Oil well blowout preventer - actuated by two piston rods on plastic ring seals with anti extrusion plates

摘要

A blow-out preventer for oil well heads is actuated by two cylinders with pistons, piston rods and seal carriers. An elastic seal is fitted with anti-extrusion plates at the joint of one semicircular carrier to the next. Inner elastic seals are housed with an upper and a lower anti-extrusion device which prevent extrusion of the seals when the pistons are moved inwards to effect a seal around a drill tube. Device is suitable for well pressures 700 kgf/cm2. It automatically adapts itself to the varying dia. of the tube against which it has to seal.