FLOATING BALL VALVES

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A floating ball valve is a type of quarter-turn valve where the ball is not fixed but “floats” between the two seats. The ball is held in place by the valve seats and is free to move slightly downstream under pressure, which helps create a tight seal.

• Design Simplicity: Fewer components than trunnion valves.
   
• Seat Load: The pressure of the fluid forces the ball against the downstream seat to seal.
   
• Size Range: Typically used in sizes up to 6" (150 mm); beyond this, trunnion ball designs are preferred.
   
• Bi-directional Sealing: In many designs, although this may depend on seat and cavity design.
   

• API 608: Floating ball valves for general use.
   
• ASME B16.34: For pressure–temperature ratings and material requirements.
   
• API 6D: Used when valves are applied in pipeline service.
   

• Class 150, 300, 600: Most common for floating ball valves.
   
• Higher classes (900, 1500): Rarely used for floating types, usually for trunnion designs.
   

• API 598: Valve inspection and testing.
   
• API 6D: Pressure testing and performance requirements.
   
  • Hydrostatic shell test
     
  • Hydrostatic seat test
     
  • Low-pressure air test
     
  • Optional fugitive emission test (per ISO 15848)
     

Service TypeMaterialsGeneral ServiceASTM A216 WCB (carbon steel)CorrosiveASTM A351 CF8M (316 SS), Duplex SSCryogenicCF8M with extended bonnetHigh TempASTM A217 WC6, WC9, C12A (chromium-molybdenum alloys)Sour ServiceNACE MR0175 compliant materials 

ComponentCommon MaterialsBall316 SS, Inconel, Duplex, Chrome Plated or HVOF-Tungsten Carbide CoatedSeatsPTFE, RPTFE, PEEK, Devlon for soft seats; Tungsten Carbide, Stellite, CrC for metal seatsStemSame as ball, or with hardfacing in severe service  

Floating ball valves are suitable for low-to-medium pressure systems with a focus on tight shutoff. Common sectors include:

• Chemical & Petrochemical Plants
   
• Oil & Gas (upstream and downstream)
   
• LNG terminals (Cryogenic versions with extended bonnets)
   
• Power Generation
   
• Water and Wastewater
   
• Mining (with erosion-resistant coatings)
   

• With metal-seated floating ball valves using Tungsten Carbide or Chromium Carbide coatings, suitable for:
   
  • Abrasive slurries
     
  • High temperatures
     
  • High cycling operations
     

• Compact, simple design
   
• Reliable tight shutoff
   
• Easy to maintain
   
• Cost-effective for small to medium sizes
   

• Seat wear due to direct ball contact under pressure
   
• Not ideal for high pressure or large bore (>6")—consider trunnion-mounted valves instead
   

While your uploaded document focused more on valve maintenance in oil & gas, the principles also apply to floating ball valves:

• Perform regular greasing and operational cycling
   
• Follow API 598/API 6D test procedures after repair or assembly
   
• Use reverse engineering for obsolete components or unique designs
   
• Ensure traceability of materials and certifications, especially for sour or cryogenic service
   

🔚 Summary
Floating ball valves are versatile, reliable, and suitable for a wide range of applications up to ANSI Class 600 and sizes up to 6". Proper material selection, testing, and maintenance are key to long-term performance, especially in corrosive or cryogenic conditions.