Tesco Steel & Engineering manufactures UNS C71640 copper nickel flanges — the iron-manganese-modified 70/30 Cu-Ni alloy (CuNi30Fe2Mn2), ~66% copper and 30% nickel with elevated ~2% iron and ~2% manganese. Developed for high-velocity and sand-laden seawater and MSF desalination, C71640 delivers the best erosion and impingement resistance of the copper-nickel grades while keeping the family's natural antifouling behaviour and chloride stress-corrosion resistance. Available in weld neck, slip-on, blind, socket-weld, threaded and lap-joint types to ASME B16.5 / B16.47 and marine standards EEMUA 145 / DIN 86019. Class 150 to 2500, NPS 1/2″ to 24″, PN6 to PN400. ISO 9001:2015 certified. Made in India.
UNS C71640 (CuNi30Fe2Mn2) Copper Nickel Flanges
C71640 Weld Neck & Blind Flanges
Tesco Steel & Engineering manufactures C71640 copper nickel flanges in all types from weld neck to blind, Class 150 to 2500 — supplied with EN 10204 3.1 / 3.2 certification, PMI and third-party inspection on request. Explore the wider copper nickel flange range, UNS C70600 (90/10) copper nickel flanges, UNS C71500 (70/30) copper nickel flanges, and the flange dimension charts.
| UNS C71640 copper nickel flanges are available in the following specifications: | |
|---|---|
| Material Grade | UNS C71640 / CuNi30Fe2Mn2 (iron-modified 70/30 Cu-Ni) |
| Alloy Type | Copper-nickel (~66% Cu, 30% Ni, ~2% Fe, ~2% Mn) — erosion-resistant marine grade |
| Size | 1/2″ NB to 24″ NB (DN 15 to DN 600); larger to ASME B16.47 |
| Class / Rating | 150#, 300#, 600#, 900#, 1500#, 2500# · 3000#, 6000#, 9000# (socket-weld / threaded) |
| Pressure Ratings | PN 6 – PN 400 (PN6, 10, 16, 25, 40, 64, 100, 160, 250, 320, 400) |
| Material Standards | ASTM B151 (rod), B171 (plate), B466 (pipe); EEMUA 145; DIN 86019 |
| Dimensional Standards | ASME B16.5, ASME B16.47 (Series A & B), MSS SP-44, DIN EN 1092-1 |
| Flange Types | Weld Neck (WNRF), Slip-On (SORF), Blind, Socket Weld (SWRF), Lap Joint, Threaded / Screwed, Plate, Long Weld Neck, Orifice |
| Flange Faces | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue & Groove (T&G) |
| Weld Filler | ERCuNi (AWS A5.7) |
| Testing | PMI, hydrostatic, UT, MT/PT per spec; EN 10204 3.1 / 3.2 |
C71640 is a 30%-nickel copper-nickel with deliberately elevated iron and manganese (~2% each, about double standard C71500). The higher Fe and Mn reinforce the protective surface film, which is what gives C71640 its superior resistance to erosion and impingement in fast, sand-laden seawater.
