How the DAN-EX Dual Expanding Plug Valve Works - Double Block and Bleed Plug Valve

A clockwise rotation of the handwheel rotates the plug 90 degrees while moving downward. As the plug moves down, the taper plug forces the slips against the body until the seals have been compressed to the fully seated position. Primary slip seals are backed up by a metal to metal seal for fire safe capabilities. Solid plug trunnions, substantial lower plate penetration and bushings are resisting flow pressure tendencies to push the slip/plug assembly off center. Proof of double block and bleed is obtained by opening the manual body bleed valve.

Retracting View

Rotating the handwheel counter clockwise, the plug begins to move up, starting the process of retracting the slips. As the tapered plug moves up, the slips begin to retract. When the slips are fully retracted, the slip/plug assembly begins to rotate to the open position. It is important to note that going from closed to open, slip/plug designed valves are potentially exposed to substantial flow, high differentials and pressures. In order to overcome these forces, solid plug trunnions, strong dovetails, and bushings have been proven to play a key role in keeping the slip/plug on center to allow for complete slip retraction prior to rotation.

Rotating View

Turning the handwheel clockwise, the slip/plug assembly begins to rotate, maintaining clearance between the seals and body. This clearance is achieved by the tapered plug in the fully open position and dovetails holding the slips to the plug. The slip/plug assembly maintains a critical center position by substantial plug trunnions, bonnet and lower plate bushings.

Open View

In the open position, the slips are retracted away from the body and protected from the flow.