ASME B16.34 vs. API 600: A Comprehensive Comparison of Two Common Valve Standards

In the complex world of industrial valves, selecting the right standard is critical for safety, performance, and compliance. Two of the most referenced and sometimes confused specifications are ASME B16.34 and API 600. While both are pillars of valve design and manufacturing, they serve distinct purposes and apply to different scenarios. This guide provides a clear, side-by-side comparison to help engineers, specifiers, and procurement professionals make informed decisions.

Understanding the Core Purpose of Each Standard

Before diving into specifics, it’s essential to grasp the fundamental intent behind each document. This foundational understanding clarifies why one standard might be mandated over another for a given application.

ASME B16.34: The Foundation for Pressure-Temperature Ratings

ASME B16.34, titled “Valves – Flanged, Threaded, and Welding End,” is a foundational standard from the American Society of Mechanical Engineers. Its primary focus is establishing pressure-temperature ratings, wall thickness requirements, and material groups for valve bodies, bonnets, and covers. It defines the minimum requirements for valves that will be integrated into a pressure-retaining system. Essentially, it answers the question: “Is this valve body strong enough to contain the specified pressure at the operating temperature?”

API 600: The Bolted Bonnet Steel Valve Standard

API 600, “Steel Gate Valves – Flanged and Butt-Welding Ends, Bolted Bonnets,” is a product-specific standard from the American Petroleum Institute. It builds upon the pressure-containing requirements of standards like ASME B16.34 but adds extensive, detailed specifications for the design, material, testing, and inspection of bolted bonnet steel gate valves. API 600 is renowned for its rigorous requirements for durability, fire safety, and performance in demanding hydrocarbon and energy sector services.

Key Differences in Scope and Application

The divergence in their core purposes leads to significant practical differences. Here’s where the choice between them becomes clear for project specifications.

Valve Type Coverage: ASME B16.34 applies to a broad range of valve types—gate, globe, check, ball, plug, etc.—as long as they have flanged, threaded, or welding ends. API 600 is exclusively for bolted bonnet steel gate valves.

Industry Focus: ASME B16.34 is universally applied across power generation, chemical, and other process industries. API 600 is heavily favored, and often required, in oil & gas, petrochemical, and refinery applications due to its stringent material and testing protocols.

Specificity: B16.34 sets the “base” requirements. API 600 adds layers of specific mandates on trim materials, stem design, packing, gasketing, fire testing (to API 607/6FA), and a more demanding shell and closure test duration.

Direct Comparison: Material, Design, and Testing

To specify correctly, one must understand the detailed requirements. The table below highlights critical distinctions.

Materials: API 600 provides a very specific list of approved body, bonnet, trim, and stem materials with detailed chemistry and mechanics. ASME B16.34 groups materials more broadly for pressure-temperature rating derivation.

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