ASME B16.34 vs. API 600: A Comparative Guide to Two Common Valve Standards

ASME B16.34 vs. API 600: Understanding the Core Differences

In the complex world of industrial valves, selecting the correct 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 foundational, they serve distinct purposes. This guide will clarify their roles and help you make informed decisions for your piping systems.

Scope and Primary Application

ASME B16.34 is a broad standard titled “Valves – Flanged, Threaded, and Welding End.” It is published by the American Society of Mechanical Engineers and provides the fundamental requirements for pressure-temperature ratings, dimensions, materials, testing, and marking for a wide variety of valve types (gate, globe, check, etc.). Its focus is on the pressure-containing boundary of the valve body, bonnet, and cover.

API 600, “Steel Gate Valves – Flanged and Butt-Welding Ends,” is a standard from the American Petroleum Institute. It is much more specific, detailing requirements for bolted bonnet steel gate valves primarily used in refinery and pipeline service. API 600 often invokes ASME B16.34 for pressure-temperature ratings and shell thickness but adds extensive requirements for design, construction, material grades, and supplementary testing tailored for the demanding hydrocarbon industry.

Key Comparative Points: Design and Testing

A major difference lies in design and testing rigor. ASME B16.34 sets the baseline for pressure integrity. API 600 builds upon this with stricter rules. For example, API 600 mandates a minimum wall thickness often greater than the minimum required by B16.34 for the same pressure class. It specifies detailed requirements for trim materials (stems, seats), bolting, and gaskets.

Regarding testing, both standards require shell and seat tests. However, API 600 frequently requires more stringent fire testing (API 607/6FA) for soft-seated valves and often dictates non-destructive examination (NDE) methods like magnetic particle or liquid penetrant testing on critical welds and areas—requirements not typically found in the base B16.34 standard.

Choosing the Right Standard for Your Project

The choice between these two commonly ASME B16.34 and API 600 standards depends on your application. For general service in power plants, chemical processing, or commercial HVAC where standard gate, globe, or check valves are used, compliance with ASME B16.34 is typically sufficient and specified.

For severe service in oil & gas production, refineries, transmission pipelines, or any application involving flammable or hazardous fluids, API 600 is the industry-preferred and often contractually mandated standard. It provides the extra margin of safety and durability needed for such critical services.

Frequently Asked Questions (FAQ)

Can a valve be compliant with both ASME B16.34 and API 600?

Yes, absolutely. In fact, an API 600 valve is inherently compliant with the relevant pressure-temperature requirements of ASME B16.34, but it includes many additional prescriptions. The valve nameplate will usually list both standards.

Which standard is more stringent?</