Abstract: An erosion resistant control valve or adjustable choke has a body with a side inlet, an end outlet and a conical valve seat in alignment with the outlet. Downstream from the valve seat are a converging passage having a smaller taper than the valve seat, a cylindrical passage and a diverging passage. A stem aligned with the seat assembly includes a plug having a tapered seal surface near its upstream end for engaging the valve seat and a converging control surface downstream therefrom with the same taper as the converging passage. The smaller end of the control surface is in the cylindrical passage when the valve is closed and in the converging passage is fully open for localizing erosion downstream from the valve seat. A bleed passage relieves pressure from within the valve before the valve bonnet can be removed. The valve can be locked in a selected control setting by a split ring engaging the stem.