The ''blowout preventors (BOPs)'' are the major component of the control system on a rig, and they are the last line of defence against a blowout. The BOPs are bolted to the wellhead and are not removed until the well is completed and production equipment is installed. BOPs usually have at least four sections: | The ''blowout preventors (BOPs)'' are the major component of the control system on a rig, and they are the last line of defence against a blowout. The BOPs are bolted to the wellhead and are not removed until the well is completed and production equipment is installed. BOPs usually have at least four sections: |