C70600 Slip On Flanges — 90/10 Copper Nickel Manufacturer
Tesco Steel & Engineering manufactures 90/10 copper-nickel slip on flanges — UNS C70600, Werkstoff 2.0872, CuNi10Fe1Mn — from certified ASTM B151 rod and B171 plate to ASME B16.5 dimensions, ½″ to 24″ NB, with EN 1092-1 and EEMUA 145 patterns to order. The world's seawater piping standard: iron-stiffened cupronickel that shrugs off flowing seawater and brine, is immune to chloride SCC, and — uniquely among engineering alloys — resists biofouling, keeping firewater mains and cooling lines clean for decades. Sister grade to 70/30 C71500 and neighbour to Monel 400. Every photo on this page is our own production — machining, inspection, XRF PMI and marked stock. EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
CuNi 90/10 · C70600 · 2.0872ASTM B151 / B171 · CuNi10Fe1MnNi 9–11% · Fe 1.0–1.8%ASME B16.5 · EN 1092-1 · EEMUA 145½″ – 24″ NB · FF & RFBiofouling-Resistant Seawater AlloyEN 10204 3.1 / 3.2 · ISO 9001:2015
90/10 Copper Nickel SORF/FF Slip On Flanges, 3″ #300 — Marked ASTM B151 UNS C70600 With CWP Rating, From Our Production
What is a C70600 Slip On Flange?
C70600 = the seawater alloy the world's navies standardised on.90% copper, 10% nickel, iron-stiffened (CuNi10Fe1Mn / 2.0872): resists flowing seawater and brine without coatings, is immune to chloride SCC, and — uniquely — resists biofouling: copper ions keep barnacles and mussels off the bore. Machined from ASTM B151 rod (as marked on our flanges above) to ASME B16.5 dimensions, usually flat face with a CWP rating — copper alloys sit outside the steel rating tables. As a slip-on: two fillet welds with ERCuNi filler, no preheat, no PWHT.
Also searched as: CuNi 90/10 slip on flange, cupro nickel slip on flange, copper nickel SORF flange, ASTM B151 C70600 flange, CuNi10Fe1Mn / 2.0872 slip on flange, EEMUA 145 flange — all refer to the product on this page. See also our 90/10 cupro nickel flanges overview and UNS C70600 flanges.
The Marine Ladder — Where 90/10 Fits
Alloy
UNS
Base
Signature Strength
Watch Out For
CuNi 90/10 (this page)
C70600
Cu-10Ni
Seawater piping default; best biofouling resistance; lowest cost
Rule of thumb: in seawater, 90/10 is the default and everything else is the exception — 70/30 for velocity and temperature, C71640 for sand, duplex or titanium for stagnation and pressure, Monel for the hardest-working components.
C70600 (CuNi 90/10) Chemical Composition
Cu
Ni
Fe
Mn
Zn
Pb
Remainder (~88%)
9.0-11.0
1.0-1.8
1.0 max
0.5 max
0.02 max
Values in weight % for UNS C70600. The iron is the quiet hero — it toughens the protective film against impingement in flowing seawater, which is why the alloy is formally CuNi10Fe1Mn and not a simple binary. The copper majority is what delivers the biofouling resistance. XRF PMI — pictured below — verifies the analysis on every lot.
C70600 Mechanical Properties
Tensile Strength, MPa (ksi)
Yield Strength 0.2%, Min, MPa (ksi)
Elongation % min
Density
275 (40) min
105 (15) min
30
8.94 g/cm³
Annealed condition. Modest numbers by steel standards — which is why copper-nickel flanges carry their own CWP pressure ratings (the pictured 3″ #300 flange is marked 200 psig CWP @ 140 °F) rather than B16.5 steel ratings, and why the alloy serves moderate-pressure seawater systems rather than high-pressure duty. Values demonstrated per lot on the EN 10204 certificate.
C70600 Slip On Flange Specifications
90/10 Copper Nickel Slip On Flanges are available in the following specifications:
Offshore projects widely cite EEMUA 144 (pipe), 145 (flanges) and 146 (fittings); naval paperwork may reference MIL-C-15726. Not an A182 or B564 material — cupronickel has its own copper-alloy B-series family, exactly as marked on the flanges pictured above.
Why C70600 Slip Ons Are Specified
The Biofouling Answer
Copper ions keep barnacles, mussels and algae from colonising the bore — firewater mains stay clean and ready without coatings, chlorination or pigging. No steel, stainless or titanium line can claim this.
Seawater Without Ceremony
No coatings, no cathodic protection, no chloride SCC anxiety — the alloy simply lives in flowing seawater, as sixty years of naval and offshore service attest.
The Economic Marine Default
10% nickel where Monel needs 67% — 90/10 covers the great majority of seawater systems at the lowest cost of any alloy that genuinely works.
Machined, Measured, Verified
Every stage in-house and pictured on this page: CNC machining, bore and thickness inspection, XRF PMI on the finished stacks — each flange marked with standard, grade, size and CWP rating.
90/10's protective film has a speed limit. Design practice keeps flowing seawater below roughly 3.5 m/s in normal bores (lower in small sizes and at fittings) and above ~1 m/s to discourage deposits — too fast erodes the film, too slow invites sediment. Where design velocity, temperature or sand loading exceed the window, the same joint moves up the family: 70/30 C71500 tolerates more, C71640 more still. Inside the window, 90/10 outlasts nearly everything — state the design velocity on the enquiry and we confirm the grade.
How Our C70600 Slip On Flanges Are Made — In Pictures
1
Certified stock — ASTM B151 rod / B171 plate of certified C70600 heats, full traceability from mill certificate to despatch.
2
CNC turning & drilling — faces, hub and bore turned on CNC lathes, bolt holes machined on vertical machining centres — both pictured below.
3
Facing — flat face (the Cu-Ni default) or raised face with serrated finish per the piping class.
4
Dimensional inspection — bore, thickness, bolt circle and facing checked against ASME B16.5 / EEMUA 145 — calipers on the shop floor, pictured below.
5
PMI & marking — XRF verification of the CuNi analysis on the finished stacks, then permanent laser marking of standard, grade, size, class, CWP rating and heat number.
6
Certification & packing — EN 10204 3.1 MTC (3.2 witnessed on request), export-packed for sea or air freight.
Production Gallery — C70600 Flanges at Our Works
Bolt-Hole Drilling on the VMCFace & Bore Turning on the CNC LatheBore Inspection — Digital CaliperThickness Check Against B16.5XRF PMI Verification on Finished StacksMarked C70600 Slip Ons — Ready for Despatch
Where C70600 Slip On Flanges Are Used
Wherever seawater flows: shipboard and submarine cooling and auxiliary systems, offshore platform firewater ring mains and deluge systems, desalination intake and brine lines, coastal power station cooling water, condenser and heat-exchanger interconnecting piping, and brackish-water service inland. Pressures are moderate and diameters large, so the slip-on and plate patterns dominate — easy fit-up over pipe suits shipyard fabrication.
C70600 Slip On Flange Dimensions
Cu-Ni slip-on dimensions follow the ASME B16.5 slip-on tables (with CWP ratings) — identical dimensions for every material. Full charts by class:
Example: “Slip On Flange, 3″ NB, ASME B16.5 #300 pattern, FF, CuNi 90/10 / ASTM B151 (C70600), EN 10204 3.1 — 20 pcs.” Quotations normally within 24 hours with price, unit weight and delivery.
C70600 Slip On Flanges — Frequently Asked Questions
What is a C70600 slip on flange?
It is a slip-on flange made from 90/10 copper-nickel — UNS C70600, Werkstoff 2.0872, CuNi10Fe1Mn — to ASME B16.5 dimensions, slid over the pipe end and secured with two fillet welds. 90/10 cupronickel is the world's default seawater piping alloy: it resists flowing seawater and brine, is immune to chloride stress corrosion cracking, and uniquely resists biofouling, because slowly released copper ions keep barnacles, mussels and algae from colonising the surface. The flanges pictured on this page are our own marked production.
What is 90/10 copper nickel?
A copper-base alloy carrying roughly 10% nickel with deliberate additions of iron (1.0-1.8%) and manganese, developed for naval seawater systems and now specified across shipbuilding, offshore platforms and desalination worldwide. Copper gives the biofouling resistance and inherent seawater compatibility; nickel and iron stiffen the protective film against flowing seawater. Designations: UNS C70600, Werkstoff 2.0872, EN CuNi10Fe1Mn, CuNi 90/10 — flange stock is supplied to ASTM B151 (rod) and B171 (plate).
What is the chemical composition of C70600?
Copper is the balance, with nickel 9.0-11.0%, iron 1.0-1.8%, manganese 1.0% max, zinc 0.5% max, lead 0.02% max and sulphur controlled low. The iron is the quiet hero — it strengthens the protective oxide film against impingement and erosion in flowing seawater, which is why the alloy is formally CuNi10Fe1Mn rather than a simple copper-nickel binary. PMI verification, as pictured on this page, confirms the analysis on every lot.
What are the mechanical properties of C70600 slip on flanges?
In the annealed condition: tensile strength 275 MPa (40 ksi) minimum, 0.2% yield strength 105 MPa (15 ksi) minimum and elongation 30% minimum, with density 8.94 g/cm³. Modest numbers by steel standards — which is why copper-nickel flanges carry their own pressure ratings rather than standard B16.5 steel ratings, and why the alloy serves Class 150/300-type duty rather than high-pressure service. Values are demonstrated per lot on the EN 10204 certificate.
Why is 90/10 copper nickel the seawater piping standard?
Because it solves the whole seawater problem at once, at the lowest cost of any alloy that does. It resists flowing seawater and brine without coatings or cathodic protection, is immune to chloride stress corrosion cracking, resists biofouling so bores stay clean and heat exchangers stay efficient, and it fabricates easily. Navies standardised on it decades ago; commercial shipbuilding, offshore firewater and cooling systems and desalination plants followed. Costlier alloys are reserved for the duties 90/10 cannot cover — higher velocity (70/30), stagnation (super duplex, titanium) or higher strength (Monel).
Does copper nickel really resist biofouling?
Yes — it is the alloy's genuinely unique property. The surface releases copper ions at a rate harmless to the system but hostile to settling organisms, so barnacles, mussels and algae largely fail to colonise it. Steel, stainless, titanium and FRP all foul and need antifouling coatings, chlorination or mechanical cleaning; copper-nickel seawater lines stay substantially clean for decades. For firewater mains — where a fouled line discovered during an emergency is unacceptable — this property alone often decides the specification.
What velocity limits apply to 90/10 copper nickel?
The alloy's protective film erodes if seawater flows too fast, so systems are designed to velocity limits — commonly around 3.5 m/s maximum for 90/10 in normal pipe sizes, with lower values in small bores and fittings, and a minimum flow (roughly 1 m/s) to discourage deposits under stagnant conditions. Where design velocities run higher, 70/30 copper-nickel (C71500) tolerates more, and the sand-strengthened C71640 more still. It is a design habit, not a defect: within its velocity window, 90/10 outlasts most alternatives.
What is the difference between C70600 and C71500?
Nickel content: 10% versus 30%. C71500 (70/30 copper-nickel) is stronger — roughly 345 MPa tensile minimum against 275 — tolerates higher seawater velocities, and handles hotter, more demanding brine duty; C70600 counters with lower cost (nickel is the expensive ingredient), better biofouling resistance from its higher copper content, and complete adequacy for the great majority of seawater systems. The practical rule: 90/10 is the default; 70/30 is specified where velocity, temperature or mechanical demands exceed it. We machine both.
How does 90/10 copper nickel compare with Monel 400?
Monel 400 is the ratio reversed — roughly 67% nickel to 30% copper — and the properties follow the nickel: about twice the strength, better impingement and cavitation resistance at high velocity, plus hydrofluoric acid and caustic capability. Copper-nickel answers with far lower cost and markedly better biofouling resistance, which nickel-rich alloys largely lose. The classic marine split: 90/10 copper-nickel for the piping runs and flanges, Monel for the pumps, shafts, and hardest-working components in the same system.
Why are copper nickel flanges often flat face?
Two reasons, both visible in the marking on our pictured flanges. First, copper alloys are not covered by the steel rating tables of ASME B16.5, so Cu-Ni flanges are made to B16.5 dimensions and assigned a cold working pressure — the pictured 3" flange is marked FF, #300 pattern, 200 psig CWP at 140 °F. Second, seawater systems frequently mate copper-nickel to composite (GRE) piping and to cast fittings, where a flat face with a full-face gasket loads the joint evenly and protects the weaker mating flange. Raised face is equally available where the piping class calls for it.
Which ASTM standards cover C70600 slip on flanges?
Copper-nickel flanges are machined from certified wrought stock: ASTM B151 rod and bar — the standard marked on the flanges pictured — or ASTM B171 plate, with dimensions to ASME B16.5 and patterns to EN 1092-1 or EEMUA 145 for offshore projects. System partners are ASTM B466 seamless and B467 welded pipe and ASTM B366 (WPT designations) or EEMUA 146 fittings. Naval procurement may cite MIL-C-15726 or MIL-T-16420 equivalents. Not an A182 or B564 material — cupronickel has its own B-series family.
How is a C70600 slip on flange welded to pipe?
With two fillet welds — hub outside, bore inside, pipe set back 1/8" (3 mm) — using 70/30-type copper-nickel filler ERCuNi (or MIG/TIG equivalents), which welds both 90/10 and 70/30 base metals; no preheat and no post-weld heat treatment. Copper's high thermal conductivity asks for slightly higher heat input than steel practice, clean joints free of lead-bearing residues, and attention to distortion on thin sections. Brazing is also long-established in shipboard Cu-Ni practice where class rules permit.
Where are C70600 slip on flanges typically used?
Seawater cooling and auxiliary systems in ships and submarines, offshore platform firewater ring mains and deluge systems, desalination plant intake and brine lines, coastal power station cooling water, heat-exchanger and condenser interconnecting piping, and brackish-water service inland. On these systems the slip-on and plate-type patterns dominate — pressures are moderate, diameters are large, and the easy fit-up over pipe suits shipyard fabrication. The stacked golden flanges pictured are exactly this duty.
What sizes and classes are C70600 slip on flanges available in?
From ½" to 24" NB to ASME B16.5 dimensions in Class 150 and 300 patterns (CWP-rated as marked), with EN 1092-1, EEMUA 145 and larger diameters machined to order — the CNC machining and inspection pictured on this page show our in-house route from certified stock to finished flange. Copper-nickel is project material machined against the order, normally dispatching within a few weeks with EN 10204 3.1 certification; state the required delivery on the enquiry and we confirm the schedule with the quotation.
Who manufactures C70600 slip on flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, machining 90/10 copper-nickel / UNS C70600 slip on flanges from ½" to 24" NB from ASTM B151 and B171 certified stock to ASME B16.5, EN 1092-1 and EEMUA 145 patterns — alongside the full C70600 range of weld neck, blind, socketweld, threaded, lapped joint and spectacle blind flanges, and the 70/30 grades C71500 and C71640 — with in-house CNC machining, dimensional inspection, XRF PMI verification and EN 10204 3.1/3.2 certification on every lot, as pictured on this page. Exported to more than 50 countries.
