# Comparison of ASME B16.34 and API 600 Standards

Introduction

When it comes to industrial valves, two commonly referenced standards are ASME B16.34 and API 600. While both standards address valve design and manufacturing, they serve different purposes and have distinct requirements. Understanding the differences between these standards is crucial for engineers, procurement specialists, and quality control professionals working in the oil and gas, petrochemical, and power generation industries.

Scope and Application

ASME B16.34 is a comprehensive standard that covers the design, materials, dimensions, and testing requirements for flanged, threaded, and welding end valves. It applies to a wide range of valve types including gate, globe, check, ball, and butterfly valves. The standard is recognized internationally and is often referenced in various industries beyond oil and gas.

API 600, on the other hand, specifically focuses on bolted bonnet steel gate valves for petroleum and natural gas industries. This standard provides more detailed requirements for gate valves used in critical service applications where reliability and safety are paramount.

Key Differences

1. Valve Types Covered

ASME B16.34 covers multiple valve types, while API 600 is exclusively for bolted bonnet steel gate valves. API 600 is essentially a subset of ASME B16.34 with additional requirements specific to gate valves in hydrocarbon service.

2. Pressure-Temperature Ratings

Both standards provide pressure-temperature ratings, but API 600 includes more stringent requirements for severe service conditions. API 600 valves must meet additional testing and performance criteria beyond what ASME B16.34 requires.

3. Material Requirements

ASME B16.34 provides general material specifications, while API 600 specifies exact material grades and their permitted combinations for body, bonnet, trim, and bolting. API 600 has more restrictive material requirements to ensure performance in harsh environments.

4. Testing Requirements

While both standards require pressure testing, API 600 includes additional tests such as shell test, backseat test, and high-pressure closure test. API 600 also specifies more rigorous acceptance criteria for these tests.

When to Use Each Standard

ASME B16.34 is appropriate for general industrial applications where standard valve performance is sufficient. It’s commonly specified for utility services, water treatment plants, and less critical process applications.

API 600 should be specified for critical hydrocarbon services, high-pressure applications, or where extended service life with minimal maintenance is required. The oil and gas industry typically mandates API 600 valves for wellhead, pipeline, and refinery applications.

Conclusion

While ASME B16.34 and API 600 share some common ground, they serve different purposes in valve specification. ASME B16.34 provides broad requirements applicable to various valve types, while API 600 offers specialized, more stringent requirements for critical service gate valves. Understanding these differences ensures proper valve selection for specific applications, balancing performance requirements with cost considerations.