US Patent 7644767 Safety valve with flapper/flow tube friction reducer

A safety valve with a flapper/flow tube friction reducer. A safety valve for use in a subterranean well includes a closure assembly, an operating member which engages the closure assembly, and at least one of the closure assembly and the operating member including a friction reducing device which provides rolling contact between the closure assembly and the operating member. Another safety valve includes a flapper which rotates about a pivot relative to a seat, a flow tube which engages the flapper to rotate the flapper, and a friction reducing device which with rolling contact biases the flow tube toward the pivot when the flow tube engages the flapper. Yet another safety valve is described in which at least one of the flapper, the seat and the flow tube has a friction reducing device attached thereto which provides rolling contact between the flapper and the flow tube, or between the flow tube and the seat.