Cold Finished ASME SB111 C44300 Copper Alloy Tube Overview
Cold finished ASME SB111 C44300 copper alloy tube is a seamless, arsenical admiralty brass product supplied to ASTM B111 / ASME SB111, the specification that governs seamless copper and copper-alloy condenser tubes and ferrule stock. The cold finishing route produces a bright, dimensionally consistent surface with tight wall concentricity, which matters when tubes have to be rolled into a tube sheet and expanded without cracking at the joint.
The alloy contains 70.0-73.0% copper, 0.9-1.2% tin and a controlled arsenic addition of 0.02-0.06%. Arsenic is the deliberate addition that gives admiralty brass its resistance to dezincification in cooling waters containing chlorides and mildly aggressive salts, which is why C44300 has been a standard choice for power station condensers and marine heat transfer equipment for decades. C68700 aluminium brass shares the same family of service conditions and offers comparable corrosion behaviour.
Because C44300 is a single-phase alpha brass, it draws, bends and expands readily. Tube is normally finished in the annealed temper (O61) so that the mechanical minimums of the specification are met while enough ductility remains for expansion into tube sheets.
Standards and Equivalent Specifications
The same material is ordered against several national specifications, and the equivalents below are the usual references for international projects.
| Country / Body | Standard | Scope |
|---|---|---|
| ASTM | ASTM B111 | Copper and Copper-Alloy Seamless Condenser Tubes and Ferrule Stock |
| ASME | ASME SB111 | Same product as ASTM B111, adopted for pressure equipment service |
| GB/T | GB/T 8890 | Seamless Copper Alloy Heat Exchanger Tubes |
| BS | BS 2871 | Copper and Copper Alloys Tubes |
| JIS | JIS H3300 | Copper and Copper Alloy Seamless Pipes and Tubes |
| DIN | DIN 1785 | Wrought Copper and Copper Alloy Tubes for Condensers and Heat Exchangers |
Chemical Composition of ASTM B111 C44300
| Element | Composition, % |
|---|---|
| Copper, incl. silver (Cu) | 70.0-73.0 |
| Tin (Sn) | 0.9-1.2 |
| Arsenic (As) | 0.02-0.06 |
| Lead (Pb) | 0.07 max |
| Iron (Fe) | 0.06 max |
| Zinc (Zn) | Balance |
| Copper plus named elements | 99.6 min |
Copper, tin and arsenic are specified as ranges because they control both the corrosion behaviour and the working characteristics of the finished tube. Zinc makes up the balance of the alloy, and the lead and iron limits keep the material clean enough for condenser service.
Mechanical and Physical Properties
| Property | Value |
|---|---|
| Tensile strength, min | 310 MPa (45 ksi) |
| Yield strength, min | 105 MPa (15 ksi) |
| Density | 8.53 g/cm3 |
| Melting point | 899-938 °C |
| Thermal conductivity | 109 W/m-K at 20 °C |
| Specific heat capacity | 0.09 cal/g-°C at 20 °C |
| Coefficient of linear thermal expansion | 20.2 x 10-6/°C, 20-300 °C |
The 310 MPa tensile and 105 MPa yield values correspond to the 45 ksi and 15 ksi annealed minimums published for the C44300 family in the seamless tube requirements, so metric and inch-based purchase orders describe the same material state. The high thermal conductivity relative to stainless steels is one reason the alloy is retained for water-cooled condensers: it keeps the tube wall temperature low and the overall heat transfer coefficient high.
Typical Applications
Condenser tubes for steam power stations and process plants
Heat exchanger tubing in oil and gas service where low corrosion rates are required
Evaporator tubing and distiller tubes for desalination and chemical processing
Ferrule stock and ferrules for condenser tube ends
Condenser tube plates and oil well pump liners
Bourdon tubes and other pressure-sensing elements
In all of these duties the selection driver is the same: a copper-based tube that resists cooling water attack, transfers heat efficiently and can be rolled or brazed into headers using well-established shop practice.
Service Benefits and Quality Testing
Durability: the structure and chemistry of C44300 give a long working life, with service periods of about ten years typical depending on the water chemistry and operating hours.
Cost efficiency: installation, operation and maintenance costs are moderate compared with higher-alloy alternatives, and thinner walls can often be used because of the corrosion allowance permitted.
Versatility: the alloy is produced as condenser tube, ferrule stock and general engineering tube, and it can be bent, expanded, welded and brazed.
Finished tube is verified by chemical analysis against the heat certificate, hardness testing, pitting tests and intergranular corrosion tests. Eddy current testing of the tube body and a hydrostatic or pneumatic pressure test are applied where the purchase specification calls for them, so that wall thickness and soundness are confirmed before dispatch.
Frequently Asked Questions
Q: What does ASME SB111 C44300 mean?
ASME SB111 is the ASME adoption of ASTM B111, the specification for seamless copper and copper-alloy condenser tubes and ferrule stock, and C44300 is the UNS number of the arsenical admiralty brass alloy within that specification.
Q: What is the chemical composition of C44300 admiralty brass?
Copper 70.0-73.0%, tin 0.9-1.2%, arsenic 0.02-0.06%, lead 0.07% maximum, iron 0.06% maximum and the balance zinc, with copper plus named elements at 99.6% minimum.
Q: What are the minimum mechanical properties of C44300 tube?
In the annealed condition the minimum tensile strength is 310 MPa and the minimum yield strength is 105 MPa, which matches the 45 ksi and 15 ksi annealed minimums used in inch-based orders.
Q: Why is arsenic added to admiralty brass?
The controlled arsenic addition inhibits dezincification, the selective leaching of zinc that would otherwise attack brass in chloride-bearing cooling water, so the tube wall keeps its integrity over long service periods.
Q: What is the difference between C44300 and C68700?
Both are copper-zinc alloys used for condenser and heat exchanger tubes and both show good corrosion resistance; C44300 achieves its resistance through tin and arsenic, while C68700 uses aluminium as the passivating addition.
Q: Which industries use cold finished C44300 copper alloy tube?
Power generation, oil and gas processing, chemical plants, desalination and marine engineering, mainly in condensers, evaporators, distillers and heat exchangers where cooling water is present.
Q: How is the tube tested before shipment?
Typical verification includes chemical analysis of the heat, hardness testing, pitting and intergranular corrosion tests, and non-destructive testing such as eddy current examination of the tube wall.
