API 608 Ball Valve

1. Scope and Applicability

• Valve Types: Floating (seat-supported) and trunnion-mounted ball valves.
• End Connections:

1. Flanged (DN 15–600 / NPS ½–24).
2. Butt-welding (DN 15–600 / NPS ½–24).
3. Socket-welding (DN 8–50 / NPS ¼–2).
4. Threaded (DN 8–50 / NPS ¼–2).

• Pressure Classes:

1. Flanged/Butt-welding: Classes 150, 300, 600.
2. Socket-welding/Threaded: Classes 150, 300, 600, 800.

• Bore Sizes: Full bore, single reduced bore, double reduced bore.

2. Design Requirements

• Flow Passageway: Must allow passage of a cylinder with diameters specified in Table 3 (e.g., full bore for DN 50: 49 mm).
• Body Construction:

1. Wall thickness conforms to ASME B16.34 (Standard Class).
2. Flange dimensions follow ASME B16.5.
3. Welded flanges require full penetration butt welds.

• Antistatic Design: Ensures electrical continuity (≤10 ohms resistance) between ball, stem, and body (critical for explosive environments).
• Stem and Ball:

1. Stem-to-ball connection must withstand 20 N·m torque or twice the manufacturer’s maximum torque.
2. Ball must be solid one-piece construction unless otherwise agreed.

• Packing Glands:

1. Adjustable glands accessible without disassembly.
2. No vertically split glands; gland bolts must not exceed 1/3 ultimate tensile strength under compression.

• Operation:

1. Manual levers or gear operators with ≤360 N input force.
2. Position stops for open/closed positions; clockwise closing.
3. Lockable devices (for open/closed positions) optional.

3. Material Requirements

• Shell: Materials per ASME B16.34 (e.g., carbon steel, stainless steel).
• Trim: Ball, stem, and seats match or exceed shell material properties. Corrosion-resistant options (e.g., NACE MR 0103 compliance) available.
• Bolting: Intermediate strength (ASME B16.5 minimum) or higher grades if specified.
• Seals/Gaskets: Compatible with valve’s pressure-temperature ratings (e.g., PTFE, R-PTFE, metal seats).

4. Testing and Inspection

• Pressure Testing: Per API 598 (shell, seat, and closure tests).
• Fire Testing: Complies with API 607 if specified (fire-resistant seats with secondary metal seals).
• Inspection: Manufacturer examination mandatory; optional purchaser inspection.

5. Marking and Identification

• Mandatory Markings:

1. "API 608" on identification plate.
2. Ring joint groove number (if applicable).
3. Directional arrows for unidirectional valves.

• Material Identification: Austenitic stainless steel/nickel alloy plates welded or pinned.

6. Packaging and Shipping

• Protection:

1. Drain test fluid; apply rust inhibitors.
2. Protective end covers/plugs (removable; prevent installation with covers).

• Position: Shipped fully open unless design restricts.

7. Optional Features (Purchaser-Specified)

Lockable devices, NACE compliance, fire-tested seats, export packaging, spare parts lists.