Stripper blow out preventer for small diameter oil field tubing or small diameter polished rods

摘要

A stripper blow out preventer for oil field equipment, wherein the stripper blow out preventer can include a housing with a bore. The housing can have an open port and close port for accepting the hydraulic fluid, and a grease port for accepting grease. An annular recess of the housing can be in communication with the bore. A retainer ring can be engaged in the annular recess. A piston can be disposed in the annular recess. A seal element can be disposed in the annular recess between the retainer ring and the piston, and can have a thru bore. An insert can be engaged with the retainer ring. When the close port is pressurized, the piston can press against the seal element to form a seal against the oil field equipment. When the open port is pressurized, the piston can move to relax the seal element.