| Element | UNS C71640 (CuNi30Fe2Mn2) |
|---|---|
| Copper (Cu) | Balance (~64–66%) |
| Nickel (Ni) | 29.0 – 32.0% |
| Iron (Fe) | 1.7 – 2.3% (erosion / impingement resistance) |
| Manganese (Mn) | 1.5 – 2.5% |
| Zinc (Zn) | 1.0% max |
| Lead (Pb) | 0.05% max |
| Mechanical Property (annealed, typical) | UNS C71640 |
|---|---|
| Tensile Strength | 415 – 480 MPa (60–70 ksi) |
| Yield Strength 0.2% | 170 – 220 MPa (25–32 ksi) |
| Elongation | ~25–30% |
| Density | 8.95 g/cm³ |
| Max Service Temperature | ~350–400 °C |
| Max Seawater Velocity (pipe) | > ~4.5 m/s (highest of the Cu-Ni grades) |
| Standard | C71640 Designation |
|---|---|
| UNS (USA) | C71640 |
| Alloy designation | CuNi30Fe2Mn2 (iron-modified 70/30) |
| ASTM material | B151 (rod), B171 (plate), B466 (pipe) |
| Marine standards | EEMUA 145, DIN 86019 |
| Common name | Iron-Modified 70/30 Copper Nickel |
C71640 Long Weld Neck Flange
C71640 Slip-On Flange (SORF)
C71640 Socket Weld Flange (SWRF)
| Flange Type | Description & C71640-Specific Use |
|---|---|
| Weld Neck (WNRF) | Tapered hub butt-welded to pipe for high-integrity, high-velocity seawater and desalination lines; weld with ERCuNi filler, no PWHT. |
| Slip-On (SORF) | Fillet-welded over the pipe; used in desalination and marine seawater piping. |
| Blind (BFF) | Seals pipe ends and vessel nozzles in evaporators, brine heaters and seawater systems. |
| Socket Weld (SWRF) | Small-bore (1/2″–2″) instrument and branch connections in seawater service. |
| Lap Joint (LJRF) | Used with a Cu-Ni stub end where frequent dismantling is needed; economises on alloy in the backing ring. |
| Threaded (TRFF) | Internal NPT/BSP threads for non-welded low-pressure seawater connections. |
| Long Weld Neck / Orifice / Plate | Nozzle, flow-metering and plate flanges in C71640 for desalination and high-velocity marine duty. |
| Property | C71640 (CuNi30Fe2Mn2) | C71500 (70/30) | C70600 (90/10) |
|---|---|---|---|
| Nickel content | ~30% | ~30% | ~10% |
| Iron + manganese | ~2% Fe + ~2% Mn (high) | ~0.5% Fe + ~1% Mn | ~1.5% Fe + ~0.8% Mn |
| Erosion / impingement resistance | Best | High | Moderate |
| Max seawater velocity | > ~4.5 m/s | ~4.0–4.5 m/s | ~3.0–3.5 m/s |
| Antifouling | Excellent | Excellent | Excellent |
| Relative cost | Highest | Higher | Lowest |
| Best For | Sand-laden, high-velocity seawater; MSF desalination | High-velocity / high-strength / hotter seawater | General seawater piping, shipboard |
~2% Fe + ~2% Mn reinforce the protective film — the highest seawater velocity and sand tolerance of the copper-nickel grades.
Developed for MSF desalination evaporators and brine heaters where hot, fast, aerated seawater erodes lesser alloys.
Copper content inhibits barnacle, mussel and algae settlement — keeps pipe bores clear without coatings or biocides.
Readily welded with ERCuNi filler, no preheat or PWHT — straightforward marine and desalination fabrication.
| Industry | Typical Application |
|---|---|
| Desalination (MSF / Thermal) | Evaporator and brine-heater nozzle flanges, high-temperature seawater stages |
| High-Velocity Seawater Intakes | Intake, pump-suction and turbulent seawater piping flanges |
| Naval & Marine | Demanding seawater cooling and firewater systems with abrasive/turbulent water |
| Offshore Platforms | High-velocity seawater and firewater ring-main connections |
| Power Generation | Seawater-cooled condenser and cooling-water circuit flanges in severe service |
| Heat Exchangers | Tube-sheet and nozzle flanges in desalination and seawater exchangers |
Made from certified CuNi30Fe2Mn2 with PMI verification of Ni, Fe and Mn — the elevated Fe/Mn confirmed on the MTC.
Manufactured to ASME B16.5 with EEMUA 145 / DIN 86019 compliance for desalination and offshore work.
WNRF, SORF, blind, socket-weld, threaded, lap-joint, LWN, orifice and plate — in RF, FF, RTJ and T&G faces.
EN 10204 3.1 / 3.2 MTC, heat/lot traceability, hydrostatic and third-party inspection on request.
C71640 flange prices track copper and the high nickel content plus the added iron/manganese processing, size, pressure class, flange type and quantity — it is the premium copper-nickel grade for severe seawater erosion service. Tesco Steel & Engineering offers competitive ex-works pricing from Mumbai with full export documentation and material traceability. Click Ask for Quote or message us on WhatsApp at +91 92233 66922 with flange type, size (NB), pressure class, quantity and documentation requirements.
Q1. What is a UNS C71640 copper nickel flange?
