Difference Between API 600 and API 602 Valve Standards: A Complete Guide

In the industrial valve industry, international standards are crucial to ensure safety, reliability, and interchangeability. Among the most widely recognized valve standards are API 600 and API 602, both published by the American Petroleum Institute (API).

Although both standards apply to steel gate valves, they differ significantly in design scope, pressure ratings, and application areas. This article provides a clear explanation of the differences between API 600 and API 602, helping engineers, procurement managers, and end users select the right valves for their projects.

1. Overview of API 600

• Standard Title: Steel Gate Valves – Flanged and Butt-welding Ends, Bolted Bonnets

• Size Range: Typically NPS 2 to NPS 48 (large-diameter valves)

• Pressure Class: ASME Class 150 to 2500

• Design Features:

  • Bolted bonnet construction

  • Full-bore port design for minimum pressure drop

  • Renewable seats, often welded or threaded in

  • Rising stem with outside screw and yoke (OS&Y)

• Applications:

  • Large pipelines in oil & gas, power plants, and petrochemical facilities

  • High-temperature, high-pressure services

👉 In short, API 600 covers large-diameter, heavy-duty gate valves designed for severe service conditions.

2. Overview of API 602

• Standard Title: Compact Steel Gate Valves for Refinery Use

• Size Range: Typically NPS 1/4 to NPS 4 (small-diameter valves)

• Pressure Class: ASME Class 150 to 2500

• Design Features:

  • Compact and forged steel body construction

  • Socket weld, threaded, or flanged ends

  • Often non-rising stem for space-saving installations

  • Seats usually integral with the body

• Applications:

  • Refineries, chemical plants, and power generation where small-bore, high-pressure isolation is required

  • Frequently used as block valves on instrumentation, auxiliary piping, and steam lines

👉 In short, API 602 applies to small-bore forged steel gate valves designed for compact and high-pressure applications.

3. Key Differences Between API 600 and API 602

4. How to Choose Between API 600 and API 602

• Choose API 600 valves if:
  ✅ You need large-diameter gate valves for main process lines.
  ✅ Your application involves severe service conditions (high temperature, high pressure).
  ✅ You require replaceable seats for extended service life.

• Choose API 602 valves if:
  ✅ You need small-bore valves for refinery or chemical plant applications.
  ✅ Your piping system requires compact design with socket weld or threaded ends.
  ✅ You are dealing with high-pressure, small-diameter pipelines (e.g., steam, chemical feed lines).

5. Conclusion

Both API 600 and API 602 are essential standards in the valve industry, but they serve different applications:

• API 600 → Large cast steel gate valves for main pipeline isolation.

• API 602 → Compact forged steel gate valves for small-bore, high-pressure services.

Understanding these differences ensures the right valve selection, improving safety, performance, and cost-effectiveness in industrial projects.

FAQ: API 600 vs API 602

Q1: Can API 600 and API 602 valves be used interchangeably?
Not usually. API 600 valves are for large pipelines, while API 602 valves are for small-bore auxiliary lines.

Q2: Are API 602 valves stronger than API 600?
Not exactly. API 602 valves are compact and forged, making them durable for small lines, but API 600 valves are designed for large-scale, high-pressure pipelines.

Q3: Which industries use API 602 valves most commonly?
Refineries, chemical plants, and power stations often use API 602 valves in auxiliary and high-pressure small-diameter lines.

Q4: Do both standards cover other valve types like globe or check valves?
Yes, both API 600 and API 602 mainly specify gate valves, but related standards (e.g., API 602 also covers forged steel globe and check valves).