Cameron ram-type blowout preventer

[1][2][4] While drilling an oil or gas well, the top of the wellbore is lined with a casing.

This has caused spills of large quantities of oil and fires on drilling rigs.

This resulted in the first ram-type blowout preventer, which they called the MO BOP.

[1][2][4] Cameron Iron Works successfully marketed their blowout preventer and developed other tools for petroleum exploration.

Then wrenches are used to manually close the rams around the drill string to seal the wellbore.

[3] The MO BOP was tested to withstand 3,000 pounds per square inch (21,000 kPa).