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API 600 and API 602 Valve Standards Differences & Selection Guide
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Introduction
When it comes to industrial piping systems, picking the right valve standard is a big deal—it directly affects safety, reliability, and how long the equipment holds up.
The two most common standards for steel gate valves are API 600 and API 602. They're both published by the American Petroleum Institute (API) and both cover steel valves used in oil, gas, petrochemical, and power plants.
They're built for completely different valve types, size ranges, and operating conditions. This guide walks you through the key differences between API 600 and API 602, so engineers, procurement folks, and plant operators can make a more informed choice for their specific applications.
1. What's API 600?
API 600 is the go-to standard for bolted bonnet steel gate valves—the kind you typically see in larger-diameter piping systems. It lays out the design, manufacturing, testing, and inspection requirements for cast steel gate valves.
You'll find API 600 valves pretty much everywhere in heavy industry:
·Oil and gas production sites
·Refineries
·Petrochemical plants
·Power generation stations
·General industrial process systems
These valves are built to deliver reliable shut-off performance, especially when you're dealing with high pressure and high heat.
Key Features of API 600 Valves
·Cast steel construction
·Bolted bonnet design
·Outside screw and yoke (OS&Y) stem
·Rising stem operation
·Full-port flow path
·Available in larger sizes
·Suitable for severe service conditions
2. What's API 602?
API 602 is all about compact steel gate, globe, and check valves—the kind you use when pipe sizes are on the smaller side. Unlike API 600, which deals with larger cast steel gate valves, API 602 covers both forged and cast steel designs that are built to handle high pressures but need to fit into tight spaces.
You'll typically spot API 602 valves in:
·Utility piping systems
·Steam lines
·Instrumentation hookups
·Chemical processing units
·High-pressure auxiliary services
They're small but tough—built for the jobs where space is tight but the pressure is anything but.
Key Features of API 602 Valves
·Forged steel or cast steel construction
·Compact body design
·Available as gate, globe, and check valves
·Socket weld, threaded, butt weld, or flanged ends
·Designed for small bore piping systems
·Excellent pressure containment capability
| Feature | API 600 | API 602 |
| Valve Type | Gate valves only | Gate, globe,check valves |
| Construction | Primarily cast steel | Forged steel and cast steel |
| Typical Size Range | NPS 2 and larger | NPS 4 and smaller |
| Application | Main process pipelines | Small-bore and auxiliary piping |
| Body Design | Larger, heavier construction | Compact design |
| Pressure Service | High pressure and temperature | High pressure in smaller systems |
| End Connections | Mainly flanged and butt weld | Threaded, socket weld, butt weld, flanged |
| Cost | Higher material and installation cost | More economical for small sizes |
3. When Should You Choose API 600?
API 600 is typically the preferred choice when:
1) Large Diameter Pipelines Are Required
Main process lines in refineries, power plants, and petrochemical facilities often require larger valves that comply with API 600.
2) Full Bore Flow Is Important
Gate valves manufactured to API 600 provide minimal pressure drop when fully open, making them suitable for critical flow applications.
3) Severe Operating Conditions Exist
High temperatures, high pressures, and demanding operating cycles often favor robust API 600 valve designs.
4) Long-Term Reliability Is a Priority
The heavy-duty construction of API 600 valves supports extended service life in critical applications.
4. When Should You Choose API 602?
API 602 is generally the better option when:
1) Space Is Limited
Compact forged steel valves are ideal for installations where piping layouts are crowded.
2) Small Bore Piping Systems Are Used
Instrumentation lines, utility systems, and auxiliary process lines commonly use API 602 valves.
3) High Pressure with Smaller Sizes Is Required
Forged steel construction provides excellent mechanical strength for demanding pressure conditions.
4) Multiple Valve Types Are Needed
API 602 covers gate, globe, and check valves, allowing standardization across various functions within a plant.
Industry Applications
API 600 Applications
·Crude oil transmission
·Refining process units
·Power plant main steam systems
·Petrochemical process pipelines
·Water treatment facilities
API 602 Applications
·Boiler auxiliary systems
·Steam tracing lines
·Chemical injection systems
·Instrumentation piping
·Drain and vent services
In Conclusion
Choosing between API 600 and API 602 depends primarily on valve size, service requirements, installation conditions, and operating pressure.
·Choose API 600 gate valves for larger process pipelines requiring robust construction and reliable shut-off performance.
·Choose API 602 forged steel valves when working with small-bore, high-pressure systems where compact size and superior strength are essential.
Understanding these differences helps engineers and procurement teams improve system reliability, reduce maintenance costs, and ensure compliance with industry standards.