API Standard 6D

API Standard 6D, from the American Petroleum Institute, provides specifications for pipeline valves.

Scope

API 6D covers the design, manufacture, testing, and documentation for pipeline ball, check, gate, and plug valves for pressure ratings up to ASME class 2500.

Valve specifications

The standard specifies configurations for the following types of valves:

  • Gate valves
  • Lubricated and non-lubricated plug valves
  • Ball valves
  • Check valves
  • Full-opening valves
  • Reduced-opening valves

The valve ends may be flanged or welding. If fluid can become trapped in the body cavity, then valves for both gas and liquid service must have a pressure relief. Actuators may be electric, hydraulic, or pneumatic.

Tests

API 6D specifies the following tests:

Test

Details

Stem backseat test
  • Pressure at 1.1 times valve rating for 2 to 5 minutes depending on valve size
  • No visible leakage
Hydrostatic shell test
  • Pressure at 1.5 times valve rating for 2 to 30 minutes depending on valve size
  • No visible leakage
Hydrostatic seat test
  • Pressure at 1.1 times valve rating for 2 to 5 minutes depending on valve size
  • Soft-seated valves: No visible leakage
  • Metal-seated valves: Leakage not more than two times ISO 5208 Rate D

A full copy of API 6D can be purchased from the American Petroleum Institute.

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