Product Scope and the Dimensional Question
ASTM B466/B466M defines seamless copper-nickel pipe and tube in straight lengths for general engineering service, and covers UNS C70400, C70600, C70620, C71000, C71500, C71520 and C72200. The specification fixes the alloy, the tempers, the mechanical requirements and the test regime. It does not, by itself, fix the wall thickness series: the purchaser either states exact outside diameter and wall thickness, or cites a recognised dimensional standard.
In export and marine practice the dimensional reference most often cited for copper-nickel pipe is the schedule system, because it aligns the copper-nickel line with the rest of the plant piping. Marine and offshore piping specifications also refer to the dedicated copper-nickel piping standards used in shipbuilding practice, and defence and naval projects add their own material schedules on top. The practical consequence is that the same C70600 material can be ordered in several diameter and wall combinations, and the enquiry must state which one applies.
Alloy Data for UNS C70600
| Element | Content, % |
|---|---|
| Nickel, incl. cobalt | 9.0 - 11.0 |
| Iron | 1.0 - 1.8 |
| Manganese | 1.0 max |
| Zinc | 1.0 max |
| Lead | 0.05 max |
| Copper, incl. silver | Remainder |
C70600 is also known commercially as cupro-nickel 90/10, and in European designation systems as CuNi10Fe1Mn or CW352H. Whatever the designation, the controlling fact for performance is the combination of about 10% nickel with 1.0 to 1.8% iron: the iron addition is what maintains the protective film in seawater, and a pipe outside that iron window will not deliver the expected service life even if the nickel content is correct.
Mechanical Requirements by Temper
| Property | O60 soft annealed | H55 light drawn | H80 hard drawn |
|---|---|---|---|
| Tensile strength, min | 260 MPa | 310 MPa | 345 MPa |
| Yield strength, min | 90 MPa | 240 MPa | 275 MPa |
| Hardness, Rockwell 30T | 45 max | 45 - 70 | 63 min |
Annealed pipe is the normal choice for welded systems because it bends and flanges without risk of cracking, and the lower yield strength is not a limitation in most marine and water systems. Drawn tempers are selected where the pipe must resist mechanical damage or where a higher design pressure is required in a small bore.
Size Range and Supply Details
| Item | Supply range |
|---|---|
| Nominal bore | 1/4 in to 12 in |
| Outside diameter | Approximately 6 mm to 325 mm |
| Wall thickness | Schedule 5 through Schedule 160 |
| Length | Single random, double random or fixed lengths |
| Ends | Plain or bevelled |
| Delivery condition | As rolled, cold drawn, hot finished, stress relieved, annealed |
| Surface | Mill, pickled, polished, passivated |
Export packing normally uses bundle and wooden case protection with plastic end caps, and bevel protectors where bevelled ends are specified. Pipe is supplied with the ends capped because the alloy tarnishes and picks up contaminants readily in transit.
Applications
Cooling water and seawater piping in power plants and industrial plants.
Chillers, condensers and heat exchangers, including tube sheet side connections.
Desalination plants, evaporator circuits and brine lines.
Shipbuilding and ship repair, including ballast, bilge and fire main systems.
Refinery and petrochemical cooling circuits, and distiller tube systems.
Fabrication, Welding and Testing
Cut and bevel with tools reserved for copper-nickel where possible; carbon steel swarf embedded in the pipe surface causes localised corrosion later.
Weld with a matching copper-nickel filler metal using gas tungsten arc for the root and, where required, a controlled heat input for fill passes.
Do not preheat; copper-nickel conducts heat rapidly and excessive preheat or interpass temperature damages the alloy's metallurgical condition.
Clean all weld areas and heat tint, and keep marking inks and paints free of sulfur and chloride.
Hydrostatic testing, eddy-current examination, hardness testing and dimensional verification are the usual inspection items; certificates to EN 10204 3.1 are normal for export contracts.
FAQ
Q: Does ASTM B466 include the wall thickness schedule?
No. The specification covers the alloy, temper, mechanical properties and testing of seamless copper-nickel pipe and tube. Wall thickness is either given as an exact value on the enquiry or taken from the dimensional standard that the project cites, which is why the diameter and wall must always appear on the order.
Q: Why is C70600 used instead of stainless steel in seawater piping?
Because it does not suffer chloride stress corrosion cracking and it resists marine biofouling better than steel or stainless steel. Copper alloys are more sensitive to very high flow velocities and to ammonia-bearing environments, so the selection is made on the actual water chemistry.
Q: What tempers are available in seamless pipe?
Annealed, light drawn and hard drawn conditions are all supplied, and stress-relieved and as-rolled conditions are available depending on the mill route. Annealed is the usual choice for pipe that will be bent, flanged or welded on site.
Q: How is the pipe tested before despatch?
Chemical analysis of the heat, tensile testing and hardness testing are performed, and hydrostatic or pneumatic pressure testing and eddy-current examination are added where specified. Where sour or critical service applies, hardness limitation and grain size testing are commonly requested.
Q: Can copper-nickel pipe be joined by flanging rather than welding?
Yes. Flanges are bolted with suitable gaskets, and this is common where maintenance access is required. The flange material should also be copper-nickel or a compatible alloy, because joining copper-nickel to carbon steel in a seawater line creates a galvanic couple that will corrode the steel.
