Copper Nickel Pipe for Marine and Shipbuilding: EEMUA 144, EEMUA 234, and Seawater Service Selection

When a pipe carries raw seawater across the hull of a chemical tanker, through the keel cooler of a frigate, or along the cooling circuit of an offshore platform, copper-nickel is almost always the material the specification ends on. Not because it is the cheapest. Because it is the material that survives. EEMUA 144 234 Cu-Ni pipe has been the default for marine and shipbuilding seawater service for more than four decades, and the reason is straightforward. A 90/10 or 70/30 pipe laid in 1975 in a North Sea platform is, in many cases, still in service in 2026 without a single internal replacement.

Most procurement guides on this topic focus on the chemistry book. This one is different. It is written for the people who actually have to specify, order, weld, and inspect a marine & ship-building piping system: shipyard buyers, classification society surveyors, offshore package engineers, and the EPC procurement team that has to balance weight, weld procedure, lead time, and total cost of ownership in a single RFQ.

EZ Steel Industrial has supplied copper-nickel pipe, fittings, and flanges into shipbuilding and offshore projects since 1994. With more than 500 employees, an annual capacity above 480,000 tonnes, and dedicated stainless and copper-nickel production at its Lishui facility, the company supports shipyards, vessel operators, and offshore fabricators with bundled mill-direct supply: pipe, weldolet fittings, Cu-Ni and steel flanges, plus the full documentation package required by Lloyd's, DNV, ABS, BV, and CCS classification.

Why Copper-Nickel Owns the Seawater Loop

Seawater is not just salt water. It is a complex electrolyte that promotes pitting, crevice corrosion, galvanic attack, and erosion at every elbow, tee, and pump discharge. Plain carbon steel fails in months. Aluminium bronzes work in some roles but gall under vibration. Super-duplex stainless steel works but is expensive and unforgiving in fabrication. B466 copper nickel tube in 90/10 or 70/30 composition sits in a narrow band where all of these failure modes are simultaneously under control.

Three corrosion mechanisms that copper-nickel resists

• General corrosion. In clean, aerated seawater, 90/10 corrodes at roughly 0.025-0.05 mm/year and 70/30 at roughly 0.015-0.03 mm/year. That gives a design life of 30-50 years on standard wall thicknesses in normal service, well beyond what carbon steel or aluminium bronze can deliver.
• Biofouling and macrofouling. The protective oxide film that forms on copper-nickel in seawater releases small amounts of copper ion, which discourages barnacle and mussel attachment. A properly conditioned system needs far less biocide dosing and can be designed for lower fouling factors than carbon steel or stainless loops.
• Impingement attack. At high local velocities (above roughly 4 m/s for 90/10 and 4.5 m/s for 70/30 in clean seawater), turbulence can break down the protective film. Selecting the right alloy, controlling design velocity, and adding small amounts of iron content (typically 0.5-2.0% in the alloy) push the impingement limit well above operating conditions.

90/10 vs 70/30: When to Pick Which

The two alloys are not interchangeable. They sit in the same family but solve different problems. The 90/10 grade (UNS C70600) is the workhorse: lower cost, easier to fabricate, sufficient for the vast majority of marine seawater loops. The 70/30 grade (UNS C71500) is the higher-performance option: better strength, higher allowable velocity, better resistance to localised corrosion in hotter or more aggressive water.

The straightforward rule for new marine & ship-building systems: specify 90/10 by default, and reserve 70/30 for the high-velocity, high-temperature, or critical-service applications where 90/10 is borderline. The cost premium on 70/30 is justified only when the design velocity, fluid temperature, or consequence of failure clearly demands it.

Reading EEMUA 144 and EEMUA 234 Without Getting Lost

EEMUA 144 and EEMUA 234 are the two publications shipyard and offshore buyers cite most often. They are not competing standards. They cover different alloys and different inspection regimes, and the procurement team needs to understand which one to call out on the RFQ.

