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MoComp Products

Drill String Compensator

Control Flow’s newest Drill String Compensator features the latest and most improved technology in the industry.  The benefits are lighter weight, improved operational reliability, and better “Weight On Bit“ performance. Available in both 20 and 25 foot stroke lengths, this new DSC is suitable for both new installations and upgrades of your present Drilling Package.

Contact Control Flow, Inc. and let us show you the benefits of using the CFI DRILL STRING COMPENSATOR as part of your rigs drilling equipment /motion compensation package.

Data Sheet

Control Flow/Mo-Comp Products


  • 400K Compensating / 1300K Mechanical Lock
  • 600K Compensating / 1600K Mechanical Lock
  • 800K Compensating / 1800K Mechanical Lock

Control Flow DSC Design Features:

  • Rod End Down/Tension Rod Design
  • Hydraulic Fluid Operated Cylinder/More Positive Control
  • Accumulators Repositioned From Mast to DSC
  • Air Powers DSC Up To DSC Mounted Accumulators
  • Quick Acting Flow Control Valve
  • Increase/Decrease Control Via Remote Air Control Skid
  • Touch Screen HMI For Electronic Control and Monitoring
  • APV Gas Energy Conversion to Fluid At DSC
  • Cylinders Direct Tension Loaded 1:1
  • Maximum Working Pressure 3500 PSI
  • No Pressure In Drillers House
  • Only Two Hydraulic Locking Valves Required
  • No Chains To Maintain, Adjust or Cause Misalignment
  • No Bearings Required
  • No Air-Oil Reservoir Required
  • Mechanical Lock
  • Smaller Cylinders and Lighter Weight Than Other DSC’s
  • Improved Design Provides Greater Compensation and Lower Weight On Bit Variation Than Other Designs
  • Adaptable to All Traveling Blocks and Top Drives and For All DSC Replacements and Upgrades

Crown Block Compensator™

Crown Block Mounted Drill String Compensation

  • Drill Ship and Semi-Submersible Applications
  • Innovative Design - pneumatic/hydraulic power combination provides positive control and flexibility.
  • More Usable Derrick Height – more compact dual cylinder design.
  • On Demand Hydraulic Lockup - in any position allowing faster drilling operations.
  • Automatic Safety Arrest - limits hook velocity and prevents equipment damage in event of drill string failure.

Active and Passive Modes- easy switch between modes while compensating.

Data Sheet

Portable Drill String Compensator™

Developed by Control Flow, Inc.’s Mo-Comp group.

The CFI Portable Drill String Compensator (PDSC) can be used in conjunction with an electric powered Active Heave Draw Works and used to compensate tension on the pipe in the well in the event of power loss on the drilling rig.  This is a major safety issue and need for the Portable Drill String Compensator.  The PDSC is installed in-line between the traveling block and top drive and requires only a small umbilical to operate and monitor the DSC’s functions. Conventional in-line DSC’s require a bank of remotely located APV’s with heavy piping and large diameter hoses to provide the operating pressure to the DSC. These hoses combined with the control lines create bulky, heavy hose bundle. The PDSC is built in capacities ranging from 250,000 to 1,000,000 lbs.

The PDSC is designed to function with the load directly attached to the lower end of the rod. Hydraulic pressure supports the load in an air over oil arrangement. The hydraulic fluid is stored in the accumulator, which surrounds the cylinder assembly and flows through the port connecting the two chambers at the lower end. High-pressure air enters the accumulator at the upper end and pressurizes the fluid. In this arrangement the cylinder assembly is situated within the accumulator allowing for a compact design. The port at the lower end also houses a shut off valve. This valve may be closed at any point in the stroke of the DSC hydraulically locking the load for lifting.

The Portable DSC integrates the APV’s into the main frame and requires no other APV’s to operate. Stand-by APV’s are the only other external vessels needed, and they are only used to boost working pressure when necessary.  

Data Sheet

Production Riser Tensioner Module

The patented Production Riser Tensioner (PRT)® from Control Flow’s WesTech Heavy Machinery Operation can produce savings in excess of seven days per well. This patented tool allows rapid transition from drilling to completion activity by allowing the entire marine riser and BOP to remain in the water during well testing / completion operations, avoiding the need to pull and re-run the BOP / marine riser at the conclusion of completion operations. Through this technique, BOP tripping time is eliminated when running and setting Subsea Trees, Production Risers, or during completion, intervention and abandonment operations. The PRT® offers a replacement for cable and sheave riser tensioning systems. The unit is designed to run through and hang off in the rig’s rotary table.

The PRT® provides up to 1,500,000 pounds of tension and up to 45 feet of motion compensation. Measuring 55-ft in total length, the PRT® weighs less than 60 metric tons and is stored on deck, when not in service, much like a standard telescopic joint. The system is designed for year-round operations in normal and heavy weather operations.

Data Sheet


CONTROL FLOW, INC. manufactures and designs a complete line of motion compensation/riser tensioner systems and in addition, owns the technical rights and properties of the former ABB Vetco, WesTech/HMD (Owner of the Tensioner and Compensation Designs of the former Western Gear Corporation) and RETSCO motion compensation product lines.  CFI Motion Compensation Systems include all tensioners, single or dual, accumulators, auxiliary pressure vessels (APV), associated sheaves and controls including its patented RIMAC® riser anti-recoil system.  Available in various size capacity up to and including 300 Kips per tensioner, CFI tensioners are available in both wire rope and direct connect types.

Designed for extended service and trouble free maintenance, CFI  tensioners are manufactured to meet and exceed the requirements of API 16F and today’s deepwater offshore drilling requirements. Tensioner rods are available in both our standard chrome over nickel or laser applied inconel coatings.

Whether repairing or upgrading an existing tensioner system or considering a new build, Control Flow, Inc. can engineer and supply the Riser Tensioner System equipment you need based on industry developed and proven equipment technology.

Data Sheet

Ultimate Mo-Comp Cylinder (UMCCA)™

The Patented Ultimate Mo-Comp Cylinder Assembly (UMCCA) is a design that is different from most conventional compensator assemblies. The UMCCA integrates the accumulator into the cylinder itself. The hydraulic fluid is stored inside the  hollow ram and is pressurized with high-pressure air via an air transfer tube. This arrangement provides an air over oil operation. The air pressure acting on the internal surface of the rod provides the force to extend the rod. The rod extends with a force relative to the system air pressure, however with the lower end of the rod submerged in the fluid, hydraulic dampening is maintained to prevent excessive rod speeds.

Data Sheet