What ASME SB 111 and ASME SB 466 C70600 Pipe Is
ASME SB 111 and ASME SB 466 are the ASME code designations that correspond to ASTM B111/B111M and ASTM B466/B466M, the two specifications most often called up for seamless copper-nickel pipe and tube in marine, desalination and process service. SB 111 covers seamless copper and copper-alloy tube, while SB 466 covers seamless copper-nickel pipe and tube in the same alloy family. The two documents are technically aligned, so a C70600 item may be ordered to either one and still be produced to the same metallurgical basis.
C70600 is the UNS designation for the 90/10 copper-nickel alloy: approximately nine parts copper to one part nickel, with controlled iron and manganese additions that give the alloy its resistance to flowing seawater. The material is normally supplied in the annealed (O60) or light-drawn (H55) temper as cold-drawn seamless pipe and tube. Wall thicknesses are selected against design pressure and are checked to the permitted minus tolerance of the governing specification, and lengths are ordered in single random or double random ranges unless fixed lengths are agreed.
Chemical Composition of C70600
| Element | Requirement (mass %) | Function |
|---|---|---|
| Copper (Cu) | Remainder | Base metal, corrosion resistance and thermal conduction |
| Nickel (Ni) | 9.0 - 11.0 | Primary alloying element, raises strength and seawater resistance |
| Iron (Fe) | 1.0 - 1.8 | Refines the protective corrosion-product film in seawater |
| Manganese (Mn) | 1.0 max | Deoxidation, improves the iron distribution in the matrix |
| Zinc (Zn) | 1.0 max | Residual element, controlled to protect ductility |
| Lead (Pb) | 0.05 max | Residual impurity limit |
The limits above follow the C70600 row of ASME SB 111 and SB 466. Iron is the element most often out of balance in poorly melted stock, and an iron content below the specified window degrades seawater performance even when nickel is on target, so a mill certificate carrying both the heat analysis and the product analysis is the normal way to demonstrate compliance.
Mechanical Properties and Size Range
| Property (annealed temper) | ASME SB 111 / SB 466 requirement |
|---|---|
| Tensile strength, min | 40 ksi (275 MPa) |
| Yield strength at 0.5 % extension under load, min | 15 ksi (105 MPa) |
| Elongation in 2 in (50 mm), min | 30 % |
| Grain size | Annealed structure, average grain size as specified for the temper ordered |
| Electrical conductivity, typical | Approximately 9 % IACS |
Yield strength for wrought copper alloys is conventionally reported at 0.5 % extension under load rather than the 0.2 % offset used for steel, and that convention is written into the copper-nickel product specifications. Thermal conductivity is of the order of 45 W/(m·K), roughly ten times that of austenitic stainless steel, which is why C70600 is preferred where a seawater circuit must also transfer heat. The alloy is not strengthened by heat treatment, so cold work is the only way to raise strength above the annealed level, and any subsequent anneal for stress relief or forming recovery is carried out between 593 and 816 °C (1100 and 1500 °F).
Seamless pipe and tube are produced in outside diameters from small instrument sizes up to 12 in (about 305 mm), with wall thicknesses matched to the pressure class of the system. Where the buyer works to ASME B36.10M or B36.19M schedules, the nominal pipe size and schedule govern the dimensions; where condenser and heat exchanger tubing is required, the outside diameter and wall gauge are taken from the tube tables of ASME SB 111.
Marine and Process Applications
Seawater intake, discharge and cooling lines on ships, ferries and offshore platforms.
Condenser, cooler and heat exchanger tubing in power stations and desalination plants.
Firefighting and ballast systems where chloride stress corrosion cracking rules out stainless steel.
Refinery and petrochemical cooling water circuits handling brackish or high-chloride water.
Earthing and grounding conductors and offshore cable protection hardware.
The alloy resists both general seawater attack and the biofouling that plagues titanium-free circuits, forming a thin, adherent corrosion-product film that slows further metal loss. It is immune to chloride stress corrosion cracking at normal service temperatures, which is the main reason it displaces stainless steel in marine piping.
Fabrication, Installation and Inspection Notes
Seamless pipe is normally eddy-current tested to ASTM E243 and hydrostatically tested in accordance with the product specification before despatch.
Cutting may be done by machining or abrasive methods; thermal cutting should be followed by removal of the heat-affected layer.
Annealed material can be cold bent to a radius of about two to three times the outside diameter without intermediate annealing.
Welding uses ERCuNi or equivalent copper-nickel filler with argon shielding; joint areas must be clean and free of grease or marking ink.
Hot forming is carried out in the 870-980 °C range and a full anneal restores the annealed properties afterwards.
Inspection plans commonly combine visual examination, dimensional check, eddy-current test, flattening or expansion test and, where specified, a corrosion test on a sample.
FAQ
Q: What is the difference between ASME SB 111 and ASME SB 466 for C70600?
SB 111 corresponds to ASTM B111 for seamless copper and copper-alloy tube, and SB 466 to ASTM B466 for seamless copper-nickel pipe and tube. Both use the same C70600 composition and annealed temper requirements; the choice usually follows the product form and the sizing table used by the designer.
Q: Is C70600 pipe suitable for untreated seawater?
Yes. The 90/10 copper-nickel alloy is one of the standard choices for flowing seawater and brackish water up to velocities of roughly 2.5 to 3 m/s in clean conditions. Very high solids content or severely polluted water requires a derating of the allowable velocity.
Q: Why is the iron range so important in C70600?
Iron is what makes the protective film stable in seawater. When iron falls below the 1.0 % minimum the uniform corrosion rate rises sharply, so the product analysis is checked against the range even when the nickel content looks correct.
Q: Can C70600 pipe be welded in the field?
Yes, with copper-nickel filler metal and controlled heat input. The alloy conducts heat quickly, so preheat is not used and interpass temperature is kept low; joint preparation and cleanliness matter more than on carbon steel.
Q: Which tempers are available?
Annealed (O60) is standard for tube and pipe that will be bent or expanded into tube sheets. Light-drawn (H55) material offers higher strength for straight runs where forming is limited. Hard tempers are available only as agreed, because they reduce the elongation needed for tube-sheet rolling.
Q: How are the ends and surfaces supplied?
Seamless pipe is supplied with plain ends, beveled ends or threaded ends as ordered, with the surfaces free of harmful scale and with ends capped for transport. Pickled or bright-annealed finishes are common for tube destined for export packing in wooden crates.
