CuNi 70/30 Copper Nickel 90 Degree Elbow ASME B16.9 Butt Weld Fittings C71500

CuNi 70/30 Copper Nickel 90 Degree Elbow ASME B16.9 Butt Weld Fittings C71500

1.Product Description

This specification covers copper-nickel elbows, which are pipeline directional fittings manufactured from copper-nickel binary alloys through hot-forming processes. The alloy system is divided into two primary categories: 90/10 type with 9%–11% nickel content (UNS C70600) and 70/30 type with 29%–33% nickel content (UNS C71500). The product takes the form of an arc-shaped pipe section with a central bending angle determined by engineering requirements, with standard series including 45°, 90°, and 180°.

The manufacturing process is classified into seamless forming and welded forming. Seamless elbows are produced by mandrel hot-push forming or medium-frequency induction bending, where the entire pipe blank undergoes deformation with continuous grain flow lines and no longitudinal or transverse welds. Welded elbows are manufactured by press-bending steel plates followed by seam welding, suitable for large diameters (above DN400) or extra-heavy wall conditions. The curvature radius is uniformly expressed as a multiple of the nominal diameter (DN): Long Radius type is 1.5DN, Short Radius type is 1.0DN, and Extra-Long Radius type can reach 2.0DN to 3.0DN.

End connection configurations include Butt-Weld ends (BW) with single-V or compound bevels machined per ASME B16.25; Socket-Weld ends (SW) with recessed socket structures; and Threaded ends with NPT (American taper pipe) or BSP (British standard pipe) threads. Each elbow shall be clearly marked on its outer surface with material grade, size designation, heat/lot number, and manufacturer's identification to ensure full traceability throughout its lifecycle.

2.Product Applications

As a standard directional element in corrosion-resistant piping systems, copper-nickel elbows serve the following specific scenarios:

• Marine and Offshore Equipment: Including, but not limited to, engine-room seawater cooling systems on cargo vessels, cruise ships, and naval vessels; turning nodes of platform firewater risers and jet lines; subsea pipeline expansion bends and riser top elbows.

• Petrochemical and Refining Units: Overhead condenser return lines on atmospheric/vacuum distillation units; high-temperature, high-pressure air-cooler inlet piping on hydrocracking units; turn sections of tracer lines and steam trap systems.

• Nuclear and Thermal Power Facilities: Buried pipeline turns in nuclear island equipment cooling water systems; inlet/outlet water conduits for thermal power plant condenser circulating water; annular distribution connections for auxiliary cooling tower water lines.

• Water Treatment and Environmental Engineering: Corrosion-resistant elbows for leachate transfer lines in waste incineration plants; wear- and corrosion-resistant turning pieces for flue gas desulfurization (FGD) slurry circulation pipelines.

• Food and Pharmaceutical Industries: Sanitary elbows for pure steam distribution lines; turning connections for CIP (Clean-in-Place) systems, requiring smooth internal surfaces with no dead corners.

3.Product Advantages

(I) Intrinsic Corrosion Resistance
Copper-nickel alloys achieve self-passivation in chloride-containing media through a dense cuprous oxide (Cu₂O) surface film, which possesses self-healing characteristics—even if mechanically scratched, the film rapidly regenerates in the medium. This property allows the elbow to maintain a low corrosion rate under combined erosion-corrosion conditions, with a Critical Pitting Temperature (CPT) exceeding 60°C in 3.5% NaCl solution.

(II) Impact and Vibration Resistance
With elongation ≥30% and high reduction of area, copper-nickel alloys exhibit excellent energy absorption capacity under water hammer or mechanical vibration conditions, making them resistant to brittle fracture. Simulated marine vibration table tests confirm structural integrity after 10⁶ cycles at 10–200Hz frequency and 5g acceleration.

(III) Assembly and Maintenance Convenience
When welding to same-grade piping, conventional austenitic stainless steel electrodes or copper-nickel specific electrodes (e.g., ENiCu-7) can be used, with a wide welding operation window. Additionally, the relatively high thermal conductivity of copper-nickel (approx. 30–40 W/m·K) results in a narrow heat-affected zone and low residual stress levels, eliminating the need for post-weld stress-relief heat treatment and significantly shortening construction schedules.

(IV) Lifecycle Environmental Friendliness
Copper-nickel alloys are fully recyclable materials with high scrap value. In service, they require no organic antifouling coatings, thereby avoiding marine microplastic pollution from coating detachment, aligning with the progressive requirements of International Maritime Organization (IMO) environmental regulations.

(V) Supply Chain Reliability and Spare Parts Interchangeability
Major industrial nations worldwide have mature production capabilities for copper-nickel elbows. Specifications follow unified ISO and ASME standards, ensuring complete interchangeability among products from different manufacturers. In emergency repairs, off-the-shelf stock can be procured for immediate replacement without custom fabrication.

​4.Key Product Specifications

FAQ

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