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The FLS™ gate valve is part of Cameron’s F Series of valves, which have been supplied for production and drilling service since 1958. Many of the features of the FLS are common to our original Type F gate valve, such as full- and internally flushed-bore, forged construction; metal-to-metal sealing; a slab gate; and design simplicity. In other areas such as seat seals and stem seals, the FLS design takes advantage of our latest technology in materials and seal design.                                                               

Cameron’s FLS gate valve is widely recognized as a high-quality valve for severe applications. It is a full-bore, through-conduit valve available in pressure ratings from 2000 to 20,000 psi and bore sizes from 1-13/16” to 11”. The FLS is our standard valve for critical requirements, including extreme sour and subsea applications. In addition, it can be fitted with a wide range of Cameron’s actuators.

Design Features and Benefits

  • Metal-to-Metal Sealing – The FLS gate valve features bonnet, gate-to-seat, and seat-to-body seals, which all include metal-to-metal sealing. Seal surfaces on both sides of the seats and gate are lapped to ensure gas-tight sealing without sealant. Lubricant is used to limit wear, friction, and intrusion of contaminants into the valve cavity, not as an aid to sealing. Sealant is neither required nor recommended for the FLS gate valve.
  • Reliability Through Simplicity of Design – Two-piece floating seats and a floating slab gate provide reliable performance due to the simplicity of operation and a minimum number of sealing interfaces. Cavity clearances are carefully controlled to limit the amount of float needed, and special modified acme threads at the gate-to-stem interface provide sufficient freedom of movement in all directions to affect a positive downstream seal.
  • Bi-Directional Sealing – The FLS gate valve has a symmetrical, bi-directional design without a preferred direction of operation. The seal diameters and bearing areas of the seats are designed to prevent trapping of pressure inside the valve cavity.

  • Stem Backseat – The FLS gate valve incorporates a metal-to-metal stem backseat that can be energized to isolate the stem packing stuffing box from line pressure. The bonnet grease fitting port can be used to test the backseat integrity, and the stem packing can be replaced with the valve cavity under pressure.

  • Stem Seal – The FLS gate valve features a non-elastomeric stem seal spring-loaded and pressure-energized so that no longitudinal preload or precise space-out is required. Sealant injection is neither required nor recommended. The seal has been extensively tested in laboratory fixtures with applications of temperature cycles, pressure cycles, and both rotary and linear mechanical actuation cycles.

  • Seat Design – The feature that differentiates the FLS gate valve from the FL™ gate valve is the seat design. In both valves, the seats are lapped on both sides for metal-to-metal sealing against the gate and body. However, the FL valve has a single-pressure, energized PEEK lip seal in the seat-to-body interface, while the FLS valve employs two lip seals. 

  • The lip seals in the FLS valve perform several functions:
    • Contaminants and debris face an added barrier from the metal sealing surface of the seat and body between the two seals.
    • The spring-loaded design of the seals maintains contact between the gate and seats, wiping the seal surfaces and protecting them from damage due to sand or other contaminants. Body cavity clearance is effectively reduced to zero, while the downstream sealing function of the slab gate is retained.
    • Sealing integrity is enhanced at very low differential pressures, where low bearing stresses tend to limit the effectiveness of the metal-to-metal seal.
  • Qualification Testing – The FLS gate valve design has been successfully qualified in accordance with API 6A, Annex F (PR-2) and Annex I (Class II). Additional qualification tests have been performed for gate and seat materials and coating, stem seals, and stem thread materials.
  • Optional Torque Multiplier – Where specified in the proposal, the manually actuated FLS valves will be equipped with a removable torque multiplier. This unit is easily installed on or removed from the valve bonnet assembly and uses the same handwheel as the standard valve. A planetary gear train provides a 4-to-1 multiplication with an efficiency of approximately 87%. Both multiplied (4:1) and direct drive (1:1) handwheel adapters are included in the design so that the handwheel can be moved from one position to the other to reduce opening time and input torque requirements. The multiplier also has environmental seals and shear pins in the input shafts to protect the gear train from overloading. 


Slab-Style Gate Valve Availability

Nominal Bore Size
Working Pressure: 2000 psi (13.8 MPa) Working Pressure: 3000 psi (20.7 MPa) Working Pressure: 5000 psi (34.5 MPa) Working Pressure: 10,000 psi (69.0 MPa) Working Pressure: 15,000 psi (103.5 MPa) Working Presure: 20,000 psi (138.0 MPa) Working Pressure: 30,000 psi (a) (206.8 MPa)
- - - FLS FLS FLS/FLS-R (b) -
- - - -
- - - FLS FLS/FLS-R FLS/FLS-R (b) -
- - - -
- - FLS FLS/FLS-R (b) FLS/FLS-R (b) - -
- - FLS/FLS-R  FLS/FLS-R (b) FLS/FLS-R (b) - -
- - FLS/FLS-R (b) - - - -


FL and FLS gate valves may be manual or actuated unless otherwise noted.

(a)    This is a working pressure not currently covered in API 6A.

(b)   FLS gate valves for this size/pressure combination are power actuated.

For FL, FLS, and FLS-R™ gate valves, this chart represents typical valves for API material classes AA, BB, CC, DD, EE, FF, and HH (except FL); temperature ratings K, L, P, S, T, U, and V; and product specification levels 1, 2, 3, 3G, and 4. For other designs, please contact your Cameron representative. 


Product Support - Asia Pacific Middle East

Johnson Koa +65.649.47726

Product Support - Europe Africa Caspian Russia

Dave Brown +44.122.4282241

Product Support - North and South America

Moises Nava +1.713.469.7923