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Nickel Alloy 625 is a versatile material renowned for its excellent resistance to corrosion, high strength, and its ability to withstand extreme temperatures. These properties make it particularly suitable for a variety of applications across industries such as marine, aerospace, and chemical processing. The following is an in-depth overview of Nickel Alloy 625 tubing and pipe, including its specifications, tolerances, physical properties, and composition.

Sizes and Standard Tolerances

Nickel Alloy 625 tubing and pipe come in a variety of sizes to suit diverse applications. The outer diameter (OD) ranges from 1/16" (1.59 mm) to 4" (101.6 mm), with smaller metric sizes also available. Wall thicknesses span from 0.010" (0.25 mm) to 0.220" (5.59 mm), accommodating different pressure requirements and structural conditions. The products are available in random or cut lengths up to 40 feet (12.9 meters), or in coils of up to 1-1/2" in outer diameter.

Standard tolerances are crucial for maintaining quality and performance standards. For tubing with an OD under 5/8" (15.9 mm), the tolerance is ±0.005" (0.127 mm). Tubing with an OD from 5/8" up to 1-1/2" (38.1 mm) has a tolerance of ±0.007". For larger diameters up to 3" (76.2 mm), the tolerance is ±0.010" (0.25 mm), and for diameters greater than 3" (76.2 mm) up to 4" (101.6 mm), the tolerance is ±0.015" (0.38 mm).

Specifications

Nickel Alloy 625 tubing and pipe meet or exceed key industry standards for welded pressure and corrosion tubing, including ASTM B704, ASME SB704, ASTM B705, and ASME SB705. This ensures high reliability and compliance with industry requirements for safety and performance.

Physical Properties

In the annealed condition, Nickel Alloy 625 exhibits impressive mechanical properties:

• Tensile Strength: Up to 120,000 psi (827 MPa)
• Yield Strength: 60,000 psi (414 MPa)
• Elongation: Minimum of 30% in 2 inches
• Modulus of Elasticity: Approximately 30 x 10^6 psi
• Mean Coefficient of Thermal Expansion: 7.1 x 10^-6 in./in./°F
• Thermal Conductivity: 68 BTU-in/ ft2-h-°F

These properties enable the alloy to maintain structural integrity and resist deformation under high thermal and mechanical stress.

Chemical Composition

The chemical composition of Nickel Alloy 625 contributes to its robust performance in harsh environments. The nickel content is at least 58%, combined with chromium (20.0-23.0%) and molybdenum (8.0-10.0%), which enhance corrosion resistance. The alloy also contains niobium plus tantalum (3.15-4.15%), which improves its strength. Other elements in trace amounts include iron (Fe), cobalt (Co), titanium (Ti), and aluminum (Al).

Applications and Industry Standards

Because of its remarkable characteristics, Nickel Alloy 625 is preferred in industries that demand highly resistant materials. For instance, its application in the aerospace sector includes exhaust systems and other components exposed to high temperatures and corrosive environments. In marine applications, its resistance to seawater corrosion is invaluable, while in chemical processing, its durability and strength are critical for handling hot, corrosive materials.

The alloy meets stringent industry standards, ensuring its applicability in demanding environments. Its specifications under ASTM and ASME authorize its use in critical applications, affirming its reliability and safety.

Conclusion

Nickel Alloy 625 tubing and pipe offer a reliable and robust solution for challenging industrial applications. Their wide size range, precise tolerances, and adherence to recognized standards make them an ideal choice for high-performance projects in hostile environments. Whether used in aerospace, marine, or chemical processing, Nickel Alloy 625 remains a top choice for engineers and designers aiming to ensure longevity and reliability in their equipment and structures.