What ASTM B466 and ASME SB466 Cover
ASTM B466/B466M and ASME SB466 are the standard specifications for seamless copper-nickel pipe and tube in straight lengths, intended for general engineering purposes rather than for a single restricted duty. The alloys named in the specification are UNS C70400, C70600, C70620, C71000, C71500, C71520 and C72200, so a single document covers the whole family of wrought copper-nickel piping grades and gives the designer one reference point for piping, tube and fittings that must work together.
UNS C70600 is the 90/10 grade: nominally 90% copper and 10% nickel with controlled iron and manganese. It is the workhorse of seawater piping because it resists chloride-bearing environments where stainless steels are vulnerable to chloride stress corrosion cracking, and because it keeps a stable protective film even in aerated, flowing seawater.
Chemical Composition of 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 |
Mechanical Properties by Temper
| Property | O60 soft annealed | H55 light drawn | H80 hard drawn |
|---|---|---|---|
| Tensile strength, min | 260 MPa / 38 ksi | 310 MPa / 45 ksi | 345 MPa / 50 ksi |
| Yield strength, min | 90 MPa / 13 ksi | 240 MPa / 35 ksi | 275 MPa / 40 ksi |
| Rockwell 30T hardness | 45 max | 45 - 70 | 63 min |
Density of the alloy is 8.94 g/cm³. The annealed temper is the normal supply condition for pipe that will be bent, flanged or welded, because the high elongation allows shop and site forming without cracking. The drawn tempers are used where higher pressure ratings or better resistance to mechanical damage are needed and forming is limited.
Dimensions, Lengths and Delivery Conditions
| Parameter | Range |
|---|---|
| Nominal bore | 1/4 in to 12 in |
| Outside diameter | Approximately 6 mm to 325 mm depending on schedule |
| Wall thickness | Schedule 5 to Schedule 160 |
| Lengths | Single random, double random and fixed lengths to order |
| End finish | Plain ends or bevelled ends |
| Delivery condition | Annealed, cold drawn, as rolled, stress relieved |
Pipe is normally supplied in straight lengths, cleaned and with end protection for export packing. Tubes for heat exchangers are supplied to the exchanger drawing with the specified developed length and, where required, in U-bent form.
Corrosion Behaviour and Applications
C70600 works in seawater because the alloy forms a thin, adherent, copper-oxide-rich surface film that is continuously repaired by the iron and manganese in the metal. The practical consequences of that mechanism are worth stating plainly:
Good resistance to flowing seawater, including moderately high velocities once the protective film has formed.
Immunity to chloride stress corrosion cracking, which is the failure mode that limits austenitic stainless steel in chloride service.
Low biofouling tendency compared with steel and stainless steel, because copper ions in the surface film discourage marine organism attachment.
Good cold working capacity and weldability, so pipe can be fabricated in the shop and installed with conventional marine piping practice.
Typical duties include heat exchanger and condenser piping, shipbuilding and ship repair systems, desalination plant piping, petrochemical and natural gas installations, water supply and cooling water lines, and offshore process pipework.
Fabrication, Welding and Inspection
Use a matching copper-nickel filler metal and gas tungsten arc welding for root passes; keep heat input moderate and interpass temperature controlled.
Support the pipe during welding and avoid fast cooling; copper-nickel has high thermal conductivity and distortion control depends on sequencing.
Clean weld areas and remove all traces of iron contamination, sulfide marking and carbon steel grinding dust, which are the main causes of localised attack.
Inspection typically covers chemical analysis, tensile and hardness testing, hydrostatic or pneumatic testing and eddy-current examination, with hardness limitation commonly requested for sour service.
Material certificates to EN 10204 3.1, together with third-party inspection where the project requires it, are standard on export orders.
FAQ
Q: Is there a difference between ASTM B466 and ASME SB466?
No substantive difference. ASME SB466 is the ASME Code version of the ASTM specification, with the same alloys, tempers, dimensions and test requirements. A pipe certified to one is accepted under the other by the relevant codes.
Q: When should 90/10 be replaced by 70/30 copper-nickel?
Choose 70/30, UNS C71500, when seawater velocity is high, when the water is polluted or sand-laden, or when a longer design life is required. The higher nickel content of C71500 widens the tolerance to impingement and erosion-corrosion, at higher material cost.
Q: Can C70600 pipe be welded in the field like carbon steel?
It can be welded, but not with carbon steel procedures. A matching copper-nickel filler is required, heat input must be controlled, and the joint must be kept free of iron contamination. With those precautions, field welding is routine in shipbuilding and plant work.
Q: What is the advantage over stainless steel in seawater?
The decisive advantage is immunity to chloride stress corrosion cracking and a lower biofouling tendency. Stainless steels generally outperform copper-nickel in erosion resistance at very high velocities and in strongly oxidising conditions, so the choice depends on the actual water chemistry and flow regime.
Q: Which tests should be specified on the purchase order?
Chemical analysis, tensile test, flattening or expansion tests where applicable, hydrostatic or pneumatic pressure testing and eddy-current examination are the usual requirements. Where the pipe will see sour or seawater duty, hardness verification and grain size are commonly added.
