Inside B.O.P. Dart Valves

5,000 psi, 10,000 psi & 15,000 psi W.P.

The WN-2 Inside BOP is a heavy-duty drop check valve that is positioned in the drill string to control formation pressure during kicks. It controls the backflow through the inside of the drill pipe itself, preventing damage to the swivel, drilling hose, standpipe and circulation equipment.

During normal circulation of drilling fluids down the drill pipe, the valve remains open to permit the flow through it. A conical plug, or dart, minimizes the erosive action of the drilling fluid on the valve seat and assures a long lasting seal between the valve dart and valve seat.

When any backflow occurs, the valve closes automatically to contain it, protecting the drilling equipment as well as controlling the kick that could otherwise lead to a blowout.


A special release tool allows the valve to be held open to permit stabbing into position against a backflow of fluid. This optional release tool can be installed on the float valve and the entire assembly kept ready on the rig floor for quick installation at the first signs of serious backflow when drill pipe is pulled from the well.


It is recommended that each inside BOP should have a working pressure rating as high as the blowout preventers since it must be expected to withstand the same pressure. WNCO offers standard models designed for working pressures of 5,000 / 10,000 psi and for H2S service.


The WN-2 Inside BOP is designed and manufactured with a threaded pin bottom and box top to accommodate a tool joint thread. Installation is a simple procedure of making up the valve in the drill string at the desired location.


After prolonged exposure to the flow of drilling mud, the seal ring on the valve seat may become damaged or worn, causing a slight leakage past the seal when the valve is returned to the closed position. When such leakage is noted, the assembly should be removed as soon as possible, the body halves disassembled and the seal ring replaced. If prolonged exposure to the fluid and cuttings has damaged the dart, it may be replaced at this time also.

The seat in the body segment (upper body) may also be replaced when worn, but as it is press-fit into the body, replacement in the field is normally not recommended.

NOTE: Maximum pressure of all valves are limited by the pressure rating of end connections.

To order your WN-2 Inside BOP be sure to specify: (1) Working Pressure (2) Connection Size (3) Outside Diameter

Connection OD ID Overall Length
With Release Subs
Working Length
Without Release Subs
with Release Subs
3 1/2" IF 5" 2" 45" 36" 105 lbs
4" FH
4 1/2" FH 6 3/8" 2 1/4" 45" 36" 190 lbs
4 1/2" XH
4 1/2" IF
5 1/2" FH 7" 2 1/4" 45" 36" 235 lbs

Parts List   Maintenance

  • Down Hole Safety
  • Rig Floor Safety

How Can We Help You?

Contact Us