EEMUA 144 — 90/10 copper-nickel for offshore

EEMUA Publication 144 covers seamless and welded 90/10 copper-nickel pipe for offshore applications. It defines the chemical composition (with the iron range 1.0-2.0% that is critical for impingement resistance), the mechanical properties, the dimensional tolerances, and the test regime. Eddy current or ultrasonic testing is required on the full length, with hydrostatic testing on every pipe. The latest revision also tightens requirements on internal surface condition, which directly affects biofilm formation and long-term fouling.

EEMUA 234 — 70/30 copper-nickel for offshore and naval

EEMUA Publication 234 covers 70/30 copper-nickel pipe and fittings for offshore and naval applications. The mechanical property bar is higher, the inspection regime is more demanding, and the documentation requirements often include additional traceability to casting and billet. EEMUA 234 is the standard to call out for naval surface ship seawater systems, for high-pressure fire-fighting mains, and for systems operating at sustained temperatures above 60°C where 90/10 starts to lose margin.

The Standards Family Around EEMUA 144 / 234

EEMUA does not stand alone. Shipyards and classification societies cross-reference it with the ASTM, ASME, EN, and JIS families. Knowing how the standards map to each other saves weeks in technical clarification and prevents the mill from quoting against the wrong document.

Material and Welding: What the Yard Actually Has to Do

Copper-nickel fabrication is not hard, but it is different from carbon steel. Welders used to carbon steel work will over-preheat, over-travel, and over-grind. The right approach saves hours per joint and prevents the burn-through and porosity that drive rework on the quay.

Cutting and joint prep

Use a fine-tooth bandsaw or a rotary cutting tool. Avoid abrasive cutting wheels; they leave an embedded iron layer that will rust and pit. The joint prep is a standard 30-37.5° bevel for butt welds, with a 1.5-2.0 mm root face. The root gap should be tighter than for carbon steel — typically 1.5-2.0 mm — to prevent burn-through.

Welding process and filler

GTAW (TIG) is the default for root and cap on Cu-Ni 90/10. GMAW (MIG) with pulsed transfer is used for longer runs and for 70/30. The filler is ERCuNi (matching the parent alloy) or ERCuNiAl for higher-strength joints. Preheat is mild — typically 30-60°C on 90/10 above 3 mm wall, and 60-150°C on 70/30 — and interpass temperature should be kept under 150°C. Argon backing gas is essential for the root pass to prevent internal oxidation.

NDT and inspection

Dye-penetrant inspection is the standard NDT method. Radiography is possible on thinner wall sections but is less reliable on Cu-Ni because of the high attenuation. Hydrostatic testing is mandatory on the full loop at 1.5× design pressure, held for at least 30 minutes. B466 copper nickel tube in the as-welded and tested condition, with a clean internal bore, is the deliverable the surveyor is looking for.

Bundled Sourcing: Pipe, Fittings, and Flanges in One RFQ

The most expensive line item on a copper-nickel order is rarely the pipe itself. It is the dozens of fittings, flanges, gaskets, and stud bolts that the yard has to order separately if the supplier cannot bundle them. A yard that sources pipe from one supplier, butt-weld fittings from another, and flanges from a third typically sees two to three weeks of slippage on the materials schedule, plus three different MTC packages to reconcile for the surveyor.

EZ Steel Industrial supplies the full marine package from a single RFQ: EEMUA 144 234 Cu-Ni pipe in seamless and welded form, long-radius elbows, equal and reducing tees, concentric and eccentric reducers, weldolets and sockolets, plus matching Cu-Ni weld-neck flanges and the corresponding gaskets and stud-bolt-and-nut sets. The package is heat-number traceable end to end, with EN 10204 3.1 mill test certificates issued at the same time and reviewed against the same RFQ line items.

For shipyards that prefer a single-source guarantee, EZ Steel Industrial also supplies the carbon and alloy steel components for non-seawater service in the same vessel — structural pipe for engine room platforms, alloy steel pipe for the boiler uptake, and stainless steel pipe for the hygienic side of the galley and accommodation. The Lishui facility runs the Cu-Ni and stainless lines; the Yangzhou and Cangzhou facilities cover the carbon and alloy side. Three mills, one quality plan, one point of accountability for the surveyor.

Quality Systems and Classification Society Acceptance

Classification society acceptance is non-negotiable for any pipe entering a classed vessel. The mill supplying the order has to be on the society's approved list, with a valid audit certificate covering the specific product and process. Before issuing the PO, the buyer's QA team should confirm three items in writing.

• Mill approval scope. Confirm the mill is approved by the relevant society (Lloyd's Register, DNV, ABS, Bureau Veritas, CCS, or others as required) for the specific product family. A general ISO 9001 certificate is not sufficient.
• Welder and WPSR qualification. Confirm the weld procedure is pre-qualified to the relevant standard (ASME IX, EN ISO 15614, or classification society equivalent) for Cu-Ni 90/10 or 70/30, with valid welder certificates for the actual joints and positions used on the vessel.
• Documentation package. Confirm the mill will issue EN 10204 3.1 certificates, hydrostatic test reports, dimensional reports, and material traceability linking every pipe to its heat number, with the same documentation reviewed by the society surveyor during the in-mill inspection.

Common Procurement Mistakes on Copper-Nickel Orders

After three decades of copper-nickel supply into shipyards and offshore projects, the same procurement mistakes keep showing up. They are easy to avoid once the team knows what to look for.

• Quoting nominal wall instead of minimum wall. The standard allows a wall-thickness tolerance, and a mill that quotes nominal wall can deliver below the design minimum. Specify minimum wall on the RFQ and check the MTC.
• Skipping iron-content verification. Iron in the 1.0-2.0% range is what gives 90/10 its impingement resistance. Mills that do not ｄｅｃｌａｒｅ the iron content should be asked to add it to the MTC.
• Mixing 90/10 and 70/30 fittings on the same line. It happens when the yard runs short on one alloy and substitutes the other for expedience. The galvanic mismatch and the difference in thermal expansion rate will show up as accelerated joint failure.
• Ordering fittings without a full dimensional drawing. Cu-Ni long-radius elbows in particular have non-standard center-to-face dimensions in some regional standards. A sketch and a tolerance band on the RFQ prevents the wrong fitting arriving on the quay.
• Forgetting the class society survey window. The surveyor has to be present for the hydrostatic test and final visual. Book the survey window with the mill at the time of order, not at the time of delivery.

Field Checklist: 8 Items to Confirm Before Releasing the PO

A short checklist run before issuing the purchase order prevents the most common delivery, fabrication, and acceptance problems on copper-nickel marine orders.

1. Alloy specified explicitly: 90/10 (C70600) or 70/30 (C71500), with standard called out (EEMUA 144, EEMUA 234, ASTM B466, JIS H 3300, etc.)
2. Iron content range declared on the MTC, 1.0-2.0% for 90/10, 0.4-1.0% for 70/30
3. Minimum wall thickness specified, not nominal
4. End finish and bevel confirmed: plain end, bevelled to ASME B16.25, or flared for flared-tube connections
5. Class society approval scope confirmed in writing for the specific product family
6. WPSR and welder qualification scope confirmed for the joint types and positions used on the vessel
7. Documentation package defined: EN 10204 3.1 MTC, hydrostatic test report, dimensional report, material traceability
8. Survey window booked at the mill, with confirmation that the same documentation will be available for the surveyor

Mill-Direct Sourcing: Why It Matters on Copper-Nickel

Copper-nickel is a small-volume, high-discipline product. A trading house that buys from a mill and resells adds margin without adding quality. A mill-direct supplier, on the other hand, controls the heat, the rolling, the cold-pilgering, the test regime, and the documentation from start to finish. For EEMUA 144 234 Cu-Ni pipe going into a classed vessel, that direct chain is the difference between a smooth survey and a six-week delay.

EZ Steel Industrial runs the Lishui facility as a dedicated stainless and copper-nickel line, with eddy current testing, ultrasonic testing, hydrostatic testing, and PMI verification on every heat. The Yangzhou and Cangzhou facilities cover carbon, alloy, and structural pipe for the rest of the vessel. Together, the network delivers a single RFQ, a single quality plan, a single point of accountability, and the full documentation package that Lloyd's, DNV, ABS, BV, and CCS surveyors require.