Blowout Preventers (BOPs) are safety devices used to "prevent" the uncontrolled flow of liquids and gases during well drilling operations. Blowout preventers are large, high-pressure valves that are capable of being remotely controlled. When the driller closes the valve, a pressure-tight seal is formed at the top of the well, preventing the fluids from escaping. There are two major types of Blowout Preventers, Annular (also known as Spherical) and RAM. Annular BOPs are usually mounted to the very top of the BOP stack. The drilling crew then mounts two, three, or four RAM BOPs below the Annular preventer. If a kick is detected, the annular is usually closed first and then the RAM is used as a backup if the Annular should fail.

National Oilwell Varco's Pressure Control Group has more than 80 years of experience in building BOPs to meet the changing demands of the petroleum industry. National Oilwell Varco offers a wide range of RAM BOPs to fit your drilling needs. The various models vary by size, features, and pressure ratings. The following RAM BOP models are currently offered: