UNS N04400 Pipe

UNS N04400 pipe is a solid-solution nickel-copper alloy engineered for severe corrosive environments where standard austenitic stainless steels fail. With a minimum of 63% nickel and roughly 30% copper, it maintains structural integrity from cryogenic temperatures up to 1000°F (538°C), making it a primary spec for offshore marine engineering, hydrofluoric acid processing, and sour gas handling. HT PIPE is a monel 400 pipe supplier with 15+ export experience. Contact us for more information and quotes for free!

Product Forms

Bar & Rod

Plate & Sheet

Coil & Strip

Pipe & Tube

Fitting: Flange, Tee, Elbow, Reducer etc.

Forging: Ring, Shaft, Circle, Block etc.

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ASTM B165 Dimensional & Manufacturing Standards

Procurement of Monel 400 seamless pipe and tube is strictly governed by the ASTM B165 (ASME SB-165) specification. To meet international export quality standards, manufacturers must execute a rigorous production sequence: cold rolling, cold drawing, annealing, pickling, and straightening.

Pipes are generally supplied in two primary tempers depending on the required yield strength:

Annealed (Condition A/B): Yields a soft, ductile pipe with a dull matte finish, ideal for severe forming or bending.

Stress-Relieved (Condition C): Thermally treated below the annealing threshold to remove internal stress from cold working, providing significantly higher tensile strength with a darker surface finish.

Every length of ASTM B165 seamless pipe requires 100% hydrostatic testing to verify pressure retention before dispatch.

Chemical Composition (Heat Analysis)

The precise balance of nickel and copper prevents the galvanic corrosion often seen in welded multimetal systems.

Mechanical Properties (ASTM B165)

Because Monel 400 has relatively low strength in the annealed state, structural applications often require the stress-relieved temper.

Strategic Industry Applications

Marine Engineering: The alloy's resistance to bio-fouling and high-velocity seawater makes it the standard for propeller shafts, pump casings, and seawater desalination valve components.

Chemical Processing: Used extensively for heat exchanger tubing and pressure vessels handling sulfuric and hydrochloric acids (under non-oxidizing conditions).

Oil & Gas: Specified for downhole components, crude column cladding, and valves operating in sour gas (H₂S) environments where traditional alloys suffer rapid hydrogen embrittlement.

Welding Metallurgy & Fabrication Guidelines

Monel 400 exhibits excellent weldability using standard commercial processes, but its physical properties demand strict heat input management to prevent hot cracking.

Matching Filler Metals:

GTAW / GMAW: ERNiCu-7 (Monel Filler Metal 60) for optimal strength and porosity resistance.

SMAW: ENiCu-7 (Monel Welding Electrode 190) covered electrodes.

Purging Requirements: 100% high-purity Argon backing gas is essential for root passes on seamless pipes to eliminate oxidation and heavy oxide scale formation.

Preheat & Post-Weld Heat Treatment (PWHT): Preheat is generally unnecessary unless the metal temperature falls below 60°F (15°C). PWHT is not required for corrosion resistance, though stress relief annealing at 1000°F–1200°F (538°C–649°C) is recommended for services handling hydrofluoric acid to prevent stress corrosion cracking in heat-affected zones.

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