Product Overview

What is CuNi 90/10?

Copper-Nickel 90/10 (CuNi 90/10) is an alloy containing 90% copper and 10% nickel, with small additions of iron and manganese that significantly enhance its resistance to seawater erosion-corrosion. Designated as C70600 (UNS) and CW352H (CEN), it is the most widely used copper-nickel grade in marine engineering worldwide.

Its combination of moderate strength, excellent corrosion resistance in seawater, inherent resistance to macrofouling, and good weldability make it the default material for seawater piping in naval ships, offshore platforms, desalination plants, and coastal power stations.

Outstanding Seawater Corrosion Resistance

Resists seawater corrosion up to 3 m/s flow velocity; suitable for all salinities including concentrated brines.

Natural Biofouling Resistance

Inherent anti-fouling property reduces barnacle and marine organism attachment — no biocide coatings required.

Excellent Weldability

Readily welded by TIG, MIG, and manual metal arc processes. Compatible with ERCuNi filler metal (AWS A5.7).

Good Thermal Conductivity

Thermal conductivity of ~40 W/m·K makes it ideal for heat exchangers, condensers, and coolers.

Chemical Composition

Alloy Chemistry — CuNi 90/10

Chemical composition per ASTM B466 / ASTM B111 (C70600). The iron and manganese additions are critical to seawater corrosion resistance.

Copper

Balance

Nickel + Co

9.0 – 11.0%

Iron

1.0 – 1.8%

Manganese

0.5 – 1.0%

Element	Symbol	Min (%)	Max (%)	Role in Alloy
Copper	Cu	Balance	Balance	Primary matrix — conductivity & corrosion base
Nickel + Cobalt	Ni+Co	9.0	11.0	Strengthens and stabilises protective oxide film
Iron	Fe	1.0	1.8	Key to erosion-corrosion resistance in flowing seawater
Manganese	Mn	0.5	1.0	Improves hot workability; deoxidiser
Lead	Pb	—	0.02	Trace impurity limit
Zinc	Zn	—	0.50	Trace impurity limit
Carbon	C	—	0.05	Trace impurity limit
Sulphur	S	—	0.02	Trace impurity limit

* Cobalt is counted as nickel for the purpose of determining conformance to this composition. Composition per ASTM B466 / ASTM B111 Table 1.

Dimensional Standards & Charts

Pipe Dimensions — CuNi 90/10

All dimensions are manufactured to the tolerances specified in ASTM B466, DIN 86019, and BS EN 12449. Custom sizes available on request.

Standard Pipe Sizes — Outer Diameter × Wall Thickness (ASTM B466) ASTM B466

NPS (inch)	OD (mm)	Schedule 5S WT (mm)	Schedule 10S WT (mm)	Schedule 40S WT (mm)	Schedule 80S WT (mm)	ID Sch 40S (mm)
1/4"	13.72	1.65	2.24	3.02	3.73	7.68
3/8"	17.15	1.65	2.31	3.20	3.96	10.75
1/2"	21.34	1.65	2.77	3.73	4.78	13.88
3/4"	26.67	1.65	2.87	3.91	5.56	18.85
1"	33.40	1.65	2.77	4.55	6.02	24.30
1-1/4"	42.16	1.65	2.77	4.85	6.35	32.46
1-1/2"	48.26	1.65	2.77	5.08	7.14	38.10
2"	60.33	1.65	2.77	5.54	8.74	49.25
2-1/2"	73.03	2.11	3.05	7.01	9.53	59.01
3"	88.90	2.11	3.05	7.62	11.13	73.66
3-1/2"	101.60	2.11	3.05	8.08	12.70	85.44
4"	114.30	2.11	3.05	8.56	13.49	97.18
5"	141.30	2.77	3.40	9.53	15.88	122.24
6"	168.28	2.77	3.40	10.97	18.26	146.34
8"	219.08	2.77	3.76	12.70	23.01	193.68

WT = Wall Thickness. ID = Internal Diameter. Tolerances: OD ±0.5%, WT −0/+20% per ASTM B466.

Metric Pipe Sizes — DIN 86019 (Marine Grade) DIN 86019

OD (mm)	WT 1.0 mm	WT 1.5 mm	WT 2.0 mm	WT 2.5 mm	WT 3.0 mm	WT 4.0 mm	WT 5.0 mm	WT 6.0 mm
6	✓	✓	✓	—	—	—	—	—
8	✓	✓	✓	—	—	—	—	—
10	✓	✓	✓	✓	—	—	—	—
12	✓	✓	✓	✓	—	—	—	—
14	—	✓	✓	✓	✓	—	—	—
16	—	✓	✓	✓	✓	—	—	—
18	—	✓	✓	✓	✓	—	—	—
22	—	✓	✓	✓	✓	✓	—	—
28	—	—	✓	✓	✓	✓	—	—
35	—	—	✓	✓	✓	✓	✓	—
42	—	—	—	✓	✓	✓	✓	—
54	—	—	—	✓	✓	✓	✓	✓
76.1	—	—	—	—	✓	✓	✓	✓
88.9	—	—	—	—	✓	✓	✓	✓
108	—	—	—	—	—	✓	✓	✓
133	—	—	—	—	—	✓	✓	✓
159	—	—	—	—	—	✓	✓	✓
219	—	—	—	—	—	—	✓	✓

✓ = Standard size available. Custom wall thicknesses available on request. Tolerance per DIN ISO 1127 / EN 10220.

Pipe Weight per Metre Chart kg/m

OD (mm)	WT 1.5 mm (kg/m)	WT 2.0 mm (kg/m)	WT 2.5 mm (kg/m)	WT 3.0 mm (kg/m)	WT 4.0 mm (kg/m)	WT 5.0 mm (kg/m)	WT 6.0 mm (kg/m)
12	0.37	0.48	0.58	—	—	—	—
18	0.58	0.76	0.93	1.09	—	—	—
22	0.72	0.95	1.17	1.38	1.77	—	—
28	0.93	1.24	1.53	1.81	2.35	—	—
35	1.17	1.57	1.95	2.32	3.04	3.71	—
42	—	1.90	2.36	2.81	3.70	4.54	—
54	—	2.47	3.07	3.66	4.82	5.95	7.03
76.1	—	—	4.36	5.21	6.88	8.52	10.12
88.9	—	—	5.11	6.10	8.07	10.01	11.91
108	—	—	—	7.45	9.87	12.25	14.60
133	—	—	—	9.21	12.21	15.18	18.11
159	—	—	—	—	14.64	18.22	21.76
219	—	—	—	—	—	25.23	30.18

Density of CuNi 90/10: 8.9 g/cm³. Formula: Weight (kg/m) = 0.02491 × WT × (OD − WT). Values rounded to 2 decimal places.

Mechanical Properties

Physical & Mechanical Data — CuNi 90/10

275

MPa (min)

Tensile Strength

Annealed condition per ASTM B466

105

MPa (min)

Yield Strength (0.2%)

Annealed condition per ASTM B466

% (min)

Elongation

On 50 mm gauge length

8.9

g/cm³

Density

At 20°C

W/m·K

Thermal Conductivity

At 20°C

16.2

×10⁻⁶/°C

Thermal Expansion

Mean coefficient 20–300°C

Complete Physical Properties Table

Property	Value	Unit	Condition / Notes
Density	8.9	g/cm³	At 20°C
Melting Range	1100 – 1145	°C	Liquidus to solidus
Tensile Strength (min)	275	MPa	Annealed, ASTM B466
Yield Strength 0.2% (min)	105	MPa	Annealed, ASTM B466
Elongation (min)	30	%	50 mm gauge length
Rockwell Hardness	55 – 75	HRB	Annealed condition
Elastic Modulus	135	GPa	At room temperature
Thermal Conductivity	40	W/m·K	At 20°C
Thermal Expansion Coeff.	16.2	×10⁻⁶/°C	Mean 20–300°C
Specific Heat Capacity	377	J/kg·K	At 20°C
Electrical Resistivity	0.187	μΩ·m	At 20°C
Max Service Temp (dry)	500	°C	Oxidising atmosphere
Max Service Temp (seawater)	200	°C	Continuous immersion

Pressure Ratings

Allowable Working Pressure — CuNi 90/10

Calculated per ASME B31.1 (Power Piping) using allowable stress S = 55 MPa at ambient temperature. These values are indicative — always verify with a qualified piping engineer for your specific project design conditions.

Burst & Working Pressure by Size and Schedule ASME B31.1

NPS	OD (mm)	Schedule	WT (mm)	Burst Pressure (bar)	Allow. Work. Press. (bar)	Allow. Work. Press. (psi)
1/2"	21.34	10S	2.77	247	62	900
1/2"	21.34	40S	3.73	333	83	1205
1"	33.40	10S	2.77	158	40	575
1"	33.40	40S	4.55	260	65	943
2"	60.33	10S	2.77	87	22	319
2"	60.33	40S	5.54	175	44	638
3"	88.90	10S	3.05	65	16	236
3"	88.90	40S	7.62	163	41	595
4"	114.30	10S	3.05	51	13	183
4"	114.30	40S	8.56	143	36	522
6"	168.28	10S	3.40	38	10	145
6"	168.28	40S	10.97	124	31	450

Working pressure = Burst pressure ÷ 4 (safety factor). All values at ambient temperature (20°C). Reduce by 25% for temperatures above 150°C. Corrosion allowance not included — add as required by design code.

Design Derating Factors (Temperature)

Up to 20°C (ambient)1.00 × (no derating)

50°C0.97 ×

100°C0.93 ×

150°C0.87 ×

200°C0.75 ×

250°C0.68 ×

Corrosion Allowance Guidance (Seawater)

Stagnant seawater0.025 mm/year

Flowing seawater (<1 m/s)0.025 mm/year

Flowing seawater (1–3 m/s)0.025 mm/year

Flowing seawater (>3 m/s)Consult engineer

Polluted seawaterUse CuNi 70/30

Typical design life25 – 40 years

Complete Piping Guide

CuNi 90/10 Piping — Design, Installation & Welding Guide

A practical guide for engineers, procurement specialists, and installation teams working with CuNi 90/10 seamless pipes in marine and industrial piping systems.

Applicable Design Codes & Standards

ASME B31.1 — Power Piping
ASME B31.3 — Process Piping
DNV-RP-0034 — Marine Copper-Nickel Piping
MIL-P-24691 — US Navy Shipboard Piping
Lloyd's Register & Bureau Veritas type approval
IMO/SOLAS requirements for fire-main systems
ASTM B466 / DIN 86019 material supply standard
AWS A5.7 — Filler metal specification for welding

Velocity Limits for Flow Design

Maximum continuous velocity: 3.0 m/s (seawater)
Maximum short-term velocity: 4.5 m/s (transient)
Minimum velocity: 0.9 m/s (prevent sedimentation)
Pump suction/discharge: 1.2 – 2.4 m/s
Heat exchanger tubes: 1.5 – 2.5 m/s
Fire-main systems: Up to 4 m/s (intermittent)
Note: Velocity limits are critical — exceeding 3 m/s in seawater can cause erosion-corrosion. Consider upgrading to CuNi 70/30 for higher velocities.

Welding Procedures & Guidelines

Preferred process: GTAW/TIG (best quality)
Acceptable: GMAW/MIG, SMAW (MMAW)
Filler metal: ERCuNi (AWS A5.7 / ISO 24034)
Shielding gas: Pure Argon (99.99%)
Preheat: Not required for wall thickness <12 mm
Interpass temp: Max 100°C — control heat input
Post-weld: No PWHT required; clean weld area
Critical: Avoid contamination with iron — use dedicated tools and stainless steel wire brushes only
Purge: Back-purge with argon for pipe welds (root pass)

Fabrication & Bending

Cold bending: Minimum bend radius = 3 × OD
Hot bending: Temp range 650–850°C; air cool
Flattening test: No cracking at 1/3 OD flatten
Cutting: Band saw, disc cutter, or plasma
Machining: Excellent machinability; use carbide tools
Flaring: Suitable for double-flared tube fittings
Threading: Not recommended — use flanged or compression fittings
Annealing after cold work: 650–750°C, water quench

Corrosion Considerations

Galvanic compatibility: Compatible with stainless steel (SS316) with Monel or CuNi isolation flanges between dissimilar metals
Avoid contact with: Carbon steel, aluminium alloys without isolation
Dezincification: Not applicable (no zinc present)
SCC (Stress Corrosion Cracking): Not susceptible in seawater service
Sulphide attack: Susceptible to H₂S — avoid use where sulphides present
Ammonia: Susceptible to SCC — avoid in ammonia-bearing environments
Impressed current cathodic protection: Avoid over-protection — can cause hydrogen embrittlement

Joining Methods & Fittings

Butt welding: Preferred for permanent joints (ASME BPE / B16.9)
Socket welding: Acceptable for NPS ≤ 2"
Flanged joints: ASME B16.5 or EN 1092 flanges; use non-metallic gaskets
Compression fittings: Suitable for small bore (≤28 mm OD) instrumentation lines
Grooved couplings: Victaulic-type couplings acceptable for large bore above deck
Flared fittings: Suitable for hydraulic instrumentation lines
CuNi fittings: Use matching C70600 elbows, tees, reducers (ASTM B467)

Installation & Support Spacing

Hanger spacing — 1" NPS: 2.1 m (horizontal)
Hanger spacing — 2" NPS: 2.7 m
Hanger spacing — 4" NPS: 3.6 m
Hanger spacing — 6" NPS: 4.2 m
Support material: Use SS316 or coated steel supports with neoprene/EPDM liners to prevent galvanic contact
Thermal expansion: Allow 1.62 mm/m per 100°C rise; use expansion loops or bellows
Slope for drainage: Min 1:200 gradient towards low point

Inspection & Testing Requirements

Hydrostatic test: 1.5 × design pressure per ASME B31.1 (min 30 min hold)
Pneumatic test: 1.1 × design pressure (with Hazard analysis)
Eddy current testing: For heat exchanger tube bundles
Radiographic testing: Category D welds per ASME B31.3
PMI (Positive Material Identification): XRF verification for critical systems
Dimensional inspection: 100% OD, WT, and length per ASTM B466
Visual inspection: Free of seams, scale, laps, and cracks
MTR (Mill Test Report): Chemical, mechanical, and hydrostatic test results

Applications

Where CuNi 90/10 Pipes Are Used

Marine Seawater Pipelines

Main seawater circuits in naval and commercial vessels — cooling, firefighting, and ballast systems.

Offshore Platform Piping

Seawater lift and injection systems, fire suppression, and cooling water on FPSOs and fixed platforms.

Desalination Plants

Feedwater, brine circuits, and reject water piping in MSF, MED, and RO desalination installations.

Power Plant Condensers

Once-through cooling water piping and condenser tube systems in coastal and ship-mounted power plants.

Naval & Defence Systems

Shipboard fire-main, hydraulic, and damage-control systems requiring the highest corrosion performance.

Oil & Gas Refineries

Process cooling water, heat exchanger shells, and seawater-cooled condensers in coastal refineries.

Need higher performance for aggressive environments?

Compare with CuNi 70/30 — ideal for higher flow velocities, polluted seawater, and elevated pressure applications.

View CuNi 70/30 Pipes →

CuNi 90/10Seamless Pipes