Overview

The Cameron M3D WILLIS type drilling choke valve, a multiple-orifice valve (MOV), is the industry’s preferred choke because of its positive closure and absolute control of downhole pressure. The reason is our WILLIS disc design, distinguished by its easy maintenance and unequalled reliability. Two circular tungsten carbide discs operate independently of pressure drops across the plates. One disc is fixed in the choke body, while the other rotates through a control range from full open flow to 100% closure. This design delivers reliable control for well killing and pressure control, especially in severe service involving H2S, abrasive fluids, and high pressures. 

Each disc has a half-moon shaped orifice, designed especially for mud service. The shape of the flow area provides a small wearing surface for a given area. Also, there is no interfering shape in the center of the MOV’s flow area. The net result is reduced wear on the throttling and shutoff area. The real payoff is dependable, long-term service with minimal and simple maintenance. 

Differential pressure across the discs holds one face against the other. There are no loose or unsupported parts to cause vibration, noise, and fatigue failure. Further, the exposed portion of the disc’s surface is wiped clean of foreign deposits each time the disc is rotated. This shearing action cuts most debris and assures a tight shutoff. 

Cameron MOVs incorporate an extended sleeve of tungsten carbide. This field-replaceable sleeve extends through the outlet flange to reduce wear on the outlet spool. The four-part design allows for the field replacement of only the damaged parts. 

The MOV’s actuator features a heavy-duty, twin rack design that was selected for precise control, reliable operation, and minimal maintenance. The rotary actuator provides an exceptionally fast open and close, with accurate adjustments everywhere in between. 

The rack and pinion design uses an oversized pinion for reduced tooth loading. Its hardened chrome alloy steel components are specifically heat-treated for maximum shock resistance. Additional features include heavy-walled cylinders, high-strength pistons, and hard-coated bushings that are lubricated for the life of the product. 

Self-energizing piston seals deliver extremely long life, assure zero leakage, and guarantee that the unit will perform accurately in critical conditions. For simple servicing, all pressure-containing seals can be inspected or replaced simply by removing the cylinder end caps. 

The actuator also contributes to installation versatility. It can be specified as mounted in line with the choke body or at a 90° angle. 

Specifications

Standard end connections include 

  •  2 9/16-in API 10,000 psi 
  •  2 9/16-in API 15,000 psi 
  •  3 1/16-in API 10,000 psi 
  •  3 1/16-in API 15,000 psi 
  •  3 1/8-in API 5,000 psi 
  •  4 1/16-in API 10,000 psi 
  •  4 1/16-in API 15,000 psi