Safety valve in lower end of tube string of oil or gas prodn. well - has tubular housing with upward tapering bore portion and ball supported below it lifted by excessive prod. flow to lodge in taper bore

摘要

The safety valve (3) is intended for use in a tube string (2) in the bore hole (1) of a producing oil or gas well to shut-off the flow (A,B) when the flow velocity and possibly the density of the product reaches a predetermined maximum. It comprises a tubular housing (4) with internal diameter reducing conically (11) in upward direction from a given level and near its lower end containing a seat (pins 7) to support a ball (8) at at least three circumferentially spaced points. The diameter of the ball exceeds that measured at a given level (11') in the conical construction.