ASTM B564 vs. ASME SB564: Understanding the Difference for Your Nickel Alloy Fittings

ASTM B564 vs. ASME SB564: Understanding the Difference for Your Nickel Alloy Fittings

If you're sourcing nickel alloy fittings like Alloy 625, 400, or C-276, you've likely encountered both ASTM B564 and ASME SB564 on material test reports, purchase orders, and design specifications. It's a common point of confusion: are these two different standards? Is one better than the other?

The short answer is no, they are not meaningfully different in their technical requirements. However, using the correct designation is critical for compliance, especially in regulated industries. Choosing the wrong one can lead to rejected materials, project delays, and unnecessary costs.

Let's demystify these two designations and provide a clear guide for your procurement process.

The Core Relationship: The Same Technical Foundation

Fundamentally, the technical requirements for the material—its chemical composition, mechanical properties, heat treatment, and testing methods—are identical between ASTM B564 and ASME SB564.

Think of it this way:

• ASTM B564 is the base material standard created by ASTM International. This organization develops and publishes technical standards for a wide range of materials.

• ASME SB564 is the adopted and endorsed version for use in ASME Code construction. The American Society of Mechanical Engineers (ASME) incorporates ASTM standards directly into its Boiler and Pressure Vessel Code (BPVC).

The "B" in both designations signifies a "nonferrous" material standard. ASME simply adds the prefix "S" to the ASTM designation to indicate it is a Code-approved material.

Where the Distinction Becomes Critical: The "Code Stamp"

The key difference isn't in the chemistry or the tensile strength; it's in the legal and regulatory context. The choice between the two hinges entirely on the application of your nickel alloy fittings.

Use ASME SB564 when:

Your project falls under the jurisdiction of the ASME Boiler and Pressure Vessel Code or the ASME B31 Code for Pressure Piping. This includes:

• Pressure vessels

• Boilers

• Nuclear power components

• Process piping in chemical plants, refineries, and LNG facilities

In these scenarios, the ASME Code is often a legal requirement. To be "Code-compliant," the materials used must be produced, tested, and documented according to the ASME version of the standard. A fabricator or manufacturer with an ASME "U" or "S" Stamp is legally obligated to use materials specified to the ASME designation (e.g., SB564) to maintain their certification.

Use ASTM B564 when:

Your project is for a non-Code application. This could include:

• Architectural and structural components

• Marine fittings for non-pressure applications

• General industrial machinery

• Any application where local regulations do not mandate ASME Code compliance

In these cases, the material is perfectly sound and meets the same technical quality. You are simply not required to pay for the specific chain of documentation and certification required for ASME Code stamps.

A Practical Comparison Table

Actionable Guidance for Your Projects

To avoid costly mistakes, follow this simple decision tree:

1. Review Your Design Specifications: This is your first and most important step. The engineer or client will explicitly state the required standard (e.g., "ASME SB564").

2. Know Your Application's Jurisdiction: If your system is a registered pressure vessel or falls under safety regulations for process piping, you almost certainly need the ASME designation.

3. Communicate Clearly with Your Supplier: When requesting a quote, specify the exact standard you require. Say, "We require Nickel Alloy 625 fittings to ASME SB564." This ensures the supplier provides material from a mill qualified for ASME Code work and that the MTRs will be correctly marked.

4. Never Assume Interchangeability for Code Work: While a fitting meeting ASTM B564 is technically identical, a Code Inspector will reject it if the design calls for ASME SB564. The paperwork is part of the product.

Conclusion: It's About Compliance, Not Quality

The difference between ASTM B564 and ASME SB564 is not a matter of material quality but one of regulatory compliance and documentation.

• ASTM B564 defines the "recipe."

• ASME SB564 provides the "stamp of approval" for use in Code-bound projects.

Understanding this distinction is a small but critical piece of knowledge that ensures your nickel alloy fittings are not only high-performing but also fully compliant, keeping your projects on schedule and within the bounds of the law. Always default to the specification mandated by your engineering documents and the governing jurisdiction of your application.