A UNS C71640 copper nickel flange is a pipe flange made from the iron-manganese-modified 70/30 copper-nickel alloy CuNi30Fe2Mn2 — about 66% copper, 30% nickel, with elevated iron (~2%) and manganese (~2%). It was developed specifically for high-velocity and sand-laden seawater, giving the best erosion and impingement resistance of the copper-nickel family while keeping their antifouling behaviour and chloride stress-corrosion resistance. Flanges are machined to ASME B16.5 / B16.47 and supplied to marine standards EEMUA 145 and DIN 86019.
Q2. What is the difference between C71640, C71500 (70/30) and C70600 (90/10)?
All three are copper-nickel marine alloys with antifouling and chloride-SCC resistance. C70600 (90/10) is the economical general grade for velocities up to ~3.0–3.5 m/s. C71500 (70/30) has 30% nickel for higher strength, temperature and velocity tolerance (~4.0–4.5 m/s). C71640 keeps the 30% nickel but roughly doubles the iron and manganese (to ~2% each), giving the highest resistance to erosion and impingement in turbulent or sand-bearing seawater — which is why it was developed for MSF desalination and high-velocity intakes.
Q3. What is the chemical composition of C71640 copper nickel?
UNS C71640 (CuNi30Fe2Mn2) composition: nickel ~29–32%, iron ~1.7–2.3%, manganese ~1.5–2.5%, copper balance (~64–66%), with limits on zinc, lead and other residuals. The elevated iron and manganese (about double those of standard C71500) reinforce the protective film and are the key to its superior erosion and impingement resistance in fast, sand-laden seawater.
Q4. Why was C71640 developed for desalination?
C71640 was developed for multi-stage flash (MSF) desalination plants, where seawater is hot, fast-flowing and often carries sand and entrained air that erode standard copper-nickel. The higher iron and manganese give a tougher protective film that resists impingement attack and erosion-corrosion at high velocity, so C71640 lasts where 90/10 and even standard 70/30 would suffer film breakdown — making it a standard tube and flange material for MSF evaporators and brine heaters.
Q5. What standards apply to C71640 copper nickel flanges?
C71640 copper nickel flanges are made to ASME B16.5 / B16.47 dimensional standards in copper-nickel material per ASTM B151 (rod), B171 (plate) and B466 (pipe), and to marine fabrication standards EEMUA 145 and DIN 86019. The alloy is designated CuNi30Fe2Mn2 (the iron-modified 70/30). Certification is supplied per EN 10204 3.1 / 3.2.
Q6. What is the maximum seawater velocity for C71640?
C71640 tolerates the highest continuous seawater velocity of the common copper-nickel grades — typically above ~4.5 m/s, higher than standard 70/30 (C71500) at ~4.0–4.5 m/s and 90/10 (C70600) at ~3.0–3.5 m/s. Its elevated iron and manganese make it the preferred choice for high-velocity intakes, pump suctions and sand-bearing seawater where the other grades would erode.
Q7. Can C71640 copper nickel flanges be welded?
Yes. C71640 is readily welded by GTAW (TIG) and GMAW using matching copper-nickel filler such as ERCuNi (AWS A5.7). No preheat or post-weld heat treatment is required. Joints should be clean and welded with controlled heat input; copper-nickel has higher thermal conductivity than steel, so technique differs slightly, but it is considered easy to weld for marine fabrication.
Q8. What are the mechanical properties of C71640 copper nickel?
Typical C71640 properties in the annealed condition: tensile strength about 415–480 MPa, yield strength about 170–220 MPa, elongation about 25–30%, density 8.95 g/cm³. The higher iron and manganese give it slightly higher strength than standard 70/30 (C71500) along with its superior erosion resistance.
Q9. What industries use C71640 copper nickel flanges?
C71640 copper nickel flanges are used in MSF and thermal desalination plants (evaporators, brine heaters), high-velocity seawater intakes and pump-suction piping, naval and offshore seawater systems exposed to turbulent or sand-bearing water, and power-station seawater condenser circuits — wherever erosion and impingement resistance beyond standard 70/30 is required.
Q10. Are C71640 copper nickel flanges supplied with material test certificates?
Yes. Every C71640 copper nickel flange is supplied with EN 10204 3.1 (or 3.2) mill test certificates confirming chemistry, mechanical properties and heat/lot traceability, with PMI, hydrostatic testing and third-party inspection on request. Tesco Steel & Engineering is an ISO 9001:2015 certified manufacturer and exporter from Mumbai, India.