API 600 Gate Valve

1. Scope and Application

• ‌Type of Valves‌: Covers heavy-duty bolted bonnet steel gate valves intended for petroleum refinery and related applications.
• ‌Design Features‌: Includes bolted bonnet, outside screw and yoke, rising stems, non-rising handwheels, single or double gates, wedge or parallel seating, metallic seating surfaces, and flanged or butt-welding ends.
• ‌Size Range‌: Nominal pipe sizes from DN 25 to DN 1050 (NPS 1 to NPS 42).
• ‌Pressure Classes‌: Rated for pressure classes 150, 300, 600, 900, 1500, and 2500.

2. Design Features

2.1 Body and Bonnet

• ‌Minimum Wall Thickness‌: Specified for both body and bonnet, ensuring structural integrity.
• ‌Body Dimensions‌: Flanged ends comply with ASME B16.5 for sizes up to DN 600 (NPS 24) and ASME B16.47 for larger sizes.
• ‌Butt-welding Ends‌: Conform to ASME B16.25, with weld preparations that do not reduce body wall thickness below specified limits.

2.2 Bonnet-to-Body Joint

• ‌Joint Types‌: Flange and gasket type, with options including flat face, raised face, tongue and groove, spigot and recess, or ring joint.
• ‌Gasket Materials‌: Include solid metal, metal ring joint, spiral-wound metal gasket, etc.
• ‌Bolting‌: Minimum of four through-type stud bolts, with sizes and cross-sectional areas specified.

2.3 Gate

• ‌Gate Types‌: One-piece wedge gate (solid or flexible wedge), two-piece split wedge gate, or parallel seat double-disc gate.
• ‌Seating Surfaces‌: Integral or faced with weld metal, with specified minimum finished thickness.
• ‌Guide Surfaces‌: Provided to minimize wear, position the gate accurately, and ensure alignment.

2.4 Yoke, Stem, and Stem Nut

• ‌Yoke Design‌: Retains the stem nut and permits stem nut removal under pressure.
• ‌Stem Design‌: One-piece wrought material, with minimum diameters specified for different pressure classes and sizes.
• ‌Stem Nut‌: Design allows removal of the handwheel while keeping the stem in a fixed position.

2.5 Packing and Packing Box

• ‌Packing Materials‌: Graphitic material suitable for steam and petroleum fluids.
• ‌Packing Box Dimensions‌: Accommodate a minimum of five uncompressed rings of packing, with specified surface finish and clearances.

3. Materials

• ‌Body, Bonnet, and Cover‌: Selected from ASME B16.34 material groups 1, 2, and 3.
• ‌Trim Materials‌: Include various options for seating surfaces, stems, and backseat bushings, with specified hardness and composition.
• ‌Bolting Materials‌: Recommended materials listed, with options for body-to-bonnet and gland/yoke bolting.

4. Testing, Inspection, and Examination

• ‌Inspection and Examination‌: In accordance with API 598 to ensure compliance with standards.
• ‌Pressure Tests‌: Performed to verify valve integrity.
• ‌Repair of Defects‌: Defects in cast or forged steel valves may be repaired as permitted by applicable ASTM specifications.

5. Marking and Shipment

• ‌Marking‌: Valves marked in accordance with ASME B16.34, with additional designation "API 600" on the nameplate.
• ‌Shipment Preparation‌: Unmachined exterior surfaces painted; machined or threaded surfaces coated; protective covers for valve ends; valves shipped with gate closed and packing installed.

6. Auxiliary Connections and Operation

• ‌Auxiliary Connections‌: Drains and other connections furnished only if specified.
• ‌Operation‌: Valves supplied with a direct-operated handwheel, with options for chainwheel, gearbox, or power actuator operation.