, nominal | 0.005 % |
| Tensile strength | 200 to 250 MPa |
| Yield strength | 50 to 75 MPa |
| Elongation | 35 to 50 % |
| Hardness | 40 to 60 HB |
| Density | 0.323 lb/cu in |
| Electrical resistivity at 68 deg F | 10.5 microhm-cm |
| Melting point | 1981 deg F |
| Mean coefficient of thermal expansion | 9.4 |
| Modulus of elasticity in tension | 17 000 ksi |
The soft temper drives the bending and flaring behaviour, while the low oxygen content keeps the metal stable when it is joined by brazing or welding. Where higher working pressures are needed, hard-drawn and half-hard tempers are available with thinner walls and a smaller bend radius allowance.
Working Pressure and Wall Thickness Selection
Allowable working pressure falls as outside diameter grows. For half-hard annealed tube, an 8 mm outside diameter with a 0.8 mm wall carries a maximum working pressure of roughly 10.5 N/mm2, whereas a 42 mm tube needs about 1.5 mm of wall to hold 3.4 N/mm2. Half-hard light-gauge and hard-drawn thin-wall variants reach comparable pressure at reduced wall thickness, which cuts weight and cost in large heat exchanger bundles. Tube is normally selected on the combination of outside diameter, wall thickness and temper that satisfies both the pressure duty and the bending radius of the circuit.
Typical Applications
Shell-and-tube and finned heat exchangers, condensers and evaporators
Air conditioning and refrigeration coils, including pancake and level-wound coils
Bus bars, transformers and conductors where energy transfer efficiency matters
Water, gas and oil transport lines in general engineering systems
Vacuum, medical gas and semiconductor process lines
Automotive and aerospace fluid circuits
Frequently Asked Questions
Q: Why is C10300 supplied bright annealed rather than open-air annealed?
Bright annealing runs in a reducing atmosphere, so the surface stays oxide-free and needs no pickling before bending, brazing or installation.
Q: Can ASTM B111 C10300 tube be welded and brazed?
Yes. The residual phosphorus acts as a deoxidiser and the low oxygen content limits hydrogen embrittlement, so the grade joins reliably by brazing and welding under normal copper practice.
Q: Which temper should be chosen for tight-radius bending?
Light annealed and full annealed tempers give the greatest ductility and are used for tight bends and flares. Half-hard and hard-drawn tempers suit straight runs and higher pressure duty.
Q: How does C10300 differ from C11000?
C10300 is a low-oxygen copper with a controlled phosphorus addition and a minimum of 99.95 % Cu. C11000 is electrolytic tough pitch copper with a minimum of 99.90 % Cu and no deliberate deoxidiser, so it is less suited to welding.
Q: How is the maximum working pressure of a copper tube determined?
It is calculated from outside diameter, wall thickness and temper condition. Smaller diameters and heavier walls raise the allowable pressure, and each temper has its own table of values.
Q: Is C10300 suitable for medical gas and vacuum service?
The high purity and low oxygen content make the grade a common choice for medical gas, vacuum and semiconductor process lines, where clean internal surfaces matter.
