2016年6月29日星期三

Valve Types And Configurations Covered In API 6D

Scope This International Standard specifies requirements and gives recommendations for the design, manufacturing,testing and documentation of ball, check, gate and plug valves for application in pipeline systems meeting therequirements of ISO 13623 for the petroleum and natural gas industries. Valves for pressure ratings exceeding PN 420 (Class 2500) are not covered by this International Standard.Annex A of this International Standard provides guidelines to assist the purchaser with valve type selection andspecification of specific requirements when ordering valves.

Valve types and configurations 
2.1 Valve types
2.1.1 Gate valves
Typical configurations for gate valves with flanged and welding ends are shown, for illustration purposes only, inFigures 1 and 2. Gate valves shall have an obturator which moves in a plane perpendicular to the direction of flow. The gate can beconstructed 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.

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

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

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

2.2 Valve configurations
2.2.1 Full-opening valves Full-opening valves shall be unobstructed in the fully opened position and have an internal bore as specified inTable 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 nominalsize 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.

2.2.2 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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