Frac Stacks

OSES supplies and services frac stacks that temporarily replace the production wellhead during pressure pumping operations. In addition to protecting an operator’s production wellhead from the effects of pressure and abrasion during the fracturing process, our frac stacks allow high pressures and volumes of proppant to pass to the formation for maximum well response.

To minimize operating torque, our valves are available with quick turn hand-wheel or hydraulic actuators. The quick turn design incorporates a ball screw assembly that allows easy
operation under pressure, even for large bore systems.


OSES offers three types of assemblies:

  • Special pin assembly
  • Screw-on assembly
  • Upgrade spools

Available in full bore:

  • 3-1/16” (77.8mm) x 69 MPa (10,000 psi)
  • 3-1/16” (77.8mm) x 103.5 MPa (15,000 psi)
  • 4-1/16” (103.2mm) x 69 MPa (10,000 psi)
  • 4-1/16” (103.2mm) x 103.5 MPa (15,000 psi)
  • 5-1/8” (130.2mm) x 69 MPa (10,000 psi)
  • 7-1/16” (179.4mm) x 69 MPa (10,000 psi)
  • 7-1/16” (179.4mm) x 103.5 MPa (15,000 psi)


Various configurations built to customer needs/specs

  • Special Pin protects tubing hanger threads
  • Full bore access to accommodate packers, balls, and other down hole tools
  • Manufactured to API standards

Installation & Removal

  • Without a service rig and without killing the well, install tubing plug or back-pressure valve in tubing hanger
  • Remove production wellhead
  • Install special pin into the tubing hanger, install seal bonnet and frac head, torque to specs
  • Pressure test adapter spool seals
  • Remove tubing plug or back pressure valve

Reverse procedure to remove.

Coil Tubing Frac Head

The coil tubing frac Head protects coil tubing at surface from erosion while fracturing with coil in the well.


  • Wash on coil tubing is minimized with our patented design providing optimum protection on coil erosion
  • The connection configurations on both the top and bottom of the coil tubing frac head can accommodate many sizes and set ups depending upon customer requirements
  • It can be configured with two or four plug valves depending on the pumping rates required


Pressure Rating:

  • 69 Mpa (10,000 psi) working pressure

Blast joints available in:

  • 4.0” (101.6mm)
  • 5.0” (127.0mm)

Ball Catchers

As with any flow-back operation, particularly those of gas producing wells, the number of shut-ins relies heavily on the type of equipment that can handle high pressures. Disruptions in the flow stream greatly reduce the efficiency of any operation.

Flowing back after fracturing is especially problematic due to the composition of mud, balls, and sealers that comes up. Without the proper equipment, manifolds and other surface equipment can quickly clog resulting in costly down time.

To eliminate these problems, our ball catcher traps frac balls with outer diameters up to 3-7/8”. Handling working pressures from 5,000 to 15,000 PSI, these durable apparatuses significantly reduce flow-back disruptions after fracture.


Pressure Ratings:

  • 4-1/16” (103.2mm) x 69 MPa (10,000 psi)
  • 4-1/16” (103.2mm) x 103.5 MPa (15,000 psi)

Manual and Hydraulic Frac Valves

  • Metal-to-metal sealing at the gate-to-seat
  • Available studded or flanged
  • A truly symmetric bi-directional design
  • A metal-to-metal stem backseat on both the upper stem and tail rod to permit replacement of either stem packing with the valve cavity under pressure
  • Design meets API 6A and PSL 3. All materials meet and exceed specified criteria including NACE MR-01-75 criteria
  • Valve Sizes
    • 4-1/16” (10K, 15K)
    • 5-1/8” (10K)
    • 7-1/16” (5K, 10K, 15K)
  • Temperature rate is -40°C to 120°C
  • Material class: DD (Sour Service)
  • Ball Screw is used for most of manual valves, which reduces the required work to operate the valves to less than 1/3 of that required to operate the conventional design. The ball screw uses “rolling” friction in place of “sliding” friction. The low torque and reduced number of turns allows the valve to be stroked in less time with less effort than conventional high pressure valve designs.


FracStack_Special Pin Assembly Diagram

FracStack Diagram with Special Pin