Scope: ASTM B111, DIN 86019 and the C70600 Pipe Family
Copper-nickel 90/10 seamless pipe is produced from UNS C70600, a wrought copper alloy that pairs roughly 90% copper with 10% nickel and small, deliberate additions of iron and manganese. Two documents normally sit behind a purchase order. ASTM B111 covers seamless copper and copper-alloy tube for condensers, heat exchangers and general service, and it defines the chemistry, tempers, mechanical requirements and test methods. DIN 86019 fixes the dimensions and pressure ratings of seamless copper-nickel tubes used in shipbuilding and in seawater piping. When the item is ordered as pipe rather than tube, ASTM B466 governs the seamless copper-nickel pipe form, while ASME B36.19 supplies the schedule-based wall thickness series.
UNS C70600 Chemical Composition
Nickel is the element that governs resistance to flowing seawater, while iron and manganese support a protective surface film that keeps erosion-corrosion under control. The limits typically applied to C70600 seamless tube and pipe are summarised below.
| Element | Typical requirement, % | Function |
|---|---|---|
| Copper | Balance | Matrix; slow copper ion release limits biofouling |
| Nickel | 9.0 - 11.0 | Seawater corrosion resistance, strength |
| Iron | 1.0 - 1.8 | Protective film formation in seawater |
| Manganese | 0.5 - 1.0 | Deoxidation, film stability |
| Carbon | 0.05 max | Residual control |
| Lead | 0.05 max | Residual control |
| Sulphur | 0.02 max | Residual control |
| Phosphorus | 0.02 max | Residual control |
| Zinc | 0.50 max | Residual control |
| Copper + nickel + iron + manganese | 99.5 min | Minimum combined content |
Equivalent designations across regional standards include CuNi10Fe1Mn and material number 2.1972 under DIN, the EN symbol CW352H, the British Standard grade CN102 and JIS C7060. They describe the same 90/10 cupronickel family, so C70600, CN102 and 2.1972 material is interchangeable when the temper, tolerances and test regime are specified identically.
Mechanical and Physical Properties of C70600
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength, ultimate | 303 - 414 MPa | 43,900 - 60,000 psi |
| Tensile strength, yield (temper dependent) | 110 - 393 MPa | 16,000 - 57,000 psi |
| Elongation at break | approx. 42% | approx. 42% |
| Elastic modulus | 140 GPa | 20,300 ksi |
| Shear modulus | 52.0 GPa | 7,540 ksi |
| Poisson ratio | 0.34 | 0.34 |
| Machinability (free-cutting brass = 100%) | 20% | 20% |
Sizes, Tempers, Ends and Pressure Ratings
Seamless pipe is supplied from DN15 to DN500 with outside diameters between 15 mm and 508 mm and wall thicknesses from 1 mm to 11 mm. Standard delivery length is 6 m, and sch10, sch40, sch80 and STD wall series are available. Product is seamless up to and including 419 mm outside diameter and seam welded above that size. Ends can be supplied plain, bevelled or threaded.
| Parameter | Range or value |
|---|---|
| Nominal size | DN15 - DN500 (1/2 in. - 20 in.) |
| Outside diameter | 15 mm - 508 mm |
| Wall thickness | 1 mm - 11 mm |
| Length | mainly 6 m, other lengths on request |
| Pressure rating, DIN 86019 | 10 bar and 14 bar |
| Pressure rating, EEMUA 144 / EEMUA 234 | 16 bar and 20 bar |
| Pressure class, MIL-T-16420K | Class 200 and Class 700 |
| Related grades offered | C70600, C71500, C71640 |
Corrosion Behaviour and Service Limits
Chloride stress corrosion cracking: C70600 is effectively immune in seawater and in chloride-bearing atmospheres, which is why it is preferred over austenitic stainless steels for wet marine service.
Erosion-corrosion: the alloy tolerates higher seawater velocities than plain copper or aluminium brass. Projects normally set a design velocity ceiling for the specific pipe size, and fittings and bends are kept smooth to limit local turbulence.
Biofouling: slow release of copper ions suppresses barnacle and mussel settlement inside seawater lines.
Ammoniacal environments: with oxygen present, ammonia and ammonium compounds attack copper-nickel. Steam condensate carrying ammonia requires an evaluation before C70600 is selected.
Sulphide-polluted seawater: elevated sulphide levels can disrupt the protective film, so polluted harbour water or stagnant conditions may call for an upgrade to C71500 or additional wall allowance.
Manufacturing, Welding and Inspection
Seamless pipe is produced by hot extrusion followed by cold pilgering or drawing, with intermediate anneals and a final anneal or light draw to deliver the ordered temper. Typical acceptance testing includes chemical analysis of the cast, tension testing, flattening and expansion tests, eddy-current examination of the finished product, hydrostatic or pneumatic pressure testing where specified, and microscopical examination for inclusions and grain structure. Certification and a mill test report accompany each delivery.
Welding is normally performed by gas tungsten arc welding with a matching copper-nickel filler; no preheat is required and interpass temperature is kept low to avoid hot cracking.
Post-weld cleaning must remove all traces of iron contamination, since embedded steel particles become initiation sites for pitting in seawater.
Tube sheet joints are expanded and, where required, seal welded after rolling.
Frequently Asked Questions
Q: What is the difference between ASTM B111 and ASTM B466 for C70600?
ASTM B111 covers seamless tube for condensers, heat exchangers and general service, while ASTM B466 covers seamless copper-nickel pipe. For a pipeline ordered to nominal pipe size with schedule walls, B466 with ASME B36.19 dimensions is the usual route.
Q: Why is 90/10 rather than 70/30 copper-nickel specified for seawater pipe?
C70600 offers lower cost and adequate corrosion resistance for clean seawater at moderate velocity. C71500 is chosen where higher velocity, polluted water, higher temperature or greater mechanical strength is required.
Q: Can C70600 seamless pipe be used above atmospheric temperature?
Yes. The alloy retains useful strength to elevated temperature in dry service, but seawater applications should follow the temperature and velocity limits stated in the project specification or the relevant marine piping code.
Q: How is the pipe protected during shipping and storage?
Ends are capped, bundles are banded, and the surface is kept free of carbon steel contact. Pipe should be stored under cover and lifted with non-metallic slings to avoid iron pick-up.
Q: Which tests are normally witnessed on a C70600 pipe order?
Chemical analysis, tension test, flattening and expansion tests, eddy-current test and, when specified, hydrostatic pressure test. Hydrogen embrittlement and grain structure examination are added where the purchase specification demands them.
Q: Is a 90/10 tube interchangeable with a CN102 or 2.1972 tube?
Yes, provided the temper, dimensional tolerances and pressure rating match. The three designations describe the same copper-nickel 90/10 alloy family.
