API Gate Valve Technical Overview

Overview of API Gate Valves

API gate valves refer to gate valves designed in compliance with the standards of the American Petroleum Institute (API). They are primarily used in industrial applications such as oil and natural gas.

Structural Features

Body Design:

Typically two-piece or three-piece construction

Flanged or butt-weld end connections

Gate Types:

Wedge gate (rigid wedge, flexible wedge)

Parallel gate (single disc, double disc)

Stem Design:

Rising stem (OS&Y – Outside Screw & Yoke)

Non-rising stem

Material Requirements

Body materials: Typically carbon steel, stainless steel, or alloy steel

Seat materials: Often hard-faced alloys (e.g., Stellite) or other wear-resistant materials

Material selection must comply with API standards

Performance Requirements

Pressure Ratings:

Per ASME B16.34 standard

Common classes: Class 150, 300, 600, 900, 1500, 2500

Temperature Range:

Varies based on material selection

Must account for high-temperature and cryogenic conditions

Sealing Performance:

Leakage rates as per API 598

Low-pressure and high-pressure seat tests

Testing Requirements

Shell strength test

Seat leakage test

Operating torque test

Fire resistance test (API 6FA)

Selection Considerations

Fluid characteristics (corrosiveness, particulate content, etc.)

Operating pressure & temperature

End connections (flanged, butt-weld, etc.)

Actuation method (manual, gear-operated, electric, pneumatic, etc.)

Special requirements (fire-safe, anti-static, etc.)

Maintenance Guidelines

Regularly inspect stem sealing

Maintain stem lubrication

Check flange bolt tightness

Exercise valves periodically to prevent sticking