Detailed Description

The FXE wireline-retrievable flapper valve, which is normally closed, is held open by hydraulic control pressure from the surface. The valve operates on a hydraulic piston principle. To open, hydraulic pressure slightly higher than the well pressure is applied to move the piston downward. This pressure unseats the secondary seat, allowing pressure to enter through equalizing ports. Then, as additional hydraulic pressure is applied to the piston, it continues downward movement, pushing the flapper open. The flapper hinge assembly is designed such that the force on the piston is not applied directly on the hinge pin. Upon loss of hydraulic pressure in the control line, the valve’s large spring serves to lift the hydrostatic head of the control fluid. The flapper spring is designed to close the valve when the piston moves up past the flapper. Opening Prong Nose Seal The FXE valve uses the valve housing as the downstop for the opening prong. This metal-to-metal (MTM) interface is designed to prevent flow from passing between the valve housing and the opening prong. The MTM interface isolates the flapper and seat from fluid flow while the valve is open. This design creates an MTM interface with the full force exerted by the hydraulic piston, minus the spring compression force, holding the two metal faces in contact. Radius of Curvature at Flow Entrance Halliburton conducted a study with various curvatures on the entrance to the valve. The study tested abrasive fluids flowing through different test subs and examined the resulting wear patterns. As a result, an optimum radius of curvature was determined and implemented on the valve housings of all wireline-retrievable safety valves. Applications » General production completions Features » Equalizing-type flapper closure » Solid construction flapper made from bar stock » Spherical radius seat on flapper improves seal reliability » Sealing and seating surfaces are out of the well production flow path when valve is in the open position *information referenced from supplier catalog.