5 Valve types and configurations
5.1 Valve types
5.1.1 Gate valves

Typical configurations for gate valves with flanged and welding ends are shown, for illustration purposes only, in Figures 1 and 2.
Gate valves shall have an obturator which moves in a plane perpendicular to the direction of flow. The gate can be constructed of one piece for slab-gate valves or of two or more pieces for expanding-gate valves.
Gate valves shall be provided with a back seat or secondary stem sealing feature in addition to the primary stem seal.

5.1.2 Lubricated and non-lubricated plug valves
Typical configurations for plug valves with flanged and welding ends are shown, for illustration purposes only, in Figure 3. Plug valves shall have a cylindrical or conical obturator which rotates about an axis perpendicular to the direction of flow.

5.1.3 Ball valves
Typical configurations for ball valves with flanged or welding ends are shown, for illustration purposes only, in Figures 4, 5 and 6. Ball valves shall have a spherical obturator which rotates on an axis perpendicular to the direction of flow.

5.1.4 Check valves
Typical configurations for check valves are shown, for illustration purposes only, in Figures 7 to 11. Check valves may also be of the wafer type. Check valves shall have an obturator which responds automatically to block fluid in one direction.

5.2 Valve configurations
5.2.1 Full-opening valves
Full-opening valves shall be unobstructed in the fully opened position and have an internal bore as specified in Table 1. There is no restriction on the upper limit of valve bore sizes.
Full-opening through-conduit valves shall have a circular bore in the obturator that will allow a sphere with a nominal size not less than that specified in Table 1 to pass. Welding-end valves may require a smaller bore at the welding end to mate with the pipe.

5.2.2 Reduced-opening valves
The internal bore of reduced-opening valves shall be less than the internal bore specified in Table 1.

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