Description

Technical Data Sheet – API 6A FC Balanced Stem Gate Valve

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1. Product Overview

• Product Name: API 6A FC Balanced Stem Gate Valve

• Valve Type: Gate Valve (Balanced Stem, Double Expanding Gate Design)

• Design Standard: API Specification 6A (21st Edition)

• Size Range: 1-13/16″ to 7-1/16″ (46mm to 179mm)

• Pressure Ratings: 2,000 psi to 20,000 psi (13.8 MPa to 138 MPa)

• Body Material: Forged Alloy Steel (AISI 4130, 75 KSI Yield)

• Operation: Hydraulic Actuator (Fail-Safe Closed) / Manual Override Optional

• Connection Type: Flanged End (API 6A Flange) / Clamp Hub

• Application: Subsea Production Systems, Christmas Trees, Choke & Kill Manifolds, High-Pressure Isolation

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2. Applicable Standards & Specifications

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3. Technical Parameters

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4. FC Valve Design Overview

The FC designation refers to Cameron’s Balanced Stem Gate Valve design, characterized by:

4.1 Balanced Stem Feature

• Pressure Balancing Piston: Integrally machined on the stem, with diameter equal to the gate sealing area

• Hydraulic Balance: Equalizes pressure forces above and below the piston, eliminating thrust imbalance

• Reduced Actuator Size: Balanced design requires significantly lower operating force, allowing smaller, more cost-effective actuators

• Consistent Operation: Operating torque remains stable regardless of line pressure fluctuations

4.2 Double Expanding Gate Mechanism

• Two-Piece Gate Assembly: Consists of two gate halves with angled mating surfaces

• Mechanical Expansion: Upon closing, the gate halves expand outward against the seats

• Wedging Action: Creates high unit contact pressure for bubble-tight sealing

• Compensation: Accommodates thermal expansion and pressure variations without loss of seal

• Wear Resistance: Minimizes seal face wear during cycling

4.3 Flow Path

• Through-Conduit Design: Full bore opening allows unrestricted flow and passage of pigs/tools

• Low Pressure Drop: Streamlined flow path minimizes turbulence and erosion

4.4 Actuator Configuration

• Fail-Safe Closed (FSC): Hydraulic pressure opens valve; spring or accumulator closes valve upon loss of hydraulic pressure

• Subsea Compatibility: Designed for remote operated vehicle (ROV) interface and deepwater service

• Position Indication: Visual and remote position indicators standard

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5. Main Materials of Parts

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6. FC vs. FLS Comparison

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7. Dimensional Data (Typical – Flanged End, 10,000 psi)

Note: Dimensions are for reference only. Final dimensions depend on pressure class, manufacturer, and specific configuration.

Actuator dimensions and weight vary based on pressure rating and required operating force.

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8. Actuator Specifications (Hydraulic Fail-Safe Closed)

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9. Design Features

9.1 Balanced Stem

• Eliminates thrust imbalance caused by line pressure

• Reduces actuator size and weight by up to 50% compared to unbalanced designs

• Provides consistent operating force regardless of pressure

9.2 Double Expanding Gate

• Two-piece gate expands mechanically against seats at final closure

• Achieves high seating stress independent of line pressure

• Maintains seal during pressure reversals and thermal cycles

• Prevents seal face contact during opening/closing, reducing wear

9.3 Metal-to-Metal Sealing

• All primary seals are metal-to-metal

• Body-to-bonnet utilizes API ring gaskets (RX/BX)

• Stem seals are non-elastomeric, pressure-energized lip seals

• Fire-safe design per API 6FA

9.4 Subsea Capabilities

• Designed for deepwater installation

• ROV interface for manual override and position verification

• Corrosion-resistant materials for seawater service

• Double block-and-bleed capability optional

9.5 Additional Features

• Backseat stem seal allows packing replacement under pressure

• Grease fittings for bearing lubrication (manual valves)

• Position indicators (visual and remote)

• API Monogram certification available

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10. Material & Specification Options

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11. Inspection & Testing

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12. Applications

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Remarks:

• FC is a registered trademark of Cameron/SLB for their balanced stem gate valve design.

• The FC valve is specifically designed for actuated service, particularly subsea and remote applications.

• For sour service applications, specify material class EE, FF, or HH with NACE compliance.

• Hydraulic actuator sizing must consider operating pressure, line pressure, and fail-safe requirements.

• For complete dimensional data and actuator selection, refer to manufacturer’s certified drawings and torque calculations.